Nanocarrier drug delivery systems for gynecological cancer therapeutics.

Nanocarriers for chemotherapeutics and immunotherapeutics increase the circulation time and half-life of the drugs, thereby increasing the efficacy. This addresses critical challenges for drugs with poor solubility, such as paclitaxel. Numerous nanoparticle and microparticle constructs have been FDA-approved for specific anti-cancer uses. Polymeric drug delivery systems utilize polymers from synthetic sources, such as polyethylene glycol, poly(lactic- co -glycolic acid), or natural sources such as chitosan or dextran to enhance drug and gene delivery [ 114 ]. Polymeric carriers enhance circulation, overcome organ barriers, and improve endocytosis, which contribute to enhanced drug efficacy [ 115 ]. Some of these polymers also serve as excipients, which are polymers included in the formulation to improve the delivery of the active pharmaceutical ingredient, commonly used in suppositories or with vaginal delivery. Poly(ethylene glycol) (PEG) is one of the most widely used polymers for drug delivery systems as both an excipient and component of biodegradable polymers. PEG has high water solubility, prolonged circulation times, stealth properties [ 116 ], and PEG is a neutral polymer that has been classified by the FDA as Generally Regarded as Safe (GRAS) [ 117 ]. PEG has been used in both food and pharmaceutical applications [ 117 , 118 ]. As an excipient, PEG can be used as a solvent, plasticizer, surfactant, suppository, or lubricant in oral drug delivery forms. As a DDS, PEG is commonly added to enhance the stealth properties of the DDS, allowing for longer circulation time by evading the immune system. PEG is perhaps the most common co-polymer in drug delivery systems and therefore is presented within the other sections as a co-polymer rather than in this section. Polypropylene is a polymer commonly used for multi-layer films in food packaging, automotive parts, medical devices, and others, including propylene glycol as an excipient. In drug delivery, polypropylene may be combined with other polymers to facilitate sustained-release drug delivery. Everolimus is a mTORC1 inhibitor that has shown clinical benefit for treating advanced and recurrent disease, but also has severe side effects limiting the ability to achieve adequate therapeutic doses. This inefficiency for delivering everolimus in the therapeutic range is a key area where sustained release DDS may be advantageous. Additionally, everolimus stents have been successfully employed in cardiovascular surgery [ 119 ], and were recently applied as a uterine implant, indicating a strong potential for translation to gynecological cancers. Researchers developed a polypropylene fumarate (PPF) and N-vinylpyrrolidone (NVP) crosslinked uterine implant [ 120 ]. These rods were 2 mm by 10 mm and implanted into murine uteri, resulting in controlled release of everolimus over 80 days with limited systemic exposure compared with oral delivery of everolimus. Furthermore, the rods showed good biocompatibility with limited macrophage recruitment, indicating a low inflammatory response. The implementation of polymers as uterine implants benefits from the long-standing acceptance of intrauterine devices (IUDs) for contraceptive delivery, and therefore, is a promising method for polymeric DDS in gynecological cancer. Dendrimers are a form of a nano-based drug delivery system with three major components including a core, branches, and terminal groups. These branches originate at the centralized core, and are capped by the terminal groups on the other end [ 121 ]. In fact, the word dendrimer is derived from the Greek “dendron” which translates to tree or branch [ 122 ]. Paul Flory theorized these structures in the 1940s [ 123 ], but it wasn’t until over 35 years later that researchers began synthesizing these compounds [ 124 ]. Poly(amidoamine) (PAMAM) was first synthesized in the 1980s and consists of branched amine and amide subunits [ 125 ]. These dendrimers are highly branched from a centralized core, resulting in high organization and a spherical shape [ 126 , 127 ]. When paclitaxel, a common off-label chemotherapeutic in endometrial cancer, and a BCS class IV drug with low solubility and low permeability [ 128 ], is encapsulated into PAMAM dendrimers, the solubility drastically increased by 9000-fold [ 129 ]. This mitigates a critical concern in paclitaxel delivery, which has poor water solubility and is therefore typically diluted in a sodium chloride and dextrose solution prior to intravenous injection. ¶Estrogen receptor (ER) targeting has been widely investigated for gynecological cancers, including ovarian and endometrial cancers, due to the hormonal signatures of these cancers ( Section 2.3 ). Specifically, pre-menopausal onset of endometrial cancer is often linked to ER-positive subtype [ 130 ]. Lewinska et al. developed a PAMAM dendrimer conjugated with lapatinib, a dual inhibitor of EGFR and HER2 tyrosine kinases, and fulvestrant, a selective estrogen receptor degrader, for dual targeting of HER2-positive and ER-positive breast cancers, respectively [ 131 ]. Although investigated in breast cancer, gynecological cancers also exhibit hormone positivity, and therefore, these findings may be readily transferred to gynecological cancers. Like PEG, PLGA use in DDS originated as an excipient [ 132 ]. PLGA is a copolymer of poly(lactic acid), PLA, and poly(glycolic acid), PGA. The first FDA-approved PLGA-based drug delivery system, in which PLGA was used to encapsulate the API and provide sustained-release, was approved in 1989 for Lupron ® Depot (LD) [ 133 ]. Lupron ® Depot requires a prescription containing leuprolide acetate, a gonadotropin-releasing hormone (GnRH) agonist, in a PLGA or PLA drug delivery system [ 134 ]. GnRH plays a critical role in the reproductive system’s hormonal balance in all humans. For example, GnRH has been used to successfully reduce the size of ovarian endometriomas resulting from endometriosis, and in the treatment of prostate cancer [ 135 , 136 ]. Several long-acting GnRH therapeutics are already on the market, with many more under development [ 137 ]. ¶ The composition-equivalent PLGA microsphere formulations to the 1-month LD had longer release kinetics when PLGA was prepared using a polycondensation reaction mechanism compared with a ring-opening polymerization [ 134 ]. This ring-opening polymerization mechanism also reduced the initial burst release, bringing the release profile closer to the commercially available LD [ 134 ]. This group also investigated spray-dried leuprolide PLGA microspheres and discovered that spray drying also reduces the initial burst release, dependent upon the spray dryer conditions [ 138 ]. In ovarian cancer, the adjuvant therapy monophosphoryl lipid A (MPLA) encapsulated within PLGA enhanced the immunotherapy efficacy as evaluated by quantifying tumor-specific antigens following chemotherapy [ 139 ]. PLGA scaffolds loaded with metformin and the FIK inhibitor Y15 resulted in enhanced caspase 3-mediated apoptosis in platinum-resistant OVCAR3 ovarian cancer cells over either metformin or Y15 alone [ 140 ]. In contrast, to PLGA microspheres, PLA microspheres prepared from an emulsion evaporation process released cargo in a triphasic pattern over 6 months (180 days) [ 141 ]. This triphasic release had a burst release phase, followed by a diffusion-mediated release phase, and finally an erosion-mediated release phase. The diffusion-mediated release phase contained the greatest quantity of drug released over the 180-day study. Additionally, another study demonstrated that the pharmacokinetics in mice for PLA-PEG block copolymers differed based on particle diameters. Large particles (145 nm average diameter) accumulated more in the liver and spleen whereas medium particles (110 nm average diameter) accumulated more in the ovaries and adrenals [ 142 ]. This highlights the importance of size in DDS development, especially for non-functionalized DDS for location(s) of accumulation. Poly(caprolactone) (PCL) is an aliphatic polyester formed from the ring-opening polymerization of ε-caprolactone [ 143 ]. PCL is commonly used for slow-degrading applications, such as drug eluting stents or wound healing dressings [ 144 ]. Most instances of PCL in DDS are electrospun fibers, rather than spherical particles. These meshes generally have drug dispersed throughout as a result of the electrospinning process and undergo sustained-release, like particle-based DDS. Furthermore, electrospinning is considered a “solvent free” method, which can decrease the likelihood of DDS toxicity in vivo [ 145 ]. In tumor therapy of ovarian cancer, an electrospun mat of PCL and daunorubicin resulted in daunorubicin release of 72 hours (3 days) [ 145 ]. Since these mats are akin to stents and wound dressings, they are developed with the