GSK Defeats Merck to Receive the First PD-1 Approval for Endometrial Cancer


For the treatment of some patients with recently discovered endometrial cancer, GSK has received the first FDA authorisation for an immunotherapy. A label restriction, though, tempers the industry-first approval.

According to GSK, Jemperli has received FDA approval as a chemotherapy add-on for patients with primary advanced or recurrent endometrial cancer. Patients must have tumours that are mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H), both of which refer to a particular genetic abnormality.

The clearance puts Jemperli in front of Merck & Co.’s competing PD-1 inhibitor Keytruda, which is also vying for first-line endometrial cancer treatment, and occurs roughly two months ahead of plan. However, the dMMR/MSI-H restriction is somewhat disappointing for the GSK medication.

According to GSK, 15% to 20% of the roughly 60,000 new instances of endometrial cancer that are identified each year in the U.S. will be found to be advanced-stage cases. Additionally, dMMR/MSI-H is present in 20% to 29% of all endometrial malignancies.

Prior to Monday’s announcement, GSK revealed in June that the FDA had given Jemperli’s application for first-line endometrial cancer a priority review—but only for dMMR/MSI-H illness. That constrained review contrasted with Jemperli, which demonstrated a benefit in a larger patient population.

In the phase 3 RUBY trial, patients with dMMR/MSI-H tumours had a 72% lower risk of death or progression when Jemperli was added to treatment. However, Jemperli also shown a 24% improvement in progression-free survival in patients with mismatch repair-proficient (pMMR) or microsatellite-stable (MSS) tumours.

“GSK accelerated submission in the dMMR/MSI-H patient population,” where Jemperli demonstrated the strongest treatment effect, a GSK spokesperson told Fierce Pharma. The RUBY trial is still following patients for more overall survival data, and the company is discussing a potential label expansion with the FDA, the spokesperson said.

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