Safety, Efficacy, and Immunogenicity of a Novel IgG Degrading Enzyme (KJ103): Results from Two Randomised, Blinded, Phase 1 Clinical Trials

Safety, Efficacy, and Immunogenicity of a Novel IgG Degrading Enzyme (KJ103): Results from Two Randomised, Blinded, Phase 1 Clinical Trials | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Safety, Efficacy, and Immunogenicity of a Novel IgG Degrading Enzyme (KJ103): Results from Two Randomised, Blinded, Phase 1 Clinical Trials Yanjun Liu, Mengdie Cao, Rohit Katial, Zheng Wang, Xiaoyu Lu, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4374237/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Jan, 2025 Read the published version in Gene Therapy → Version 1 posted 11 You are reading this latest preprint version Abstract The approved recombinant adeno-associated virus (AAV) intravenous drugs are limited by the high prevalence of pre-existing anti-AAV antibodies in the general population, which are known to restrict patients’ ability to receive gene therapy and limit transfection efficacy in vivo. Based on that, we developed a novel and low immunogenicity recombinant human immunoglobulin G degrading enzyme (KJ103), which has clinical value in removing anti- AAV antibodies in vivo gene transfer. Herein, we performed two randomized, blinded, placebo-controlled, single ascending dose phase I studies in China and New Zealand, to evaluate pharmacokinetics, pharmacodynamics, safety and immunogenicity of KJ103 in healthy participants. The results comfirmed that KJ103 rapidly reduced IgG and maintained low levels for 1 week. The 0.01 to 0.40 mg/kg dose range of KJ103 had a favorable safety and tolerability profile in healthy participants of different ethnic and gender groups. KJ103 has low percentage of pre-existing ADAs compared to currently licensed human IgG degrading enzyme (i.e. IdeS), and the induced ADAs mostly return to baseline six months after administration. These characteristics are well suited for the treatment of immune disorders, immune rejection, and immunotherapy where pre-existing antibodies reduce efficacy (e.g. AAV-mediated gene therapy in individuals positive for pre-existing anti-AAV antibodies). The potential of KJ103 warrants further exploration. Health sciences/Diseases/Immunological disorders Biological sciences/Drug discovery/Drug delivery Biological sciences/Immunology/Autoimmunity Recombinant human IgG degrading enzyme AAV-mediated gene therapy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction Immunoglobulin G (IgG) is an abundant protein in human serum, accounting for approximately 10–20% of plasma proteins[ 1 ]. IgG is essential for normal immune functioning in the body[ 2 ]. IgG antibodies against viruses and bacteria are present in the body after infection or vaccination, but can also form against human antigens (e.g., blood group antibodies, anti-HLA antibodies, tissue autoantibodies, etc.) as a result of blood transfusions, pregnancy, or for unknown reasons[ 3 ]. Such antibodies are usually harmless, but can sometimes impede the implementation of modern treatment techniques. A well-established example of this situation can be found in organ transplantation, where donor-specific alloantibody (DSA) positivity is a contraindication to conventional kidney transplantation[ 3 ]. A more recent and novel example concerns adeno-associated virus (AAV) capsids for intravenous delivery gene therapy. The three approved recombinant AAV intravenous drugs (Roctavian[ 4 ], Hemgenix[ 5 ] and Elevidys[ 6 ]) are limited by the high prevalence of pre-existing anti-AAV antibodies in the general population, which are known to limit transfection efficacy in vivo, thereby restricting the number of patients that can receive the gene therapy using this vector [ 7 , 8 ]. In recent years, the IgG degrading enzyme imlifidase (IdeS) has been used for conditions where pre-existing antibodies need to be depleted, making a breakthrough in renal transplantation medicine for patients with DSA-positive renal failure[ 9 ]. However, IdeS is derived from Streptococcus pyogenes , and most humans have been infected with this bacterium, resulting in over 90% of individuals harboring antibodies against IdeS. A study that screened 130 participants found that only 10 of them had anti-IdeS antibody concentrations below the detection limit (2.0 mg/L). The median level of pre-existing anti-IdeS antibodies was 6.1 mg/L (range 2.0–78.0 mg/L), and the 80th percentile was 15mg/L[ 10 ]. These anti-IdeS antibodies may increase the risk of hypersensitivity/infusion-related reactions against IdeS[ 11 , 12 ]. Moreover, there is evidence that neutralizing antibodies are able to weaken the activity of IdeS[ 10 , 13 ]. The presence and extent of pre-existing antibodies to Streptococcus pyogenes therefore limits the application of IdeS. To minimize such risk from pre-existing antibodies, we developed a novel lgG degrading enzyme, named KJ103. KJ103 is modified from IgG endopeptidase of Streptococcus equi ( S. equi ), an equine host-adapted pathogenic bacterium that typically does not infect humans[ 14 ]. The results of in vitro studies have proved that KJ103 can efficiently cleave human IgG in the hinge region, and the results from animal studies indicated that KJ103 has a good safety and efficacy profile (unpublished data). KJ103 is expected to be a potential agent for desensitization of all IgG subclasses. To further assess KJ103, Phase I studies were conducted in healthy participants in both China and New Zealand. These studies were necessary to support KJ103 through to further clinical trials to determine efficacy in clinical applications. Materials and Methods Study design Two randomized, blinded, placebo-controlled, single ascending-dose phase I studies were conducted independently in China (Identifier: NO. ChiCTR2300075920) and New Zealand (Identifier: NO. NCT05274659) using a similar design. The studies aimed to evaluate the safety, tolerability, pharmacokinetic profile, pharmacodynamic profile, and immunogenicity of KJ103 in healthy participants. The study protocols and all amendments were approved by the local Ethics Committee of each center (Suzhou Municipal Hospital, New Zealand Clinical Research), and the studies were conducted in compliance with the Declaration of Helsinki and the international standards of Good Clinical Practice. Written informed consent was obtained from all participants prior to any study-related procedures. The studies were reported according to the 2022 update to the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement. Five dose levels were chosen to explore the safety and tolerability of KJ103, ranging from 0.01-0.40mg/kg using participants actual body weight (Table 1). The first 0.01 mg/kg group enrolled 2 participants to receive KJ103. The remaining groups enrolled 8 participants, with 6 participants randomly allocated by computer to receive KJ103 and 2 participants allocated to receive placebo. Sentinel dosing was employed (except the first dose level), in which two participants were dosed with KJ103 or placebo on Day 1 in order to monitor potential acute reactions. The remaining 6 participants dosed ≥ 24 hours after the sentinel dose, once the Investigator completed the safety assessment of the first two participants. Patients were followed-up for a total of 2 months after dosing. The safety and tolerability were observed during the dose-limiting toxicity (DLT) observation period. The DLT observation period in China was 7 days, while in New Zealand it was 14 days. If none of the participants experienced an event meeting the dose escalation termination criteria (≥ grade 3), the study proceeded to the next dose level. A safety review committee was set with the responsibility to make decisions on whether to proceed to the next dose level through obtained PK, PD and safety data once the DLT observation period finished in each group. Participants In these studies, eligible participants were selected according to the major inclusion criteria: healthy male or female participants aged between 18 to 55 years; body mass index (BMI) between 18 and 30 kg/m². The participants were excluded according to the following criteria: clinically significant immunodeficiency (including but not limited to immunoglobulin A deficiency); history of tuberculosis; positive screening for HBcAb, HCV antibodies, HIV antibodies, and syphilis antibodies; allergy to KJ103 or its excipients; participation in other clinical trials; pregnant or nursing women; blood loss or donation of > 400 mL in the 3 months before enrollment; alcohol or drug abuse; clinically significant abnormalities in vital signs, 12-lead electrocardiogram (ECG) or laboratory tests. To mitigate the increased risk of opportunistic infection post-KJ103 administration, all participants received prophylactic antibiotics starting on the day of administration and continuing until Day 28 or until IgG levels were at least 6.0 g/L. If grade 2 or higher infusion-related reactions occurred in the first two dose groups, participants in the 3/4/5 dose group would receive preventive medications for infusion-related reactions (e.g., glucocorticoids or antihistamines) as needed. Assessment of Safety All adverse events that emerged during the studies were assessed and graded according to the National Cancer Institute Common Standard Terminology for Adverse Events (NCI-CTCAE), version 5.0. Parameters included in evaluations were vital signs, physical examinations, 12-ECG, clinical laboratory tests (hematology, urinalysis, biochemistry, coagulation function, etc.), clinical adverse and serious adverse events (AEs, SAEs). Pharmacokinetics Blood samples were collected at the predetermined time points for PK evaluation. For Cohorts 1 and 2, blood samples were taken at pre-dose, 1 minute before infusion completion, and at the exit visit. For Cohorts 3–5, blood samples were taken at pre-dose, 1 minute before infusion completion, 5 minutes, 45 minutes, 6 hours, 24 hours, 48 hours, 72 hours, and 144 hours after infusion and at study termination in cases of early withdrawal. Plasma KJ103 levels were measured using a validated enzyme-linked immunosorbent assay (ELISA) method at JOINN Laboratories (Beijing,China). Single-dose PK parameters of KJ103 were estimated using non-compartmental analysis, including C max , T max , AUC 0-t , AUC 0-∞ , λ z , t 1/2 , MRT 0-∞ , CL, and V z . Concentration data were tabulated, and descriptive statistics were performed for grouped planned blood sampling times. The average plasma concentration-time curves of the participants in different dose groups (0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg) were plotted. Pharmacodynamics For the purpose of pharmacodynamic assessment, blood samples were obtained according to the following schedule. For Cohort 1, samples were collected at pre-dose, 6 hours after the infusion, and at the exit visit. For Cohorts 2–5, samples were collected at pre-dose, 1 minute before infusion completion, 5 minutes, 20 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 3 hours, 6 hours, 24 hours, 48 hours, 72 hours, 144 hours, Days 14, 21, 28, and 63 after infusion and at study termination in cases of early withdrawal. Plasma IgG levels of the participants were measured by ELISA at JOINN Laboratories (Beijing,China), with the lower limit of ELISA detection being 0.40 g/L. The levels of single-chain IgG molecules (scIgG), F (ab') 2 and Fc were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) at JOINN Laboratories (Beijing,China). Population Pharmacokinetic Model and PK/PD Models The estimation method for population pharmacokinetic (PopPK) modeling was the first-order conditional estimation method (FOCEI) considering the η-ε interaction. The inter-individual variability( IIV) was modeled as an exponential model (Eq. 1): $${P}_{i}={P}_{TV}\times exp\left({\eta }_{i}\right)$$ (1) where P TV is the typical value of the PK parameter, P i is the individual parameter value, and η i is the inter-individual variation for P TV with a normal distribution of mean of 0 and variance of ω 2 . The following models, additive (Eq. 2), proportional (Eq. 3) and combined additive and proportional (Eq. 4) and logarithmic (Eq. 5) model, were investigated for residual variability (RV): \({Y}_{obs.ij}={Y}_{pred.ij}+{\epsilon }_{ij.1}\) (2) \({Y}_{obs.ij}={Y}_{pred.ij}\times (1+{\epsilon }_{ij.1})\) (3) \({Y}_{obs.ij}={Y}_{pred.ij}\times （1+{\epsilon }_{ij.1}）+{\epsilon }_{ij.2}\) (4) \({Y}_{obs.ij}=\text{L}\text{O}\text{G}\left({\text{Y}}_{\text{p}\text{r}\text{e}\text{d}.\text{i}\text{j}}\right)+{{\epsilon }}_{\text{i}\text{j}.1}\) (5) where Y obs,ij and Y pred,ij are the observed and predicted concentrations in i th participant and at j th sampling time point, respectively. ε ij,1 and ε ij,2 are normal distributions with mean of 0 and variances of σ ij,1 2 and σ ij,2 2 , respectively. Covariates included gender, age, ethnicity, body weight, body mass index, baseline alanine transaminase (ALT), post-administration anti-drug antibody (ADA), baseline IgG, were assessed by step-wise forward (P < 0.05) selection and backward elimination (P < 0.001). The PopPK models were evaluated by goodness-of-fit plots, visual predictive checks and bootstrap resampling procedures. IgG level was selected as the effect index for exposure-response (E-R) analysis of KJ103. Individual participant KJ103 blood concentration data was obtained using a Bayesian posterior estimation method through the final PopPK model. The PK/PD model of KJ103 concentration and IgG level was explored through an effect-compartment model or an indirect response model. The covariate screening method and model evaluation method are the same as PopPK. Immunogenicity Blood samples were collected at the following time points for ADA assessment: pre-dose, 24 hours, 48 hours, 72 hours, 144 hours, Days 14, 21, 28, 63, and Day 180 post-infusion and in cases of early withdrawal. Anti-KJ103 antibody in human serum were measured using a validated bridging ELISA method at JOINN Laboratories (Beijing,China). Statistical Analysis All statistical analyses were performed using SAS 9.4 except for the calculation of PK parameters which were made using Phoenix WinNonlin 8.2. Enumeration data and grade data were described by the number of cases and percentage. NONMEM (Version 7.5) and its tool software Wings for NONMEM (nm753) and Perl Speaks NONMEM (Version 5.3.0) were used to build models and simulations. R (Version 4.1.2) was used for collating and analyzing data sets, statistical analyses, modeling, mapping, and construction of virtual populations. Results Demographic Characteristics In these two independent, but similarly designed studies, a total of 68 healthy participants (China n = 34; New Zealand n = 34) were included. In the study conducted in China, 100% of the participants were of Asian ethnicity and males accounted for 85.3% of participants. In the New Zealand study, most of the participants were Caucasian (58.8%), and females accounted for 79.4.