intention of local drug delivery rather than systemic delivery with enhanced tumor specificity. Polyvalerolactone (PVL) is another polyester with properties comparable to those of PCL [ 146 ]. Paclitaxel-loaded poly(delta-valerolactone-co-allyl-delta-valerolactone) (PVL-co-PAVL) microparticles had first-order drug release over 19 days, and paclitaxel was detectable in the serum of Sprague-Dawley rats for 19 days following subcutaneous deposition, which demonstrates promise that these microparticles may be used for sustained-release drug delivery systems [ 147 ]. Importantly, the authors also investigated the fit of the release data to zero-order release, wherein drug release would be constant over time, and revealed that this microparticle formulation had extremely poor linear release of drug (R 2 = 0.285). Combined with the in vivo serum data from rats, the authors demonstrated that despite the first-order kinetics, which typically are considered non-ideal for sustained therapeutic levels, there was still much promise in this formulation. This was the first investigation of this copolymer for this DDS. HPMA is a water-soluble biomaterial for drug delivery that originated in the 1970s, and underwent rapid development from inception to conjugation and release studies, and clinical trials began in 1999 [ 148 ]. HPMA was developed to leverage the reported success of acrylic acid-derived polymers in drug delivery systems [ 148 ]. As with other polymeric drug delivery systems, the molecular weight or the chain length of these HPMA constructs can be used to mediate circulation time, which provides an innate tunable property for developing and optimizing these DDS [ 149 ]. One formulation was developed with a long-chain, multi-block doxorubicin conjugate, and resulted in improved outcomes in ovarian carcinoma xenograft tumors in nude mice, compared with earlier-generation HPMA [ 149 ]. Importantly, compared with other polymers wherein molecular weight plays an important role in delivery and degradation, Pan et al. identified that increasing the molecular weight of HPMA had no effect on efficacy, and rather the chain length was the driving factor. The Kopecek group also conducted studies using gemcitabine and paclitaxel as the model chemotherapeutics, a multiblock HPMA conjugate with both drugs conjugated to the same HPMA polymer backbone. As with the doxorubicin investigations, these multiblock conjugates outperformed free drugs and traditional (earlier-generation) conjugates in A2780 human ovarian cancer cells [ 150 ]. Similarly, sequential exposure of A2780 ovarian cancer cells to gemcitabine-HPMA conjugates followed by DACH platinum-conjugates enhanced cell death [ 151 ]. This also provides an opportunity to adapt these conjugates from ovarian cancer therapeutics to endometrial cancer therapeutics because DACH is a potential target in endometrial cancer as well, consistent with gene expression and mutation rates ( Figure 3 ) [ 60 ]. Furthermore, as mentioned in Section 3.3 and Table 2 , many chemotherapeutics used off-label in endometrial cancer are FDA-approved for treating ovarian cancer, indicating that ovarian cancer studies may be precursors to endometrial cancer therapeutic development. Liposomes are a method of drug delivery where the outer surface is comprised of a lipid layer and the cargo is contained within this construct. Target-specific liposomes can be designed with stimuli-responsive properties such as temperature or enzymatic activation [ 152 ]. Furthermore, the enhanced circulation time with lipid-based delivery greatly increases tumor accumulation of chemotherapeutics [ 153 ]. Liposomal doxorubicin first showed efficacy in metastatic vulvar adenocarcinoma, which had metastasized to the brain, lung, liver, bone, and subcutaneous space, in a 65-year-old patient in 2002 [ 154 ]. A meta-analysis of cancer prognosis following liposomal doxorubicin treatment was conducted and demonstrated that liposomal delivery may improve overall survival and progression-free survival in approximately one-quarter (25%) of the patients receiving the therapy [ 155 ]. PEGylated liposomal doxorubicin (PLD), which is expected to increase circulation time and evade the immune system via PEGylation, was first FDA-approved in 1995, and PLD primarily treats relapsed ovarian and metastatic breast cancers [ 156 ]. PEGylation is one method by which combinations of materials can enhance DDS efficacy. Although chemotherapeutics are often prescribed as combination therapies of more than one chemotherapy drug, encapsulation into a single drug delivery formulation proves challenging. For example, gemcitabine and paclitaxel co-loaded liposomes had unfavorable release kinetics, because the co-release of drugs was competitive and therefore inhibited each drug from achieving maximum efficacy. However, sequential delivery of these chemotherapeutics using liposomes elicited greater cytotoxic effects in SKOV-3 human ovarian cancer cells compared to either drug-liposome in mono-delivery [ 157 ]. The efficacy of paclitaxel-liposomes was also investigated in vivo using a paclitaxel-conjugated PEGylated liposome successfully enhanced the stealth properties of the DDS, resulting in suppressed ovarian cancer proliferation in CAOV-3 ovarian cancer in vitro and in vivo in BALB/c mice [ 158 ]. Another investigation of paclitaxel-loaded liposomes incorporated tumor-associated macrophages (TAMs). TAMs are an immunotherapy method commonly coupled with nano-drug delivery systems to improve efficacy of chemotherapeutic drugs [ 159 ]. Specifically, TAMs are macrophages that accumulate within the tumor microenvironment and contribute to tumor formation and progression. Therapeutically, these TAMs are used for immunosuppression of the tumor microenvironment, thereby enhancing the effects of chemotherapeutics [ 160 ]. Paclitaxel and TAMs were combined into a single liposome that was surface functionalized with folliclestimulating hormone (FSH) for ovarian cancer treatment it enhanced cell apoptosis above all other controls, including unfunctionalized co-loaded liposomes [ 161 ]. The FSH functionalization improves ovarian cancer targeting through receptor-mediated interactions, therefore enhancing the probability of success when translating therapeutics throughout the drug development pipeline. Metal-based chemotherapeutics are an ideal candidate for endometrial cancer therapy due to metal ions interacting with cancer cell DNA, proteins, and cell components that inhibit cancer cell growth [ 18 , 162 - 166 ]. Various platinum-based chemotherapies, such as cisplatin and carboplatin, hold current FDA approval for treatment of various cancers and are commonly used in clinical practice to treat ovarian and endometrial cancers ( Table 2 ). To date, the only metal nanoparticle-based therapy for gynecological cancers is NBTXR3 (hafnium oxide) in a Phase I clinical trial ( NCT03589339 ) for metastasis from malignant tumors of the cervix at UCSF ( Table 3 ). However, research into novel therapeutics using metals, metal oxides, and metal organic frameworks has grown in recent years with research into gold-, selenium-, zinc-, silver-, iron-, titanium-, and copper-based materials as potentially anti-neoplastic agents for gynecological cancer therapy. Further investigation of these materials will help overcome challenges associated with gynecological cancer therapeutic efficacy. Pure metal nanoparticles such as gold, selenium, silver, titanium, and platinum have promising potential as gynecological cancer therapies [ 162 , 165 , 166 ]. In a study by Yassein et al. , selenium nanoparticles (SeNPs) decorated with Spirulina polysaccharides (SP-SeNPs) demonstrated cytotoxicity towards cervical cancer cells and inhibited monolayer growth of ovarian cancer cells [ 165 ]. The cytotoxic effect of these metal nanoparticles was attributed to the disruption of cellular homeostasis through the production of reactive oxygen species (ROS), DNA damage, and apoptosis of cancer cells [ 165 ]. Furthermore, in vitro studies of SeNPs and gold nanoparticles (AuNPs) suppressed colony formation of early-stage ovarian adenocarcinoma A2780 cells due to changes in oxidative stress biomarkers [ 167 ]. Green synthesized AuNPs exhibit cytotoxicity to endometrial cancer cell lines in a dose-dependent manner and exhibit lower toxicity in healthy cell models in vitro [ 162 ]. These synthesized AuNPs with flavonoids and phenolic compounds exhibit antioxidant properties and the ability to inhibit cancer cell growth by removal of free radicals [ 162 ]. AuNPs provide an attractive drug delivery carrier to overcome challenges of drug delivery to gynecological tissues as they provide stability in the tumor microenvironment, selectivity to cancerous cells, and controlled release of drug cargo into tumor cells [ 168 ]. Iron-based nanoparticles presented significant cytotoxic