Lung cancer patients in advanced stages of the disease received a new first-line treatment option on Friday. The FDA has approved the combination of Opdivo plus Yervoy from Bristol-Myers Squibb (BMY -0.72%) as a treatment for patients with non-small cell lung cancer (NSCLC) tumors that express programmed death-ligand one (PD-L1) on at least 1% of their cells. 

Lung cancer isn't the most commonly diagnosed malignancy, but it claims more lives than any other, and NSCLC cases comprise around 85% of all lung cancer diagnoses. As a first-line treatment for NSCLC patients, annual sales of Opdivo's top competitor, Keytruda from Merck (MRK -1.22%), soared 55% in 2019 to $11.1 billion largely due to first-line NSCLC patients that tend to remain on therapy much longer than patients that have already relapsed.  

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Competition for Keytruda's NSCLC position? 

In the first quarter of 2020, Opdivo sales slid 2% compared to the previous year period to an annualized $7.1 billion. Although it's Bristol's third-largest revenue stream at the moment, this first-line NSCLC expansion could make the Opdivo plus Yervoy combination Bristol's lead growth driver in the second half of 2020.

Opdivo plus Yervoy were specifically approved to treat advanced-stage NSCLC patients with PD-L1 positive tumors that don't display epidermal growth factor receptor (EGFR) mutations or anaplastic lymphoma kinase (ALK) mutations. Keytruda is approved to treat the same group as a monotherapy and in combination with standard chemotherapy regardless of PD-L1 status. Keytruda plus chemo is also approved to treat around a third of NSCLC patients sub-classified as squamous regardless of their EGFR, and ALK mutation status.