Merck & Co is continuing on its quest to expand the approved uses of its immunotherapy Keytruda, filing the drug in the US for both first- and second-line use in bladder cancer.

In the first-line setting approval is being sought for the drug's use in patients with locally advanced or metastatic urothelial cancer who are ineligible for cisplatin-containing therapy, while second-line use is being targeted towards these patients with disease progression on or after platinum-containing chemotherapy.

In both cases the US Food and Drug Administration has assigned a priority review on the back of data from the Phase II KEYNOTE-052 and the Phase III KEYNOTE-045 trials, which means that both applications have an action target date of June 14.

Results of KEYNOTE-052 showed an overall response rate (ORR) of 24 percent in the total study population, which included patients in the first-line setting with and without PD-L1 expression, while KEYNOTE-045 met its primary endpoint of showing a significant improvement in overall survival (OS) in patients taking the drug in the second line setting.

"Over the past 30 years, there have been very few clinical advances in the treatment of bladder cancer," said Dr Roger Dansey, senior vice president and therapeutic area head, oncology late-stage development, Merck Research Laboratories.

"The data with Keytruda administered to patients with advanced urothelial cancer are promising, and we look forward to working with the FDA throughout the review process with the goal of bringing Keytruda to patients who may benefit as quickly as possible."

News of the filings came hot on the heels of FDA approval of Bristol-Myers Squibb's rival immunotherapy Opdivo (nivolumab) for patients with locally advanced or metastatic urothelial carcinoma who have disease progression during or following platinum-containing chemotherapy or have disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.