Pembrolizumab can now be used for patients who have never received treatment for non-small cell lung cancer (NSCLC) that has spread to other parts of the body. To be eligible for the drug, patients must take a test that shows their tumors produce a high amount of the protein PD-L1, which pembrolizumab has been designed to recognize. Roughly a quarter of all advanced NSCLC patients have cancer with high PD-L1 levels, according to earlier studies from Merck.
That restriction is important. The new wave of cancer immunotherapies called checkpoint inhibitors, which include pembrolizumab, work well for a minority of patients, but doctors and researchers are only beginning to understand the signs that might point to a benefit for some patients but not others. Those efforts will need to improve if the promise of precision cancer medicine—giving the right medicine to the right patients—is to bear fruit.
(Another kind of cancer immunotherapy uses live, modified T cells but has yet to be approved. Xconomy has compiled a resource of T cell clinical studies here; a second part of the resource, compiling trials of checkpoint inhibitors, is coming soon.)
Pembrolizumab becomes the first checkpoint inhibitor to be approved for first-line non-small cell lung cancer (NSCLC). Last year, the FDA approved the drug and another checkpoint inhibitor, Bristol Myers Squibb’s nivolumab (Opdivo), for second-line patients whose tumors have resisted treatment with either chemotherapy or a drug that targets specific genetic mutations.
The first-line approval for pembrolizumab comes weeks after Merck and its academic collaborators touted positive data from a 305-patient study, KEYNOTE-024.
Merck and Bristol-Myers Squibb (NYSE: BMY) have been studying their flagship drugs in several cancer types. But nivolumab produced negative first-line NSCLC results in August when it failed to show it could do a better job than chemotherapy in progression-free survival—that is, shrinking tumors or keeping them in check.
That news set the stage for pembrolizumab’s positive data. For patients taking the drug in KEYNOTE-024, they showed progression-free survival for a median of 10.3 months, compared to 6.0 months for patients on chemotherapy. Forty five percent of the pembrolizumab patients had either partial or total shrinkage of their tumors, compared to 28 percent of the chemotherapy patients.
The FDA also updated the guidelines for the use of pembrolizumab in second-line NSCLC. According to Merck, patients who have failed to improve with chemotherapy are now eligible for pembrolizumab even if their tumors produce a low level of PD-L1.
Image courtesy of the National Cancer Institute.