% of all trial participants. With the exception of sex and ethnicity, all other baseline characteristics were similar between both studies. (Table 2) Safety and Tolerability Of the total 68 participants across both studies, 52 received KJ103 and the remainder placebo. During the study, there were no DLTs or SAEs, and no treatment-emergent adverse events (TEAEs) or treatment-related adverse events (TRAEs) leading to study termination. All the predicted dose levels were escalated steadily and all participants received the proposed dose with one exception. One participant in New Zealand, receiving 0.40mg/kg, experienced a self-limited infusion reaction leading to early termination of infusion, attributable to the protocol deviation of no pre-medication. A total of 27 participants (79.4%) experienced 44 TEAEs in the Chinese study. 23 participants’ TEAEs (23/34, 67.6%) were grade 1, with fewer cases (4/34, 11.8%) being grade 2, and none grade 3 or above. A total of 9 participants (9/34, 26.5%) had 11 TRAEs in this study. Most of them (8/34, 23.5%) were grade 1, and only 1 participant (1/34, 2.9%) had a grade 2 TRAE (decreased lymphocyte count). No participants in the 0.40 mg/kg group experienced TRAE. A total of 30 participants (88.2%) experienced 79 TEAEs in the New Zealand study. 26 (26/34, 76.5%) participants’ TEAEs were grade 1; 2 cases (2/34, 5.9%) were grade 2, and 2 participants (2/34, 5.9%) had a grade 3 AE (one participant at 0.04 mg/kg developed dental caries that was assessed as unlikely to be related to the test drug, and another participant at 0.40 mg/kg developed deranged liver blood tests that were assessed as probably related to the test drug, both of whom recovered). A total of 8 participants (8/34, 23.5%) reported 8 cases of TRAEs. Combining the above results, 19 AEs observed in 17 of the 68 participants were classified as related (i.e. possible, probable or definite), as presented in Table 3. The most common AE related to KJ103 was elevated alanine aminotransferase (ALT). The primary concern with lgG degradation enzymes is the risk of infection, and in this regard, the following results demonstrate its safety. One case of grade 1 infectious illness (suspected bacterial infection) occurred in the 0.25 mg/kg group in China, and was determined by the Investigator as probably related to KJ103. One case of grade 1 vulvovaginal candidiasis occurred in the 0.25 mg/kg group in New Zealand, and was determined possibly related to KJ103. There were no severe infection events related to KJ103 (Table 3). Pharmacodynamics Compared to the placebo, IgG showed mild degradation at dose of 0.01 mg/kg of KJ103. With increasing dose, a sharper “drop off” of IgG level was observed in a dose-dependent manner. A greater reduction in IgG after administration of KJ103 at a dose of 0.12 mg/kg to Asian participants in both studies. In both the 0.25 mg/kg and 0.40 mg/kg group, IgG levels reached their lowest point within 6 hours of dose administration, falling by over 90%, and remained consistently below 70% of normal levels for the first week after dosing. After the initial fallward, IgG levels gradually increased after one week of administration. IgG recovered to near or above baseline levels within 1 to 2 months post-dose in most patients. It is worth noting that dose levels of KJ103 did not affect the rate and extent of IgG recovery, only the initial “drop off”. These results indicate that the IgG changes related to dosing with KJ103 were consistent across different ethnicities and demonstrate a favorable pharmacological effect (Fig. 1 ) . Exploratory Pharmacodynamics Analysis Based on the mechanism of action of KJ103, the digested fragments of scIgG, F (ab') 2 and Fc were also analyzed by SDS-PAGE. SDS-PAGE results were consistent with ELISA findings. Compared with the placebo group, in which there was no change, all the samples from KJ103 groups showed an increase in fragment concentration, rising in proportion to the corresponding decrease in intact IgG. All participants in the 0.04 mg/kg group and some participants in the 0.12 mg/kg group did not undergo complete IgG cleavage. Participants in the 0.25 mg/kg and 0.40 mg/kg groups experienced rapid, efficient, and complete cleavage of most IgG into F(ab') 2 and Fc fragments by KJ103 within 45 minutes − 6 hours and 20 minutes − 6 hours post-dosing, respectively. Combining the SDS-PAGE results, the IgG signal obtained 6 hours post-dosing by ELISA primarily originates from scIgG. F(ab') 2 and Fc fragments decreased to the baseline levels within 1 to 7 days after dosing. Within one to two weeks, all participants demonstrated newly synthesized complete IgG. Within 1 to 2 months post-dosing, IgG recovered to near or above baseline levels (Fig. 2 ) . Pharmacokinetics, PopPK, and PK/PD Models Pharmacokinetics After a single intravenous infusion of KJ103, the overall blood drug concentrations of participants in the 0.01 mg/kg and 0.04 mg/kg dose groups were below the detection limit, as a result of low exposure and therefore low blood concentration of the administered drug. Pharmacokinetic concentration results showed good reproducibility of PK curves in the dose range of 0.12 mg/kg to 0.40 mg/kg for all dose groups. The mean KJ103 concentration peaked immediately after administration, reaching the plateau phase during which the distribution and metabolism of the drug achieve equilibrium in the body, followed by slow elimination of the drug. Most of the KJ103 was eliminated within 24 hours after administration (Fig. 3 ). After a single intravenous infusion of KJ103 in Chinese participants, the median T max of 0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg dose groups were 0.333 hours, 0.333 hours and 0.583 hours, respectively. C max (Mean ± SD) were 2.208 ± 0.4985 mg/L, 5.142 ± 0.2922 mg/L and 9.200 ± 1.3049 mg/L, respectively. AUC 0-t (Mean ± SD) were 28.405 ± 29.6554 h*mg/L, 43.114 ± 21.7201 h*mg/L and 170.261 ± 176.5502 h*mg/L, respectively. After excluding abnormal PK data, the average t 1/2 of each dose group was 6.260 h, 4.862 h and 81.648 h, respectively. t 1/2 showed a non-linear increase with the increase of dose. After the New Zealand participants received a single intravenous infusion of KJ103, excluding the participant in the 0.40 mg/kg dose group who interrupted the dose due to an infusion reaction, the median T max of 0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg dose groups were 0.4583 hours, 0.3333 hours and 0.5833 hours, respectively. C max (Mean ± SD) were 2.8135 ± 0.5216 mg/L, 6.5245 ± 0.9994 mg/L and 10.0124 ± 2.6712 mg/L, respectively. AUC 0-t (Mean ± SD) were 45.2515 ± 47.9476 h*mg/L, 101.9423 ± 113.8636 h*mg/L and 61.9188 ± 29.7180 h*mg/L, respectively. After excluding abnormal PK data, the average t 1/2 of each dose group was 11.3978 hours, 2.2629 hours and 8.4130 hours, respectively (Table 4). Based on the analysis of pharmacokinetic parameters using a non-compartmental model, KJ103 exhibited characteristics of rapid distribution and slow elimination in healthy participants in China and New Zealand. The exposure of KJ103 in various dosage groups demonstrated a non-linear increase with dosage escalation. PopPK and PK/PD Models Based on clinical trial data from both studies, we established a KJ103 population pharmacokinetic (PopPK) model to explore the covariates affecting PopPK parameters. We found that only body weight affects the clearance of KJ103. For a participant with body weight at the 10th ~ 90th percentile of the study population relative to the median body weight in the study population, the C max and AUC 0 ~ 168 varied from − 29%~26%. Other covariates such as region and ethnicity did not impact PopPK parameters ( P > 0.05). The results also indicate similar PK characteristics of populations between China and New Zealand. The optimal PopPK model was a two-compartment model with first-order elimination. The population typical values (RSE%) of CL, V c , V p and Q were 0.162 L/h (13.6), 3.23 L/h (4.3), 14.2 L/h (18.5) and 0.591 L/h (5.0), respectively. The results of the prediction-corrected visual predictive check (pcVPC) are presented in Fig. 4 . The median, upper and lower 5th percentiles of the observed values were mostly contained within the 95% confidence intervals of the predicted values. Additionally, the predicted interval encompassed most of the observed values, indicating a good predictive performance of the model. A total of 48 participants were included in the pharmacokinetic/pharmacodynamic (PK/PD) analyses, using IgG levels as the effect indicator. Individual participants' KJ103 blood concentration data were obtained using the PopPK final model using Bayesian a posteriori estimation to explore the PK/PD model of KJ103 concentration and IgG level. The relationship between KJ103 concentration and IgG level was described by an effector chamber model. The results revealed that IgG began to decline after the administration of KJ103 at a dose of 0.25 mg/kg, and was maintained near the nadir and close to the lower limit of detection after 5–19 hours. The IgG recovered to more than 1 g/L after 36 hours of administration, and more than 2 g/L after 96 hours, and stayed lower than 4 g/L for 7 days. Analyses of covariates showed that gender influenced the IC50(Concentration of KJ103 when IgG level reaches half of its maximum inhibitory effect), whereas different ethnicities had no effect on the PK/PD model. The results of the prediction-corrected visual predictive check (pcVPC) are presented in Fig. 5 . The median and upper and lower 5th percentiles of the observed values were mostly contained within the 95% confidence intervals of the predicted values. Additionally, the predicted interval encompassed most of the observed values, indicating a good predictive performance of the model. Simulation of IgG change levels after a single administration of 0.25 mg/kg in male and female typical healthy participants showed that the overall trend of IgG change in males and females was similar, with IgG starting to decline after administration, remaining near the trough value after 5–24 hours, and then recovering slowly (Fig. 6 ). However, the IgG trough value was 0.66 g/L higher in females than in males, and females recovered faster than males, although both sexes were lower than 5 g/L for 7 days. Simulating IgG trough levels after a single dose in the range of 0.01 to 0.40 mg/kg in healthy male participants shows that the IgG trough levels decrease with increasing dosage (Fig. 7 ). At 0.25 mg/kg of KJ103, enzymatic digestion of IgG is more than 90% effective and reaches a plateau. During the process of covariate selection, after statistical tests, we found that baseline IgG levels and gender affect the efficacy of KJ103 in reducing IgG levels, however the overall trend remained similar. The IgG levels at 0.25 mg/kg dosage remained at a low level within a week under various conditions. Immunogenicity The pre-existing antidrug antibody positivity rate for all enrolled participants was 33.82% (23/68), and the median value of pre-existing antibody titers was 0 (range: 0 to 1:429.61). There were no significant differences in the proportion and titer of pre-existing antibodies among participants of different ethnicities enrolled in China and New Zealand (Fig. 8 ). The low proportion of pre-existing anti-KJ103 antibodies in participants’ indicated that most of them had not developed these antibodies due to S. equi infection. The relatively low levels of anti-KJ103 support the safety of KJ103 administration. Only one participant from the 0.40 mg/kg group in New Zealand experienced an infusion reaction post-administration attributable to the failure to use prophylactic medication as per protocol. No infusion reactions occurred in the remaining participants from both studies. Among participants in the China cohort, the median baseline ADA value was 0 (titer range: 0 ~ 1: 429.61); on the 7th day after KJ103 administration, the median ADA titer was 0 (range: 0 ~ 1: 408.25); on day 14 post-dose, ADA levels were near peak, with a median ADA value of 1:1,041.97 (range: 0 to 1:144,433.38). Two months after administration, the median ADA titer for all KJ103 users was 1: 605.89 (range: 1: <10 ~ 1: 10,989.27). Six months after administration, the median ADA titer for all KJ103 users was 1:524.77 (range: 0 ~ 1: 4,921.42) (Table 5). In the New Zealand cohort, the median baseline ADA titer was 0 (range: 0 ~ 1: 242.58); on the 7th day after KJ103 administration, the median ADA titer was 0 (range: 0 ~ 1: 246.78); on day 14 post-dose, ADA levels were near peak, with a median ADA value of 1:257.50 (range 0, 1: 20,855.78). Subsequently, ADA levels gradually declined, and after two months of administration, the median ADA titer for all participants was 1: 158.64 (range: 0 ~ 1: 7171.39), and the median value of ADA titer at 6 months after administration was 1:214.35 (range: 0 ~ 1: 5,782.43) (Table 5).After 2 weeks and 2 months of KJ103 administration, Chinese participants showed a wider range of ADA titer change in the 0.25 mg/kg and 0.40 mg/kg dose groups than New Zealand participants. There were no significant differences in the median values and ranges of change in ADA titers among participants in the two countries in each of the dose groups prior to KJ103 administration, at 1 week and at 6 months after KJ103 administration. The majority of participants in the two studies showed ADA changes beginning on Day 14 after KJ103 administration, peaking at approximately two weeks and then gradually declining. After 6 months of KJ103 administration, 56.86% (29/51) of participants’ ADA were back to baseline levels (Fig. 9 ). Although there are significant individual differences in the development of immunogenic responses, in general, immunogenic responses appear to be dose-related. Discussion IgG‑degrading enzyme have made breakthroughs in the field of kidney transplantation. In vitro, IgG‑degrading enzyme inhibits HLA antibody-mediated NK cell activation and antibody-dependent cell-mediated cytotoxicity [ 15 ]. IgG‑degrading enzyme degrades also the IgG of the B cell Receptor (BCR), inhibiting BCR-mediated cell signal, transiently preventing memory B cell response to antigenic stimulation and their transition into antibody-producing cells [ 16 ]. DSA positive patients who have received IdeS can successfully undergo allogeneic kidney transplantation surgery, achieving higher kidney and patient survival rates [ 17 ]. The French consensus guidelines indicate that Imlifidase (IgG degrading enzyme) has been authorized for early use in highly sensitized adult kidney transplant candidates who are cross matched positive for ABO compatible deceased donors [ 18 ]. IgG‑degrading enzyme also demonstrate enormous therapeutic potential in the field of gene therapy. The most commonly used viral vectors for in vivo gene therapy are based on AAV, a non-enveloped single-stranded DNA virus. However neutralizing antibodies (NAbs) to AAV vectors are highly prevalent in humans, block liver transduction and vector readministration, thus representing a major limitation to in AAV-based in vivo gene therapy[ 19 ]. Evidence from ongoing clinical trials (ClinicalTrials.gov NCT03368742, NCT04281485, and NCT03882437) suggests that high doses of AAV significantly increase complement activation. Some participants in these studies presented with severe and life-threatening inflammatory responses