Antibody-Drug Conjugates: A Promising Novel Therapy for the Treatment of Ovarian Cancer

Folate receptor alpha protein expression in ovarian serous cystadenocarcinoma tumors of The Cancer Genome Atlas: exploration beyond single-agent therapy

Epithelial ovarian cancer (EOC) can be highly lethal, with limited therapeutic options for patients with non-homologous recombination deficient (HRD) disease. Folate receptor alpha (FOLR1/FRα)-targeting agents have shown promise both alone and in combination with available therapies, but the relationship of FRα to other treatment-driving biomarkers is unknown. The Cancer Genome Atlas (TCGA) was queried to assess protein and mRNA expression and mutational burden in patients with differential FRα protein-expressing ovarian tumors, and the results referenced against the standard 324 mutations currently tested through FoundationOne Companion Diagnostics to identify targets of interest. Of 585 samples within TCGA, 121 patients with serous ovarian tumors for whom FRα protein expression was quantified were identified. FRα protein expression significantly correlated with FOLR1 mRNA expression (p=7.19×1014). Progression free survival (PFS) for the FRα-high group (Q1) was 20.7 months, compared to 16.6 months for the FRα-low group (Q4, Logrank, p=0.886). Overall survival (OS) was 54.1 months versus 36.3 months, respectively; however, this result was not significant (Q1 vs. Q4, Logrank, p=0.200). Mutations more commonly encountered in patients with high FRα-expressing tumors included PIK3CA and FGF family proteins. Combinations of FRα-targeting agents with PI3K, mTOR, FGF(R) and VEGF inhibitors warrant investigation to evaluate their therapeutic potential.

Immunotherapy guided precision medicine in solid tumors

Cancer is no longer recognized as a single disease but a collection of diseases each with its defining characteristics and behavior. Even within the same cancer type, there can be substantial heterogeneity at the molecular level. Cancer cells often accumulate various genetic mutations and epigenetic alterations over time, leading to a coexistence of distinct subpopulations of cells within the tumor. This tumor heterogeneity arises not only due to clonal outgrowth of cells with genetic mutations, but also due to interactions of tumor cells with the tumor microenvironment (TME). The latter is a dynamic ecosystem that includes cancer cells, immune cells, fibroblasts, endothelial cells, stromal cells, blood vessels, and extracellular matrix components, tumor-associated macrophages and secreted molecules. The complex interplay between tumor heterogeneity and the TME makes it difficult to develop one-size-fits-all treatments and is often the cause of therapeutic failure and resistance in solid cancers. Technological advances in the post-genomic era have given us cues regarding spatial and temporal tumor heterogeneity. Armed with this knowledge, oncologists are trying to target the unique genomic, epigenetic, and molecular landscape in the tumor cell that causes its oncogenic transformation in a particular patient. This has ushered in the era of personalized precision medicine (PPM). Immunotherapy, on the other hand, involves leveraging the body's immune system to recognize and attack cancer cells and spare healthy cells from the damage induced by radiation and chemotherapy. Combining PPM and immunotherapy represents a paradigm shift in cancer treatment and has emerged as a promising treatment modality for several solid cancers. In this chapter, we summarise major types of cancer immunotherapy and discuss how they are being used for precision medicine in different solid tumors.

Adverse events of antibody-drug conjugates on the ocular surface in cancer therapy

Antibody-drug conjugates consist of a monoclonal antibody attached to a cytotoxic therapeutic molecule by a connector. This association allows a highly specific therapy, which increases their effectiveness and decreases their potential toxicity. This new therapy emerged approximately 20 years ago; since then, numerous combinations have appeared in the field of treatment-related neoplasms as an alternative for patients who do not achieve good results with conventional treatment options. Adverse effects of these drugs on the ocular surface are frequent and varied. Their prevalence ranges from 20 to 90% depending on the drug and administration condition, probably due to multiple receptor-mediated factors or mechanisms not mediated by specific receptors, such as macropinocytosis. These adverse events can greatly limit patients' comfort; thus, the objectives of this article were, in the first place, to compile the information currently available on different types of adverse effects of antibody-drug conjugates on the ocular surface, including pathophysiology, prevalence, and treatment, and in second place, to contribute to the correct identification and management of these events, which will result in a lower rate of cessation of treatment, which is necessary for the survival of candidate patients.