properties based on cell viability results, depletion of glutathione (GSH), a natural occurring antioxidant in cells, and accumulation of reactive oxygen species (ROS) within the cell [ 163 ]. However, mitophagy, the removal of defective mitochondria, was cytoprotective against the oxidative stress induced by introduction of iron-based nanoparticles [ 163 ]. Silver nanoparticles (AgNPs) synthesized from Anabaena variabilis have also demonstrated anticancer potential to the HeLa and SiHa cervical cancer cell lines while demonstrating limited toxicity to normal human embryonic kidney cells of non-diseased state, HEK293, with in vitro studies [ 166 ]. The HeLa cell line is a model for aggressive cervical adenocarcinoma, and the SiHa cell line is early stage moderately differentiated squamous cell carcinoma. These differences in both cervical cancer type and stage enhance the scope of the pre-clinical investigations, improving the likelihood for clinical translation using a breadth of models. Metal nanoparticles have been studied as potential anti-cancerous materials due to their special surface characteristics and dose-dependent cytotoxicity to cancerous cells. The limited cytotoxicity to healthy human cells shows a potential targeted response and a promising foundation for integration into drug delivery systems for gynecological cancers. Gong et al. used in vitro studies with high-grade, aggressive endometrial adenocarcinoma, KLE cells, and low-grade, early-stage, hormone-responsive endometrial adenocarcinoma, Ishikawa cells, to examine the therapeutic properties of synthesized iron-based nanoparticles. Additionally, these two cell lines have known differences in chemotherapeutic responses, which make them excellent for comparison-based investigations on novel therapeutics [ 169 , 170 ]. Metal nanoparticle carriers can overcome many of the challenges to drug delivery to gynecological tissues through minimal toxicity to healthy cells while providing dose-dependent toxicity to malignant cells. These particles are also stable resulting in extended delivery in the complex tumor microenvironment of gynecological tissues. Additionally, these metal nanoparticle systems have shown to effectively reduce gynecological cancer cell proliferation in a variety of cancer cell aggressiveness proving to be a promising therapeutic agent against many forms of gynecological cancers. Further development and in vivo studies will allow for the progression of this therapeutic to clinical trials. Metal oxide (MeOx) nanoparticles such as zinc oxide (ZnO), iron oxide (Fe2O3), aluminum oxide (Al2O3), copper oxide (CuO), and titanium dioxide (TiO2) have been investigated as potential therapies for endometrial and other female upper genital tract cancers [ 18 , 167 ]. Although ZnO nanoparticles have been viewed as a cheap, non-toxic, and relatively biocompatible nanoparticle carrier [ 171 ], these particles have been shown to exhibit toxicity towards ovarian cancer through ROS production via surface catalytic reactions between O 2 and nanoparticle surface defects [ 164 ]. In vivo studies in mice provide evidence of ZnO nanoparticles causing oxidative stress, endoplasmic reticulum stress, and apoptosis to the ovaries in a dose-dependent manner of increasing Zn accumulation in the ovary [ 164 ]. It was also revealed that ZnO nanoparticles resulted in a damage to the ovarian function as described by the decrease in serum levels of the sex hormones estradiol and progesterone at doses ≥ 100 mg/kg [ 164 ]. This toxicity can be harnessed as a therapeutic as discussed in Irannejad et al. through comparison of toxicological responses between early-stage A2780 ovarian adenocarcinoma cells and human dermal fibroblasts (HDF) as a normal healthy control [ 167 ]. Selective toxicity, a common characteristic of ROS-generating nanoparticles, to cancerous cells was evident by low IC50 values for A2780 (6.03 ± 0.538 μg/mL) and high values for HDF cells (248.4 ± 564 μg/mL) after 72 hours of exposure [ 167 ]. Further in vitro studies exploring the effect stage, grade, and metastatic status has on therapeutic response will validate the potential of ZnO nanoparticles as a relevant candidate for clinical trial testing. Titanium dioxide has been increasingly investigated in combination with UV radiation for targeting gynecological tumors without the need for additional anti-neoplastic agents. When exposed to UV radiation, TiO 2 nanoparticles have been shown to be successful in eliminating HeLa cervical adenocarcinoma cells, however, UV light is only able to penetrate up to 1 mm thickness of skin unless fiber optics or surgery are also used [ 172 ], indicating limited potential as a drug delivery system for gynecological cancer as a sole therapy. These studies demonstrate how metal-based and metal oxide nanoparticles’ inherent toxicity can be harnessed as a potential therapeutic material for gynecological cancer and the increased research efforts to study the mechanistic effects of these materials. Harnessing these effects into combined therapies with existing pharmacologically active compounds FDA-approved for cancer therapy in engineered drug delivery systems could lead to enhanced reduction of late-stage, high-grade, and more aggressive forms of gynecological cancers, overcoming the challenges associated with current treatment strategies. Development of these drug delivery systems for advanced cancers can reduce the need for surgical intervention. Metal organic frameworks (MOFs) have gained increasing research attention for drug delivery for their unique properties. MOFs are a broad class of crystalline materials that have up to 90% free volume, or porosity, leading to exceptionally high surface areas [ 173 ]. MOFs have been investigated as potential drug delivery systems because of the tunability of parameters such as pore size and internal surface chemistry properties [ 173 ]. These properties can lead to the stability of pharmacologically active compounds until the intended site of action is reached and controlled release of therapeutics in a responsive manner. These materials are based on three key chemical components: the metal, the functional groups, and the linker between these groups [ 174 ]. In a study by Jam et al. the MOFs drug delivery carrier of UiO-66-VIN-PEG (zirconium-based structure) proved to be an effective anti-cancer therapy due to enhanced apoptosis and cytotoxicity against A2780 ovarian adenocarcinoma cells [ 175 ]. Their designed system showed a pH-responsive release profile to increasingly acidic environments, which is a hallmark of the tumor microenvironment [ 175 ]. This cytotoxicity was attributed to the altered expression of regulatory genes such as BAX, BCL2, P53, CCND1, and CDK4 and ROS generation leading to apoptosis [ 175 ]. These same researchers also demonstrated a functionalized MOFs to deliver cisplatin to ovarian cancer cells in vitro [ 176 ]. Their formulation of UiO-66-NH 2 -CIS-FA was biocompatible in healthy cells yet showed significant toxicity and ROS generation in ovarian cancer cells [ 176 ], further demonstrating the selective toxic properties of metal-based materials against cancer cells. MOFs have seen an increase in research and application to overcome resistance to existing treatments, including radiotherapy [ 177 ]. MOFs have been effective at target delivery of inhibitors and bismuth to enhance the sensitivity to radiotherapy in HeLa and SiHa cervical cancer cells in vivo [ 177 ]. This targeted delivery can overcome the current issues of off-target toxicity and increase drug accumulation in gynecological cancer tumors. Metal organic frameworks, although not heavily studied in less common endometrial and vulvovaginal cancers, show a promising new avenue for drug delivery in gynecological cancer due to their high drug loading and release capacity, controlled release, functionalized ability, and pH-responsive properties overall increasing their targetability. Extracellular vesicles (EVs) are membrane-bound particles released by all cells [ 178 , 179 ]. EVs can be used for cancer diagnostics and therapeutics because they are naturally taken up by cells and therefore provide excellent targeting ability [ 178 ]. Exosomes are one subtype of EVs that mediate intercellular communications. Similar to PEG, exosomes have high biocompatibility, low immunogenicity, and wide biodistribution and versatility in potential cargo [ 180 ]. Exosomes also have great promise for modulating cell signaling through receptor-binding. In cancer, exosomes can dock with overexpressed receptors such as the epidermal growth factor receptor (EGFR) or transforming growth factor alpha (TGFα). A cancer-associated fibroblast (CAF)-hybrid cell membrane vesicle was used to co-delivery the chemotherapeutic carboplatin and the siRNA targeting p65 (sip65) in ovarian cancer, and these constructs reversed the