Systematic review of recent advancements in antibody-drug and bicycle toxin conjugates for the treatment of urothelial cancer

Antibody-drug conjugates and bicycle toxin conjugates represent a tremendous advance in drug delivery technology and have shown great promise in the treatment of urothelial cancer. Previously approved systemic therapies, including chemotherapy and immunotherapy, are often impractical due to comorbidities, and outcomes for patients with advanced disease remain poor, even when receiving systemic therapy. In this setting, antibody-drug and bicycle toxin conjugates have emerged as novel treatments, dramatically altering the therapeutic landscape. These drugs harness unique designs consisting of antibody or bicycle peptide, linker, and cytotoxic payload with more targeted delivery than conventional chemotherapy, thus eliminating malignant cells while reducing systemic toxicities. Potential targets investigated in urothelial cancer include Nectin-4, TROP2, HER2, and EphA2. Initial clinical trials demonstrated efficacy in treatment of refractory advanced urothelial cancer, as well as improvement in quality of life. These initial studies led to FDA approval of two antibody-drug conjugates, enfortumab vedotin and sacituzumab govitecan. Moreover, antibody-drug and bicycle toxin conjugates are being studied in ongoing clinical trials in frontline treatment of advanced disease as well as for localized cancer. These studies highlight the potential for additional future therapies with novel targets, novel antibodies, cytotoxic and immunomodulatory payloads, and unique structural designs enhancing efficacy and safety. There is increasing evidence that combinations with other cancer therapies, especially immunotherapy, improve treatment outcomes. The combination of enfortumab vedotin and pembrolizumab was recently approved for first-line treatment of advanced urothelial carcinoma. Despite the great promise of these novel drugs, robust predictive biomarkers are needed to determine the patients who would maximally benefit. This review surveys the rationale and current state of the evidence for these new drugs and describes future directions actively being explored.

Antibody-drug conjugates and predictive biomarkers in advanced urothelial carcinoma

The use of antibody-drug conjugates (ADCs) is expanding in several malignancies, including urothelial carcinoma where two of these medications have been approved for use and several others remain under study. ADCs act by binding to specific cell surface proteins, delivering anticancer agents directly to the target cells. Preclinical studies suggest that loss of these surface proteins alters sensitivity to therapy and expression of target proteins vary significantly based on the tumor subtype, prior therapies and other characteristics. However, use of biomarkers to predict treatment response have not been regularly included in clinical trials and clinician practice. In this review we summarize what is known about potential predictive biomarkers for ADCs in UC and discuss potential areas where use of biomarkers may improve patient care.

Targeted Therapy for Locally Advanced or Metastatic Urothelial Cancer (mUC): Therapeutic Potential of Sacituzumab Govitecan

Urothelial carcinoma is the second most frequent genitourinary malignancy. Despite the poor prognosis, new treatment options have emerged and have expanded the therapeutic landscape for the disease. Although major improvements have been achieved, many patients experience rapid disease progression and low responses in subsequent lines of therapy. Sacituzumab govitecan is an ADC that targets Trop-2, which is highly expressed in urothelial cancers. Promising results in early clinical trials have led to further drug development which confirmed encouraging efficacy. Sacituzumab govitecan has been given accelerated approval in 2021 for patients with locally advanced and metastatic urothelial cancer who previously received a platinum containing chemotherapy and either a programmed death receptor-1 or programmed death ligand inhibitor. The results are promising, with encouraging efficacy and safety, however responses are not universal. There is a growing comprehension of mechanisms of resistance and predictive biomarkers that are crucial to improving outcomes. In this review, we summarize the current knowledge on antibody-drug conjugates and the clinical findings that led to the approval of Sacituzumab govitecan and discuss the therapeutic potential of new combinations, mechanisms of resistance and predictive biomarkers.

Enfortumab vedotin in the treatment of urothelial cancers and beyond

Enfortumab vedotin (EV) is the first antibody-drug conjugate approved for locally advanced or metastatic urothelial cancers (la/mUCs), a disease group historically associated with limited prognosis and therapeutic options. EV consists of monomethyl auristatin E, a microtubule-disrupting agent linked to an antibody targeting Nectin-4. In clinical trials, EV demonstrated high response rates and superior survival in the third-line setting for la/mUC compared with chemotherapy. Peripheral neuropathy and rash were among the most common serious adverse events. EV is currently approved in multiple countries for the treatment of la/mUC in the later-line setting. Ongoing trials seek to expand the indication for EV and to study therapeutic combinations with other agents.

