The Evolving Landscape of Antibody-Drug Conjugates for Urothelial Carcinoma

The combination of immune checkpoint inhibitors and antibody-drug conjugates in the treatment of urogenital tumors: a review insights from phase 2 and 3 studies

With the high incidence of urogenital tumors worldwide, urinary system tumors are among the top 10 most common tumors in men, with prostate cancer ranking first and bladder cancer fourth. Patients with resistant urogenital tumors often have poor prognosis. In recent years, researchers have discovered numerous specific cancer antigens, which has led to the development of several new anti-cancer drugs. Using protein analysis techniques, researchers developed immune checkpoint inhibitors (ICIs) and antibody-conjugated drugs (ADCs) for the treatment of advanced urogenital tumors. However, tumor resistance often leads to the failure of monotherapy. Therefore, clinical trials of the combination of ICIs and ADCs have been carried out in numerous centers around the world. This article reviewed phase 2 and 3 clinical studies of ICIs, ADCs, and their combination in the treatment of urogenital tumors to highlight safe and effective methods for selecting individualized therapeutic strategies for patients. ICIs activate the immune system, whereas ADCs link monoclonal antibodies to toxins, which can achieve a synergistic effect when the two drugs are combined. This synergistic effect provides multiple advantages for the treatment of urogenital tumors.

RC48-Antibody-Drug Conjugate in Metastatic Urothelial Carcinoma: A Multicenter Real-World Study in China

OBJECTIVES

RC48 is an antibody-drug conjugate (ADC) that targets HER2. In China, RC48 is approved for patients with HER-2-positive metastatic urothelial carcinoma (mUC) who have failed at least platinum-based chemotherapy. This study aimed to evaluate RC48 for mUC in a cohort of real-world patients.

MATERIALS AND METHODS

We retrospectively collected data from 103 mUC patients from 12 centers between July 2021 and August 2023 in China. RC48 alone or with immunotherapy was administered until disease progression, intolerable toxicity, death, or other reasons. The objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and incidence of treatment-related adverse events (TRAEs) were evaluated.

RESULTS

The median age of the patients was 68 years, and 68.0% were men. Twenty-nine (28.2%) patients received RC48 alone; 73 (70.9%) received RC48 combination therapy. The response rates were as follows: complete response in 2 (1.9%) patients, partial response in 50 (48.5%) patients, stable disease in 30 (29.1%) patients. The ORR was 50.5%. In patients with ≥80 years, Eastern Cooperative Oncology Group (ECOG) performance status ≥2 and creatinine clearance rate (CCr) <30 mL/min, the ORR was 75%, 48.6%, and 40.0%, respectively. The median PFS was 6 (3.9-8.1) months, and the median OS was not reached. The most reported TRAEs were peripheral sensory neuropathy (53.4%), alopecia (42.7%), asthenia (38.8%), decreased appetite (35.9%) and weight loss (35.9%) and TRAE did not increase in patients with poor condition or impaired renal function.

CONCLUSION

Administration of RC48 for real-world patients is both effective and safe. mUC patients can benefit from RC48-based therapy, regardless of their poor condition or impaired renal function.

Human epidermal growth factor receptor 2/neu expression in urothelial carcinomas

Introduction

Urothelial carcinomas of the bladder are more common in males, making them the sixth-most common cancer in men and the tenth-most common cancer overall, worldwide. Current guidelines do not recommend routine testing for human epidermal growth factor receptor (HER2/neu) expression on the biopsy specimens of patients with urothelial carcinoma. This study was aimed at determining the expression pattern of HER2/neu and its usefulness in muscle-invasive and nonmuscle-invasive urothelial carcinoma.

Methods

HER2/neu expression was assessed in 89 specimens of urothelial cancer by immunohistochemistry (IHC), and equivocal cases were subjected to fluorescent in situ hybridization (FISH).

Results

On IHC for HER2/neu, 17.9% (7/39) of the muscle-invasive bladder cancers (MIBCs) showed a 3+ expression, whereas 22% (11/50) of the non-muscle invasive cancers were positive with a score of 3+. A significant correlation between HER2/neu status and muscle invasion could not be established in the current study (P = 0.74, Fisher's exact test). Three cases of muscle-invasive (7.7%) and 2 cases (4%) among nonmuscle invasive cancers showed equivocal expression. All the cases with equivocal (2+) expression on IHC were subjected to FISH and none showed gene amplification on hybridization and were considered as negative.

Conclusion

Overexpression of HER-2/neu was seen in 17.9% of MIBCs and 22% of non-MIBCs. There are no norms for routine testing of HER2/neu expression in the biopsy specimens of urothelial carcinoma. There is an unmet need to establish guidelines for HER2/neu scoring, similar to that for breast and gastric cancers, to determine the proportion of positive cases and help in identification of those who may benefit from targeted therapies.