that were likely secondary to the activation of the complement system [ 20 – 24 ]. In addition to nausea, fever, and vomiting likely due to cytokine release, participants presented with complement-mediated thrombotic microangiopathy (CM-TMA) [ 25 ], acute kidney injury due to atypical hemolytic uremic syndrome–like (aHUS-like) complement activation, thrombocytopenia, and immune-mediated myocardial injury[ 22 , 25 – 27 ]. Activation of complement is a major safety consideration for gene therapy, as growing evidence suggests that high-dose intravenous (i.v.) AAV infusion or high exposure to AAV empty capsids leads to antibody-dependent activation of the complement system in human plasma[ 28 ]. It was confirmed that IgG‑degrading enzyme reduced anti-AAV antibody levels from human plasma samples in vitro, including plasma from prospective gene therapy trial participants [ 29 ]. These results provide a potential solution to overcome NAbs to AAV-mediated gene therapy and inhibit antibody-dependent activation of the complement system. Based on the above mechanisms, KJ103 has the potential to alleviate the problem of inability to accept first and second treatment due to high anti-AAV antibody titers, improve gene transduction efficiency, and prevent treatment failure caused by complement mediated immune reactions after administration in the field of AAV-mediated gene therapy. Although degrading enzymes have shown excellent therapeutic potential in many therapeutic fields, the immunogenicity of biologicals in therapy cannot be ignored. Pre-existing anti-drug antibodies may increase the risk of infusion reactions and hypersensitivity reactions during intravenous delivery of biologicals[ 30 , 31 ]. The widespread presence of pre-existing anti-IdeS antibodies limits clinical applications of IdeS, and can potentially compromise drug efficacy[ 10 ]. During clinical studies, individuals with anti-IdeS IgG titers exceeding 15mg/L were excluded from the research, and therefore not all populations can receive IdeS treatment[ 10 ]. These shortcoming are illustrated by its use in intravenous administration for AAV gene therapy. Here, we report an IdeE(IgG‑degrading enzyme of S. equi ) variant of KJ103 with lgG-cleaving activity like that of ldeS. Our studies confirm that KJ103, a novel IgG-degrading enzyme derived from S. equi , exhibits a low positivity rate and low titers of pre-existing anti-KJ103 antibodies in the population. In clinical trials of IdeS, anti-IdeS antibodies were present in all participants at baseline, and participants experienced an increase in ADAs starting on day 7 of dosing. ADA levels then peaked at approximately 19.6 times baseline at about two weeks, and then declined progressively, reaching approximately 16.6 times baseline ADA concentrations after two months of dosing [10] . In comparison to ADA formation following IdeS administration, the pre-existing anti-KJ103 antibodies positivity rate for all enrolled participants was 33.82% (23/68), and the median value of pre-existing antibodies titers was 0 (range: 0 to 1:429.61). ADAs appeared and peaked at approximately two weeks after KJ103 administration, with a median ADA titre in positive participants that was 15.95 times that of the baseline positive participants, and then declined progressively, reaching a titre of approximately 5.35 times that of the baseline in positive participants after two months of dosing. The maximum dose of IdeS applied in humans was 0.25 mg/kg, whereas the maximum dose of KJ103 first applied in humans was 0.40 mg/kg dose, with an excellent safety and tolerability profile across all dose groups of KJ103. ADA emergence post-KJ103 administration occurred later than for IdeS, with lower titers and a shorter duration to return to baseline levels, highlighting the advantage of KJ103. Due to the low prevalence and low titers of pre-existing KJ103 antibodies in the population, it is possible to administer KJ103 twice in humans at 7-day intervals without significant safety concerns. Theoretically, this would enable the salvage of intravenously administered AAV-mediated gene therapy in individuals positive for pre-existing anti-AAV antibodies. This approach could potentially ensure the sustained maintenance of low IgG levels in the body, allow sufficient time for the clearance of degraded F(ab') 2 fragments and maintain low IgG levels by second administration of KJ103 at 3 ~ 7 days interval. Validation of this hypothesis was observed in an AAV gene therapy mouse model infused with human anti-AAV antibodies (IgG), where KJ103 protected AAV9-mediated luciferase delivery from the impact of human anti-AAV antibodies. KJ103 is therefore promising as means of overcoming limitations posed by pre-existing anti-AAV antibodies in the clinical application of AAV gene therapy. We observed no events meeting the dose-escalation termination criteria during the DLT observation period in all participants. Most TEAEs and TRAEs were graded as grade 1 or 2, with a few at grade 3. Safety profiles of TRAEs for KJ103 were overall comparable to IdeS [ 32 ]. No severe infection events occurred during either studies. KJ103 demonstrated excellent tolerability and safety. Post-administration, KJ103 exhibited a dose-dependent reduction in IgG levels in healthy participants. We observed a greater reduction in IgG after administration of KJ103 at a dose of 0.12 mg/kg to Asian participants in both studies. The average IgG levels for participants in China and New Zealand were 11.67g/L and 14.63g/L, respectively, while the average levels of pre-existing anti-KJ103 antibodies were not significantly different. Our PK/PD models indicated that gender influences efficacy. Men constituted 85.3% and 20.6% of participants in China and New Zealand, respectively; while Caucasians accounted for 0% and 58.8% in China and New Zealand, respectively. A meta-analysis involving 28 studies indicated that factors such as being Caucasian, smoking, or using corticosteroids tend to decrease IgG levels, whereas the use of probiotics, hypertension, or acute psychological stress tends to elevate IgG levels[ 33 ]. Overall, differences in pharmacodynamics between the 0.12 mg/kg group in the two trials were caused by differences in baseline IgG levels. We infer that these differences may be due to gender disparities, but we do not rule out racial differences.Additionally, utilizing the PopPK model, we simulated various gender and baseline IgG levels and found their impact on efficacy to be negligible at a 0.25 mg/kg dose. Both trials demonstrate exceptional safety, tolerability and IgG cleavage efficiency of KJ103. The 0.25 mg/kg dose of KJ103 efficiently, rapidly, and specifically enzymatically cleaved human IgG and maintained a low serum IgG level for 1 week. The promising safety and tolerability of KJ103 was indicated by several lines of evidence including low positive rates and low titers of pre-existing anti-KJ103 antibody in the population and a quick return of ADA to a basal level within 6 months in nearly half of the participants after KJ103 administration. The trials show that KJ103 avoids IdeS shortcomings, with a higher safe dose, wide safety window, low pre-existing antibody ratio and titre, and a broader application population. It is likely that patients would not need to screen for pre-existing antibody titres prior to KJ103 administration. The advantages mentioned above can be leveraged in multiple patient populations including those requiring kidney transplantation and the emerging applications of AAV gene therapy in patients with anti-AAV antibodies[ 34 ]. Declarations Ethical Approval Both phase 1 clinical trials of KJ103 were approved separately by the ethics committee of the “New Zealand Clinical Research”(Protocol no. SHBJ-2021-001) and “Suzhou Municipal Hospital” (Protocol no. SHBJ-2021-002). All subjects signed written informed consent before undergoing any study-specific procedures. Competing Interests ZW, ZZ,YL are employees of Shanghai Bao Pharmaceuticals Co., Ltd, and own stock/other equities. Other authors declare no competing interests. Funding Shanghai Bao Pharmaceuticals Co., Ltd. was the formal sponsor and funder of the clinical trial. Author Contributions MC, RK, ZW analyzed the data and wrote the article. XL, QG, CC, ZZ, YY, KL, MM, YL substantially implemented the survey and consolidated the data. All authors critically revised the article and approved the final manuscript. Acknowledgments The authors would like to thank XX of XX, for XX. The authors acknowledge the editorial assistance of XX. Data Availability Statement This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. References Vidarsson G, Dekkers G, Rispens T. IgG subclasses and allotypes: from structure to effector functions. Front Immunol. 2014;5:520. 10.3389/fimmu.2014.00520 . Kapur R, Einarsdottir HK, Vidarsson G. IgG-effector functions: the good, the bad and the ugly. Immunol Lett. 2014;160(2):139–44. 10.1016/j.imlet.2014.01.015 . Ciurea SO, Cao K, Fernandez-Vina M, Kongtim P, Malki MA, Fuchs E, et al. The European Society for Blood and Marrow Transplantation (EBMT) Consensus Guidelines for the Detection and Treatment of Donor-specific Anti-HLA Antibodies (DSA) in Haploidentical Hematopoietic Cell Transplantation. Bone Marrow Transpl. 2018;53(5):521–34. 10.1038/s41409-017-0062-8 . Blair HA. Valoctocogene Roxaparvovec: First Approval. Drugs. 2022;82(14):1505–10. 10.1007/s40265-022-01788-y . Heo YA. Etranacogene Dezaparvovec: First Approval. Drugs. 2023;83(4):347–52. 10.1007/s40265-023-01845-0 . Hoy SM. Delandistrogene Moxeparvovec: First Approval. Drugs. 2023;83(14):1323–9. 10.1007/s40265-023-01929-x . George LA, Ragni MV, Rasko JEJ, Raffini LJ, Samelson-Jones BJ, Ozelo M, et al. Long-Term Follow-Up of the First in Human Intravascular Delivery of AAV for Gene Transfer: AAV2-hFIX16 for Severe Hemophilia B. Mol Ther. 2020;28(9):2073–82. 10.1016/j.ymthe.2020.06.001 . Weber T. Anti-AAV Antibodies in AAV Gene Therapy: Current Challenges and Possible Solutions. Front Immunol. 2021;12:658399. 10.3389/fimmu.2021.658399 . Published 2021 Mar 17. Lonze BE, Tatapudi VS, Weldon EP, Min ES, Ali NM, Deterville CL, et al. IdeS (Imlifidase): A Novel Agent That Cleaves Human IgG and Permits Successful Kidney Transplantation Across High-strength Donor-specific Antibody. Ann Surg. 2018;268(3):488–96. 10.1097/SLA.0000000000002924 . Winstedt L, Järnum S, Nordahl EA, Olsson A, Runström A, Bockermann R, et al. Complete Removal of Extracellular IgG Antibodies in a Randomized Dose-Escalation Phase I Study with the Bacterial Enzyme IdeS–A Novel Therapeutic Opportunity. PLoS ONE. 2015;10(7):e0132011. 10.1371/journal.pone.0132011 . Vultaggio A, Perlato M, Nencini F, Vivarelli E, Maggi E, Matucci A. How to Prevent and Mitigate Hypersensitivity Reactions to Biologicals Induced by Anti-Drug Antibodies? Front Immunol. 2021;12:765747. 10.3389/fimmu.2021.765747 . McMaster M, Mohr K, Page A, Closmore A, Towne F, Brooks BD. Epitope characterization of anti-drug antibodies-a tool for discovery and health: an overview of the necessity of early epitope characterization to avoid anti-drug antibodies and promote patient health. Expert Opin Biol Ther. 2021;21(6):705–15. 10.1080/14712598.2021.1863942 . Akesson P, Moritz L, Truedsson M, Christensson B, von Pawel-Rammingen U. IdeS, a highly specific immunoglobulin G (IgG)-cleaving enzyme from Streptococcus pyogenes, is inhibited by specific IgG antibodies generated during infection. Infect Immun. 2006;74(1):497–503. 10.1128/IAI.74.1.497-503.2006 . Hulting G, Flock M, Frykberg L, Lannergård J, Flock JI, Guss B. Two novel IgG endopeptidases of Streptococcus equi. FEMS Microbiol Lett. 2009;298(1):44–50. 10.1111/j.1574-6968.2009.01698.x . Ge S, Chu M, Choi J, Louie S, Vo A, Jordan SC, et al. Imlifidase Inhibits HLA Antibody-mediated NK Cell Activation and Antibody-dependent Cell-mediated Cytotoxicity (ADCC) In Vitro. Transplantation. 2020;104(8):1574–9. 10.1097/TP.0000000000003023 . Järnum S, Bockermann R, Runström A, Winstedt L, Kjellman C. The Bacterial Enzyme IdeS Cleaves the IgG-Type of B Cell Receptor (BCR), Abolishes BCR-Mediated Cell Signaling, and Inhibits Memory B Cell Activation. J Immunol. 2015;195(12):5592–601. 10.4049/jimmunol.1501929 . Jordan SC, Legendre C, Desai NM, Lorant T, Bengtsson M, Lonze BE, et al. Imlifidase Desensitization in Crossmatch-positive, Highly Sensitized Kidney Transplant Recipients: Results of an International Phase 2 Trial (Highdes). Transplantation. 2021;105(8):1808–17. 10.1097/TP.0000000000003496 . Couzi L, Malvezzi P, Amrouche L, Anglicheau D, Blancho G, Caillard S, et al. Imlifidase for Kidney Transplantation of Highly Sensitized Patients With a Positive Crossmatch: The French Consensus Guidelines. Transpl Int. 2023;36:11244. 10.3389/ti.2023.11244 . Published 2023 Jun 28. Earley J, Piletska E, Ronzitti G, Piletsky S. Evading and overcoming AAV neutralization in gene therapy. Trends Biotechnol. 2023;41(6):836–45. 10.1016/j.tibtech.2022.11.006 . Solid Biosciences. Solid Biosciences Provides SGT-001 Program Update. https://www.solidbio.com/about/media/press-releases/solid-biosciences-provides-sgt-001-program-update Updated November 12, 2019. Accessed November 1, 2023. Pfizer. Pfizer’s New Phase 1b Results of Gene Therapy in Ambulatory Boys with Duchenne Muscular Dystrophy (dmd) Support Advancement into Pivotal Phase 3. https://www.pfizer.com/news/press-release/press-release-detail/pfizers-new-phase-1b-results-gene-therapy-ambulatory-boys Updated May 15, 2020. Accessed November 2, 2023. Chand DH, Zaidman C, Arya K, Millner R, Farrar MA, Mackie FE, et al. Thrombotic Microangiopathy Following Onasemnogene Abeparvovec for Spinal Muscular Atrophy: A Case Series. J Pediatr. 2021;231:265–8. 10.1016/j.jpeds.2020.11.054 . Rocket Pharmaceuticals. Rocket Pharmaceuticals Announces Positive Gene Expression, Clinical BiomarkerPreliminary Functional Data from Phase 1 Trial of RP-A501 for the Treatment of Danon Disease. https://ir.rocketpharma.com/news-releases/news-release-details/rocket-pharmaceuticals-announces-positive-gene-expression Updated December 8, 2020. Accessed November 1, 2023. Guillou J, de Pellegars A, Porcheret F, Frémeaux-Bacchi V, Allain-Launay E, Debord C, et al. Fatal thrombotic microangiopathy case following adeno-associated viral SMN gene therapy. Blood Adv. 2022;6(14):4266–70. 10.1182/bloodadvances.2021006419 . George JN, Nester CM. Diagnostic approach to suspected TTP, HUS, or other thrombotic microangiopathy (TMA). https://www.uptodate.com/contents/diagnostic-approach-to-suspected-ttp-hus-or-other-thrombotic-microangiopathy-tma Updated July 11, 2023. Accessed November 1, 2023. Friese J, Geitmann S, Holzwarth D, Müller N, Sassen R, Baur U, et al. Safety Monitoring of Gene Therapy for Spinal Muscular Atrophy with Onasemnogene Abeparvovec -A Single Centre Experience. J Neuromuscul Dis. 2021;8(2):209–16. 10.3233/JND-200593 . Day JW, Mendell JR, Mercuri E, Finkel RS, Strauss KA, Kleyn A et al. Clinical Trial and Postmarketing Safety of Onasemnogene Abeparvovec Therapy [published correction appears in Drug Saf. 2022;45(2):191–192]. Drug Saf. 2021;44(10):1109–1119. 