Merck & Co notches up another lung cancer use for Keytruda

Bristol-Myers Squibb’s immunotherapy Opdivo has new competition in small cell lung cancer (SCLC) after the FDA approved its arch-rival, Merck & Co’s Keytruda in the indication.

Keytruda’s new indication is as monotherapy for patients with metastatic SCLC with disease progression on or after platinum-based chemotherapy and at least one other prior therapy.

SCLC accounts for around 10-15% of lung cancers, and is often diagnosed at an advanced stage where prognosis is poor, and when there are few treatment options.

This is an accelerated approval, based on tumour response rate and durability of response data from 83 patients from two smaller trials, the phase 1b KEYNOTE-158, and phase 2 KEYNOTE-128.

This means Merck & Co must confirm the drug’s efficacy with survival data from a larger trial to retain the licence in this indication in the longer term.

Pooled data from the two trials shows a response in 19% of patients treated with Keytruda, and of those 63% of their tumours continued to respond for a year or longer.

Response was seen in patients whose tumours expressed high levels of the biomarker PD-L1, which is consistent with Keytruda’s performance in previous studies.

With Opdivo, BMS also received an accelerated approval in SCLC in third line, also based on tumour response rate and duration of response.

But it ran into trouble with its phase 3 data announced in October, where Opdivo did not hit the primary target of improving overall survival compared with standard chemotherapy of topotecan or amrubicin.

There has been no word on how this will affect the drug’s status on the market in SCLC,  but doctors will be more likely to prescribe Keytruda if Merck can produce data showing that it can improve survival in the longer term and in a larger group of patients.

Adverse reactions that occurred were similar to those occurring in patients with other solid tumors who received Keytruda as a single agent.