tumor-promoting properties of extracellular matrix proteins [ 181 ]. PEGylated tumor cell membrane particles significantly improved survival in mice challenged with B16F10 melanoma [ 182 ]. Importantly, B16F10 melanoma is impacted by the estrous cycle and therefore has links to hormone- and female-related cancers such as endometrial cancer [ 183 ]. The human epidermal growth factor 2 (HER2) receptor is common in numerous cancers, including breast, endometrial, cervical, ovarian, bladder, pancreatic, and other cancers [ 184 ]. HER2 overexpression is common in aggressive tumors and is therefore associated with both poor prognoses and increased risk of recurrence [ 184 ]. Therefore, targeting HER2 receptors is a common area of research and investigation. Hosseini et al . prepared exosomes from HER2-overexpressing tumor cells, including BT-474 (ductal breast cancer), SK-BR3 (human breast cancer), and SK-OV3 (ovarian adenocarcinoma), and used these exosomes to promote the activity of Trastuzumab (Herceptin ® ), a monoclonal antibody that inhibits HER2 receptors [ 185 ]. Trastuzumab is closely related to antibody-drug conjugates (ADCs), which are a chemically linked antibody and cytotoxic agent, such as chemotherapy [ 25 ]. These antibody-drug conjugates target tumors by selective antigen binding to overexpressed receptors in certain cancers that also have low expression on non-cancerous cells, such as HER2 mentioned above. The ADC Rinatabart sesutecan (Rina-S) has advanced to clinical trials in advanced ovarian cancer, indicating promise for the potential of these DDS as a novel therapeutic [ 186 ]. In another ADC study, cell adhesion molecular 1 (CADM1) was targeted using ADCs and investigated in an array of cell lines, including the HEC-1-B endometrial carcinoma cell line [ 187 ]. Results indicated that co-delivery of two synthesized antibodies, 3E1 and 9D2, significantly increased CADM1 relocation rates in all cell lines. Fibroblast growth factor receptor 2 ( FGFR2 ) mutations are common in endometrial cancer and have been linked to advanced and recurrent disease [ 188 ]. FGFR2 is often used for receptor-mediated targeting because it has been characterized in almost all cancer types, including gynecological cancers ( Figure 3 ), and it is strongly associated with aggressive tumors, but expression is low in many non-cancerous tissues [ 189 ]. One study identified FGFR2 mutations in 12% of endometrial cancers [ 58 ], and per the TCGA, FGFR2 mutations occur in 14% of uterine cancers. Treating AN3CA, SKUT1B, HEC1A, and KLE endometrial carcinoma cells with small interfering RNA (siRNA) for EGFR and Notch signaling pathways resulted in changes in cell migration and proliferation, indicative of stalling disease progression [ 188 ]. Chitosan is a natural polysaccharide found in the exoskeletons of crustaceans and in the cell walls of select fungi and insects that has been broadly explored as a potential bio-derived material for drug delivery systems [ 190 ]. The root leaf from Ficus carica sap is high in antioxidants and therefore may be advantageous for cancer therapeutics. Ficus carica sap-functionalized nano-chitosan induced apoptosis and thereby inhibited tumor cell proliferation in the HeLa cervical cancer cell line [ 191 ].

Gynecological cancers include cancers of the female reproductive system. This includes the uterus, ovaries and fallopian tubes, cervix, vagina and vulva. Despite each of these tissues belonging to the female reproductive system, these cancers are heterogeneous. Here we outline the similarities and differences between these cancers, which influences how DDS may translate between cancer types, as well as which cancers have greater clinical need for DDS. Cancer staging provides patients and healthcare professionals with critical information about the size, spread, and metastasis of tumors. Staging is used to assist in clinical decisions for treatment, including clinical trial eligibility. Staging is cancer-specific, and the International Federation of Gynecology and Obstetrics (FIGO) defines the staging characteristics for all gynecological cancers. Cancers are staged based on the severity of the cancer and the spread to nearby or distant organs. Stage I (1) refers to cancer that is localized to the primary tissue of origin. Stage II (2) is defined as cancer that has locally spread to the pelvic region. Stage III (3) involves regional cancer spread to surrounding structures in the pelvic region or to the nearby lymph nodes. Finally, Stage IV (4) is the most aggressive form of cancer that has metastasized and spread to distant organs. Staging of gynecological cancers typically also includes substages (i.e. Stage IIA, Stage IIB, or Stage IIC). Although these substages provide more precision in identifying the severity and spread of the cancer, this information is omitted for brevity . When developing drug delivery systems for gynecological cancer the primary staging information is used and substaging information is more important when designing clinical trials. In 1988, FIGO revised endometrial cancer staging to include surgical findings [ 40 ]. Furthermore, the staging classification has been continuously updated as new discoveries related to the pathogenesis of endometrial cancer have led to a better understanding of the disease ( Table 1 ). In 2023, the FIGO staging of endometrial cancer was updated based on new molecular findings and additional data on clinical trial results, prognosis and survival rates, and new treatment options [ 41 ]. Providing staging information based on location, spreading behavior, and structural and molecular characteristics can lead to a better understanding of the disease and lead to more effective therapies and patient outcomes. Endometrial cancer is commonly associated with DNA mutations and Lynch syndrome (see Section 2.3.1 ); therefore, it is encouraged that all cases of endometrial cancer include complete molecular classification. Molecular markers may influence the advancement of clinical approaches to therapy. For example, all patients considering adjuvant therapy are recommended to undergo molecular testing [ 42 ]. Immunohistochemistry can be used to identify mismatch repair and TP53 mutations and POLE sequencing can identify hypermutated tumors, both of which have a large impact on treatment recommendations [ 42 ]. The heterogeneity of gynecological cancers also makes this molecular characterization extremely important when determining potentially effective chemotherapeutics, Immunotherapeutics, and novel DDS. These factors are discussed in more detail in later sections. As of 2014, the FIGO’s Committee for Gynecologic Oncology revised how staging of ovarian cancer was reported [ 48 ]. The change resulted in ovarian, fallopian tube, and peritoneal cancer to be included in the same system, with the primary site designated if possible [ 48 ]. The prevalence of fallopian tube cancers was previously underestimated; however, recent histologic, molecular and genetic evidence has indicated the origin of many ovarian cancer diagnoses originating from the fallopian tube [ 48 ]. This major change to the staging system for this group of gynecological cancers is an important consideration when designing drug delivery systems that target the site of origin or the entire affected region. Precision when staging can provide the most comprehensive understanding of the origin, spread, and characteristics of the cancer and lead to better patient outcomes through informed selection of treatment. In 2018, the FIGO Committee for Gynecologic Oncology amended the staging of cancer of the cervix uteri (cervical cancer), allowing for the use of imaging or pathology to determine stage [ 45 ]. This change in the cervical cancer staging was validated in a population-based tumor registry and confirmed the characteristic and survival differences in the substaging and classification [ 44 ]. Primary vaginal cancer is rare, with most vaginal tumors resulting from metastasis of cancer from a distant site [ 47 ]. In 2009, the FIGO Committee for Gynecologic Oncology released the current staging for vaginal cancer which, included the four major stages of this disease [ 46 ]. The most recent update to the FIGO staging of vaginal cancer from 2021 included revisions for staging based on imaging information to increase accuracy in prognosis [ 47 ]. Cancer grade classifications are used to describe the cellular abnormalities of tumor cells versus healthy cells upon microscopic inspection. Cancer type is a classification that utilizes both the information from the tissue of origin and the immunohistochemistry to describe and organize the cellular characteristics. These classifications can be used to understand the biology of the cancer cell behavior – such as growth rate and metastatic potential – to better determine the prognosis, best treatment strategies, and overall