UPDATED: Merck's Keytruda snags FDA approval for NSCLC, but label is narrow

Chalk up another approval for Merck & Co.'s ($MRK) Keytruda. And it's a significant one, as it fights for market share against Bristol-Myers Squibb's ($BMY) Opdivo in the PD-1/PD-L1 field. The FDA Friday gave an accelerated approval for Keytruda to treat advanced non-small cell lung cancer (NSCLC) in certain patients. Meanwhile, Opdivo is awaiting an accelerated approval--a potentially broader one--of its own.

The Keytruda approval is more precisely for those patients whose disease has progressed after other treatments and who have tumors that express a protein called PD-L1, the FDA said.

JP Morgan analyst Chris Schott said in a research note, "The restricted label is generally in line with expectations and is likely to broaden over time as data from additional trials support Keytruda's efficacy in a larger patient population," Reuters reported.

It is a big deal because lung cancer is the most common form of the disease worldwide and second in line in the U.S., with 221,000 new cases expected to be diagnosed this year, according to the National Cancer Institute. That translates into a market size of $10 billion. But it is expected that Opdivo will get approval for a broader label for second-line use, with FDA backing in all forms of the disease, regardless of whether patients test positive for the PD-L1 biomarker targeted by the med. That would give Bristol-Myers' candidate an edge.

So far, Keytruda and Opdivo have been mostly neck and neck. Keytruda was approved first, with an indication for melanoma, but Opdivo followed shortly with an approval for melanoma and then to treat squamous non-small cell lung cancer. While fewer patients suffer from squamous NSCLC, an analyst has forecast it could generate $1 billion to $1.5 billion from that indication. 

Now Merck has the NSCLC indication in the bag, and only time will tell whether Opdivo wins an approval with a broader label. But both are being tested in many other categories, so the race will continue. And other immuno-oncology drugs keep on coming. Roche ($RHHBY) could quickly come in and complicate matters; its atezolizumab is coming on strong with a "breakthrough" designation in lung cancer and potential approval next year.

- here's the release
- read more from Reuters

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