Targeted drug conjugate systems for ovarian cancer chemotherapy

Ovarian cancer is a highly lethal disease that affects women. Early diagnosis and treatment of women with early-stage disease improve the probability of survival. Unfortunately, the majority of women with ovarian cancer are diagnosed at advanced stages 3 and 4 which makes treatment challenging. While the majority of the patients respond to first-line treatment, i.e. cytoreductive surgery integrated with platinum-based chemotherapy, the rate of disease recurrence is very high and the available treatment options for recurrent disease are not curative. Thus, there is a need for more effective treatment options for ovarian cancer. Targeted drug conjugate systems have emerged as a promising therapeutic strategy for the treatment of ovarian cancer. These systems provide the opportunity to selectively deliver highly potent chemotherapeutic drugs to ovarian cancer, sparing healthy normal cells. Thus, the effectiveness of the drugs is improved and systemic toxicity is greatly reduced. In this review, different targeted drug conjugate systems that have been or are being developed for the treatment of ovarian cancer will be discussed.

[Ovarian cancer: molecular pathology and molecularly targeted therapy]

Ovarian cancer is a common malignant genital neoplasm in women. Due to its frequent diagnosis only in advanced stages, prognosis is poor, although biomarker-driven targeted therapeutic approaches are evolving. These are currently based on molecular pathological analyses of homologous recombination deficiency (HRD) and the BRCA1/2 mutational status. The current CME article focuses on the histo- and molecular pathology of ovarian cancer, relevant molecular mechanisms, and test systems. These are discussed in the context of biomarker-driven targeted therapy.

Therapeutic strategies targeting folate receptor α for ovarian cancer

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and presents a major clinical challenge due to limited treatment options. Folate receptor alpha (FRα), encoded by the FOLR1 gene, is an attractive therapeutically target due to its prevalent and high expression in EOC cells. Recent basic and translational studies have explored several modalities, such as antibody-drug conjugate (ADC), monoclonal antibodies, small molecules, and folate-drug conjugate, to exploit FRα for EOC treatment. In this review, we summarize the function of FRα, and clinical efficacies of various FRα-based therapeutics. We highlight mirvetuximab soravtansine (MIRV), or Elahere (ImmunoGen), the first FRα-targeting ADC approved by the FDA to treat platinum-resistant ovarian cancer. We discuss potential mechanisms and management of ocular adverse events associated with MIRV administration.

Antibody-Drug Conjugates in Solid Tumor Oncology: An Effectiveness Payday with a Targeted Payload

Antibody-drug conjugates (ADCs) are at the forefront of the drug development revolution occurring in oncology. Formed from three main components-an antibody, a linker molecule, and a cytotoxic agent ("payload"), ADCs have the unique ability to deliver cytotoxic agents to cells expressing a specific antigen, a great leap forward from traditional chemotherapeutic approaches that cause widespread effects without specificity. A variety of payloads can be used, including most frequently microtubular inhibitors (auristatins and maytansinoids), as well as topoisomerase inhibitors and alkylating agents. Finally, linkers play a critical role in the ADCs' effect, as cleavable moieties that serve as linkers impact site-specific activation as well as bystander killing effects, an upshot that is especially important in solid tumors that often express a variety of antigens. While ADCs were initially used in hematologic malignancies, their utility has been demonstrated in multiple solid tumor malignancies, including breast, gastrointestinal, lung, cervical, ovarian, and urothelial cancers. Currently, six ADCs are FDA-approved for the treatment of solid tumors: ado-trastuzumab emtansine and trastuzumab deruxtecan, both anti-HER2; enfortumab-vedotin, targeting nectin-4; sacituzuzmab govitecan, targeting Trop2; tisotumab vedotin, targeting tissue factor; and mirvetuximab soravtansine, targeting folate receptor-alpha. Although they demonstrate utility and tolerable safety profiles, ADCs may become ineffective as tumor cells undergo evolution to avoid expressing the specific antigen being targeted. Furthermore, the current cost of ADCs can be limiting their reach. Here, we review the structure and functions of ADCs, as well as ongoing clinical investigations into novel ADCs and their potential as treatments of solid malignancies.