disease outcome. These factors can also be used in DDS system design and determining factors such as potential receptor-mediated targets that may improve specificity for cancer cells over non-cancerous cells. The FIGO grading system is primarily used to describe the degree of glandular differentiation in cancer cells. Adenocarcinomas, cancers arising from glandular cells, account for up to 90% of endometrial cancers [ 40 ], whereas 2015 Surveillance Epidemiology and End Results (SEER) data indicates that adenocarcinomas account for only about 25% of all cervical cancers, further highlighting the heterogeneity in gynecological cancers depending upon the tissue of origin. Grade 1 (G1) tumors exhibit the lowest percentage of solid non-glandular and non-squamous growth at less than 5%; grade 2 (G2) tumors at 6% - 50%; and grade 3 (G3) tumors above 50% [ 41 , 49 , 50 ]. Grade 1 tumors are well-differentiated and appear similar to normal cells, whereas 3 tumors are poorly differentiated or undifferentiated and cells appear very abnormal. G2 tumor cells are between G1 and G3, with moderate differentiation and some abnormalities [ 47 ]. High grades of gynecological cancers are typically associated with an “aggressive” form of cancer that is more likely to spread quickly to regional and distant sites rendering this an important factor in determining the clinical course of treatment. Histological subtypes are an additional layer to the grading system for gynecological cancers that helps describe and organize the cellular characteristics. Endometrial carcinoma is classified into two different types. Approximately 80-90% of all endometrial cancer cases are classified as Type I [ 21 , 49 ]. Type I tumors are classified as mostly endometroid adenocarcinomas and are associated with unregulated estrogen stimulation [ 51 ]. Type I has characteristics of low-grade and endometrioid histology [ 49 , 52 ]. These cancers are often associated with risk factors, such as obesity and heightened exposure to exogenous estrogen. Additionally, these cancers are frequently preceded by endometrial hyperplasia and are typically low-grade cancers [ 21 , 51 ]. Endometrial hyperplasia is the abnormal thickening of the endometrial tissue and can be either benign or pre-malignant [ 53 ]. In ovarian cancer, Type I tumors are generally slow growing and include endometroid, clear cell, mucinous, and low-grade serous carcinoma [ 54 ]. The remaining cases of endometrial cancer are classified as Type II. Type II endometrial cancer cases commonly contain mutations in the tumor promoter 53 ( TP53 ) oncogene, are often diagnosed later, and contribute to approximately 75% of all endometrial cancer deaths. Type II accounts for 10-20% of diagnoses and is characterized by a high cancer grade, non-endometrioid tissue, poorly differentiated endometrioid histology, and overexpression of KRAS, HER2/neu, and p53 [ 49 , 52 ]. Type II has negative hormone receptor expression and is more common than Type I to have regional or distant metastasis, representative of highly aggressive cancers [ 49 , 52 ]. Type II ovarian cancer is the more aggressive type and includes the histological subtypes of high-grade serous carcinoma and account for 68% of ovarian cancer diagnosis and have characteristics of TP53 mutations in 80% of cases reported [ 54 ]. Upon cancer biopsy, gynecological cancers are classified according to DNA mutations, which are the molecular signatures of the cancer; several genes linked with cancers are commonly mutated across these gynecological cancers ( Figure 3 ). The mutation type in gynecological cancers can be used to make clinical treatment decisions [ 55 - 57 ]. Typical mutations for endometrial cancer include DNA polymerase epsilon (POLE) ultramutated, microsatellite instability (MSI) hypermutated, copy-number low endometrioid tumors with high frequency of CTNNB1 mutations, and copy-number high TP53 mutations. Most endometrial cancers with TP53 , CDH1, ERBB2, and CDKN2A mutations are the more aggressive Type II cancers, whereas the less aggressive Type I cancers are more frequently mutated in MSI, PTEN , KRAS, PIK3CA , and CTNNB1 [ 21 , 53 ]. Furthermore, according to the Cancer Genome Atlas (TCGA), endometrial cancers often have a mutated PI3K-AKT pathway. Other common mutations not mentioned above, many of which have been used for targeted therapy, include: BRCA1/2, PLAC1, DACH1, FGFR2 S252W and HABP2 [ 58 - 61 ]. Although the gene mutations in Type I cancers are more prevalent than the mutations for Type II cancers, the Type II cancers are the more aggressive subtype. Therefore, gene therapy may not be as effective in uterine cancer compared with ovarian cancer. Ovarian cancer is often treated with monoclonal antibody therapeutics that inhibit critical pathways in cancer development, informed from the molecular signatures of ovarian cancers. For example, ovarian cancer is more strongly linked to BRCA1/2 compared with endometrial cancer and therefore responds well to PARP-inhibitors [ 27 ]. Akin to endometrial cancer, the genetic mutations in ovarian cancer are linked to the subtype, Type I or Type II [ 54 ]. For instance, TP53 and BRCA1/2 mutations are more common in more aggressive Type II ovarian cancers. Other epithelial ovarian cancer mutations may occur in the BRAF, KRAS, ARID1A, PIK3CA, PTEN, CTNNB1 oncogenes [ 62 ]. Compared with endometrial cancer and ovarian cancer, cervical cancer has an overall lower mutation frequency in the genes commonly mutated in the other gynecological cancers such as TP53, PLAC1 , FGFR2 and HABP2 . This highlights the heterogeneity of gynecological cancers as unique to the tissue of origin, despite that local spread encompasses the other tissues. Furthermore, it signifies the importance of cancer-specific FDA approvals. The similarities between ovarian cancer and endometrial cancer may explain why the off-label uses of ovarian cancer chemotherapeutics to treat endometrial cancers are effective ( Table 2 ). Lynch syndrome is a genetic condition that increases the risk of developing certain cancers, including colon and endometrial cancers. Lynch syndrome describes mutations in DNA repair, including germline mutations in MLH1 or MSH2 mismatch-repair genes or microsatellite instability. Most women diagnosed with endometrial cancer who have Lynch syndrome are diagnosed at a median age of 48; 15 years earlier than the overall median age of 63 years. Loss of mismatch repair proteins such as MLH1, MSH2, MSH6, and PMS2 is observed in 30-40% of endometrial cancers [ 63 ]. Emerging technologies may advance diagnostic measures for women with Lynch syndrome and endometrial cancer [ 64 ], similar to colonoscopy screening advances for colorectal cancer [ 65 ].

Overall, there are several investigative DDS for gynecological cancers, with most focused on ovarian cancer and endometrial cancer. These foci reflect the incidence and mortality rates in these cancers, as well as clinical failures to existing treatments. Although the female reproductive system comprises all the gynecological cancers, the tissue of origin influences the aggressiveness of the cancer, the DNA mutations, and the available FDA-approved treatments. Therefore, it is important to both group these cancers as significant threats to women’s health, while also understanding that each must be given their own attention and investigations. The existing literature is skewed heavily towards ovarian cancer and includes a large portion of studies on cervical cancer ( Figure 1 ), despite the early-detection related reduction in cervical cancer incidence. This highlights limitations in in vitro investigations that begin clinical translation and therefore ultimately limit the ability for scientists to explore novel treatments for other cancers. Much of the work highlighted here was conducted in vitro in immortalized cancerous cell lines or in vivo in murine models. It is rare that in vitro investigations of drug delivery systems or experimental therapeutics includes multiple cell lines with a large range of degrees of differentiation (cancer grade), metastatic potential (cancer stage), and histological subtype. This fails to capture how the different biology of cancerous cells could impact the effectiveness of the engineered drug delivery systems. Additionally, in vitro studies in two-dimensional cell culture fail to fully capture the tumor microenvironment such as the extracellular matrix, endothelial barriers, and immune components that influence nanoparticle fate in vivo . Although these models are helpful and necessary in preclinical development, ovine are a better gynecological model when available [ 192 ]. As drug delivery systems continue to evolve, it is imperative that investigators consider the translational potential of novel findings and continue to conduct necessary research to get drug delivery systems into the clinic.

