Late-Breaking Data on Bladder Cancer Treatments from KEYNOTE-B15 Trial

Breakthroughs in Bladder Cancer Treatments at ASCO GU

Merck unveiled promising bladder cancer treatments at the 2026 ASCO Genitourinary (GU) Cancers Symposium, showcasing data from its portfolio including KEYTRUDA® (pembrolizumab), WELIREG® (belzutifan), and LENVIMA® (lenvatinib). Late-breaking results from the Phase 3 KEYNOTE-B15/EV-304 trial showed KEYTRUDA plus Padcev® (enfortumab vedotin-ejfv) as neoadjuvant and adjuvant therapy significantly boosted event-free survival, overall survival, and pathologic complete response rates in cisplatin-eligible patients with muscle-invasive bladder cancer (MIBC). Phase 3 data from LITESPARK-022 and LITESPARK-011 trials also highlighted disease-free survival gains for WELIREG plus KEYTRUDA post-nephrectomy in clear cell renal cell carcinoma (ccRCC) and progression-free survival benefits for WELIREG plus LENVIMA in advanced RCC after anti-PD-1/L1 therapy, with all studies in the ASCO GU Press Program. These advances position Merck’s therapies as frontrunners in genitourinary oncology.

KEYNOTE-B15 Survival Wins

The Phase 3 KEYNOTE-B15 trial (abstract #LBA630), where neoadjuvant and adjuvant KEYTRUDA plus enfortumab vedotin outperformed standard care in cisplatin-eligible MIBC, improving event-free survival, overall survival, and pathologic complete response. This extends prior KEYTRUDA uses in urothelial cancer and bolsters perioperative bladder cancer treatments. In RCC, LITESPARK-022 (abstract #LBA418) showed adjuvant WELIREG plus KEYTRUDA beating KEYTRUDA alone post-nephrectomy, while LITESPARK-011 (abstract #LBA417) demonstrated WELIREG plus LENVIMA surpassing cabozantinib in advanced cases. Phase 2 data on sacituzumab tirumotecan plus KEYTRUDA (abstract #744) further supports antibody-drug conjugate synergies.

Trial Designs Powering Advances

Merck’s extensive program—over 50 trials with 22,000+ patients—focusing on early-stage KEYTRUDA, WELIREG, and LENVIMA combos. KEYNOTE-B15, a randomized open-label study with Astellas/Pfizer, evaluated neoadjuvant/adjuvant therapy in cisplatin-eligible MIBC as a late-breaking oral. LITESPARK-022 tested adjuvant WELIREG plus KEYTRUDA post-nephrectomy ccRCC, and LITESPARK-011 (with Eisai) compared WELIREG plus LENVIMA to cabozantinib in advanced RCC, both late-breaking orals. These build on approved indications, strengthening evidence for survival gains as detailed in Merck’s announcement.

HEOR Impact of New Regimens

KEYNOTE-B15’s outcomes in bladder cancer treatments could justify premium pricing via reduced recurrence and cystectomy needs. For RCC, adjuvant WELIREG plus KEYTRUDA extends disease-free survival, fitting value-based care, while WELIREG-LENVIMA aids refractory settings. Amid HIF-2α and ADC trends, Merck’s 30+ early-stage studies enhance payer evidence, with models factoring in safety like KEYTRUDA’s immune reactions and WELIREG’s anemia/hypoxia to drive access and care evolution.