10.1007/s40264-021-01107-6 . Loo L, Harris S, Milton M, Meena, Lembke W, Berisha F, et al. 2021 White Paper on Recent Issues in Bioanalysis: TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparability & Cut Point Appropriateness (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccine Assays; Immunogenicity of Biotherapeutics and Novel Modalities; Integrated Summary of Immunogenicity Harmonization). Bioanalysis. 2022;14(11):737–93. 10.4155/bio-2022-0081 . Leborgne C, Barbon E, Alexander JM, Hanby H, Delignat S, Cohen DM, et al. IgG-cleaving endopeptidase enables in vivo gene therapy in the presence of anti-AAV neutralizing antibodies. Nat Med. 2020;26(7):1096–101. 10.1038/s41591-020-0911-7 . Trifirò G, Marcianò I, Ingrasciotta Y. Interchangeability of biosimilar and biological reference product: updated regulatory positions and pre- and post-marketing evidence. Expert Opin Biol Ther. 2018;18(3):309–15. 10.1080/14712598.2018.1410134 . Ingrasciotta Y, Cutroneo PM, Marcianò I, Giezen T, Atzeni F, Trifirò G. Safety of Biologics, Including Biosimilars: Perspectives on Current Status and Future Direction. Drug Saf. 2018;41(11):1013–22. 10.1007/s40264-018-0684-9 . Idefirix®, SUMMARY OF PRODUCT CHARACTERISTICS. https://www.ema.europa.eu/en/documents/product-information/idefirix-epar-product-information_en.pdf . Khan SR, van der Burgh AC, Peeters RP, van Hagen PM, Dalm VASH, Chaker L. Determinants of Serum Immunoglobulin Levels: A Systematic Review and Meta-Analysis. Front Immunol. 2021;12:664526. 10.3389/fimmu.2021.664526 . Published 2021 Apr 7. Pupo A, Fernández A, Low SH, François A, Suárez-Amarán L, Samulski RJ. AAV vectors: The Rubik's cube of human gene therapy. Mol Ther. 2022;30(12):3515–41. 10.1016/j.ymthe.2022.09.015 . Tables Tables 1 to 5 are available in the Supplementary Files section. Additional Declarations Yes there is potential conflict of interest. ZW, ZZ, YL are employees of Shanghai Bao Pharmaceuticals Co., Ltd, and own stock/other equities. Other authors declare no competing interests. Supplementary Files Table15.xlsx Table 1-5 Cite Share Download PDF Status: Published Journal Publication published 18 Jan, 2025 Read the published version in Gene Therapy → Version 1 posted Editorial decision: revise 06 Jun, 2024 Review # 2 received at journal 06 Jun, 2024 Review # 3 received at journal 03 Jun, 2024 Review # 1 received at journal 24 May, 2024 Reviewer # 3 agreed at journal 20 May, 2024 Reviewer # 2 agreed at journal 17 May, 2024 Reviewer # 1 agreed at journal 15 May, 2024 Reviewers invited by journal 15 May, 2024 Editor assigned by journal 07 May, 2024 Submission checks completed at journal 07 May, 2024 First submitted to journal 06 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4374237","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":299685381,"identity":"f88ab9da-5446-437e-873a-2cb24c22d655","order_by":0,"name":"Yanjun Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/ElEQVRIiWNgGAWjYJACAyCWYWNgPgbiJBCthYeNgS2NeC0gwANEZsRpMTh+9kAx7w4GHj6JnG8PflTcyeOffTrxA0ONTTROLWfyEox5zwAdJpG73bDnzLNiiXO5myUYjqXlNuDSciDHwJi3DaxlmwRv2+HEhjO8GyQYGw7j1nL+DUxLzjPJv0At88/wbv6BV8sNuC05bNIgWzac4d2G1xbJG28MDOe2SfCw8TwzN5Y58yxxI1CLRQIev/CdzzEzeNtmIyffnvzs4ZuKO4nzgA678aHGBqcWhQMMbMColIDxD0CoBBzKQUC+gYH5ARL/AB61o2AUjIJRMFIBAKI7WeTI1dkKAAAAAElFTkSuQmCC","orcid":"","institution":"Shanghai Bao Pharmaceuticals Co., Ltd.","correspondingAuthor":true,"prefix":"","firstName":"Yanjun","middleName":"","lastName":"Liu","suffix":""},{"id":299685384,"identity":"d44c1e08-bbe2-482b-a73d-a6000ede5ae0","order_by":1,"name":"Mengdie Cao","email":"","orcid":"","institution":"Suzhou Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mengdie","middleName":"","lastName":"Cao","suffix":""},{"id":299685387,"identity":"c6116949-f96f-4489-9726-8768e7e2d3e8","order_by":2,"name":"Rohit Katial","email":"","orcid":"","institution":"New Zealand Clinical Research","correspondingAuthor":false,"prefix":"","firstName":"Rohit","middleName":"","lastName":"Katial","suffix":""},{"id":299685389,"identity":"a5476d32-1541-4c64-a288-e7d2a49588d7","order_by":3,"name":"Zheng Wang","email":"","orcid":"","institution":"Shanghai Bao Pharmaceuticals Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Zheng","middleName":"","lastName":"Wang","suffix":""},{"id":299685391,"identity":"d09ced2e-115b-4792-a7fe-e6c394412373","order_by":4,"name":"Xiaoyu Lu","email":"","orcid":"","institution":"Suzhou Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaoyu","middleName":"","lastName":"Lu","suffix":""},{"id":299685393,"identity":"f1cb249b-e545-4a53-9f83-d80a84987975","order_by":5,"name":"Qin Gu","email":"","orcid":"","institution":"Suzhou Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Qin","middleName":"","lastName":"Gu","suffix":""},{"id":299685395,"identity":"dd2a77fc-2ae7-46c5-ba65-fc9496cdb11d","order_by":6,"name":"Chen Chen","email":"","orcid":"","institution":"Suzhou Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chen","middleName":"","lastName":"Chen","suffix":""},{"id":299685397,"identity":"3f167d48-e5c0-41ce-ac57-cce7a49c3980","order_by":7,"name":"Katie Liu","email":"","orcid":"","institution":"New Zealand Clinical Research","correspondingAuthor":false,"prefix":"","firstName":"Katie","middleName":"","lastName":"Liu","suffix":""},{"id":299685400,"identity":"a9b110fb-ac0a-477c-be51-81758dad88b7","order_by":8,"name":"Zhen Zhu","email":"","orcid":"","institution":"Shanghai Bao Pharmaceuticals Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Zhu","suffix":""},{"id":299685403,"identity":"1c0548c1-4a60-42d7-bffd-1162d9cc81c3","order_by":9,"name":"Mark Marshall","email":"","orcid":"","institution":"Tauranga Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mark","middleName":"","lastName":"Marshall","suffix":""},{"id":299685406,"identity":"042c93ac-8671-495b-853b-5fc620513a9a","order_by":10,"name":"Yanxia Yu","email":"","orcid":"","institution":"Suzhou Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yanxia","middleName":"","lastName":"Yu","suffix":""}],"badges":[],"createdAt":"2024-05-06 05:35:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4374237/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4374237/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41434-025-00512-1","type":"published","date":"2025-01-18T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":57445201,"identity":"77362790-7ee6-4585-90d1-c205577d86fc","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":67346,"visible":true,"origin":"","legend":"\u003cp\u003eQuantitative pharmacodynamics analysis by ELISA showed rapid degradation of IgG (Dose group 3-5)\u003c/p\u003e\n\u003cp\u003eA: Mean IgG values for each dose group at each visit within 48 hours after dosing in China. B: Mean IgG values for each dose group at each visit within 48 hours after dosing in New Zealand. C: Mean IgG values for each dose at each visit within D63 after dosing in China. D: Mean IgG values for each dose at each visit within D63 after dosing in New Zealand. E: Mean IgG values for 0.25mg/kg dose group at each visit within D63 after dosing. F: Mean IgG values for 0.40mg/kg dose group at each visit within D63 after dosing.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/929e5620a3c574285152f341.png"},{"id":57445202,"identity":"249e3d42-031d-43df-8b0b-fdf4bc527df2","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":471421,"visible":true,"origin":"","legend":"\u003cp\u003eQualitative pharmacodynamics analysis by SDS-PAGE\u003c/p\u003e\n\u003cp\u003eA: 0.25 mg/kg BW KJ103 in China. B: 0.40 mg/kg BW KJ103 in China. C: 0.25 mg/kg BW KJ103 in New Zealand. D: 0.40 mg/kg BW KJ103 in New Zealand.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/aecf03bf2bbdb6c833827949.png"},{"id":57445208,"identity":"ccc21d32-cf39-4b56-85dd-d77105540b63","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":19588,"visible":true,"origin":"","legend":"\u003cp\u003ePharmacokinetics of KJ103 in serum\u003c/p\u003e\n\u003cp\u003eA: pharmacokinetics analysis results in China. B: pharmacokinetics analysis results in New Zealand.\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/64064099d9927afd4ea4c74b.png"},{"id":57445211,"identity":"6bbc2082-de2b-4aac-8c6e-dfe60fa9b9be","added_by":"auto","created_at":"2024-05-30 19:16:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":211798,"visible":true,"origin":"","legend":"\u003cp\u003ePopPK final model pcVPC\u003c/p\u003e\n\u003cp\u003eBlue hollow point: measured value; Blue line: 5th and 95th quantiles of measured values; Red line: median measured value; Blue-shaded intervals: 95% prediction intervals of 5th and 95th quantiles predicted by the model; Red shaded interval: 95% prediction interval of the median predicted by the model.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/e62cff01a41cbe9839ee01d9.png"},{"id":57445206,"identity":"dcc2674e-52cd-46e7-9bd4-42cf2f1978a7","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":294183,"visible":true,"origin":"","legend":"\u003cp\u003ePK/PD final model pcVPC\u003c/p\u003e\n\u003cp\u003eBlue hollow point: measured value; Blue line: 5th and 95th quantiles of measured values; Red line: median measured value; Blue-shaded intervals: 95% prediction intervals of 5th and 95th quantiles predicted by the model; Red shaded interval: 95% prediction interval of the median predicted by the model.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/b96a8b6bf32eecd364cbe517.png"},{"id":57445804,"identity":"258b27b2-e214-4f68-aca8-db54f05d4b5a","added_by":"auto","created_at":"2024-05-30 19:24:50","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":54208,"visible":true,"origin":"","legend":"\u003cp\u003eCharacteristics of simulated IgG changes over time after administration of different sexes\u003c/p\u003e\n\u003cp\u003eSimulation of 8.5-19.4 g/L baseline IgG range (10th-90th baseline IgG level of the included population), the change of IgG decline trough after a single dose of 0.25 mg/kg in typical male healthy participants; Dots and solid lines represent predicted trough IgG values. The dashed line represents IgG=1 g/L.\u003c/p\u003e","description":"","filename":"Fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/4a4b6b092e66e44fcc816f64.png"},{"id":57445209,"identity":"53c23d5e-2d36-4a85-8494-af06760dc531","added_by":"auto","created_at":"2024-05-30 19:16:51","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":77727,"visible":true,"origin":"","legend":"\u003cp\u003eCharacteristics of trough IgG values after administration of simulated different doses\u003c/p\u003e\n\u003cp\u003eThe change of trough value of IgG in typical male healthy participants after a single dose of 0.01-0.40 mg/kg was simulated, and the baseline median IgG value of the included population was 12.8 g/L. Dots and solid lines represent predicted trough IgG values. The dashed line represents IgG=1 g/L.\u003c/p\u003e","description":"","filename":"Fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/22e89b42f875bc2a60d72ebb.png"},{"id":57445205,"identity":"406ff291-22cb-45b4-b6c0-e77a6c838a94","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":6633,"visible":true,"origin":"","legend":"\u003cp\u003eADA titers of participants before drug administration\u003c/p\u003e","description":"","filename":"Fig8.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/c13b7cc6ab7f810d61afb287.png"},{"id":57445210,"identity":"3e4b7743-62df-465c-9ebe-20184366b88f","added_by":"auto","created_at":"2024-05-30 19:16:51","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":21803,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in ADA of participants\u003c/p\u003e","description":"","filename":"Fig9.png","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/5a509de8abf05e48c4ebe7e4.png"},{"id":74127727,"identity":"2d2eb431-00bc-4b6b-9d1e-d00c5cfeb29d","added_by":"auto","created_at":"2025-01-18 08:05:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2010997,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/2e043e78-88b2-4839-8a03-181e8e87b69f.pdf"},{"id":57445200,"identity":"90690fd8-b277-41dd-af43-7b8e3f8f2ae6","added_by":"auto","created_at":"2024-05-30 19:16:50","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":21517,"visible":true,"origin":"","legend":"Table 1-5","description":"","filename":"Table15.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4374237/v1/3ee184589341ff57fd96b873.xlsx"}],"financialInterests":"\u003cb\u003eYes\u003c/b\u003e there is potential conflict of interest.\nZW, ZZ, YL are employees of Shanghai Bao Pharmaceuticals Co., Ltd, and own stock/other equities. Other authors declare no competing interests.","formattedTitle":"Safety, Efficacy, and Immunogenicity of a Novel IgG Degrading Enzyme (KJ103): Results from Two Randomised, Blinded, Phase 1 Clinical Trials","fulltext":[{"header":"Introduction","content":"\u003cp\u003eImmunoglobulin G (IgG) is an abundant protein in human serum, accounting for approximately 10\u0026ndash;20% of plasma proteins[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. IgG is essential for normal immune functioning in the body[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. IgG antibodies against viruses and bacteria are present in the body after infection or vaccination, but can also form against human antigens (e.g., blood group antibodies, anti-HLA antibodies, tissue autoantibodies, etc.) as a result of blood transfusions, pregnancy, or for unknown reasons[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Such antibodies are usually harmless, but can sometimes impede the implementation of modern treatment techniques. A well-established example of this situation can be found in organ transplantation, where donor-specific alloantibody (DSA) positivity is a contraindication to conventional kidney transplantation[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. A more recent and novel example concerns adeno-associated virus (AAV) capsids for intravenous delivery gene therapy. The three approved recombinant AAV intravenous drugs (Roctavian[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], Hemgenix[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and Elevidys[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]) are limited by the high prevalence of pre-existing anti-AAV antibodies in the general population, which are known to limit transfection efficacy in vivo, thereby restricting the number of patients that can receive the gene therapy using this vector [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn recent years, the IgG degrading enzyme imlifidase (IdeS) has been used for conditions where pre-existing antibodies need to be depleted, making a breakthrough in renal transplantation medicine for patients with DSA-positive renal failure[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, IdeS is derived from \u003cem\u003eStreptococcus pyogenes\u003c/em\u003e, and most humans have been infected with this bacterium, resulting in over 90% of individuals harboring antibodies against IdeS. A study that screened 130 participants found that only 10 of them had anti-IdeS antibody concentrations below the detection limit (2.0 mg/L). The median level of pre-existing anti-IdeS antibodies was 6.1 mg/L (range 2.0\u0026ndash;78.0 mg/L), and the 80th percentile was 15mg/L[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These anti-IdeS antibodies may increase the risk of hypersensitivity/infusion-related reactions against IdeS[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Moreover, there is evidence that neutralizing antibodies are able to weaken the activity of IdeS[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The presence and extent of pre-existing antibodies to \u003cem\u003eStreptococcus pyogenes\u003c/em\u003e therefore limits the application of IdeS.