On October 23, 2025 Merck (NYSE: MRK), known as MSD outside of the United States and Canada, reported that the U.S. Food and Drug Administration (FDA) has granted priority review for two supplemental Biologics License Applications (sBLA) for KEYTRUDA (pembrolizumab) and KEYTRUDA QLEX (pembrolizumab and berahyaluronidase alfa-pmph), each in combination with Padcev (enfortumab vedotin-ejfv), for the treatment of patients with muscle-invasive bladder cancer (MIBC) who are ineligible for cisplatin-based chemotherapy. The FDA set a Prescription Drug User Fee Act (PDUFA), or target action, date of April 7, 2026, marking the first concurrent review of both KEYTRUDA and KEYTRUDA QLEX for the same novel indication.

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"New options for muscle-invasive bladder cancer are vital — patients who are ineligible for chemotherapy have not seen a treatment advance beyond surgery in decades," said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. "With the FDA’s priority review, we are one step closer to offering KEYTRUDA or KEYTRUDA QLEX plus Padcev as a potential treatment option to these patients with MIBC who are ineligible for cisplatin-containing chemotherapy and have such high unmet medical need."

The sBLAs are based on data from the Phase 3 KEYNOTE-905 trial (also known as EV-303), which was conducted in collaboration with Pfizer and Astellas. Results, which were presented at the recent European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) Congress, showed that after a median follow-up of 25.6 months, KEYTRUDA plus Padcev, as perioperative treatment, demonstrated a statistically significant and clinically meaningful improvement in event-free survival (EFS), the trial’s primary endpoint, reducing the risk of EFS events by 60% (HR=0.40 [95% CI, 0.28-0.57]; p<0.0001) versus surgery (radical cystectomy) alone in patients with MIBC who are not eligible for or declined cisplatin-based chemotherapy. Median EFS was not reached [NR] (95% CI, 37.3-NR) for the KEYTRUDA plus Padcev regimen versus 15.7 months (95% CI, 10.3-20.5) for surgery alone.

KEYTRUDA plus Padcev also demonstrated a statistically significant and clinically meaningful improvement in key secondary endpoints of overall survival (OS) and pathologic complete response (pCR) rate. KEYTRUDA plus Padcev reduced the risk of death by 50% (HR=0.50 [95% CI, 0.33-0.74]; p=0.0002) versus surgery. The pCR rate increased from 8.6% in patients treated with surgery alone (n=15/174) to 57.1% in patients treated with perioperative KEYTRUDA plus Padcev (n=97/170), an estimated increase of 48.3 percentage points (95% CI, 39.5-56.5; p<0.000001).

KEYTRUDA plus Padcev is currently approved for the treatment of adult patients with locally advanced or metastatic urothelial cancer (la/mUC) in the U.S., the European Union (EU), Japan and several other countries around the world based on results from the Phase 3 KEYNOTE-A39 trial, also known as EV-302. KEYTRUDA as a monotherapy is also approved in the U.S., EU, Japan and other countries for the treatment of certain patients with la/mUC or a type of non-muscle-invasive bladder cancer (NMIBC).

Four additional Phase 3 studies are currently evaluating KEYTRUDA across all stages of bladder cancer, including non-muscle-invasive, muscle-invasive and metastatic disease. Three of these studies are in MIBC including KEYNOTE-B15 (NCT04700124), which is also known as EV-304 and is being conducted in collaboration with Pfizer and Astellas, KEYNOTE-866 (NCT03924856) and KEYNOTE-992 (NCT04241185). KEYTRUDA is also being evaluated in combination with Bacillus Calmette-Guerin (BCG) in patients with NMIBC in the Phase 3 KEYNOTE-676 (NCT03711032) trial.

About KEYNOTE-905/EV-303
KEYNOTE-905, also known as EV-303, is an open-label, randomized, multi-arm, controlled Phase 3 trial (ClinicalTrials.gov, NCT03924895) evaluating perioperative KEYTRUDA, with or without Padcev, versus surgery alone in patients with MIBC who are either not eligible for or declined cisplatin-based chemotherapy. The trial enrolled 595 patients who were randomized to receive either:

Arm A: Three cycles of neoadjuvant KEYTRUDA, followed by surgery to remove the bladder (radical cystectomy), followed by 14 cycles of adjuvant KEYTRUDA;
Arm B: Surgery alone;
Arm C: Three cycles of neoadjuvant KEYTRUDA plus enfortumab vedotin, followed by surgery to remove the bladder (radical cystectomy), followed adjuvantly by six cycles of KEYTRUDA plus enfortumab vedotin and then eight cycles of KEYTRUDA alone.
The primary objective of this trial is to compare EFS between arm C and arm B, defined as the time from randomization to the first occurrence of any of the following events: progression of disease that precludes RC surgery or failure to undergo RC surgery in participants with residual disease, gross residual disease left behind at the time of surgery, local or distant recurrence as assessed by imaging and/or biopsy or death due to any cause. The key secondary objectives are to compare OS and the difference in pCR rate between arm C and arm B, as well as EFS, OS and the difference in pCR rate between arm A and arm B. The study remains ongoing to test hypotheses between arm A and arm B.

About bladder cancer
Bladder cancer is the ninth most common cancer worldwide, diagnosed in more than 614,000 patients each year globally. Muscle-invasive bladder cancer represents approximately 30% of all bladder cancer cases. The standard of care for patients with MIBC has been neoadjuvant cisplatin-based chemotherapy followed by surgery, which is shown to prolong survival. However, up to half of patients with MIBC are not eligible to receive cisplatin and face limited treatment options, typically undergoing surgery alone.

(Press release, Merck & Co, OCT 23, 2025, View Source [SID1234656949])