Preferred first-line (1L) treatment for metastatic urothelial carcinoma (mUC) after prior immune checkpoint inhibitor (ICI) therapy: Results from a national survey.

e16570 Background: ICI therapy may be used for the treatment of BCG-unresponsive non-muscle invasive bladder cancer (NMIBC), or as adjuvant or perioperative therapy for localized muscle invasive bladder cancer (MIBC). The benefit of continued or retreatment with ICI for those who relapse on or after prior ICI exposure is unclear. We created a national survey to understand how expert genitourinary (GU) medical oncologists in US consider 1L ICI-based therapies for patients with mUC who had received prior ICI for NMIBC or MIBC. Methods: Under the guidance of a bladder cancer working group comprising 11 experts, we developed a survey related to treatment of mUC, including questions related to 1L ICI containing regimens (enfortumab vedotin/pembrolizumab [EVP] and gemcitabine/cisplatin/nivolumab [GCN]) after prior ICI. Questions regarding EVP or GCN were separate, so respondents were not asked to select one regimen over the other. Here, we present the pooled responses to these survey questions, using descriptive statistics. Results: We e-mailed the survey to 227 community and academic GU medical oncologists in the US from May-August 2024; 78 respondents completed at least part of the survey, of which 88% were academic, 62% were in practice for > 5 years and 72% noted seeing > 25 patients with mUC each year; 73 respondents completed the MIBC questions and 72 completed the NMIBC questions. For patients with progression while receiving adjuvant ICI, 51% (37/73) of respondents were somewhat/very likely to use EVP as the next therapy line, while only 12% (9/73) were somewhat/very likely to use GCN. For patients with progression after completion of prior ICI, 35-36% of respondents would consider 1L EVP irrespective of the interval from prior ICI completion and an additional 43-45% would consider EVP > 6 months post ICI completion. Only a small minority ( < 5%) would never consider using EVP after prior ICI (Table). Consideration of ICI-rechallenge with GCN was lower at many specified intervals with 18-26% never considering GCN after prior ICI. Conclusions: GU academic and community oncologists were more likely to consider 1L EVP than GCN for patients with mUC who had received prior ICI for NMIBC or MIBC or after prior ICI for NMIBC, with the preferred interval for ICI rechallenge being > 6 months after last ICI dose. However, the significant heterogeneity in responses highlights the data limitations guiding ICI rechallenge in these settings, rendering consensus hard to achieve. Prospective data via clinical trials to guide treatment decisions in this setting are needed. Any interval, % (n) >3 months, % (n) >6 months, % (n) >9 months, % (n) >12 months, % (n) Never, % (n) Prior adjuvant ICI for MIBC 1L EVP 36 (26) 5 (4) 45 (33) 3 (2) 10 (7) 1 (1) 1L GCN 14 (10) 5 (4) 41 (30) 3 (2) 11 (8) 26 (19) Prior ICI for NMIBC 1L EVP 35 (25) 3 (2) 43 (31) 1 (1) 14 (10) 4 (3) 1L GCN 14 (10) 6 (4) 43 (31) 3 (2) 17 (12) 18 (13)