A combination of Merck’s Keytruda and Pfizer’s Padcev has shown significant improvements in survival and treatment response for patients with muscle-invasive bladder cancer, according to results from a late-stage clinical trial. The findings were presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco.
The Phase 3 EV-304 study, also known as KEYNOTE-B15, included 808 patients eligible for cisplatin treatment. Data showed that the combination therapy reduced the risk of disease progression, recurrence, or death by 47% compared to standard care with gemcitabine and cisplatin. Additionally, overall survival improved, with a 35% reduction in risk of death from any cause versus standard care. At surgery time, the pathological complete response rate was 55.8% for those receiving Keytruda and Padcev, compared to 32.5% in the control group.
Truist Securities commented on these results: “The drug combo, consisting of the PD-1 inhibitor Keytruda and the antibody-drug conjugate Padcev, ‘rewrites the standard of care in [muscle-invasive bladder cancer],’” according to a note released Saturday. Truist added that these findings “will have downstream effect” on treatments for this type of cancer.
The companies are expected to use this data as they prepare regulatory filings for approval of their drug combination.
Truist analysts also noted: “Most importantly…the investigational regimen ‘presents a chemo-free option even to patients who are Cisplatin-eligible.’”
This latest announcement follows previous results from October 2025 involving another Phase 3 trial (KEYNOTE-905), which studied the same drug combination in patients not eligible for or denied cisplatin chemotherapy. In that study, giving Keytruda and Padcev before and after surgery led to a 60% improvement in event-free survival and halved the risk of death compared with surgery alone.
“We think the KEYNOTE-B15 data, together with KEYNOTE-905 positions Keytruda plus Padcev as the likely go-to option in MIBC,” Truist analysts wrote.
