A Retrospective Review of Ruxolitinib as Acute Graft-Versus-Host Disease Prophylaxis in Pediatric Patients with Transplant Associated Thrombotic Microangiopathy

A Retrospective Review of Ruxolitinib as Acute Graft-Versus-Host Disease Prophylaxis in Pediatric Patients with Transplant Associated Thrombotic Microangiopathy | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 18 July 2025 V1 Latest version Share on A Retrospective Review of Ruxolitinib as Acute Graft-Versus-Host Disease Prophylaxis in Pediatric Patients with Transplant Associated Thrombotic Microangiopathy Authors : Vivian Ho [email protected] , Richard Howrey , Heidi Trinkman , Belaynesh Seyoum , and David Farbo Authors Info & Affiliations https://doi.org/10.22541/au.175282399.92042490/v1 259 views 120 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background: Graft-versus-host disease (GVHD) represents a significant complication following allogeneic hematopoietic stem cell transplantation (HSCT), with tacrolimus being a standard prophylactic agent. However, tacrolimus is associated with transplant-associated thrombotic microangiopathy (ta-TMA), particularly in pediatric patients. Ruxolitinib, a JAK1/2 inhibitor, has emerged as a promising alternative, but its use for aGVHD prophylaxis in pediatric patients with ta-TMA has not been systematically studied. Methods: This retrospective cohort study evaluated pediatric HSCT recipients at Cook Children’s Medical Center from January 2018 to August 2024 who developed ta-TMA while on tacrolimus and were subsequently switched to ruxolitinib for aGVHD prophylaxis. The primary outcome was the incidence of aGVHD within 100 days post-transplant. Secondary outcomes included viral reactivation, time to engraftment, and donor chimerism. Results: Fifteen pediatric patients (median age 4.5 years) received ruxolitinib for aGVHD prophylaxis after developing ta-TMA. None developed aGVHD within the first 100 days post-transplant. Ruxolitinib did not adversely affect engraftment: all patients achieved successful neutrophil and red blood cell engraftment, with malignant disease patients maintaining ≥95% donor chimerism through day 180. Among patients negative for viral infections prior to ruxolitinib, none experienced viral reactivation. Dose adjustments were individualized based on clinical indications, and no significant cytopenias necessitating discontinuation were observed. Conclusion: Ruxolitinib appears to be a safe and effective alternative to tacrolimus for aGVHD prophylaxis in pediatric HSCT recipients who develop ta-TMA, without compromising engraftment or increasing the risk of viral reactivation. These results support further prospective studies to confirm the efficacy and safety of ruxolitinib and to establish standardized dosing protocols in this high-risk population. INTRODUCTION Hematopoietic stem cell transplantation (HSCT) has become a crucial treatment for various hematological malignancies and non-malignant diseases. However, graft-versus-host disease (GVHD) remains a significant challenge, affecting many allogeneic HSCT recipients and contributing substantially to post-transplant morbidity and mortality. Tacrolimus, a calcineurin inhibitor (CNI), has been a cornerstone of acute graft-versus-host disease (aGVHD) prophylaxis for decades, demonstrating efficacy in reducing aGVHD incidence. 1 However, tacrolimus use is associated with serious complications, such as transplant-associated thrombotic microangiopathy (ta-TMA), which occurs in approximately 10-25% of HSCT patients. 2 In recent years, ruxolitinib, a JAK1/2 inhibitor, has emerged as a promising alternative for both GVHD treatment and prevention. A retrospective study looking at pediatric β-thalassemia major patients undergoing allogeneic stem cell transplantation found that adding ruxolitinib to standard GVHD prophylaxis significantly reduced the incidence of grade III-IV aGVHD (0% vs 27.3%, p=0.005) compared to the control group. The ruxolitinib group also showed a trend towards lower overall rates of acute and chronic GVHD, with improved 2-year overall survival (96.3% vs 90.9%; p = 0.428). While not statistically significant, these findings suggest ruxolitinib may be a promising option for aGVHD prophylaxis in this patient population. 3 For pediatric patients developing ta-TMA while receiving tacrolimus for aGVHD prophylaxis, switching to ruxolitinib presents a potential alternative for aGVHD prevention. To date, there have been no published studies evaluating the use of ruxolitinib as an alternative agent for aGVHD prophylaxis in pediatric patients with ta-TMA. The aim of this study was to evaluate ruxolitinib as aGVHD prophylaxis in pediatric patients with ta-TMA. The findings provide additional insight into the safety and efficacy of ruxolitinib as a prophylactic option for patients in whom tacrolimus was discontinued in an effort to avoid contributing to toxicity. METHODS Study Population and Data Collection This retrospective cohort study, conducted at Cook Children’s Medical Center (CCMC) between January 1, 2018, and August 31, 2024, describes the use of ruxolitinib for aGVHD prophylaxis in pediatric patients. Patients were identified through EPIC based on ruxolitinib administration, with those receiving the drug