Hysterectomy is typically the first-line treatment for endometrial cancer, particularly if the cancer has not spread beyond the uterus. A bilateral salpingo-oophorectomy is often coupled with the hysterectomy to remove both ovaries and fallopian tubes as well, which may help prevent secondary cancers, including ovarian cancer and breast cancer. In endometrial cancer, spreading to para-aortic lymph nodes and pulmonary metastases are common [ 21 ]. When abnormal cells are detected via pap smear, they are typically removed either by ablation or surgical resection. Cryoablation or laser ablation destroys cervical tissue without resection, or conization may be used to resect pre-cancerous lesions of the cervix. Epithelial ovarian cancer is primarily treated with cytoreductive surgery, and epithelial ovarian cancer is one of the most sensitive solid tumors to chemotherapy, including platinum-based chemotherapy and paclitaxel [ 89 ]. Vaginovulvar surgery may be conducted to remove vaginal cancer lesions; the primary surgery for removing cancerous lesions includes pelvic exoneration, abdominoperineal resection, vulvectomy, and vaginectomy [ 90 ]. This primary surgery may be paired with vaginoplasty, which is used to reconstruct the tissue following surgery [ 91 , 92 ]. Clinical trial evidence supports adjuvant radiation therapy combined with systemic therapy for treating endometrial cancer [ 42 ]. Patients with stage IB-IIIC2 mismatch repair (MMR) deficient cancer are typically advised to undergo radiation therapy without chemotherapy [ 42 ]. Furthermore, a hysterectomy may be followed by radiation therapy if the tumor is poorly differentiated, over 50% of the myometrium is invaded, or if the primary cancer has spread to the cervix or lymph nodes [ 21 ]. In ovarian cancer, radiation therapy may be used as a single treatment or combined treatment with surgery and chemotherapy [ 93 ]. To effectively treat ovarian cancer with radiation therapy, radiation is typically delivered across the entire abdominal pelvic region [ 93 ]. Vulvovaginal cancer is typically only treated with radiation therapy when the cancer has positive or close margins at the surgical resection site [ 94 ]. Radiation therapy is typically not recommended for early-stage cervical cancer, and rather recommendations are to use combination chemotherapy [ 95 , 96 ]. Unfortunately, radiation therapy may impact secondary cancers in patients. For example, Wen et al . conducted an analysis of patients in the SEER database from 1973 – 2015 and determined that endometrial cancer patients who received radiation therapy were more likely to develop secondary bladder cancer compared with those who did not receive any radiation therapy [ 97 ]. Wang and Cai further investigated the association between radiation therapy in endometrial cancer and other second primary malignancies and discovered an increased risk for developing second primary malignancies in all tumor sites, with a significantly increased risk for colon and rectum (colorectal) cancer, lung and bronchus cancer, breast cancer, vulvar cancer, bladder cancer, and non-lymphocytic leukemia [ 98 ]. Novel radiation therapy methods have been investigated, however, novel drug delivery systems for chemotherapy prevail. According to the National Cancer Institute, there are currently two FDA-approved chemotherapies specifically for endometrial cancer: Lenvatinib Mesylate (Lenvima), and Megestrol Acetate. Megestrol acetate is a hormonal therapy and was the first FDA-approved drug for treating endometrial cancer [ 99 ]. Megestrol acetate is an effective therapeutic for low-grade endometrial cancer, endometrial hyperplasia, and endometrial gland hyperproliferation [ 100 , 101 ]. However, many FDA-approved chemotherapeutics for other types of cancer are used off-label to treat endometrial cancer and have been shown to be effective endometrial cancer chemotherapy ( Table 2 ). Cisplatin, carboplatin, paclitaxel, and doxorubicin hydrochloride are among the most prescribed chemotherapeutics, however, none of these are FDA-approved specifically for endometrial cancer. Furthermore, most pre-clinical investigations seek to find alternative methods of delivery of paclitaxel or doxorubicin ( Section 4.1 ) or alternatives to platinum-containing drugs ( Section 4.2 ). In a review of clinical use of off-label use of cancer medications, carboplatin, paclitaxel, and doxorubicin had sufficient evidence to be used as an effective and safe off-label chemotherapeutic for endometrial cancer in various combinations or alone [ 102 ]. In a 2020 advanced endometrial cancer phase III trial, carboplatin administered with paclitaxel was a suitable alternative to treatment with cisplatin, paclitaxel, and doxorubicin adjunctively due to less toxicity and greater measures of quality of life [ 103 ]. Research indicates that combined paclitaxel and carboplatin should be used as the primary treatment for advanced and recurrent endometrial cancer and is also an effective support treatment in combination with target treatments [ 103 ]. This further supports the advancement of paclitaxel and doxorubicin containing DDS, as outlined in Section 4.1 . Ovarian cancer treatment is challenging due to high rates of drug resistance during treatment with currently available therapeutics, including cisplatin, carboplatin, and paclitaxel [ 28 ], which is perhaps why ovarian cancer has higher numbers of FDA-approved chemotherapeutics, immunotherapies, and clinical trials initiated compared with other gynecological cancers. Ovarian cancer drug resistance has been linked to the high mortality rates in ovarian cancer [ 104 , 105 ]. Combination chemotherapy in a single drug formulation presents a promising solution with increased efficacy to overcome a variety of drug resistance mechanisms [ 28 ]. In ovarian cancer, the development of controlled-release DDS of multiple FDA-approved drugs to treat gynecological cancers can overcome resistance, improve selectivity, and reduce off-target effects improving the current course of treatment. In 2024, three new immunotherapy checkpoint inhibitors were FDA-approved for treating advanced endometrial cancer. The first of these to be approved was durvalumab (Imfinzi). Durvalumab is typically combined with a combination therapy of carboplatin and paclitaxel in advanced endometrial adenocarcinoma, particularly those cancers with genetic markers for mismatch repair deficiency (dMMR) [ 84 , 106 ]. Pembrolizumab (Keytruda) and dostarlimab-gxly (Jemperli) were approved by the FDA shortly after durvalumab. Keytruda and Jemperli are administered with adjunct therapy of carboplatin and paclitaxel but can be used regardless of dMMR markers. Pembrolizumab has also been shown to be an effective treatment for endometrial cancer in conjunction with Lenvatinib Mesylate (Lenvima) [ 107 ]. Dostarlimab-gxly and Pembrolizumab are immunotherapies that are composed of monoclonal antibodies (mAb) that bind to the PD-1 receptor on T cells. This receptor-mediated interaction prevents cancer cell suppression of the immune cell response to cancer, and therefore allows the immune system recognize cancer cells as foreign. The results of the RUBY NCT03981796 clinical trial indicated that progression-free survival significantly increased for patients with advanced or recurrent endometrial cancer when treated with Dostarlimab combined with carboplatin-paclitaxel [ 108 ] This clinical trial led to FDA approval in 2023 for advanced endometrial cancers initially for cancers with dMMR, and eventually regardless of dMMR status [ 108 ]. The increasing investigation and recent FDA-approval of three new immunotherapies to target gynecological cancers presents a promising solution to combat many of the challenges with current therapeutics, including toxicity, by achieving much greater selectivity. Immunotherapy can also overcome many of the resistance mechanisms of commonly used chemotherapies, such as drug efflux and deficient DNA repair mechanisms. Combining immunotherapy with chemotherapy can harness the benefits of both immune activation and cancer cell cytotoxicity, ultimately leading to more control over the therapeutic outcomes. Despite the boom in pre-clinical investigations for DDS, translation to clinical use is lagging. Most pre-clinical investigations of new drugs fail somewhere in the pipeline ( Figure 2 ), and novel DDS follow similar trends. The major limitations to therapeutic efficacy with the current chemotherapies available include variable pharmacokinetics, hormonal effects, and high off-target toxicity. To overcome these challenges, research and development of sustained release therapies have resulted in two FDA-approved nanoparticle formulations for oncology patients: Abraxane ® and Doxil ® . Abraxane administration includes a colloidal suspension of 130 nm particles allowing for significantly higher doses than paclitaxel alone without the need for additives to enhance the solubility of paclitaxel [ 81 ]. Abraxane (nab-paclitaxel) is an albumin-bound paclitaxel drug formulation intended to avoid the toxicities associated with the polyethylated castor oil required for parenteral administration [ 81 ]. Clinical trial data showed a significant improvement from free paclitaxel administration, specifically a reduction in toxicity allowing for higher dose regimens and overall increased antitumor activity and suppression [ 81 ]. Abraxane is approved to treat breast cancer, lung cancer, and pancreatic cancer, typically when a patient has an allergic reaction to paclitaxel, however, it is not approved specifically for any gynecological cancers. Ongoing clinical trials support its use as an effective treatment for advanced or recurrent endometrial cancer. Doxil is one of the first clinically translated examples available for enhanced chemotherapy using a DDS. Doxil is a PEG-coated liposomal doxorubicin hydrochloride formulation that shows superior clinical performance to the long-existing doxorubicin hydrochloride [ 109 ]. Doxil is FDA-approved for ovarian cancer that has progressed or recurred after a platinum-based chemotherapy regimen, such as carboplatin or cisplatin. Doxil reduces the toxicity side effects compared with doxorubicin hydrochloride through favorable pharmacokinetics and biodistribution [ 109 ]. This mechanism persists with PEGylated DDS ( Section 4.1.1 ) and other novel DDS constructions. For example, small molecule inhibitors and antibody-drug conjugates (ADCs) are under investigation as potential treatments for gynecological cancer ( Table 3 ) [ 110 ]. This trial is executing the goal of personalized medicine by utilizing patients’ profiles of tumor gene expression to accurately predict responses to treatment [ 110 ].

