Patients with a certain form of lung cancer will, for the first time, be able to get treatment with Merck & Co's immunotherapy Keytruda as a first-line of attack instead of chemotherapy, following a green light from European regulators in this setting.

The European Commission has approved Keytruda (pembrolizumab) for the first-line treatment of metastatic non-small cell lung cancer (NSCLC) in adults whose tumours have high PD-L1 expression (tumor proportion score [TPS] of 50 percent or more) with no EGFR or ALK positive tumour mutations.

Clearance is based on data from the Phase III Keynote-024 trial, which showed superior overall survival (OS) and progression-free survival (PFS) with Keytruda compared to chemotherapy, the current standard of care for advanced NSCLC.

In the study, Keytruda reduced the risk of disease progression or death by 50 percent compared to chemotherapy, while the median PFS was 10.3 months versus 6.0 months for chemotherapy.

"The approval of Keytruda as a first treatment instead of chemotherapy for patients who express high levels of PD-L1 has the potential to transform the way metastatic non-small cell lung cancer is treated," said Dr Roy Baynes, senior vice president, head of clinical development, and chief medical officer, Merck Research Laboratories.

"We are committed to ensuring that patients in Europe - who are in need of new treatment options - are able to quickly gain access to Keytruda."

Keytruda is a humanised monoclonal antibody that works by increasing the ability of the body's immune system to help detect and fight tumour cells, by blocking the interaction between PD-1 and its ligands to activate T lymphocytes.

The new green light follows the drug's approval in August 2016 for previously-treated patients with locally advanced or metastatic NSCLC whose tumours express PD-L1 (TPS of 1 percent or more) and who have received at least one prior chemotherapy regimen. It is also on the market in Europe to treat advanced melanoma.