Bristol-Myers Squibb Co. (BMY - Get Report) fell sharply Monday after the U.S. Food & Drug Administration extended the approval date for a combination-drug treatment for lung cancer patients. 

Bristol-Myers said the marketing application for its Opdivo plus Yervoy cancer therapy combination will be delayed by three months, until May 2019. EU regulators asked for more information on the therapy, which is being tested as part of a trial the group calls 'CheckMate -227', including an overall survival (OS) analysis for certain types of patients. Bristol-Myers said an OS analysis for the same patient sub-group was also submitted to the FDA. 

"The FDA determined that the submission of this new information constituted a major amendment to the sBLA and notified the Company today that the review period was extended by three months with a new Prescription Drug User Fee Act goal date of May 20, 2019," Bristol-Myers said. "The Company previously announced the application was accepted for review in June 2018."

Bristol Myers shares closed 6.3% lower at $50.88 each, a move that extends the stock's year-to-date decline to around 17%. 

Opdivo, which Bristol-Myers classifies as a "prioritized brand" that harnesses the body's own immune system to fight cancer, earned just under 30% of the group's $5.704 billion in overall second quarter revenues, after rising 36% from the same period last year to $1.627 billion. Yervoy revenues, by contrast, fell 2% to $315 million. 

"We had a very good second quarter where we delivered strong performance for Eliquis and Opdivo, and achieved important regulatory and data milestones supporting our Immuno-Oncology portfolio," said CEO Giovanni Caforio at the time. "Looking forward, we are focused on robust commercial execution and the evolution of our diversified pipeline to deliver transformational medicines to the patients we serve."

Opdivo plus low-dose Yervoy (injections for intravenous use), for the treatment of adult and pediatric patients 12 years and older with microsatellite instability high or mismatch repair deficient metastatic colorectal cancer that has progressed following treatment with a fluoropyrimidine, oxaliplatin and irinotecan, was approved by the FDA in July, the company said.