Immune checkpoint inhibitors in ovarian cancer: where do we go from here?

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and despite advancements in therapeutics, most women unfortunately still succumb to their disease. Immunotherapies, in particular immune checkpoint inhibitors (ICI), have been therapeutically transformative in many tumour types, including gynaecological malignancies such as cervical and endometrial cancer. Unfortunately, these therapeutic successes have not been mirrored in ovarian cancer clinical studies. This review provides an overview of the ovarian tumour microenvironment (TME), particularly factors associated with survival, and explores current research into immunotherapeutic strategies in EOC, with an exploratory focus on novel therapeutics in navigating drug resistance.

The evolving landscape of antibody-drug conjugates in gynecologic cancers

Despite significant advances in the treatment of cervical, ovarian, and uterine cancers with the approvals of checkpoint and PARP inhibitors into standard treatment, patients with recurrent metastatic gynecologic malignancies still experience poor outcomes, and most of these patients will experience disease relapse. Once standard preferred treatments are exhausted, options have historically been limited to treatments associated with poor outcomes and notable toxicities. Consequently, novel therapies that are effective and well-tolerated are needed for patients with recurrent and metastatic gynecologic malignancies. Antibody-drug conjugates (ADCs) are a class of targeted therapies that are well established in several cancers including hematologic malignancies and some solid tumors. Significant strides in ADC technology and design have led to improvements in efficacy and safety with newer-generation ADCs. Consequently, ADCs are gaining traction in gynecologic cancers with the recent US Food and Drug Administration approvals of tisotumab vedotin in cervical cancer and mirvetuximab soravtansine in ovarian cancer. Many additional ADCs against various targets are being explored in patients with metastatic or recurrent gynecologic malignancies. The purpose of this review is to summarize the nuanced structural and functional properties of ADCs, while outlining opportunities for innovation. Further, we highlight the ADCs in clinical development for gynecologic malignancies, exploring how ADCs may be able to address the clinical care gap for patients with gynecologic cancers.

Antibody therapeutics for epithelial ovarian cancer

INTRODUCTION

High-grade serous ovarian carcinoma (HGSC) is an aggressive subtype of epithelial ovarian carcinoma (EOC) and remains the most lethal gynecologic cancer. A lack of effective and tolerable therapeutic options and nonspecific symptoms at presentation with advanced stage of disease are among the challenges in the management of the disease.

AREAS COVERED

An overview of ovarian cancer, followed by a discussion of the current therapeutic regimes and challenges that arise during and after the treatment of EOC. We discuss different formats of antibody therapeutics and their usage in targeting validated targets implicated in ovarian cancer, as well as three emerging novel proteins as examples recently implicated in their contribution to adaptive resistance in ovarian cancer.

EXPERT OPINION

Antibody therapeutics allow for a unique and effective way to target proteins implicated in cancer and other diseases, and have the potential to radically change the outcomes of patients suffering from ovarian cancer. The vast array of targets that have been implicated in ovarian cancer and yet the lack of effective therapeutic options for patients further stresses the importance of discovering novel proteins that can be targeted, as well as predictive biomarkers that can inform the stratification of patients into treatment-specific populations.

New Technologies Bloom Together for Bettering Cancer Drug Conjugates

Drug conjugates, including antibody-drug conjugates, are a step toward realizing Paul Ehrlich's idea from over 100 years ago of a "magic bullet" for cancer treatment. Through balancing selective targeting molecules with highly potent payloads, drug conjugates can target specific tumor microenvironments and kill tumor cells. A drug conjugate consists of three parts: a targeting agent, a linker, and a payload. In some conjugates, monoclonal antibodies act as the targeting agent, but new strategies for targeting include antibody derivatives, peptides, and even small molecules. Linkers are responsible for connecting the payload to the targeting agent. Payloads impact vital cellular processes to kill tumor cells. At present, there are 12 antibody-drug conjugates on the market for different types of cancers. Research on drug conjugates is increasing year by year to solve problems encountered in conjugate design, such as tumor heterogeneity, poor circulation, low drug loading, low tumor uptake, and heterogenous expression of target antigens. This review highlights some important preclinical research on drug conjugates in recent years. We focus on three significant areas: improvement of antibody-drug conjugates, identification of new conjugate targets, and development of new types of drug conjugates, including nanotechnology. We close by highlighting the critical barriers to clinical translation and the open questions going forward. SIGNIFICANCE STATEMENT: The development of anticancer drug conjugates is now focused in three broad areas: improvements to existing antibody drug conjugates, identification of new targets, and development of new conjugate forms. This article focuses on the exciting preclinical studies in these three areas and advances in the technology that improves preclinical development.

