The FDA has approved the use of Keytruda in combination with chemotherapy as a first-line treatment for the most common type of lung cancer.

Last year, the FDA approved it for lung cancer patients whose tumors produce a high amount of the protein PD-L1, which covered only a fraction of the total cases of lung cancer. The FDA approval for pembrozlizumab (Keytruda) to treat metastatic non-squamous non-small cell lung cancer widens the use of the immunotherapy.

The Merck drug blocks the signals that some cancers use to evade attack by the immune system.

FDA decision approves a combined use of pembrolizumab and the chemotherapy pemetrexed (Almita) to treat lung cancer patients whether or not their tumors express PD-L1. There are more than 200,000 new cases of lung cancer each year in the U.S., and it is the leading cause of cancer death, according to the American Cancer Society.

According to media reports, the FDA granted accelerated approval of the combination after a study in 123 patients showed it had an effect on 55 percent of them, nearly double the effect in the pemetrexed-only group. Among patients treated with the combination, 93 percent showed a response to the drug for six months or more, compared to 81 percent of patients treated with only chemotherapy.

The study also was based on the patients’ progression-free survival, which is a measure of time after treatment that a patient lives without the cancer worsening. Median progression-free survival was 13 months in the combination treatment group, compared to 8.9 months in the chemotherapy group.

Pembrolizumab is also approved for certain kinds of skin cancer, head-and-neck cancer, and Hodgkin lymphoma.