A combination of Merck’s Keytruda and Pfizer’s Padcev could offer a chemotherapy-free treatment alternative for patients with muscle-invasive bladder cancer, even those eligible for cisplatin treatment.
A duet of blockbuster drugs from Merck and Pfizer significantly improved survival and treatment response in a late-stage muscle-invasive bladder cancer study, potentially changing the treatment paradigm in this indication.
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],” Truist Securities wrote in a Saturday note to investors. The late-stage findings “will have downstream effect” on the broader space, the analysts added.
The results will also help the companies build toward regulatory filings for the drug doublet, according to Pfizer’s press announcement.
The new data, presented Friday at the American Society of Clinical Oncology Genitourinary Cancers Symposium in San Francisco, come from the Phase 3 EV-304 study (also called KEYNOTE-B15), which enrolled 808 patients with muscle-invasive bladder cancer (MIBC) eligible for cisplatin treatment. Results showed the combo therapy cut the risk of disease progression, recurrence or death by 47% with standard of care, a regimen consisting of gemcitabine and cisplatin.
Keytruda plus Padcev also hit the key secondary endpoint of overall survival (OS), lowering the risk of death from any cause by 35% versus standard of care. At the time of surgery, pathological complete response rate hit 55.8% in patients treated with Merck and Pfizer’s doublet, as compared with 32.5% in the control arm.
Across these three efficacy measures, the combo significantly outperformed standard of care, according to the Friday release.
In its note, Truist called the event-free survival finding “strong,” adding that the combo’s OS advantage over gemcitabine plus cisplatin “compares favorably to other [standards of care] in the MIBC setting.”
“Most importantly,” the analysts continued, the investigational regimen “presents a chemo-free option even to patients who are Cisplatin-eligible.”
Friday’s ASCO GU readout comes after the partners released data in October 2025 from the Phase 3 KEYNOTE-905 study, which similarly combined Keytruda and Padcev for the treatment of MIBC, this time in patients who were not eligible for or were denied cisplatin chemotherapy. When given before and after surgery, the drug doublet improved event-free survival by 60% and decreased death risk by 50% as compared with surgery alone, the current standard of care in this patient population.
“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 in their Saturday note.
