Advanced lung cancer patients will now have access to one of the most promising new cancer therapies as a first-line treatment instead of chemotherapy, following the drug’s EU approval. 

Merck Sharp & Dohme’s (MSD) key PD-1 inhibitor drug Keytruda (pembrolizumab) is now approved in patients with metastatic non-small cell lung cancer (NSCLC) whose tumours have increased PD-L1 expression and no EGFR or ALK mutations.

The EU approval was based on data from the drug’s phase 3 Keynote-024 trial where Keytruda treatment led to better overall survival and progression-free survival compared to standard-of-care chemotherapy.

Keytruda reduced the risk of disease progression or death by 50% and demonstrated superior progression-free survival of 10.3 months, compared to 6 months using traditional first-line 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 of Merck Research Laboratories.

Keytruda is an antibody therapy that interferes with the activation of a molecule called PD-1. The molecule sits on the surface of immune system cells called T-lymphocytes and, when activated, prevents T-lymphocytes from destroying other cells.

In normal circumstances, PD-1 protects healthy cells from destruction by T-lymphocytes. However, cancer cells often exploit this tactic to protect themselves from the immune system.

The EU approval comes three months after the same indication was approved in the US and five months after it received European approval to treat previously-treated locally advanced or metastatic NSCLC.

The news is another blow to PD-1 inhibitor market leader Bristol-Myers Squibb (BMS), developer of Opdivo. Last month, BMS decided against filing for US approval for Opdivo in combination with Yervoy as a first-line treatment for lung cancer following disappointing results from its pivotal Checkmate-026 phase 3 trial.

The gap is closing in terms of revenue too with MSD reporting $919 million in sales in the first three quarters of 2016, compared to Opdivo’s $920 million.