\u003c/p\u003e \u003cp\u003eTo minimize such risk from pre-existing antibodies, we developed a novel lgG degrading enzyme, named KJ103. KJ103 is modified from IgG endopeptidase of \u003cem\u003eStreptococcus equi\u003c/em\u003e (\u003cem\u003eS. equi\u003c/em\u003e), an equine host-adapted pathogenic bacterium that typically does not infect humans[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The results of in vitro studies have proved that KJ103 can efficiently cleave human IgG in the hinge region, and the results from animal studies indicated that KJ103 has a good safety and efficacy profile (unpublished data). KJ103 is expected to be a potential agent for desensitization of all IgG subclasses. To further assess KJ103, Phase I studies were conducted in healthy participants in both China and New Zealand. These studies were necessary to support KJ103 through to further clinical trials to determine efficacy in clinical applications.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eTwo randomized, blinded, placebo-controlled, single ascending-dose phase I studies were conducted independently in China (Identifier: NO. ChiCTR2300075920) and New Zealand (Identifier: NO. NCT05274659) using a similar design. The studies aimed to evaluate the safety, tolerability, pharmacokinetic profile, pharmacodynamic profile, and immunogenicity of KJ103 in healthy participants.\u003c/p\u003e \u003cp\u003e The study protocols and all amendments were approved by the local Ethics Committee of each center (Suzhou Municipal Hospital, New Zealand Clinical Research), and the studies were conducted in compliance with the Declaration of Helsinki and the international standards of Good Clinical Practice. Written informed consent was obtained from all participants prior to any study-related procedures. The studies were reported according to the 2022 update to the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement.\u003c/p\u003e \u003cp\u003eFive dose levels were chosen to explore the safety and tolerability of KJ103, ranging from 0.01-0.40mg/kg using participants actual body weight (Table\u0026nbsp;1). The first 0.01 mg/kg group enrolled 2 participants to receive KJ103. The remaining groups enrolled 8 participants, with 6 participants randomly allocated by computer to receive KJ103 and 2 participants allocated to receive placebo. Sentinel dosing was employed (except the first dose level), in which two participants were dosed with KJ103 or placebo on Day 1 in order to monitor potential acute reactions. The remaining 6 participants dosed\u0026thinsp;\u0026ge;\u0026thinsp;24 hours after the sentinel dose, once the Investigator completed the safety assessment of the first two participants. Patients were followed-up for a total of 2 months after dosing.\u003c/p\u003e \u003cp\u003eThe safety and tolerability were observed during the dose-limiting toxicity (DLT) observation period. The DLT observation period in China was 7 days, while in New Zealand it was 14 days. If none of the participants experienced an event meeting the dose escalation termination criteria (\u0026ge;\u0026thinsp;grade 3), the study proceeded to the next dose level. A safety review committee was set with the responsibility to make decisions on whether to proceed to the next dose level through obtained PK, PD and safety data once the DLT observation period finished in each group.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eIn these studies, eligible participants were selected according to the major inclusion criteria: healthy male or female participants aged between 18 to 55 years; body mass index (BMI) between 18 and 30 kg/m\u0026sup2;. The participants were excluded according to the following criteria: clinically significant immunodeficiency (including but not limited to immunoglobulin A deficiency); history of tuberculosis; positive screening for HBcAb, HCV antibodies, HIV antibodies, and syphilis antibodies; allergy to KJ103 or its excipients; participation in other clinical trials; pregnant or nursing women; blood loss or donation of \u0026gt;\u0026thinsp;400 mL in the 3 months before enrollment; alcohol or drug abuse; clinically significant abnormalities in vital signs, 12-lead electrocardiogram (ECG) or laboratory tests.\u003c/p\u003e \u003cp\u003eTo mitigate the increased risk of opportunistic infection post-KJ103 administration, all participants received prophylactic antibiotics starting on the day of administration and continuing until Day 28 or until IgG levels were at least 6.0 g/L. If grade 2 or higher infusion-related reactions occurred in the first two dose groups, participants in the 3/4/5 dose group would receive preventive medications for infusion-related reactions (e.g., glucocorticoids or antihistamines) as needed.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eAssessment of Safety\u003c/h2\u003e \u003cp\u003eAll adverse events that emerged during the studies were assessed and graded according to the National Cancer Institute Common Standard Terminology for Adverse Events (NCI-CTCAE), version 5.0. Parameters included in evaluations were vital signs, physical examinations, 12-ECG, clinical laboratory tests (hematology, urinalysis, biochemistry, coagulation function, etc.), clinical adverse and serious adverse events (AEs, SAEs).\u003c/p\u003e \u003cp\u003ePharmacokinetics\u003c/p\u003e \u003cp\u003eBlood samples were collected at the predetermined time points for PK evaluation. For Cohorts 1 and 2, blood samples were taken at pre-dose, 1 minute before infusion completion, and at the exit visit. For Cohorts 3\u0026ndash;5, blood samples were taken at pre-dose, 1 minute before infusion completion, 5 minutes, 45 minutes, 6 hours, 24 hours, 48 hours, 72 hours, and 144 hours after infusion and at study termination in cases of early withdrawal. Plasma KJ103 levels were measured using a validated enzyme-linked immunosorbent assay (ELISA) method at JOINN Laboratories (Beijing,China).\u003c/p\u003e \u003cp\u003eSingle-dose PK parameters of KJ103 were estimated using non-compartmental analysis, including C\u003csub\u003emax\u003c/sub\u003e, T\u003csub\u003emax\u003c/sub\u003e, AUC\u003csub\u003e0-t\u003c/sub\u003e, AUC\u003csub\u003e0-\u0026infin;\u003c/sub\u003e, λ\u003csub\u003ez\u003c/sub\u003e, t\u003csub\u003e1/2\u003c/sub\u003e, MRT\u003csub\u003e0-\u0026infin;\u003c/sub\u003e, CL, and V\u003csub\u003ez\u003c/sub\u003e. Concentration data were tabulated, and descriptive statistics were performed for grouped planned blood sampling times. The average plasma concentration-time curves of the participants in different dose groups (0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg) were plotted.\u003c/p\u003e \u003cp\u003ePharmacodynamics\u003c/p\u003e \u003cp\u003eFor the purpose of pharmacodynamic assessment, blood samples were obtained according to the following schedule. For Cohort 1, samples were collected at pre-dose, 6 hours after the infusion, and at the exit visit. For Cohorts 2\u0026ndash;5, samples were collected at pre-dose, 1 minute before infusion completion, 5 minutes, 20 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 3 hours, 6 hours, 24 hours, 48 hours, 72 hours, 144 hours, Days 14, 21, 28, and 63 after infusion and at study termination in cases of early withdrawal. Plasma IgG levels of the participants were measured by ELISA at JOINN Laboratories (Beijing,China), with the lower limit of ELISA detection being 0.40 g/L. The levels of single-chain IgG molecules (scIgG), F (ab')\u003csub\u003e2\u003c/sub\u003e and Fc were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) at JOINN Laboratories (Beijing,China).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePopulation Pharmacokinetic Model and PK/PD Models\u003c/h2\u003e \u003cp\u003eThe estimation method for population pharmacokinetic (PopPK) modeling was the first-order conditional estimation method (FOCEI) considering the η-ε interaction.\u003c/p\u003e \u003cp\u003eThe inter-individual variability( IIV) was modeled as an exponential model (Eq.\u0026nbsp;1):\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$${P}_{i}={P}_{TV}\\times exp\\left({\\eta }_{i}\\right)$$\u003c/div\u003e\u003c/div\u003e(1) \u003c/p\u003e \u003cp\u003ewhere P\u003csub\u003eTV\u003c/sub\u003e is the typical value of the PK parameter, P\u003csub\u003ei\u003c/sub\u003e is the individual parameter value, and η\u003csub\u003ei\u003c/sub\u003e is the inter-individual variation for P\u003csub\u003eTV\u003c/sub\u003e with a normal distribution of mean of 0 and variance of ω\u003csup\u003e2\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe following models, additive (Eq.\u0026nbsp;2), proportional (Eq.\u0026nbsp;3) and combined additive and proportional (Eq.\u0026nbsp;4) and logarithmic (Eq.\u0026nbsp;5) model, were investigated for residual variability (RV):\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({Y}_{obs.ij}={Y}_{pred.ij}+{\\epsilon }_{ij.1}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(2)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({Y}_{obs.ij}={Y}_{pred.ij}\\times (1+{\\epsilon }_{ij.1})\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(3)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({Y}_{obs.ij}={Y}_{pred.ij}\\times （1+{\\epsilon }_{ij.1}）+{\\epsilon }_{ij.2}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(4)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({Y}_{obs.ij}=\\text{L}\\text{O}\\text{G}\\left({\\text{Y}}_{\\text{p}\\text{r}\\text{e}\\text{d}.\\text{i}\\text{j}}\\right)+{{\\epsilon }}_{\\text{i}\\text{j}.1}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ewhere Y\u003csub\u003eobs,ij\u003c/sub\u003e and Y\u003csub\u003epred,ij\u003c/sub\u003e are the observed and predicted concentrations in i\u003csup\u003eth\u003c/sup\u003e participant and at j\u003csup\u003eth\u003c/sup\u003e sampling time point, respectively. ε\u003csub\u003eij,1\u003c/sub\u003e and ε\u003csub\u003eij,2\u003c/sub\u003e are normal distributions with mean of 0 and variances of σ\u003csub\u003eij,1\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e and σ\u003csub\u003eij,2\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e, respectively.\u003c/p\u003e \u003cp\u003eCovariates included gender, age, ethnicity, body weight, body mass index, baseline alanine transaminase (ALT), post-administration anti-drug antibody (ADA), baseline IgG, were assessed by step-wise forward (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) selection and backward elimination (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The PopPK models were evaluated by goodness-of-fit plots, visual predictive checks and bootstrap resampling procedures.\u003c/p\u003e \u003cp\u003eIgG level was selected as the effect index for exposure-response (E-R) analysis of KJ103. Individual participant KJ103 blood concentration data was obtained using a Bayesian posterior estimation method through the final PopPK model. The PK/PD model of KJ103 concentration and IgG level was explored through an effect-compartment model or an indirect response model. The covariate screening method and model evaluation method are the same as PopPK.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eImmunogenicity\u003c/h2\u003e \u003cp\u003eBlood samples were collected at the following time points for ADA assessment: pre-dose, 24 hours, 48 hours, 72 hours, 144 hours, Days 14, 21, 28, 63, and Day 180 post-infusion and in cases of early withdrawal. Anti-KJ103 antibody in human serum were measured using a validated bridging ELISA method at JOINN Laboratories (Beijing,China).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eAll statistical analyses were performed using SAS 9.4 except for the calculation of PK parameters which were made using Phoenix WinNonlin 8.2. Enumeration data and grade data were described by the number of cases and percentage. NONMEM (Version 7.5) and its tool software Wings for NONMEM (nm753) and Perl Speaks NONMEM (Version 5.3.0) were used to build models and simulations. R (Version 4.1.2) was used for collating and analyzing data sets, statistical analyses, modeling, mapping, and construction of virtual populations.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eDemographic Characteristics\u003c/h2\u003e \u003cp\u003eIn these two independent, but similarly designed studies, a total of 68 healthy participants (China n\u0026thinsp;=\u0026thinsp;34; New Zealand n\u0026thinsp;=\u0026thinsp;34) were included. In the study conducted in China, 100% of the participants were of Asian ethnicity and males accounted for 85.3% of participants. In the New Zealand study, most of the participants were Caucasian (58.8%), and females accounted for 79.4.% of all trial participants. With the exception of sex and ethnicity, all other baseline characteristics were similar between both studies. (Table\u0026nbsp;2)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eSafety and Tolerability\u003c/h2\u003e \u003cp\u003eOf the total 68 participants across both studies, 52 received KJ103 and the remainder placebo. During the study, there were no DLTs or SAEs, and no treatment-emergent adverse events (TEAEs) or treatment-related adverse events (TRAEs) leading to study termination. All the predicted dose levels were escalated steadily and all participants received the proposed dose with one exception. One participant in New Zealand, receiving 0.40mg/kg, experienced a self-limited infusion reaction leading to early termination of infusion, attributable to the protocol deviation of no pre-medication.\u003c/p\u003e \u003cp\u003eA total of 27 participants (79.4%) experienced 44 TEAEs in the Chinese study. 23 participants\u0026rsquo; TEAEs (23/34, 67.6%) were grade 1, with fewer cases (4/34, 11.8%) being grade 2, and none grade 3 or above. A total of 9 participants (9/34, 26.5%) had 11 TRAEs in this study. Most of them (8/34, 23.5%) were grade 1, and only 1 participant (1/34, 2.9%) had a grade 2 TRAE (decreased lymphocyte count). No participants in the 0.40 mg/kg group experienced TRAE.\u003c/p\u003e \u003cp\u003eA total of 30 participants (88.2%) experienced 79 TEAEs in the New Zealand study. 26 (26/34, 76.5%) participants\u0026rsquo; TEAEs were grade 1; 2 cases (2/34, 5.9%) were grade 2, and 2 participants (2/34, 5.9%) had a grade 3 AE (one participant at 0.04 mg/kg developed dental caries that was assessed as unlikely to be related to the test drug, and another participant at 0.40 mg/kg developed deranged liver blood tests that were assessed as probably related to the test drug, both of whom recovered). A total of 8 participants (8/34, 23.5%) reported 8 cases of TRAEs.