for treatment of acute GVHD subsequently excluded from the analysis. The primary objective was to assess the incidence of aGVHD in patients who switched from tacrolimus to ruxolitinib for prophylaxis due to developing ta-TMA following HSCT. Secondary objectives included evaluating viral reactivation, the time to engraftment and assessing the percentage of donor cell engraftment in patients switched from tacrolimus to ruxolitinib for aGvHD prophylaxis after developing ta-TMA. For the primary endpoint, patients were closely monitored for the development of GVHD following the initiation of ruxolitinib therapy. For the secondary endpoint, viral reactivation was followed and engraftment data was assessed. Full donor engraftment was defined as greater than 95% donor cells, while mixed chimerism would be considered less than 95% recipient cells. Transplant related information such as type of HSCT, conditioning regimen and date of engraftment were collected. Additional data points included information related to ruxolitinib, such as date of initiation and dosing. For safety, viral status before and after ruxolitinib initiation were assessed. Statistical Analysis All data was stored in RedCap and analyzed using SPSS v24.0. Descriptive statistics were used to determine median, interquartile range (IQR), and frequencies of the demographic variables. Due to low sample size, median and IQR were reported instead of mean and standard deviation. Descriptive statistics were also used to determine outcomes for the primary and secondary objectives. RESULTS Forty-two patients were prescribed ruxolitinib during the inclusion dates and were initially screened for inclusion criteria. The final study cohort consisted of 15 pediatric patients (median age 4.5 years, median weight 20.2 kg; 46.7% male, 53.3% female) who received ruxolitinib as prophylaxis for aGVHD, with a median prophylaxis duration of 91 days and ruxolitinib initiated at a median of 25.5 (5-49) days post-transplant. Of these, ten patients had a non-malignant condition, including sickle cell disease (SCD), primary hemophagocytic lymphohistiocytosis, and osteopetrosis, while five patients were diagnosed with acute leukemia (Table 1). The majority of these patients underwent matched related donor bone marrow transplantation. With regard to ruxolitinib administration, there was no prospectively determined dosing protocol. Table 2 summarizes the initial ruxolitinib doses administered in this cohort, stratified by patient weight. Three patients were dosed outside of these dose bands due to physician preference. Dose reductions were implemented in response to specific clinical indications, including cytopenia, increased mixed chimerism, pre-existing viral infections (such as cytomegalovirus (CMV) or Epstein–Barr virus (EBV)), or potential drug-drug interactions. All dose modifications involved reductions. In addition, some patients underwent planned dose tapering for ruxolitinib discontinuation. Fig. 1 illustrates the total number of patients who required dose reductions. When assessing the primary objective, none of the 15 patients who received ruxolitinib prophylactically developed aGVHD within the first 100 days post-transplant. The secondary objective of this study was to assess the time to engraftment and evaluate whether ruxolitinib influenced the percentage of donor engraftment in these patients. All patients had engrafted prior to the initiation of ruxolitinib with the exception of one patient in whom ruxolitinib was started at day +25, shortly after there had been presumed graft rejection. This patient was maintained on ruxolitinib through her second transplant and successfully engrafted. Fig. 2 illustrates donor engraftment percentages at days 30, 60, and 180 post-transplant for both the non-malignant and malignant groups. The data indicate that ruxolitinib did not adversely affect engraftment rates in either group. Patients with malignant disease consistently demonstrated high levels of donor engraftment, maintaining at least 95% of engraftment through day 180. All patients had achieved neutrophil engraftment at the time of ruxolitinib initiation, except for one with primary graft failure who subsequently engrafted after a second transplant with continuation of ruxolitinib from a 9/10 matched unrelated donor. With the non-malignant group, majority of patients in this cohort were diagnosed with sickle cell disease. All sickle cell patients in our cohort achieved approximately 100% red blood cell (RBC) engraftment. Hemoglobin S (HbS) solubility being negative is the equivalent of no HbS detected. As illustrated in Fig. 3, patients with trait donors maintained residual HbS levels around 30%, while those with non-trait donors showed no detectable residual HbS. Assessment of viral status before and after initiation of ruxolitinib revealed that eight patients were negative for active viral infections prior to switching to ruxolitinib (Table 3). Notably, none of these eight patients experienced viral reactivation following ruxolitinib administration. Three patients in the cohort did not survive, with an overall survival rate of 80% in this study population. One patient developed late-onset ta-TMA accompanied by severe respiratory failure. Another patient