An update on antibody-drug conjugates in urothelial carcinoma: state of the art strategies and what comes next

In recent years, considerable progress has been made in increasing the knowledge of tumour biology and drug resistance mechanisms in urothelial cancer. Therapeutic strategies have significantly advanced with the introduction of novel approaches such as immune checkpoint inhibitors and Fibroblast Growth Factor Receptor inhibitors. However, despite these novel agents, advanced urothelial cancer is often still progressive in spite of treatment and correlates with a poor prognosis. The introduction of antibody–drug conjugates consisting of a target-specific monoclonal antibody covalently linked to a payload (cytotoxic agent) is a novel and promising therapeutic strategy. In December 2019, the US Food and Drug Administration (FDA) granted accelerated approval to the nectin-4-targeting antibody–drug conjugate, enfortumab vedotin, for the treatment of advanced or metastatic urothelial carcinomas that are refractory to both immune checkpoint inhibitors and platinum-based treatment. Heavily pre-treated urothelial cancer patients reported a significant, 40% response to enfortumab vedotin while other antibody–drug conjugates are currently still under investigation in several clinical trials. We have comprehensively reviewed the available treatment strategies for advanced urothelial carcinoma and outlined the mechanism of action of antibody–drug conjugate agents, their clinical applications, resistance mechanisms and future strategies for urothelial cancer.

Antibody-Drug Conjugates in Urothelial Carcinoma: A New Therapeutic Opportunity Moves from Bench to Bedside

Significant progress has been achieved over the last decades in understanding the biology and mechanisms of tumor progression in urothelial carcinoma (UC). Although the therapeutic landscape has dramatically changed in recent years with the introduction of immune checkpoint inhibitors, advanced UC is still associated with rapidly progressing disease and poor survival. The increasing knowledge of the pathogenesis and molecular pathways underlying cancer development and progression is leading the introduction of target therapies, such as the recently approved FGFR inhibitor Erdafitinib, or the anti-nectin 4 antibody drug-conjugate Enfortumab vedotin. Antibody drug conjugates represent an innovative therapeutic approach that allows the combination of a tar get-specific monoclonal antibody covalently conjugated via a linker to a cytotoxic agent (payload). UC is a perfect candidate for this therapeutic approach since it is particularly enriched in antigen expression on its surface and each specific antigen can represent a potential therapeutic target. In this review we summarize the mechanism of action of ADCs, their applications in localized and metastatic UC, the main mechanisms of resistance, and future perspectives for their use in clinical practice.

The evolving treatment landscape of advanced urothelial carcinoma

PURPOSE OF REVIEW

Bladder cancer is the 10th most common cancer in the world and the 6th most common cancer among men. In the past few years, several new agents have been approved for the treatment of urothelial tumors. In this paper, we review the evolving treatment landscape of advanced urothelial carcinoma (UC).

RECENT FINDINGS

Since 2016, the Food and Drug Administration (FDA) has approved five immunotherapies targeting programmed cell death 1/programmed cell death 1 legend, an antinectin-4 antibody drug conjugate (ADC), and a fibroblast growth factor receptor (FGFR) inhibitor for the treatment of patients with advanced UC. Moreover, there are multiple targeted agents, immune checkpoint inhibitors (ICI), ADCs, and their combinations currently being tested in clinical studies with the goal of obtaining FDA approval.

SUMMARY

Precision oncology efforts continue to advance our understanding of the UC biology and transform the existing treatment paradigms. An enlarging arsenal of treatment options promises further personalization of UC therapy.

The Evolving Landscape of Antibody-Drug Conjugates for Urothelial Carcinoma

Metastatic urothelial carcinoma (UC) carries a poor prognosis and a 5-year overall survival of less than 5%, despite standard of care therapy using cisplatin-based chemotherapy and immune checkpoint inhibitors. Thus, novel agents that improve survival and have an acceptable toxicity profile are urgently needed. Antibody-drug conjugates (ADCs) represent a promising new treatment option that utilizes the targeting ability of an antibody to deliver cytotoxic drugs directly to tumors. Many ADCs are currently being investigated for treatment of UC, with enfortumab vedotin being recently approved by the US Food and Drug Administration for treatment of metastatic UC with progressive disease after chemotherapy and/or immune checkpoint inhibitors. Overall, ADCs hold promise as a long-awaited treatment option for UC.

