The expanded FDA approval for the GSK drug positions the immunotherapy for a broader market.
On Tuesday, the FDA approved the drug, known as Jemperli (dostarlimab) for treating adults with mismatch repair-deficient recurrent (dMMR) or advanced solid tumors, usually found in endometrial, colorectal or other gastrointestinal cancers. Various solid tumors classified as "mismatch repair-deficient" or dMMR affects a cell’s ability to repair the DNA mutations that lead to cancer. The expanded label approval may support GSK in competing against Merck & Co.'s Keytruda, which in 2017 was approved for certain patients with hard-to-treat solid tumors that have the dMMR biomarker. Jemperli has now received two FDA approvals. The first came in April and was more narrowly tailored, allowing the drug only in previously treated dMMR endometrial cancer. The latest approval was based on the results of an open-label Phase 1 study called GARNET.
The study evaluated 209 patients with recurrent or advanced solid tumors carrying the dMMR mutation. Overall, Jemperli shrank tumors in 41.6% of the patients, with the median response lasting almost three years. Among the responders, about 95% were still in remission after six months or longer. In the non-endometrial cancer cohort, the response rate was 38.7%. The drug is the seventh of its kind to come to market and stands in direct competition with other immunotherapies like Keytruda, Bristol Myers Squibb's Opdivo, and others sold by Roche, Pfizer, AstraZeneca and Regeneron. GSK earned the expanded label due to tumor shrinkage data. As is the case with any conditional nod, the British Pharma company needs to verify Jemperli’s benefit in a confirmatory trial for continued approval.