A Molecular Inquiry into the Role of Antibody-Drug Conjugates in Bacillus Calmette-Guérin-exposed Non–muscle-invasive Bladder Cancer

The treatment landscape for advanced urothelial cancer has changed dramatically owing to the US Food and Drug Administration approval and introduction of antibody-drug conjugates (ADCs), including enfortumab vedotin and sacituzumab govitecan. Efforts have begun to use these therapies in earlier disease states, specifically bacillus Calmette-Guérin (BCG)-unresponsive non–muscle-invasive bladder cancer (NMIBC). We assessed gene expression associated with these newly approved therapies in a novel cohort of treatment-naïve NMIBC tumors before and after BCG therapy. Multiple genes, including Nectin-4, Trop-2, and Her-2, exhibited increased expression after BCG therapy compared to baseline. However, few of the tumors with increased expression of ADC targets also exhibited increased PD-L1/PD-1 expression. Taken together, these data demonstrate the heterogeneous genomic landscape of BCG-exposed NMIBC, and provide evidence supporting the evaluation of ADCs in NMIBC. Patient summary: We evaluated the potential role of targeted therapies that have been approved in the USA for advanced non–muscle-invasive bladder cancer (NMIBC) that has recurred after treatment with bacillus Calmette-Guérin (BCG). By assessing levels of specific genes and proteins linked to the targeted therapies, we demonstrate that there is rationale for further evaluation of these therapies in NMIBC.