\u003c/p\u003e \u003cp\u003eCombining the above results, 19 AEs observed in 17 of the 68 participants were classified as related (i.e. possible, probable or definite), as presented in Table\u0026nbsp;3. The most common AE related to KJ103 was elevated alanine aminotransferase (ALT). The primary concern with lgG degradation enzymes is the risk of infection, and in this regard, the following results demonstrate its safety. One case of grade 1 infectious illness (suspected bacterial infection) occurred in the 0.25 mg/kg group in China, and was determined by the Investigator as probably related to KJ103. One case of grade 1 vulvovaginal candidiasis occurred in the 0.25 mg/kg group in New Zealand, and was determined possibly related to KJ103. There were no severe infection events related to KJ103 (Table\u0026nbsp;3).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePharmacodynamics\u003c/h2\u003e \u003cp\u003eCompared to the placebo, IgG showed mild degradation at dose of 0.01 mg/kg of KJ103. With increasing dose, a sharper \u0026ldquo;drop off\u0026rdquo; of IgG level was observed in a dose-dependent manner. A greater reduction in IgG after administration of KJ103 at a dose of 0.12 mg/kg to Asian participants in both studies. In both the 0.25 mg/kg and 0.40 mg/kg group, IgG levels reached their lowest point within 6 hours of dose administration, falling by over 90%, and remained consistently below 70% of normal levels for the first week after dosing. After the initial fallward, IgG levels gradually increased after one week of administration. IgG recovered to near or above baseline levels within 1 to 2 months post-dose in most patients. It is worth noting that dose levels of KJ103 did not affect the rate and extent of IgG recovery, only the initial \u0026ldquo;drop off\u0026rdquo;. These results indicate that the IgG changes related to dosing with KJ103 were consistent across different ethnicities and demonstrate a favorable pharmacological effect (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eExploratory Pharmacodynamics Analysis\u003c/h2\u003e \u003cp\u003eBased on the mechanism of action of KJ103, the digested fragments of scIgG, F (ab')\u003csub\u003e2\u003c/sub\u003e and Fc were also analyzed by SDS-PAGE. SDS-PAGE results were consistent with ELISA findings. Compared with the placebo group, in which there was no change, all the samples from KJ103 groups showed an increase in fragment concentration, rising in proportion to the corresponding decrease in intact IgG. All participants in the 0.04 mg/kg group and some participants in the 0.12 mg/kg group did not undergo complete IgG cleavage. Participants in the 0.25 mg/kg and 0.40 mg/kg groups experienced rapid, efficient, and complete cleavage of most IgG into F(ab')\u003csub\u003e2\u003c/sub\u003e and Fc fragments by KJ103 within 45 minutes \u0026minus;\u0026thinsp;6 hours and 20 minutes \u0026minus;\u0026thinsp;6 hours post-dosing, respectively. Combining the SDS-PAGE results, the IgG signal obtained 6 hours post-dosing by ELISA primarily originates from scIgG. F(ab')\u003csub\u003e2\u003c/sub\u003e and Fc fragments decreased to the baseline levels within 1 to 7 days after dosing. Within one to two weeks, all participants demonstrated newly synthesized complete IgG. Within 1 to 2 months post-dosing, IgG recovered to near or above baseline levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003ePharmacokinetics, PopPK, and PK/PD Models\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003ePharmacokinetics\u003c/h2\u003e \u003cp\u003eAfter a single intravenous infusion of KJ103, the overall blood drug concentrations of participants in the 0.01 mg/kg and 0.04 mg/kg dose groups were below the detection limit, as a result of low exposure and therefore low blood concentration of the administered drug. Pharmacokinetic concentration results showed good reproducibility of PK curves in the dose range of 0.12 mg/kg to 0.40 mg/kg for all dose groups. The mean KJ103 concentration peaked immediately after administration, reaching the plateau phase during which the distribution and metabolism of the drug achieve equilibrium in the body, followed by slow elimination of the drug. Most of the KJ103 was eliminated within 24 hours after administration (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAfter a single intravenous infusion of KJ103 in Chinese participants, the median T\u003csub\u003emax\u003c/sub\u003e of 0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg dose groups were 0.333 hours, 0.333 hours and 0.583 hours, respectively. C\u003csub\u003emax\u003c/sub\u003e (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) were 2.208\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4985 mg/L, 5.142\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2922 mg/L and 9.200\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3049 mg/L, respectively. AUC\u003csub\u003e0-t\u003c/sub\u003e (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) were 28.405\u0026thinsp;\u0026plusmn;\u0026thinsp;29.6554 h*mg/L, 43.114\u0026thinsp;\u0026plusmn;\u0026thinsp;21.7201 h*mg/L and 170.261\u0026thinsp;\u0026plusmn;\u0026thinsp;176.5502 h*mg/L, respectively. After excluding abnormal PK data, the average t\u003csub\u003e1/2\u003c/sub\u003e of each dose group was 6.260 h, 4.862 h and 81.648 h, respectively. t\u003csub\u003e1/2\u003c/sub\u003e showed a non-linear increase with the increase of dose.\u003c/p\u003e \u003cp\u003eAfter the New Zealand participants received a single intravenous infusion of KJ103, excluding the participant in the 0.40 mg/kg dose group who interrupted the dose due to an infusion reaction, the median T\u003csub\u003emax\u003c/sub\u003e of 0.12 mg/kg, 0.25 mg/kg and 0.40 mg/kg dose groups were 0.4583 hours, 0.3333 hours and 0.5833 hours, respectively. C\u003csub\u003emax\u003c/sub\u003e (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) were 2.8135\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5216 mg/L, 6.5245\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9994 mg/L and 10.0124\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6712 mg/L, respectively. AUC\u003csub\u003e0-t\u003c/sub\u003e (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) were 45.2515\u0026thinsp;\u0026plusmn;\u0026thinsp;47.9476 h*mg/L, 101.9423\u0026thinsp;\u0026plusmn;\u0026thinsp;113.8636 h*mg/L and 61.9188\u0026thinsp;\u0026plusmn;\u0026thinsp;29.7180 h*mg/L, respectively. After excluding abnormal PK data, the average t\u003csub\u003e1/2\u003c/sub\u003e of each dose group was 11.3978 hours, 2.2629 hours and 8.4130 hours, respectively (Table\u0026nbsp;4).\u003c/p\u003e \u003cp\u003eBased on the analysis of pharmacokinetic parameters using a non-compartmental model, KJ103 exhibited characteristics of rapid distribution and slow elimination in healthy participants in China and New Zealand. The exposure of KJ103 in various dosage groups demonstrated a non-linear increase with dosage escalation.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003ePopPK and PK/PD Models\u003c/h2\u003e \u003cp\u003eBased on clinical trial data from both studies, we established a KJ103 population pharmacokinetic (PopPK) model to explore the covariates affecting PopPK parameters. We found that only body weight affects the clearance of KJ103. For a participant with body weight at the 10th\u0026thinsp;~\u0026thinsp;90th percentile of the study population relative to the median body weight in the study population, the C\u003csub\u003emax\u003c/sub\u003e and AUC\u003csub\u003e0\u0026thinsp;~\u0026thinsp;168\u003c/sub\u003e varied from \u0026minus;\u0026thinsp;29%~26%. Other covariates such as region and ethnicity did not impact PopPK parameters (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The results also indicate similar PK characteristics of populations between China and New Zealand.\u003c/p\u003e \u003cp\u003eThe optimal PopPK model was a two-compartment model with first-order elimination. The population typical values (RSE%) of CL, V\u003csub\u003ec\u003c/sub\u003e, V\u003csub\u003ep\u003c/sub\u003e and Q were 0.162 L/h (13.6), 3.23 L/h (4.3), 14.2 L/h (18.5) and 0.591 L/h (5.0), respectively. The results of the prediction-corrected visual predictive check (pcVPC) are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The median, upper and lower 5th percentiles of the observed values were mostly contained within the 95% confidence intervals of the predicted values. Additionally, the predicted interval encompassed most of the observed values, indicating a good predictive performance of the model.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA total of 48 participants were included in the pharmacokinetic/pharmacodynamic (PK/PD) analyses, using IgG levels as the effect indicator. Individual participants' KJ103 blood concentration data were obtained using the PopPK final model using Bayesian a posteriori estimation to explore the PK/PD model of KJ103 concentration and IgG level. The relationship between KJ103 concentration and IgG level was described by an effector chamber model. The results revealed that IgG began to decline after the administration of KJ103 at a dose of 0.25 mg/kg, and was maintained near the nadir and close to the lower limit of detection after 5\u0026ndash;19 hours. The IgG recovered to more than 1 g/L after 36 hours of administration, and more than 2 g/L after 96 hours, and stayed lower than 4 g/L for 7 days. Analyses of covariates showed that gender influenced the IC50(Concentration of KJ103 when IgG level reaches half of its maximum inhibitory effect), whereas different ethnicities had no effect on the PK/PD model. The results of the prediction-corrected visual predictive check (pcVPC) are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The median and upper and lower 5th percentiles of the observed values were mostly contained within the 95% confidence intervals of the predicted values. Additionally, the predicted interval encompassed most of the observed values, indicating a good predictive performance of the model.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSimulation of IgG change levels after a single administration of 0.25 mg/kg in male and female typical healthy participants showed that the overall trend of IgG change in males and females was similar, with IgG starting to decline after administration, remaining near the trough value after 5\u0026ndash;24 hours, and then recovering slowly (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). However, the IgG trough value was 0.66 g/L higher in females than in males, and females recovered faster than males, although both sexes were lower than 5 g/L for 7 days. Simulating IgG trough levels after a single dose in the range of 0.01 to 0.40 mg/kg in healthy male participants shows that the IgG trough levels decrease with increasing dosage (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). At 0.25 mg/kg of KJ103, enzymatic digestion of IgG is more than 90% effective and reaches a plateau. During the process of covariate selection, after statistical tests, we found that baseline IgG levels and gender affect the efficacy of KJ103 in reducing IgG levels, however the overall trend remained similar. The IgG levels at 0.25 mg/kg dosage remained at a low level within a week under various conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eImmunogenicity\u003c/h2\u003e \u003cp\u003eThe pre-existing antidrug antibody positivity rate for all enrolled participants was 33.82% (23/68), and the median value of pre-existing antibody titers was 0 (range: 0 to 1:429.61). There were no significant differences in the proportion and titer of pre-existing antibodies among participants of different ethnicities enrolled in China and New Zealand (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). The low proportion of pre-existing anti-KJ103 antibodies in participants\u0026rsquo; indicated that most of them had not developed these antibodies due to \u003cem\u003eS. equi\u003c/em\u003e infection. The relatively low levels of anti-KJ103 support the safety of KJ103 administration. Only one participant from the 0.40 mg/kg group in New Zealand experienced an infusion reaction post-administration attributable to the failure to use prophylactic medication as per protocol. No infusion reactions occurred in the remaining participants from both studies.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong participants in the China cohort, the median baseline ADA value was 0 (titer range: 0\u0026thinsp;~\u0026thinsp;1: 429.61); on the 7th day after KJ103 administration, the median ADA titer was 0 (range: 0\u0026thinsp;~\u0026thinsp;1: 408.25); on day 14 post-dose, ADA levels were near peak, with a median ADA value of 1:1,041.97 (range: 0 to 1:144,433.38). Two months after administration, the median ADA titer for all KJ103 users was 1: 605.89 (range: 1: \u0026lt;10\u0026thinsp;~\u0026thinsp;1: 10,989.27). Six months after administration, the median ADA titer for all KJ103 users was 1:524.77 (range: 0\u0026thinsp;~\u0026thinsp;1: 4,921.42) (Table\u0026nbsp;5).\u003c/p\u003e \u003cp\u003eIn the New Zealand cohort, the median baseline ADA titer was 0 (range: 0\u0026thinsp;~\u0026thinsp;1: 242.58); on the 7th day after KJ103 administration, the median ADA titer was 0 (range: 0\u0026thinsp;~\u0026thinsp;1: 246.78); on day 14 post-dose, ADA levels were near peak, with a median ADA value of 1:257.50 (range 0, 1: 20,855.78). Subsequently, ADA levels gradually declined, and after two months of administration, the median ADA titer for all participants was 1: 158.64 (range: 0\u0026thinsp;~\u0026thinsp;1: 7171.39), and the median value of ADA titer at 6 months after administration was 1:214.35 (range: 0\u0026thinsp;~\u0026thinsp;1: 5,782.43) (Table\u0026nbsp;5).After 2 weeks and 2 months of KJ103 administration, Chinese participants showed a wider range of ADA titer change in the 0.25 mg/kg and 0.40 mg/kg dose groups than New Zealand participants. There were no significant differences in the median values and ranges of change in ADA titers among participants in the two countries in each of the dose groups prior to KJ103 administration, at 1 week and at 6 months after KJ103 administration.\u003c/p\u003e \u003cp\u003eThe majority of participants in the two studies showed ADA changes beginning on Day 14 after KJ103 administration, peaking at approximately two weeks and then gradually declining. After 6 months of KJ103 administration, 56.86% (29/51) of participants\u0026rsquo; ADA were back to baseline levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). Although there are significant individual differences in the development of immunogenic responses, in general, immunogenic responses appear to be dose-related.