Dive Brief:

• A broader group of patients with metastatic lung cancer can now receive Merck & Co.'s immunotherapy Keytruda as initial treatment, following the Food and Drug Administration's approval of the drug plus chemotherapy for previously untreated squamous non-small cell lung cancer (NSCLC) on Tuesday. 
• Keytruda is the first PD-1 inhibitor to receive an OK in first-line squamous NSCLC — an edge that should help it strengthen its leading position in lung cancer over rivals Bristol-Myers Squibb and Roche. 
• Squamous NSCLC is a harder-to-treat and more aggressive tumor type, estimated to account for about a quarter of lung cancer cases. Merck previously secured first-line approvals for Keytruda monotherapy and in combination for first-line non-squamous NSCLC. 

Dive Insight:

With Tuesday's approval, Keytruda (pembrolizumab) in combination with chemo is now a first-line treatment option for all eligible patients with metastatic NSCLC, excepting those with certain mutations targetable by other therapies. 

It's a powerful position, and one that's likely to fuel rising sales of the immunotherapy. While Bristol-Myers and Roche still threaten in lung cancer, the FDA has pushed back decisions on first-line approvals for their respective drugs. The extended window without competition in the first-line setting should help Merck, at least for the time being. 

Approval of Keytruda in first-line squamous NSCLC was supported by results from the KEYNOTE-407 study, which was detailed this summer at the annual meeting of the American Society for Clinical Oncology.

In the trial, treatment with Keytruda plus Abraxane (paclitaxel) and platinum chemotherapy extended median overall survival by nearly 5 months over Abraxane and chemo alone — a relative risk reduction of 36%.

Notably, a benefit in progression-free survival was seen regardless of PD-L1 expression levels.

Roche also read out positive results for its immunotherapy Tecentriq (atezolizumab) in first-line squamous NSCLC, but awaits overall survival data from the study. 

Bristol-Myers' Opdivo (nivolumab), meanwhile, has held an approval for second-line squamous NSCLC since 2015. 

While the approval opens up a broader addressable market for Keytruda, the impact on sales might not be felt immediately.

On a recent earnings call, Adam Schechter, Merck's head of global human health, noted that the sales ramp for first-line approvals is usually slower in general, because there is no built-up group of patients awaiting treatment as there might be in later settings. Instead, physicians will consider the option of giving Keytruda plus chemo as patients are diagnosed. 

Elsewhere, Merck has also reported positive results for Keytruda combinations in first-line head and neck cancer, as well as in first-line kidney cancer.