experienced a complex clinical course involving severe veno-occlusive disease (VOD), ta-TMA, and CMV pneumonitis, ultimately requiring extracorporeal membrane oxygenation (ECMO). The third patient succumbed to acute lung toxicity attributed to busulfan, which progressed to worsening respiratory failure. DISCUSSION In this retrospective study, dosing practices were individualized, reflecting the absence of a standardized protocol. Most patients were dosed according to weight-based bands, with adjustments made for clinical indications such as cytopenia, mixed chimerism, or viral infections. All dose adjustments involved reductions in response to specific clinical indications. This pragmatic approach underscores the need for prospective studies to establish optimal dosing strategies for pediatric patients. Zhao et al. investigated the use of ruxolitinib as replacement of a CNI for pediatric patients, ages 14 years and older, that did not tolerate a CNI for GVHD prophylaxis. The results showed that only 1 out of 10 patients developed grade II aGVHD within 100 days post-transplant and the 1-year cumulative incidence of moderate/severe chronic GVHD was 21.4%. The study reported a 70% overall survival rate after a median follow-up of 11 months, suggesting that ruxolitinib could be a promising alternative for aGVHD prophylaxis in patients intolerant to calcineurin inhibitors. 4 These findings are consistent with our results, as we observed no cases of aGVHD following ruxolitinib initiation for prophylaxis. Our analysis demonstrated that replacing tacrolimus with ruxolitinib, as prophylaxis for aGVHD in patients experiencing ta-TMA, was effective in 100% of our patients, with no patients developing aGVHD within the first 100 days post-transplant. This finding is particularly significant given the high-risk nature of the patient cohort, which included both malignant and non-malignant conditions. The absence of aGVHD in our cohort aligns with emerging evidence supporting the efficacy of ruxolitinib in the prevention of GVHD. For example, a retrospective study of 35 aplastic anemia patients, including both adults and children, undergoing allogeneic HSCT found that adding ruxolitinib to standard of care GVHD prophylaxis significantly reduced the incidence of moderate to severe aGVHD and infections. The study also showed that the addition of ruxolitinib improved GVHD-free and failure-free survival without impacting engraftment. 5 Given the absence data on ruxolitinib for aGVHD prevention in patients who develop ta-TMA while receiving tacrolimus, our findings suggest that ruxolitinib may serve as a viable prophylactic alternative to tacrolimus. Our study found that ruxolitinib did not appear to compromise engraftment outcomes. Both malignant and non-malignant patients achieved effective donor engraftment, with those in the malignant group maintaining at least 95% donor chimerism through day 180 post-transplant. All patients, including those with non-malignant conditions, achieved at least stable mixed chimerism, indicating that ruxolitinib did not adversely affect engraftment stability. With sickle cell transplantation, patients with sickle cell disease do not require full donor chimerism to achieve a cure. Donor graft chimerism in our patients with sickle cell disease ranged between 70.8 and 100%, however RBC donor engraftment, the key to reversing the disease, appeared to be closer to 100% in all sickle cell patients. In this study, all patients had close to 100% engraftment of RBC lineage based on RBC % or hemoglobin electrophoresis. In patients who receive grafts from donors with sickle cell trait (HbAS), the resulting red blood cell population will include both donor-derived cells (containing approximately 30% hemoglobin S per cell) and residual host cells (containing 100% hemoglobin S per cell). There is no well-established threshold for the proportion of host-derived RBCs that can be considered safe or curative, as even patients with less than 30% total hemoglobin S, such as those maintained on chronic transfusions, can still experience complications. For example, a patient with 70% donor trait cells and 30% host cells would have a total hemoglobin S percentage just over 50%, which may not be sufficient to prevent sickling-related complications or to be considered a cure. Fortunately, in our cohort, all patients achieved full donor red cell engraftment, eliminating this concern. The safety profile of ruxolitinib in our cohort was favorable. Among the eight patients who were negative for viral infections prior to ruxolitinib initiation, none developed viral reactivation during prophylaxis, suggesting that ruxolitinib did not increase the risk of viral reactivation in this population. Although three patients experienced significant complications resulting in mortality, these events were not attributable to ruxolitinib use. Furthermore, the median initiation of ruxolitinib at day +25.5 post-transplant indicates that early post-transplant administration was well tolerated and safe within our cohort. However, in the report by Zhao et al., they observed that while ruxolitinib was effective as GVHD prophylaxis in pediatric patients intolerant to CNIs, it was associated with notable hematologic adverse effects. In