Sustained- and controlled-release drug delivery systems have potential advantages in diseases to improve treatment and prognosis due to marked improvements over free-drugs ( Figure 4 ). DDS improve upon poor solubility, permeability, pharmacokinetics and/or bioavailability of drugs to enhance tumor accumulation and reduction as introduced in Section 1.1 . Furthermore, these DDS may be functionalized for enhanced tumor accumulation and the molecular signatures or gene mutations in gynecological cancers can be used to inform these designs. In gynecological cancers, improved chemotherapeutic pre-clinical investigations are critical to improving the observed mortality rates, particularly with the corresponding increasing incidence across gynecological cancers as outlined in Section 1.2 . Endometrial cancer and ovarian cancer are prevalent worldwide, and account for many cancer-related deaths in females [ 21 , 25 - 27 ]. In contrast, vulvovaginal cancer is exceedingly rare, and cervical cancer incidence and mortality have been drastically decreased thanks to screening recommendations [ 31 , 33 ]. The stage, grade, and molecular signature of gynecological cancers influences the course of treatment and which novel treatment strategies may be efficacious ( Sections 2 -0). Molecular signatures may influence the course of treatment. For example, dMMR is used to determine immunotherapeutic and chemotherapeutic recommendations. Furthermore, Lynch syndrome is linked to earlier onset of colorectal cancer and endometrial cancer and is a hereditary condition [ 63 , 84 , 106 ]. Importantly, the presence of gene mutations influences how populations are chosen for clinical trials, and therefore this information may be critical in determining a course of treatment and novel treatment investigations ( Section 3.5 ). Advances in drug delivery systems enhances the therapeutic efficacy of gynecological cancer treatments. Polymeric and liposomal DDS were outlined in Section 4.1 . These formulations are particularly advantageous for increasing the circulation time of drugs and surface functionalization can further improve targeting of these drugs. Chemoresistance to platinum-containing chemotherapeutics, such as cisplatin and carboplatin, is prevalent, and therefore alternatives to these therapies are explored in Section 4.2 . Additionally, early chemotherapeutics were derived using platinum, and metals are known to induce DNA damage leading to cancer cell apoptosis. Thus, advances in metals and metal oxide drug delivery systems are also particularly applicable to cancer therapeutics. Other vehicles derived from biological sources ( Section 4.3 ), including biopolymers and extracellular vesicles, further enhance targeting ability, such as when surface receptors are overexpressed on cancer cells compared with non-cancerous cells. Furthermore, these sources leverage biological properties to provide enhanced drug efficacy and biocompatibility.

Controlled-release drug delivery systems (DDS) are advantageous for improving diagnostic, prophylactic, and therapeutic treatment for diseases, including cancers. Controlled-release drug delivery technology dates back to the 1950s, and systems span a range of administration methods [ 1 ]. In gynecological cancers, which encompasses vulvovaginal, cervical, uterine (endometrial), and ovarian cancers, first-line treatment is typically surgical removal of the tumor and neighboring tissues. This is highly effective at early stages of cancer, but not as effective once cancer has begun to spread even regionally. In many cases, surgery is combined with either adjuvant or neoadjuvant chemotherapy or immunotherapy. There is an opportunity in gynecological cancer treatment to enhance the efficacy of these treatments through DDS. For example, encapsulating drugs or genetic material such as RNA within a protective shell improves drug solubility and bioavailability [ 2 ]. ¶ Drug delivery systems may be based on bio-inspired polymers, synthetic polymers, lipids, or metals. The choice of which drug carrier and the preparation method depends upon the desired cargo, or active pharmaceutical ingredient (API). In pharmaceutical development, drugs are classified according to the Biopharmaceutical Class System (BCS) using their solubility and permeability as Class I through Class IV. Based on the solubility and permeability, Class II and Class IV drugs have at high toxicity because they and require a high dose, whereas drugs in Class I and Class III require lower doses and have lower toxicity. Only drugs in Class I are truly effective in treatment without incorporating significant inactive ingredients. Some inactive ingredients are inert, such as excipients in oral delivery, whereas others impact additional toxicity, such as Cremophor EL ® with paclitaxel chemotherapy. ¶ Systemic delivery is typically achieved through intravenous infusion, and tumor targeting for these systems can be through passive targeting and the enhanced permeability and retention (EPR) effect, in which nanoparticles preferentially accumulate in tumors due to the unique nature of the tumor vasculature [ 3 , 4 ]. However, several groups have refuted the concept of the EPR effect when considering in vivo efficacy [ 5 , 6 ]. Targeting may be active, using surface moieties for receptors overexpressed in cancers or stimuli-driven such as temperature-responsive, pH-responsive, or ultrasound-responsive, for example [ 7 ]. Without these drug delivery systems, estimates report that as low as 0.7% of an injected dose reaches solid tumors [ 8 ]. Therefore, targeting methods are exceptionally important, especially when considering decreasing systemic toxicity associated with intravenous delivery of chemotherapeutic drugs, which is the primary focus for this review. ¶ Many chemotherapeutic drugs have poor solubility or stability, and DDS can improve each of these facets. Additionally, many existing chemotherapy drugs exhibit off-target toxicity, or low tumor specificity, thereby resulting in low amounts of drug accumulation at the target site and severe side effects. Formulation strategies can overcome many of the solubility and instability challenges of commonly used chemotherapeutics used to treat gynecological cancers, such as with polymeric drug delivery systems discussed in Section 4.1 . Drug delivery systems for women’s health represent an area of research that has been underserved and underfunded [ 9 , 10 ]. In the past 25 years, publications on gynecological cancers and drug delivery have increased in volume ( Figure 1 ). We have highlighted the number of publications in cervical, ovarian, uterine, and vulvovaginal cancer, which peaked in 2020, and declined from 2021 – 2024. Thus far in 2025, the number of publications is trending upward compared to the 4 years prior. Advances in nanomedicine and polymeric delivery systems have improved diagnostics and therapeutics in several cancers, including gynecological cancers. However, the research in these cancers is still drastically lower than other cancers with known immunotherapy success, such as prostate cancers, or hormone-linked treatments, such as breast cancer [ 11 - 15 ]. Despite the striking mortality of ovarian and endometrial cancers especially, these therapeutic innovations are still lagging in the field. Challenges exist across the entire process of developing therapeutics for FDA approval. The pipeline of many cancer therapeutics includes initial discovery and cellular response analysis using in vitro studies as well as in vivo safety and efficacy studies prior to clinical trials. These hurdles result in only a small fraction of investigations reaching FDA approval, and the entire process from initial pre-clinical developments to FDA approval takes a minimum of 12 years ( Figure 2 ). Overcoming challenges at each stage involves careful considerations of drug chemistry and biopharmaceutical properties, physiological and biological barriers, and engineering properties. However, cancer drug delivery is a complex challenge and dependent on a variety of factors including both the drug chemistry, formulation properties, physiological and biological barriers, and regulatory hurdles before clinical FDA-approval. Formulation properties can influence nanocarrier size, shape, charge, composition, functionalization, targetability, and release kinetics. These effects all directly impact the therapeutic efficacy of the DDS and should be optimized for ideal performance providing the greatest chance to clinical