The combination of Keytruda and Padcev is taking another step forward as a powerful treatment for bladder cancer, showing it can significantly improve survival rates for patients with muscle-invasive bladder cancer (MIBC).
Results from the phase 3 Keynote-B15 (EV-304) trial showed that using Keytruda and Padcev, both before and after surgery, improved survival for MIBC patients who are eligible for cisplatin-based chemotherapy. The study compared this combination therapy with standard chemotherapy, and the results were overwhelmingly positive.
Merck & Co., the developer of Keytruda, partnered with Astellas and Pfizer, the makers of Padcev, to sponsor the study. The positive results were announced after an interim analysis on December 17, 2025.
In addition to significantly improving overall survival rates—one of the main goals of the trial—the combination therapy also met other key endpoints, such as event-free survival. This is defined as the time until an initial negative event, like tumor recurrence or disease progression. The therapy also met the secondary goal of achieving a pathologic complete response, meaning there was no sign of cancer in the removed tissue after surgery.
The results are being considered both clinically meaningful and statistically significant. Further details from the study will be shared at upcoming medical meetings and submitted to regulators for potential approval.
This success comes just a month after the FDA approved the Keytruda-Padcev combination as the first perioperative treatment for MIBC patients who cannot receive cisplatin-based chemotherapy. This approval was based on the Keynote-905 (EV-303) trial, which showed the combo significantly reduced the risk of death by 50% for patients undergoing surgery alone.
Dr. Matthew Galsky, a leading expert in genitourinary oncology at Mount Sinai and one of the principal investigators of the study, highlighted that the risk of recurrence in cisplatin-eligible patients remains high, underlining the need for effective new treatments. Nearly half of MIBC patients who receive existing treatments progress to metastatic disease within three years of diagnosis, according to Dr. Christopher Hoimes of Duke Cancer Institute, another principal investigator.
“The combined results of the EV-303 and EV-304 trials show that Keytruda and Padcev can have a significant positive impact on the treatment of bladder cancer, offering patients a much-needed survival boost and a shift away from traditional chemotherapy treatments,” Dr. Hoimes said.
The latest trial results further solidify the combination of Keytruda and Padcev as one of the most effective tools in bladder cancer treatment, following their historic FDA approval in 2023 for first-line metastatic bladder cancer treatment. Keytruda is also approved for treating high-risk non-muscle invasive bladder cancer (NMIBC) that does not respond to standard BCG treatment.
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