their cohort, 40% of patients developed grade II cytopenia, and two patients required dose reduction or discontinuation due to grade III cytopenia. Viral reactivations were also observed, with CMV DNAemia in 40% and EBV reactivation in 30% of patients; however, these infections were successfully managed with preemptive therapy, and no cases of CMV disease or EBV-associated lymphoproliferative disorder occurred. Notably, the 100-day non-relapse mortality was 10%, with one patient succumbing to severe infection and complications unrelated to ruxolitinib itself. In contrast, our cohort did not experience significant cytopenias necessitating ruxolitinib discontinuation, and viral reactivation was not observed in previously negative patients, suggesting that while cytopenias and viral reactivation are important risks to monitor, the incidence may vary depending on other factors such as patient population and underlying conditions. 5 The strengths of this study include well-defined inclusion and exclusion criteria, and the duration of data collection spanning over five years. Despite the promising findings, several limitations warrant consideration. Limitations of this study include the retrospective, single-center design and the relatively small cohort of only 15 patients, which may limit the generalizability of the findings. Additionally, the absence of a standardized dosing protocol for ruxolitinib prospectively posed challenges in evaluating the optimal starting dose for each patient. Future studies should aim to include larger, multi-center cohorts and prospective, randomized designs to better delineate the efficacy and safety of ruxolitinib for aGVHD prophylaxis. CONCLUSION In this retrospective study, it was found that ruxolitinib is a feasible and potentially effective alternative to tacrolimus for aGVHD prophylaxis in pediatric HSCT recipients who develop TA-TMA, without adversely affecting engraftment or increasing viral reactivation risk in both malignant and non-malignant patients. These findings support further investigation of ruxolitinib in larger, controlled studies to validate its role in this setting and to optimize dosing protocols for diverse pediatric populations. Conflicts of Interest: The authors have no relevant conflicts of interest to disclose. Acknowledgements : Cook Children’s Medical Center Forth Worth, Texas References 1. Bolaños-Meade J, Reshef R, Fraser R, et al. Three prophylaxis regimens (tacrolimus, mycophenolate mofetil, and cyclophosphamide; tacrolimus, methotrexate, and bortezomib; or tacrolimus, methotrexate, and maraviroc) versus tacrolimus and methotrexate for prevention of graft-versus-host disease with haemopoietic cell transplantation with reduced-intensity conditioning: a randomised phase 2 trial with a non-randomised contemporaneous control group (BMT CTN 1203). Lancet Haematol. 2019;6(3):e132-e143. doi:10.1016/S2352-3026(18)30221-7 2. Jodele S, Zhang K, Zou F, et al. The genetic fingerprint of susceptibility for transplant-associated thrombotic microangiopathy. Blood. 2016;127(8):989-996. doi:10.1182/blood-2015-08-663435 3. Hong X, Chen Y, Lu J, Lu Q. Addition of ruxolitinib in Graft-versus-Host disease prophylaxis for pediatric β-Thalassemia major patients after allogeneic stem cell transplantation: A retrospective cohort study. Pediatr Transplant. 2023;27(2):e14466. doi:10.1111/petr.14466 4. Zhao Y, Shi J, Luo Y, et al. Calcineurin Inhibitors Replacement by Ruxolitinib as Graft-versus-Host Disease Prophylaxis for Patients after Allogeneic Stem Cell Transplantation. Biol Blood Marrow Transplant. 2020;26(5):e128-e133. doi:10.1016/j.bbmt.2020.01.012 5. Zhang X, Zhao X, Chen S, et al. Addition of ruxolitinib to standard graft-versus-host disease prophylaxis for allogeneic stem cell transplantation in aplastic anemia patients. Bone Marrow Transplant. 2024;59(7):997-1005. doi:10.1038/s41409-024-02266-7 6. Lebon D, Dujardin A, Caulier A, et al. Ruxolitinib-induced reactivation of cytomegalovirus and Epstein-Barr virus in graft-versus-host disease. Leuk Res. 2023;125:107005. doi:10.1016/j.leukres.2022.107005 Supplementary Material File (manuscript_tables_figures (1).docx) Download 145.57 KB File (manuscript_tables_figures.docx) Download 145.57 KB Information & Authors Information Version history V1 Version 1 18 July 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords graft vs host disease pediatric oncology stem cell transplantation transplantation Authors Affiliations Vivian Ho [email protected] Cook Children's Medical Center View all articles by this author Richard Howrey Cook Children's Medical Center View all articles by this author Heidi Trinkman Cook Children's Medical Center View all articles by this author Belaynesh Seyoum Cook Children's Medical Center View all articles by this author David Farbo Cook Children's Medical Center View all articles by this author Metrics & Citations Metrics Article Usage 259 views 120 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Vivian Ho, Richard Howrey, Heidi Trinkman, et al. A Retrospective Review of Ruxolitinib as Acute Graft-Versus-Host Disease Prophylaxis in Pediatric Patients with Transplant Associated Thrombotic Microangiopathy. Authorea . 18 July 2025. 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