Phase III Data Supports Jemperli Label Expansion for Endometrial Cancer

GSK has recently reported promising results from its Phase III RUBY program, which indicates that Jemperli (dostarlimab), a PD-1 inhibitor, provides superior survival rates for endometrial cancer patients. The study's findings suggest that this treatment could extend its benefits to a wider range of individuals suffering from this type of cancer.

The RUBY program is a Phase III clinical trial that is divided into two parts. The first segment evaluated the combination of Jemperli with carboplatin-paclitaxel as a primary treatment, followed by Jemperli as a maintenance therapy, against chemotherapy with a placebo and maintenance therapy with a placebo. The second segment of the study introduced GSK’s PARP inhibitor Zejula (niraparib) alongside Jemperli for maintenance treatment after the initial treatment with carboplatin-paclitaxel and Jemperli.

The first segment's results were particularly encouraging, showing a significant 31% reduction in the risk of death for patients treated with the Jemperli regimen compared to those receiving chemotherapy alone. Moreover, these patients experienced a substantial overall survival improvement, with an average lifespan extended to 16.4 months.

The benefits of the Jemperli combination were also observed in an additional analysis of patients with mismatch repair proficient (MMRp)/microsatellite stable (MSS) tumors, where the risk of death was reduced by 21%, and overall survival was enhanced by seven months.

Based on these positive results, GSK intends to submit a regulatory application in the first half of the year to expand the indication for Jemperli to include the general endometrial cancer patient population.

The second part of the RUBY study focused on progression-free survival (PFS) and demonstrated that the Jemperli-Zejula combination led to a 40% decrease in the risk of disease progression or death. The median PFS for these patients improved by 6.2 months. In the MMRp/MMS patient group, the combined regimen reduced the risk of death or disease progression by 37% and increased the median PFS by six months.

Jemperli is a monoclonal antibody designed to target the PD-1 receptor, blocking its interaction with its ligands and thereby preventing cancer cells from evading the immune system. This enhances the body's natural defenses against cancer. Initially approved in 2021 for the treatment of endometrial cancer patients with mismatch repair deficiency, Jemperli has since gained additional approvals, including one for frontline endometrial cancer treatment in August 2023, positioning it as a competitor to Merck’s Keytruda (pembrolizumab).