- Merck's Keytruda (pembrolizumab) has been approved by the FDA for second-line treatment of non-small cell lung cancer (NSCLC) tumors that express high levels of the PD-L1 protein.
- The FDA also approved a companion diagnostic from Dao North America to test PD-L1 levels.
- Based on Merck's estimates, approximately 25% of NSCLC patients have PD-L1 levels that make them eligible for treatment with Keytruda. That likely means a continued market advantage for Bristol-Myers Squibb's Opdivo, which doesn't have a similar patient population restriction.
Keytruda is now the second immuno-oncologic drug approved for NSCLC, in addition to BMS's Opdivo (nivolumab). According to the National Cancer Institute, roughly 221,00 people will receive a lung cancer diagnosis this year, and 158,040 people will die from it. Keytruda is an important second-line option for patients with a specific type of lung cancer, NCSLS, which affects approximately 85% to 90% of all patients with lung cancer.
Initially, the stock was down on the news, because some investors were concerned that the need for a certain level of PD-L1 expression would limit uptake. However, the science supporting that limit on the overall patient pool is clear: In Merck's phase 1 study of 495 patients with advanced NSCLC, 45% of subjects with high PD-L1 levels (levels above 50%) responded to Keytruda, compared with 16.5% of subjects with PD-L1 levels between 1% and 49%.
The monthly cost of Keytruda is roughly $12,500 per year, with a total annual cost of around $150,000.