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIgG‑degrading enzyme have made breakthroughs in the field of kidney transplantation. In vitro, IgG‑degrading enzyme inhibits HLA antibody-mediated NK cell activation and antibody-dependent cell-mediated cytotoxicity [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. IgG‑degrading enzyme degrades also the IgG of the B cell Receptor (BCR), inhibiting BCR-mediated cell signal, transiently preventing memory B cell response to antigenic stimulation and their transition into antibody-producing cells [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. DSA positive patients who have received IdeS can successfully undergo allogeneic kidney transplantation surgery, achieving higher kidney and patient survival rates [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The French consensus guidelines indicate that Imlifidase (IgG degrading enzyme) has been authorized for early use in highly sensitized adult kidney transplant candidates who are cross matched positive for ABO compatible deceased donors [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIgG‑degrading enzyme also demonstrate enormous therapeutic potential in the field of gene therapy. The most commonly used viral vectors for \u003cem\u003ein vivo\u003c/em\u003e gene therapy are based on AAV, a non-enveloped single-stranded DNA virus. However neutralizing antibodies (NAbs) to AAV vectors are highly prevalent in humans, block liver transduction and vector readministration, thus representing a major limitation to in AAV-based \u003cem\u003ein vivo\u003c/em\u003e gene therapy[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Evidence from ongoing clinical trials (ClinicalTrials.gov NCT03368742, NCT04281485, and NCT03882437) suggests that high doses of AAV significantly increase complement activation. Some participants in these studies presented with severe and life-threatening inflammatory responses that were likely secondary to the activation of the complement system [\u003cspan additionalcitationids=\"CR21 CR22 CR23\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In addition to nausea, fever, and vomiting likely due to cytokine release, participants presented with complement-mediated thrombotic microangiopathy (CM-TMA) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], acute kidney injury due to atypical hemolytic uremic syndrome\u0026ndash;like (aHUS-like) complement activation, thrombocytopenia, and immune-mediated myocardial injury[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Activation of complement is a major safety consideration for gene therapy, as growing evidence suggests that high-dose intravenous (i.v.) AAV infusion or high exposure to AAV empty capsids leads to antibody-dependent activation of the complement system in human plasma[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. It was confirmed that IgG‑degrading enzyme reduced anti-AAV antibody levels from human plasma samples in vitro, including plasma from prospective gene therapy trial participants [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. These results provide a potential solution to overcome NAbs to AAV-mediated gene therapy and inhibit antibody-dependent activation of the complement system. Based on the above mechanisms, KJ103 has the potential to alleviate the problem of inability to accept first and second treatment due to high anti-AAV antibody titers, improve gene transduction efficiency, and prevent treatment failure caused by complement mediated immune reactions after administration in the field of AAV-mediated gene therapy.\u003c/p\u003e \u003cp\u003eAlthough degrading enzymes have shown excellent therapeutic potential in many therapeutic fields, the immunogenicity of biologicals in therapy cannot be ignored. Pre-existing anti-drug antibodies may increase the risk of infusion reactions and hypersensitivity reactions during intravenous delivery of biologicals[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The widespread presence of pre-existing anti-IdeS antibodies limits clinical applications of IdeS, and can potentially compromise drug efficacy[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. During clinical studies, individuals with anti-IdeS IgG titers exceeding 15mg/L were excluded from the research, and therefore not all populations can receive IdeS treatment[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These shortcoming are illustrated by its use in intravenous administration for AAV gene therapy.\u003c/p\u003e \u003cp\u003eHere, we report an IdeE(IgG‑degrading enzyme of \u003cem\u003eS. equi\u003c/em\u003e) variant of KJ103 with lgG-cleaving activity like that of ldeS. Our studies confirm that KJ103, a novel IgG-degrading enzyme derived from \u003cem\u003eS. equi\u003c/em\u003e, exhibits a low positivity rate and low titers of pre-existing anti-KJ103 antibodies in the population. In clinical trials of IdeS, anti-IdeS antibodies were present in all participants at baseline, and participants experienced an increase in ADAs starting on day 7 of dosing. ADA levels then peaked at approximately 19.6 times baseline at about two weeks, and then declined progressively, reaching approximately 16.6 times baseline ADA concentrations after two months of dosing\u003csup\u003e[10]\u003c/sup\u003e. In comparison to ADA formation following IdeS administration, the pre-existing anti-KJ103 antibodies positivity rate for all enrolled participants was 33.82% (23/68), and the median value of pre-existing antibodies titers was 0 (range: 0 to 1:429.61). ADAs appeared and peaked at approximately two weeks after KJ103 administration, with a median ADA titre in positive participants that was 15.95 times that of the baseline positive participants, and then declined progressively, reaching a titre of approximately 5.35 times that of the baseline in positive participants after two months of dosing. The maximum dose of IdeS applied in humans was 0.25 mg/kg, whereas the maximum dose of KJ103 first applied in humans was 0.40 mg/kg dose, with an excellent safety and tolerability profile across all dose groups of KJ103. ADA emergence post-KJ103 administration occurred later than for IdeS, with lower titers and a shorter duration to return to baseline levels, highlighting the advantage of KJ103.\u003c/p\u003e \u003cp\u003eDue to the low prevalence and low titers of pre-existing KJ103 antibodies in the population, it is possible to administer KJ103 twice in humans at 7-day intervals without significant safety concerns. Theoretically, this would enable the salvage of intravenously administered AAV-mediated gene therapy in individuals positive for pre-existing anti-AAV antibodies. This approach could potentially ensure the sustained maintenance of low IgG levels in the body, allow sufficient time for the clearance of degraded F(ab')\u003csub\u003e2\u003c/sub\u003e fragments and maintain low IgG levels by second administration of KJ103 at 3\u0026thinsp;~\u0026thinsp;7 days interval. Validation of this hypothesis was observed in an AAV gene therapy mouse model infused with human anti-AAV antibodies (IgG), where KJ103 protected AAV9-mediated luciferase delivery from the impact of human anti-AAV antibodies. KJ103 is therefore promising as means of overcoming limitations posed by pre-existing anti-AAV antibodies in the clinical application of AAV gene therapy.\u003c/p\u003e \u003cp\u003eWe observed no events meeting the dose-escalation termination criteria during the DLT observation period in all participants. Most TEAEs and TRAEs were graded as grade 1 or 2, with a few at grade 3. Safety profiles of TRAEs for KJ103 were overall comparable to IdeS [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. No severe infection events occurred during either studies. KJ103 demonstrated excellent tolerability and safety.\u003c/p\u003e \u003cp\u003ePost-administration, KJ103 exhibited a dose-dependent reduction in IgG levels in healthy participants. We observed a greater reduction in IgG after administration of KJ103 at a dose of 0.12 mg/kg to Asian participants in both studies. The average IgG levels for participants in China and New Zealand were 11.67g/L and 14.63g/L, respectively, while the average levels of pre-existing anti-KJ103 antibodies were not significantly different. Our PK/PD models indicated that gender influences efficacy. Men constituted 85.3% and 20.6% of participants in China and New Zealand, respectively; while Caucasians accounted for 0% and 58.8% in China and New Zealand, respectively. A meta-analysis involving 28 studies indicated that factors such as being Caucasian, smoking, or using corticosteroids tend to decrease IgG levels, whereas the use of probiotics, hypertension, or acute psychological stress tends to elevate IgG levels[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Overall, differences in pharmacodynamics between the 0.12 mg/kg group in the two trials were caused by differences in baseline IgG levels. We infer that these differences may be due to gender disparities, but we do not rule out racial differences.Additionally, utilizing the PopPK model, we simulated various gender and baseline IgG levels and found their impact on efficacy to be negligible at a 0.25 mg/kg dose.\u003c/p\u003e \u003cp\u003eBoth trials demonstrate exceptional safety, tolerability and IgG cleavage efficiency of KJ103. The 0.25 mg/kg dose of KJ103 efficiently, rapidly, and specifically enzymatically cleaved human IgG and maintained a low serum IgG level for 1 week. The promising safety and tolerability of KJ103 was indicated by several lines of evidence including low positive rates and low titers of pre-existing anti-KJ103 antibody in the population and a quick return of ADA to a basal level within 6 months in nearly half of the participants after KJ103 administration. The trials show that KJ103 avoids IdeS shortcomings, with a higher safe dose, wide safety window, low pre-existing antibody ratio and titre, and a broader application population. It is likely that patients would not need to screen for pre-existing antibody titres prior to KJ103 administration. The advantages mentioned above can be leveraged in multiple patient populations including those requiring kidney transplantation and the emerging applications of AAV gene therapy in patients with anti-AAV antibodies[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthical Approval\u003c/h2\u003e \u003cp\u003eBoth phase 1 clinical trials of KJ103 were approved separately by the ethics committee of the \u0026ldquo;New Zealand Clinical Research\u0026rdquo;(Protocol no. SHBJ-2021-001) and \u0026ldquo;Suzhou Municipal Hospital\u0026rdquo; (Protocol no. SHBJ-2021-002). All subjects signed written informed consent before undergoing any study-specific procedures.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003cstrong\u003eCompeting Interests\u003c/strong\u003e \u003cp\u003eZW, ZZ,YL are employees of Shanghai Bao Pharmaceuticals Co., Ltd, and own stock/other equities. Other authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eShanghai Bao Pharmaceuticals Co., Ltd. was the formal sponsor and funder of the clinical trial.\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e\u003cp\u003eMC, RK, ZW analyzed the data and wrote the article. XL, QG, CC, ZZ, YY, KL, MM, YL substantially implemented the survey and consolidated the data. All authors critically revised the article and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e\u003cp\u003eThe authors would like to thank XX of XX, for XX. The authors acknowledge the editorial assistance of XX.\u003c/p\u003e\u003ch2\u003eData Availability Statement\u003c/h2\u003e\u003cp\u003e This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVidarsson G, Dekkers G, Rispens T. IgG subclasses and allotypes: from structure to effector functions. Front Immunol. 2014;5:520. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2014.00520\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2014.00520\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKapur R, Einarsdottir HK, Vidarsson G. IgG-effector functions: the good, the bad and the ugly. Immunol Lett. 2014;160(2):139\u0026ndash;44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.imlet.2014.01.015\u003c/span\u003e\u003cspan address=\"10.1016/j.imlet.2014.01.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCiurea SO, Cao K, Fernandez-Vina M, Kongtim P, Malki MA, Fuchs E, et al. The European Society for Blood and Marrow Transplantation (EBMT) Consensus Guidelines for the Detection and Treatment of Donor-specific Anti-HLA Antibodies (DSA) in Haploidentical Hematopoietic Cell Transplantation. Bone Marrow Transpl. 2018;53(5):521\u0026ndash;34. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41409-017-0062-8\u003c/span\u003e\u003cspan address=\"10.1038/s41409-017-0062-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBlair HA. Valoctocogene Roxaparvovec: First Approval. Drugs. 2022;82(14):1505\u0026ndash;10. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40265-022-01788-y\u003c/span\u003e\u003cspan address=\"10.1007/s40265-022-01788-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHeo YA. Etranacogene Dezaparvovec: First Approval. Drugs. 2023;83(4):347\u0026ndash;52. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40265-023-01845-0\u003c/span\u003e\u003cspan address=\"10.1007/s40265-023-01845-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHoy SM. Delandistrogene Moxeparvovec: First Approval. Drugs. 2023;83(14):1323\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40265-023-01929-x\u003c/span\u003e\u003cspan address=\"10.1007/s40265-023-01929-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeorge LA, Ragni MV, Rasko JEJ, Raffini LJ, Samelson-Jones BJ, Ozelo M, et al. Long-Term Follow-Up of the First in Human Intravascular Delivery of AAV for Gene Transfer: AAV2-hFIX16 for Severe Hemophilia B. Mol Ther. 2020;28(9):2073\u0026ndash;82. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ymthe.2020.06.001\u003c/span\u003e\u003cspan address=\"10.1016/j.ymthe.2020.06.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeber T. Anti-AAV Antibodies in AAV Gene Therapy: Current Challenges and Possible Solutions. Front Immunol. 2021;12:658399. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2021.658399\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2021.658399\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Published 2021 Mar 17.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLonze BE, Tatapudi VS, Weldon EP, Min ES, Ali NM, Deterville CL, et al. IdeS (Imlifidase): A Novel Agent That Cleaves Human IgG and Permits Successful Kidney Transplantation Across High-strength Donor-specific Antibody. Ann Surg. 2018;268(3):488\u0026ndash;96. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/SLA.0000000000002924\u003c/span\u003e\u003cspan address=\"10.1097/SLA.0000000000002924\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWinstedt L, J\u0026auml;rnum S, Nordahl EA, Olsson A, Runstr\u0026ouml;m A, Bockermann R, et al. Complete Removal of Extracellular IgG Antibodies in a Randomized Dose-Escalation Phase I Study with the Bacterial Enzyme IdeS\u0026ndash;A Novel Therapeutic Opportunity. PLoS ONE. 2015;10(7):e0132011. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0132011\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0132011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVultaggio A, Perlato M, Nencini F, Vivarelli E, Maggi E, Matucci A. How to Prevent and Mitigate Hypersensitivity Reactions to Biologicals Induced by Anti-Drug Antibodies? Front Immunol. 2021;12:765747. