Enfortumab Vedotin: Sex Differences in Urothelial Cancer Response

The emerging success story of antibody-drug conjugates (ADCs) in urothelial cancer is facing a critical nuance: effectiveness appears significantly diminished for female patients. New data presented at the ESMO Congress 2025 reveals a substantial difference in overall survival between men and women treated with enfortumab vedotin (EV), raising questions about personalized treatment strategies and the need for more inclusive clinical trial design.

Urothelial carcinoma, a cancer of the bladder and urinary system, has historically had limited treatment options, particularly in the metastatic setting. EV, an ADC targeting NECTIN-4, represented a major step forward, demonstrating impressive response rates and survival benefits. The initial enthusiasm, however, is now tempered by the realization that these benefits aren’t universally experienced. This isn’t an isolated incident; sex-based differences in drug metabolism, immune response, and disease biology are increasingly recognized across oncology, but often understudied. The ARON2-EV study, a real-world data analysis of 454 patients treated with EV between 2016 and 2024, provides compelling evidence that this is a critical factor in urothelial cancer.

The research points to a potential biological explanation: lower NECTIN-4 expression in female tumors. Analysis of data from The Cancer Genome Atlas (TCGA) confirms this, showing significantly higher NECTIN-4 levels in male patients with T2-T4a urothelial cancer. Researchers hypothesize this difference may be linked to molecular subtypes and the impact of estrogen levels, potentially influenced by smoking history. This is a complex interplay, as smoking is a known risk factor for urothelial cancer and also affects estrogen metabolism.

The Forward Look: This finding is likely to trigger a cascade of re-evaluation. First, expect a deeper dive into biomarker analysis within existing EV clinical trials to confirm and refine the link between NECTIN-4 expression and treatment response, stratified by sex. More importantly, future ADC trials *must* incorporate robust sex-specific analyses from the outset. We can anticipate a push for companion diagnostics to assess NECTIN-4 levels before initiating EV treatment, potentially guiding treatment decisions. Beyond EV, this research serves as a crucial warning for the broader ADC pipeline – a rapidly expanding field in cancer therapy. The success of these novel agents hinges on understanding and addressing these fundamental biological differences to ensure equitable benefit for all patients. The question now isn’t just *if* ADCs work, but *for whom* they work best, and how we can tailor treatment to maximize efficacy for every individual.