POTOMAC Subgroup Data: Cystectomy Risk and Rare Adverse Events in NMIBC

In this installment, Neal D. Shore, MD, FACS, shares additional POTOMAC (NCT03528694) data. Time to cystectomy showed an HR of 0.63 favoring the durvalumab (Imfinzi)-plus-BCG combination, translating to roughly a 37% lower rate of proceeding to cystectomy; patients who ultimately needed surgery in the combination arm did so approximately 5 months later, on average, than those on BCG alone. Cystectomy-free survival also favored the combination (HR, 0.69), as did time to high-grade recurrence. Subgroup analyses by papillary tumor status, the population most community urologists actually see, all landed below the overall 0.68 HR.

Chandler Park, MD, responds that patients never walk in asking for a cystectomy, so delaying or preventing one resonates strongly with how he frames the conversation. He highlights Shore's papillary-subgroup overall survival data: an HR of 0.80 with no detriment to overall survival (OS) at a median follow-up of more than 5 years (66 months).

Shore notes that with 5-plus years of follow-up, an OS benefit is trending favorably, although event counts remain modest. On safety, he reiterates that thyroid events, transient lab abnormalities, and rash stay largely grade 1/2, with grade 3/4 events in the single digits, and flags very rare (under 1%) but serious events, including encephalitis, myocarditis, and panhypopituitarism, that warrant close collaboration between urologist and medical oncologist.

In the next episode, "Bringing POTOMAC Data Into Community Urology Practice for High-Risk NMIBC," Shore asks Park what community practices should actually do with these data, and Park offers a concrete framework for putting it into practice.