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2021.765747\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2021.765747\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcMaster M, Mohr K, Page A, Closmore A, Towne F, Brooks BD. Epitope characterization of anti-drug antibodies-a tool for discovery and health: an overview of the necessity of early epitope characterization to avoid anti-drug antibodies and promote patient health. Expert Opin Biol Ther. 2021;21(6):705\u0026ndash;15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/14712598.2021.1863942\u003c/span\u003e\u003cspan address=\"10.1080/14712598.2021.1863942\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAkesson P, Moritz L, Truedsson M, Christensson B, von Pawel-Rammingen U. IdeS, a highly specific immunoglobulin G (IgG)-cleaving enzyme from Streptococcus pyogenes, is inhibited by specific IgG antibodies generated during infection. Infect Immun. 2006;74(1):497\u0026ndash;503. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/IAI.74.1.497-503.2006\u003c/span\u003e\u003cspan address=\"10.1128/IAI.74.1.497-503.2006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHulting G, Flock M, Frykberg L, Lannerg\u0026aring;rd J, Flock JI, Guss B. Two novel IgG endopeptidases of Streptococcus equi. FEMS Microbiol Lett. 2009;298(1):44\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/j.1574-6968.2009.01698.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1574-6968.2009.01698.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGe S, Chu M, Choi J, Louie S, Vo A, Jordan SC, et al. Imlifidase Inhibits HLA Antibody-mediated NK Cell Activation and Antibody-dependent Cell-mediated Cytotoxicity (ADCC) In Vitro. Transplantation. 2020;104(8):1574\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/TP.0000000000003023\u003c/span\u003e\u003cspan address=\"10.1097/TP.0000000000003023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJ\u0026auml;rnum S, Bockermann R, Runstr\u0026ouml;m A, Winstedt L, Kjellman C. The Bacterial Enzyme IdeS Cleaves the IgG-Type of B Cell Receptor (BCR), Abolishes BCR-Mediated Cell Signaling, and Inhibits Memory B Cell Activation. J Immunol. 2015;195(12):5592\u0026ndash;601. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.4049/jimmunol.1501929\u003c/span\u003e\u003cspan address=\"10.4049/jimmunol.1501929\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJordan SC, Legendre C, Desai NM, Lorant T, Bengtsson M, Lonze BE, et al. Imlifidase Desensitization in Crossmatch-positive, Highly Sensitized Kidney Transplant Recipients: Results of an International Phase 2 Trial (Highdes). Transplantation. 2021;105(8):1808\u0026ndash;17. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/TP.0000000000003496\u003c/span\u003e\u003cspan address=\"10.1097/TP.0000000000003496\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCouzi L, Malvezzi P, Amrouche L, Anglicheau D, Blancho G, Caillard S, et al. Imlifidase for Kidney Transplantation of Highly Sensitized Patients With a Positive Crossmatch: The French Consensus Guidelines. Transpl Int. 2023;36:11244. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/ti.2023.11244\u003c/span\u003e\u003cspan address=\"10.3389/ti.2023.11244\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Published 2023 Jun 28.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEarley J, Piletska E, Ronzitti G, Piletsky S. Evading and overcoming AAV neutralization in gene therapy. Trends Biotechnol. 2023;41(6):836\u0026ndash;45. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.tibtech.2022.11.006\u003c/span\u003e\u003cspan address=\"10.1016/j.tibtech.2022.11.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSolid Biosciences. Solid Biosciences Provides SGT-001 Program Update. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.solidbio.com/about/media/press-releases/solid-biosciences-provides-sgt-001-program-update\u003c/span\u003e\u003cspan address=\"https://www.solidbio.com/about/media/press-releases/solid-biosciences-provides-sgt-001-program-update\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Updated November 12, 2019. Accessed November 1, 2023.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePfizer. Pfizer\u0026rsquo;s New Phase 1b Results of Gene Therapy in Ambulatory Boys with Duchenne Muscular Dystrophy (dmd) Support Advancement into Pivotal Phase 3. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.pfizer.com/news/press-release/press-release-detail/pfizers-new-phase-1b-results-gene-therapy-ambulatory-boys\u003c/span\u003e\u003cspan address=\"https://www.pfizer.com/news/press-release/press-release-detail/pfizers-new-phase-1b-results-gene-therapy-ambulatory-boys\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Updated May 15, 2020. Accessed November 2, 2023.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChand DH, Zaidman C, Arya K, Millner R, Farrar MA, Mackie FE, et al. Thrombotic Microangiopathy Following Onasemnogene Abeparvovec for Spinal Muscular Atrophy: A Case Series. J Pediatr. 2021;231:265\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jpeds.2020.11.054\u003c/span\u003e\u003cspan address=\"10.1016/j.jpeds.2020.11.054\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRocket Pharmaceuticals. Rocket Pharmaceuticals Announces Positive Gene Expression, Clinical BiomarkerPreliminary Functional Data from Phase 1 Trial of RP-A501 for the Treatment of Danon Disease. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ir.rocketpharma.com/news-releases/news-release-details/rocket-pharmaceuticals-announces-positive-gene-expression\u003c/span\u003e\u003cspan address=\"https://ir.rocketpharma.com/news-releases/news-release-details/rocket-pharmaceuticals-announces-positive-gene-expression\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Updated December 8, 2020. Accessed November 1, 2023.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGuillou J, de Pellegars A, Porcheret F, Fr\u0026eacute;meaux-Bacchi V, Allain-Launay E, Debord C, et al. Fatal thrombotic microangiopathy case following adeno-associated viral SMN gene therapy. Blood Adv. 2022;6(14):4266\u0026ndash;70. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1182/bloodadvances.2021006419\u003c/span\u003e\u003cspan address=\"10.1182/bloodadvances.2021006419\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeorge JN, Nester CM. Diagnostic approach to suspected TTP, HUS, or other thrombotic microangiopathy (TMA). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.uptodate.com/contents/diagnostic-approach-to-suspected-ttp-hus-or-other-thrombotic-microangiopathy-tma\u003c/span\u003e\u003cspan address=\"https://www.uptodate.com/contents/diagnostic-approach-to-suspected-ttp-hus-or-other-thrombotic-microangiopathy-tma\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e Updated July 11, 2023. Accessed November 1, 2023.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFriese J, Geitmann S, Holzwarth D, M\u0026uuml;ller N, Sassen R, Baur U, et al. Safety Monitoring of Gene Therapy for Spinal Muscular Atrophy with Onasemnogene Abeparvovec -A Single Centre Experience. J Neuromuscul Dis. 2021;8(2):209\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3233/JND-200593\u003c/span\u003e\u003cspan address=\"10.3233/JND-200593\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDay JW, Mendell JR, Mercuri E, Finkel RS, Strauss KA, Kleyn A et al. Clinical Trial and Postmarketing Safety of Onasemnogene Abeparvovec Therapy [published correction appears in Drug Saf. 2022;45(2):191\u0026ndash;192]. Drug Saf. 2021;44(10):1109\u0026ndash;1119. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40264-021-01107-6\u003c/span\u003e\u003cspan address=\"10.1007/s40264-021-01107-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLoo L, Harris S, Milton M, Meena, Lembke W, Berisha F, et al. 2021 White Paper on Recent Issues in Bioanalysis: TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 \u0026amp; CAR-T Immunogenicity; PCR \u0026amp; Vaccine Assay Performance; ADA Assay Comparability \u0026amp; Cut Point Appropriateness (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccine Assays; Immunogenicity of Biotherapeutics and Novel Modalities; Integrated Summary of Immunogenicity Harmonization). Bioanalysis. 2022;14(11):737\u0026ndash;93. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.4155/bio-2022-0081\u003c/span\u003e\u003cspan address=\"10.4155/bio-2022-0081\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLeborgne C, Barbon E, Alexander JM, Hanby H, Delignat S, Cohen DM, et al. IgG-cleaving endopeptidase enables in vivo gene therapy in the presence of anti-AAV neutralizing antibodies. Nat Med. 2020;26(7):1096\u0026ndash;101. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41591-020-0911-7\u003c/span\u003e\u003cspan address=\"10.1038/s41591-020-0911-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTrifir\u0026ograve; G, Marcian\u0026ograve; I, Ingrasciotta Y. Interchangeability of biosimilar and biological reference product: updated regulatory positions and pre- and post-marketing evidence. Expert Opin Biol Ther. 2018;18(3):309\u0026ndash;15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/14712598.2018.1410134\u003c/span\u003e\u003cspan address=\"10.1080/14712598.2018.1410134\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIngrasciotta Y, Cutroneo PM, Marcian\u0026ograve; I, Giezen T, Atzeni F, Trifir\u0026ograve; G. Safety of Biologics, Including Biosimilars: Perspectives on Current Status and Future Direction. Drug Saf. 2018;41(11):1013\u0026ndash;22. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40264-018-0684-9\u003c/span\u003e\u003cspan address=\"10.1007/s40264-018-0684-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIdefirix\u0026reg;, SUMMARY OF PRODUCT CHARACTERISTICS. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ema.europa.eu/en/documents/product-information/idefirix-epar-product-information_en.pdf\u003c/span\u003e\u003cspan address=\"https://www.ema.europa.eu/en/documents/product-information/idefirix-epar-product-information_en.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhan SR, van der Burgh AC, Peeters RP, van Hagen PM, Dalm VASH, Chaker L. Determinants of Serum Immunoglobulin Levels: A Systematic Review and Meta-Analysis. Front Immunol. 2021;12:664526. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2021.664526\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2021.664526\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Published 2021 Apr 7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePupo A, Fern\u0026aacute;ndez A, Low SH, Fran\u0026ccedil;ois A, Su\u0026aacute;rez-Amar\u0026aacute;n L, Samulski RJ. AAV vectors: The Rubik's cube of human gene therapy. Mol Ther. 2022;30(12):3515\u0026ndash;41. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ymthe.2022.09.015\u003c/span\u003e\u003cspan address=\"10.1016/j.ymthe.2022.09.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 5 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"gene-therapy","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"gt","sideBox":"Learn more about [Gene Therapy](http://www.nature.com/gt/)","snPcode":"41434","submissionUrl":"https://mts-gt.nature.com/cgi-bin/main.plex","title":"Gene Therapy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Recombinant human IgG degrading enzyme, AAV-mediated gene therapy","lastPublishedDoi":"10.21203/rs.3.rs-4374237/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4374237/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe approved recombinant adeno-associated virus (AAV) intravenous drugs are limited by the high prevalence of pre-existing anti-AAV antibodies in the general population, which are known to restrict patients’ ability to receive gene therapy and limit transfection efficacy in vivo. Based on that, we developed a novel and low immunogenicity recombinant human immunoglobulin G degrading enzyme (KJ103), which has clinical value in removing anti- AAV antibodies in vivo gene transfer. Herein, we performed two randomized, blinded, placebo-controlled, single ascending dose phase I studies in China and New Zealand, to evaluate pharmacokinetics, pharmacodynamics, safety and immunogenicity of KJ103 in healthy participants. The results comfirmed that KJ103 rapidly reduced IgG and maintained low levels for 1 week. The 0.01 to 0.40 mg/kg dose range of KJ103 had a favorable safety and tolerability profile in healthy participants of different ethnic and gender groups. KJ103 has low percentage of pre-existing ADAs compared to currently licensed human IgG degrading enzyme (i.e. IdeS), and the induced ADAs mostly return to baseline six months after administration. These characteristics are well suited for the treatment of immune disorders, immune rejection, and immunotherapy where pre-existing antibodies reduce efficacy (e.g. AAV-mediated gene therapy in individuals positive for pre-existing anti-AAV antibodies). The potential of KJ103 warrants further exploration.\u003c/p\u003e","manuscriptTitle":"Safety, Efficacy, and Immunogenicity of a Novel IgG Degrading Enzyme (KJ103): Results from Two Randomised, Blinded, Phase 1 Clinical Trials","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-30 19:16:45","doi":"10.21203/rs.3.rs-4374237/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"revise","date":"2024-06-06T15:37:20+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-06-06T09:00:19+00:00","index":2,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-06-03T13:38:02+00:00","index":3,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2024-05-24T08:13:50+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-05-20T12:16:03+00:00","index":3,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-05-17T09:45:08+00:00","index":2,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2024-05-15T11:33:43+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewersInvited","content":"","date":"2024-05-15T10:30:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-07T11:07:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-07T11:07:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Gene Therapy","date":"2024-05-06T05:30:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"gene-therapy","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"gt","sideBox":"Learn more about [Gene Therapy](http://www.nature.com/gt/)","snPcode":"41434","submissionUrl":"https://mts-gt.nature.com/cgi-bin/main.plex","title":"Gene Therapy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ff9182a1-f555-4bdb-ab3a-3036d3d60d25","owner":[],"postedDate":"May 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":31617334,"name":"Health sciences/Diseases/Immunological disorders"},{"id":31617335,"name":"Biological sciences/Drug discovery/Drug delivery"},{"id":31617336,"name":"Biological sciences/Immunology/Autoimmunity"}],"tags":[],"updatedAt":"2025-01-18T08:05:43+00:00","versionOfRecord":{"articleIdentity":"rs-4374237","link":"https://doi.org/10.1038/s41434-025-00512-1","journal":{"identity":"gene-therapy","isVorOnly":false,"title":"Gene Therapy"},"publishedOn":"2025-01-18 05:00:00","publishedOnDateReadable":"January 18th, 2025"},"versionCreatedAt":"2024-05-30 19:16:45","video":"","vorDoi":"10.1038/s41434-025-00512-1","vorDoiUrl":"https://doi.org/10.1038/s41434-025-00512-1","workflowStages":[]},"version":"v1","identity":"rs-4374237","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4374237","identity":"rs-4374237","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}