Options to Improve the Action of PROTACs in Cancer: Development of Controlled Delivery Nanoparticles

Classical targeting in cancer focuses on the development of chemical structures able to bind to protein pockets with enzymatic activity. Some of these molecules are designed to bind the ATP side of the kinase domain avoiding protein activation and the subsequent oncogenic activity. A further improvement of these agents relies on the generation of non-allosteric inhibitors that once bound are able to limit the kinase function by producing a conformational change at the protein and, therefore, augmenting the antitumoural potency. Unfortunately, not all oncogenic proteins have enzymatic activity and cannot be chemically targeted with these types of molecular entities. Very recently, exploiting the protein degradation pathway through the ubiquitination and subsequent proteasomal degradation of key target proteins has gained momentum. With this approach, non-enzymatic proteins such as Transcription Factors can be degraded. In this regard, we provide an overview of current applications of the PROteolysis TArgeting Chimeras (PROTACs) compounds for the treatment of solid tumours and ways to overcome their limitations for clinical development. Among the different constraints for their development, improvements in bioavailability and safety, due to an optimized delivery, seem to be relevant. In this context, it is anticipated that those targeting pan-essential genes will have a narrow therapeutic index. In this article, we review the advantages and disadvantages of the potential use of drug delivery systems to improve the activity and safety of PROTACs.

Revisiting antibody-drug conjugates and their predictive biomarkers in platinum-resistant ovarian cancer

Until to date, platinum derived drugs are still the backbone of treating ovarian cancer (OC). Most patients treated with platinum-based chemotherapy develop resistance during the course of their management. The treatment of platinum-resistant ovarian cancer (PROC) is challenging. Few therapeutic options are available for patients with this aggressive disease. Besides, there are liminal advances regarding new anticancer drugs as well as validated predictive biomarkers of clinical outcomes in this setting. The enrollment of PROC patients in interventional studies is limited as compared to newly launched clinical trials for platinum-sensitive OC. Enthusiastically, the emergence of antibody-drug conjugates (ADCs) has provided promising findings for further clinical development in PROC. ADCs have the advantage to selectively deliver cytotoxic drugs to cancer cells expressing several of antigens using specific monoclonal antibodies based on the concept of immune bioconjugation. This innovative class of therapeutics showed encouraging early signs of clinical efficacy in PROC particularly mirvetuximab soravtansine that has been successfully introduced into three randomized and controlled phase III studies. In this review, the evidence from clinical trials supporting the development of ADCs targeting folate receptor alpha, sodium-dependent phosphate transporter 2B, dipeptidase 3, mesothelin, mucin 16, and tissue factor using various cytotoxic payloads in PROC is reviewed.

Antibody-Antineoplastic Conjugates in Gynecological Malignancies: Current Status and Future Perspectives

In the last decade, antibody-drug conjugates (ADCs), normally formed by a humanized antibody and a small drug via a chemical cleavable or non-cleavable linker, have emerged as a potential treatment strategy in cancer disease. They allow to get a selective delivery of the chemotherapeutic agents at the tumor level, and, consequently, to improve the antitumor efficacy and, especially to decrease chemotherapy-related toxicity. Currently, nine antibody-drug conjugate-based formulations have been already approved and more than 80 are under clinical trials for the treatment of several tumors, especially breast cancer, lymphomas, and multiple myeloma. To date, no ADCs have been approved for the treatment of gynecological formulations, but many formulations have been developed and have reached the clinical stage, especially for the treatment of ovarian cancer, an aggressive disease with a low five-year survival rate. This manuscript analyzes the ADCs formulations that are under clinical research in the treatment of gynecological carcinomas, specifically ovarian, endometrial, and cervical tumors.