Antibody-Drug Conjugates in the Treatment of Urothelial Cancer

Antibody-drug conjugates (ADCs) have transformed the treatment landscape in oncology and become an essential therapeutic modality. In urothelial carcinoma (UC), the two ADCs that have been especially successful in clinical practice are enfortumab vedotin and sacituzumab govitecan. These drugs are currently approved as monotherapy for later lines of treatment in locally advanced or metastatic UC and have had a significant impact for patients with limited treatment options. Combinational trials, as well as additional ADCs, are currently being investigated in the treatment of UC for subsequent lines of therapy as overall survival rates remain dismal.

Immunotherapy for Bladder Cancer: Latest Advances and Ongoing Clinical Trials

For nearly 50 years, immunotherapy has been used in patients with bladder cancer in the form of Mycobacterium bovis Bacillus Calmette-Guerin (BCG), which is still the first-line therapy for non-muscle invasive disease. However, the remarkable results obtained with checkpoint inhibitor drugs, including Pembrolizumab and Atezolizumab, have fueled the quest to optimize these and other forms of immunotherapy for both non-muscle invasive as well as advanced bladder cancer. In this review we summarize the current state of the rapidly evolving field of immunotherapy in bladder cancer highlighting novel approaches and ongoing trials in this exciting area of research.

HER2 expression in urothelial carcinoma, a systematic literature review

Background

Urothelial carcinoma (UC) is a common malignancy with significant associated mortality. Recent clinical trials suggest an emerging role for HER2-targeted therapy. Testing for HER2 expression in UC is not part of current routine clinical practice. In consequence, the prevalence of HER2 expression in UC is not well defined.

Methods

A systematic literature review (SLR) was conducted to characterize HER2 expression in both locally advanced unresectable or metastatic (LA/mUC) and earlier stage UC, classified as HER2+, HER2-low, HER2-. HER2+ was defined as an immunohistochemistry (IHC) score of 3+ or IHC 2+ and ISH/FISH+. HER2-low was defined as an IHC score of 2+ and ISH/FISH- or IHC 1+. HER2- was defined as an IHC score of 0. Weighted averages were calculated to generate an estimate of the population prevalence.

Results

A total of 88 studies were identified, with 45, 30, and 13 studies investigating LA/mUC, earlier stage UC, and mixed stage/unspecified, respectively. The most common assays used were Dako HercepTest and Ventana Pathway anti-HER2/neu (4B5) for IHC to assess HER2 protein expression; Abbott PathVysion HER-2 DNA Probe Kit, FoundationOne CDx, and Guardant360 CDx for assessing HER2 gene amplification. The most frequently cited scoring guidelines were ASCO/CAP guidelines for breast cancer and gastric cancer, though most studies defined their own criteria for HER2 expression. Using the pre-specified definition, HER2+ prevalence ranged from 6.7% to 37.5% with a weighted average of 13.0% in LA/mUC. Only 1 study presented data that could be classified as HER2+ based on pre-specified criteria in earlier stage UC patients, and this study represented a likely outlier, at 76.0%.

Conclusion

The results from this SLR help to shed light on HER2 expression in UC, a potentially clinically relevant biomarker-driven subpopulation for emerging HER2-directed regimens. Results of this SLR illuminate the variability in how HER2+ status expression levels are being assessed and how HER2+ is defined. Consensus on standardized HER2 testing and scoring criteria is paramount to better understand the clinical relevance in patients with UC.

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.

Clinical Benefit of Pembrolizumab in Advanced Urothelial Cancer Patients in Real-Life Setting: An Efficacy and Safety Monocentric Study

Background: Pembrolizumab is approved for patients with metastatic urothelial carcinoma (UC) who progressed under platinum therapy. The aim of this study was to assess the efficacy and safety of pembrolizumab in a cohort of real-life UC patients. Methods: This retrospective, observational study included advanced UC patients treated with pembrolizumab in a single institution in France. The co-primary endpoints were overall survival (OS) and progression-free survival (PFS) at 6 months. Secondary endpoints were objective response rate (ORR), duration of response (DOR), disease control rate (DCR) and safety. Results: 78 patients were included in the study. The median OS was 7.3 months (3.8–12.2). The estimated OS rate at 6 months was 61.5% (50.5–72.6). The median PFS was 3.1 months (1.4–7.2). The estimated PFS rate at 6 months was 42.3% (31.1–53.5). The best ORR was 35.9%. The mean DOR was 95.5 days. The DCR was 30.8%. The most common treatment-related adverse events (AEs) of any grade were fatigue (46.2%), diarrhea (11.5%), pruritus (10.3%) and nausea (9.0%). There were no grade 3 AEs that occurred with an incidence of 5% or more. Conclusion: Our results confirmed those of randomized clinical trials concerning the treatment with pembrolizumab in patients with advanced UC that progressed after platinum-based chemotherapy.