Current Status and Future Perspectives of Immunotherapy for Locally Advanced or Metastatic Urothelial Carcinoma: A Comprehensive Review

Advancements in the understanding of tumor immunology in urothelial carcinoma (UC) have led to U.S Food and Drug Administration (FDA) approval of five novel anti-programmed cell death protein-1/ligand 1 (PD-1/L1) checkpoint inhibitors. In 2017, the anti-PD-L1 antibody atezolizumab and the anti-PD-1 antibody pembrolizumab gained approval for use in cisplatin-ineligible patients with locally advanced and metastatic UC. These approvals were based on single-arm trials, IMvigor210 (atezolizumab) and KEYNOTE-052 (pembrolizumab). Since then, additional checkpoint inhibitors, including avelumab, durvalumab, and nivolumab, have gained approval. Preliminary results suggest additional benefits with combinations of these agents in both first- and subsequent-line therapies, inferring a paradigm shift in the future treatment approach in advanced UC. Ongoing clinical trials will investigate how to utilize predictive biomarkers for optimal patient selection and to incorporate immunotherapy into earlier lines of multimodal treatment. In this comprehensive review, we summarize the evidence supporting the use of checkpoint inhibitors for patients with UC, and highlight ongoing clinical trials that are investigating novel combinations of immunotherapy in various disease settings.

Enfortumab Vedotin, a fully human monoclonal antibody against Nectin 4 conjugated to monomethyl auristatin E for metastatic urothelial Carcinoma

Introduction: The conventional management of most patients with metastatic urothelial carcinoma (UC) is platinum-based chemotherapy followed by immunotherapy. Erdafitinib is an option in post-platinum patients with activating mutations in fibroblast growth factor receptor (FGFR)-3 and -2. Salvage therapy with taxanes or vinflunine has demonstrated minimal efficacy. Enfortumab Vedotin (EV), a monoclonal antibody-drug conjugate (ADC) targeting nectin-4 is under investigation in patients with advanced UC. Areas covered: This review describes the epidemiology and unmet needs of patients with metastatic UC and is focused specifically on heavily treated patients. We explore the rationale for targeting nectin 4 and the clinical development of EV; efficacy and safety data from the completed phase I and II studies are examined. Ongoing trials to definitively assess clinical outcomes in comparison to current therapy and trials exploring EV in combination are also highlighted. Expert opinion: There is an unmet need for new therapies in most patients with advanced UC and who progress after platinum and immunotherapy. EV has shown promising efficacy and safety in this population in phase 1 and 2 trials including those with poor prognostic factors such as liver metastases. Ongoing trials exploring this agent in combination will continue to advance the treatment of UC.

The continuing role of chemotherapy in the management of advanced urothelial cancer

Despite intense drug development in the last decade in metastatic urothelial carcinoma and the incorporation of novel compounds to the treatment armamentarium, chemotherapy remains a key treatment strategy for this disease. Platinum-based combinations are still the backbone of first-line therapy in most cases. The role of chemotherapy in the second line has been more ill-defined due to the complexity of this setting, where patient selection remains critical. Nevertheless, two regimens, one in monotherapy (i.e. vinflunine) and one in combination with antiangiogenics (i.e. docetaxel + ramucirumab) have shown efficacy. Immunotherapy through checkpoint inhibition has revealed remarkably durable benefit in a small proportion of patients in the first and second line and is currently the preferred partner for combinations with chemotherapy. Difficult populations such as patients with liver metastases or those progressing to checkpoint inhibition represent a medical challenge and selective ways of delivering cytotoxics, like the antibody-drug conjugates, might represent a valid alternative. This article reviews the current role of chemotherapy in the management of advanced urothelial carcinoma and the ongoing and coming studies involving this treatment strategy.

Systemic Therapy for Advanced Urothelial Carcinoma: Current Standards and Treatment Considerations

Urothelial carcinoma is the sixth most common malignancy in the United States. Although most are diagnosed with non-muscle-invasive malignancy, many patients will develop recurrent disease within 5 years, with 10% to 20% developing advanced muscle-invasive or more distant incurable disease. For such patients, clinical outcomes have remained suboptimal, although recent therapeutic advances have brought new hope to the field. Here, we discuss the main systemic treatment options available for the treatment of patients with advanced disease. This review begins with traditional chemotherapy, which remains a first-line treatment option for many patients. The second section focuses on the evolving landscape of immunotherapy, specifically on approved checkpoint inhibitors and future challenges. Last, we address advances in targeted treatments, including angiogenesis and fibroblast growth factor receptor (FGFR) inhibitors as well as antibody-drug conjugates. As the number of available treatment options continues to expand, ongoing trials to investigate the best sequence and combination strategies to incorporate these drugs into clinical practice will help delineate the future.