Tuning the Cytotoxicity of Bis-Phosphino-Amines Ruthenium(II) Para-Cymene Complexes for Clinical Development in Breast Cancer

Despite some limitations such as long-term side effects or the potential presence of intrinsic or acquired resistance, platinum compounds are key therapeutic components for the treatment of several solid tumors. To overcome these limitations, maintaining the same efficacy, organometallic ruthenium(II) compounds have been proposed as a viable alternative to platinum agents as they have a more favorable toxicity profile and represent an ideal template for both, high-throughput and rational drug design. To support the preclinical development of bis-phoshino-amine ruthenium compounds in the treatment of breast cancer, we carried out chemical modifications in the structure of these derivatives with the aim of designing less toxic and more efficient therapeutic agents. We report new bis-phoshino-amine ligands and the synthesis of their ruthenium counterparts. The novel ligands and compounds were fully characterized, water stability analyzed, and their in vitro cytotoxicity against a panel of tumor cell lines representative of different breast cancer subtypes was evaluated. The mechanism of action of the lead compound of the series was explored. In vivo toxicity was also assessed. The results obtained in this article might pave the way for the clinical development of these compounds in breast cancer therapy.

Advances in the treatment of platinum resistant epithelial ovarian cancer: an update on standard and experimental therapies

Introduction: Platinum-resistant ovarian cancer (PROC) is broadly defined as disease recurrence within 6 months of completing platinum-based chemotherapy, either in the primary or recurrent setting. Although there is significant heterogeneity, PROC is generally associated with poor outcomes and low response rates to standard chemotherapy. There have been novel developments in therapeutics for PROC based on biomarkers and a more nuanced understanding of DNA repair and immunologic pathways.Areas covered: This review provides a summary of standard of care and experimental therapies for patients with PROC. Recent advances in our understanding of the DNA damage response and immunobiology of ovarian cancer have paved the way for single agent and combinatorial strategies involving PARP inhibitors, cell cycle checkpoint inhibitors, and immune checkpoint inhibitors to overcome PARP resistance, capitalize on high replication stress, and promote effective anti-tumor immunity, respectively. Furthermore, novel agents including antibody drug conjugates, bispecific antibodies, and recombinant fusion proteins show promise as experimental treatment options.Expert opinion: Standard and experimental treatment options available to patients with PROC have expanded. Testing for BRCA status, tumor mutational burden, and mismatch repair deficiency is recommended to guide therapy. Clinical trial participation is strongly encouraged with a focus on biomarker-driven trials targeting specific patient populations. Novel approaches such as ADCs, bispecific antibodies, targeting the GAS6/AXL and Notch pathways, and oncolytic virotherapy show considerable promise as emerging therapies.

Anti-tumour drugs of marine origin currently at various stages of clinical trials (review)

Oncological diseases for a long time have remained one of the most significant health problems of modern society, which causes great losses in its labour and vital potential. Contemporary oncology still faces unsolved issues as insufficient efficacy of treatment of progressing and metastatic cancer, chemoresistance, and side-effects of the traditional therapy which lead to disabilities among or death of a high number of patients. Development of new anti-tumour preparations with a broad range of pharmaceutical properties and low toxicity is becoming increasingly relevant every year. The objective of the study was to provide a review of the recent data about anti-tumour preparations of marine origin currently being at various phases of clinical trials in order to present the biological value of marine organisms – producers of cytotoxic compounds, and the perspectives of their use in modern biomedical technologies. Unlike the synthetic oncological preparations, natural compounds are safer, have broader range of cytotoxic activity, can inhibit the processes of tumour development and metastasis, and at the same time have effects on several etiopathogenic links of carcinogenesis. Currently, practical oncology uses 12 anti-tumour preparations of marine origin (Fludarabine, Cytarabine, Midostaurin, Nelarabine, Eribulin mesylate, Brentuximab vedotin, Trabectedin, Plitidepsin, Enfortumab vedotin, Polatuzumab vedotin, Belantamab mafodotin, Lurbinectedin), 27 substances are at different stages of clinical trials. Contemporary approaches to the treatment of oncological diseases are based on targeted methods such as immune and genetic therapies, antibody-drug conjugates, nanoparticles of biopolymers, and metals. All those methods employ bioactive compounds of marine origin. Numerous literature data from recent years indicate heightened attention to the marine pharmacology and the high potential of marine organisms for the biomedicinal and pharmaceutic industries.