translation. The selection of systemic or local drug delivery greatly influences the formulation such as changes in size and drug loading in the dosage form. Systemic delivery typically has greater constraints on formulation but can improve patient compliance and is applicable to a greater number of individuals—furthermore, the inherent properties of a drug limit DDS development. For example, hydrophilicity or lipophilicity of drugs impact the drug loading capacity of nanocarriers, and these are properties which cannot be altered using DDS and rather must be leveraged. Or these studies may be limited by the available pre-clinical models. In vitro studies with immortalized human cell lines, although high throughput, lack the complex characteristics of the tumor microenvironment. The two-dimensional monolayers allow for initial understanding of the direct drug-cell interactions and provide a screening for potential antineoplastic agents for incorporation into drug delivery systems. The development of many cancer therapeutics typically involved initial discovery from cellular response analysis using in vitro studies. Immortalized cell lines in a two-dimensional monolayer are typically used to explore the cellular responses to developing therapies [ 16 ]. However, three-dimensional tumor models have been explored to more accurately represent the tumor microenvironment and provide a more clinically relevant in vitro platform [ 16 ]. To more accurately demonstrate the systemic response to a novel drug delivery system, in vivo studies are used to model distribution, systemic toxicity, targeting, and effectiveness. This presents another significant challenge as there are few animal models that can accurately model the human female reproductive system [ 17 ]. Small rodents such as mice and rats do not accurately mimic human gynecological diseases and therefore larger animal models such as pigs, monkeys, and sheep are more suitable models, yet have stringent regulations, requirements and ethical considerations [ 17 ]. The female anatomy and physiological barriers of the gynecological system are significant hurdles to drug delivery for women’s health. One of the major physiological barriers includes the mucosal lining in the female upper genital tract, which functions to trap unwanted foreign materials from reaching delicate tissues [ 18 ]. However, this mucosal lining also prevents potential therapeutic drugs from reaching diseased tissues in these regions [ 18 ]. Drug pharmacokinetics of the upper genital tract are influenced by a variety of conditions including the variable menstrual cycle stage and pregnancy [ 18 ]. Specific gynecological physiology such as tissue permeability and fluid retention as well as drug transporters, protein binding, and enzyme activity levels can leading to variations in drug profiles and overall efficacy [ 18 ]. Development of DDS that can overcome challenges in this specialized environment are ideal candidates for translation and should be consistently evaluated and formulated accordingly. Systems such as biopolymers present promising biocompatibility and adhesion for enhanced delivery to these tissues. As gynecological cancers advance from early to late stages ( Section 2 ), the efficacy for chemotherapeutic delivery becomes increasingly important to achieve survival without progression to regional or distant tissues. Furthermore, due to lack of screening mechanisms, gynecological cancers are typically diagnosed at high grade and later stages, highlighting the need for DDS in gynecological cancer treatment to enhance therapeutic efficacy with lower doses, thereby reducing off-target toxicity. Gynecological cancers are cancers that affect the female reproductive organs, including the uterus, fallopian tubes, ovaries, cervix, vagina and vulva. These cancers are frequently grouped as uterine cancer of the endometrium, uterine cancer of the cervix, ovarian cancer, and vulvovaginal cancer. Throughout this review, we will refer to cancers using these classifications, with uterine cancer of the endometrium referred to as endometrial cancer, and uterine cancer of the cervix referred to as cervical cancer. Currently the standard of care for most gynecological cancers is surgical removal of the tumor and cancerous tissue [ 19 ]. Surgery is typically required since most gynecological cancers are identified in late stages since the efficacy of current therapeutics is limited by the size of tumors. For example, ovarian cancer typically remains undetected with no obvious symptoms, typically leading to a late-stage diagnosis [ 20 ]. This presents treatment challenges including targeting multiple tissue sites and large tumor sizes. See Section 0 for more detailed information on clinical treatment. Endometrial carcinoma is the sixth most frequent cancer diagnosed in women worldwide. Endometrial cancer is also the most common gynecological malignancy worldwide, and the most common form of uterine cancer [ 21 ]. Specifically, endometrial cancer is cancer of the uterine lining; the endometrium and makes up 90% of uterine cancer cases [ 22 ]. Uterine endometrial cancer encompasses both low-grade and high-grade endometrioid tumors, where low-grade tumors have an 83% five-year survival rate versus 44% for high-grade tumors [ 23 ]. Endometrial cancer risk increases with age, and the median age of diagnosis in the United States is 63 years of age. Therefore, endometrial cancer is typically diagnosed in postmenopausal women, however, risk factors for developing endometrial cancer may occur early in life. As of 2020, the incidence and mortality rates for endometrial cancer were rising at approximately 1.3% annually [ 24 ], highlighting the need for advanced therapeutics, such as controlled-release drug delivery systems, to treat this cancer effectively. Ovarian cancer is the second-most common gynecological malignancy and is the most lethal gynecological cancer globally [ 25 - 27 ]. Most diagnoses are made at later stages, and the five-year survival at these advanced stages is only 30% [ 25 , 28 ]. Early detection of ovarian cancer is rare, which further contributes to the mortality rates [ 27 ]. Ovarian cancer risk is at least twice as high when a first-degree relative has been diagnosed with ovarian cancer compared with no family history [ 29 ]. Additionally, individuals of Ashkenazi Jewish ancestry may have higher mutation rates of oncogenes promoting ovarian cancer [ 30 ], see: Section 2.3 . Ovarian cancer may affect germ cells, stromal cells, or epithelial cells, with epithelial ovarian cancer being the most common. The estimated number of new cervical cancer cases in the United States is 13,360 for 2025 [ 31 ]. Global estimates for the incidence and mortality of cervical cancer have declined in response to HPV vaccinations and regular pap smears. Pap smears were first used in 1943 and named for the inventor of this screening technique, Dr. George Papanicolaou [ 32 ]. Cervical cancer is commonly caused by the human papillomavirus (HPV). Gardasil ® is an HPV vaccine which protects against 9 strains of HPV. This vaccine is available to individuals from ages 9 – 45 in the United States, as part of an optional vaccination schedule. The World Health Organization has indicated that cervical cancer incidence can be eliminated by achieving 90% vaccination in females by age 15, 70% of women aged 35 – 45 years screened and treated when precancerous lesions are detected, and 90% of women with cervical disease receive adequate treatment. Estimates state that these three measures will eliminate 74 million new cases of cervical cancer and 62 million cervical cancer-related deaths in 78 middle- and low-income countries [ 33 ]. These estimates were confirmed in a longitudinal study of over 1.6 million individuals [ 34 ]. The estimated number of new vulvar and vaginal cases in the United States is approximately equal to that for cervical cancers at 15,550 for 2025 [ 31 ]. Compared with other gynecological cancer sites, much less is reported on vulvovaginal cancers, due to its rarity [ 35 ]. Of concern, the incidence rates for pre-menopausal onset of vulvovaginal cancers are increasing [ 36 ]. HPV infections may also contribute to squamous cell carcinomas of the vagina and vulva [ 37 ]. Vulvar examinations may help with early cancer detection, similar to detecting cervical cancer lesions with routine pap smears. However, the accuracy of this screening lags behind that of cervical and other more prevalent cancers [ 38 , 39 ].