Singapore Approves Jemperli for First-Line Treatment of Advanced dMMR/MSI-H Endometrial Cancer

On August 7, 2023, GlaxoSmithKline (GSK) Singapore announced the Health Sciences Authority of Singapore (HSA) has approved a new use for Jemperli (dostarlimab). This approval allows Jemperli to be used alongside carboplatin and paclitaxel, and then as a standalone treatment, for patients with primary advanced or recurrent endometrial cancer, especially those with mismatch repair defects (dMMR) or high microsatellite instability (MSI-H). Jemperli is a PD-1 blocking antibody that disrupts the interaction between the PD-1 receptor and the PD-L1 and PD-L2 ligands.

According to GSK's press release, this approval makes Jemperli the first first-line immuno-oncology therapy in Singapore for treating primary advanced or recurrent endometrial cancer of dMMR/MSI-H, making it suitable for early treatment of these patients. Jemperli was already approved by the HSA Singapore for treating adult patients with recurrent or advanced endometrial cancer of dMMR who have not responded to prior platinum-containing treatments and are not candidates for surgery or radiotherapy.

Jemperli is a humanized anti-PD-1 monoclonal antibody developed by GSK and received approval from the U.S. Food and Drug Administration (FDA) in 2021 for treating patients with advanced solid tumors that are dMMR or MSI-H.

In March 2023, the FDA extended Jemperli’s indication to include treatment of recurrent or metastatic endometrial cancer when used with carboplatin and paclitaxel. This marked a new indication for Jemperli.

The Phase III RUBY clinical trial played a crucial role in this approval. The trial demonstrated that Jemperli combined with chemotherapy significantly increased progression-free survival compared to chemotherapy alone (carboplatin + paclitaxel). Specifically, the median progression-free survival was 18.4 months for the Jemperli combination group versus 10.8 months for the chemotherapy-only group. These outcomes showed that the combination therapy provided significant clinical benefits for patients with recurrent or metastatic endometrial cancer.

Additionally, the combination of Jemperli and chemotherapy showcased superior response rates. The overall response rate was 56.5%, significantly higher than the 42.3% observed in the chemotherapy-only group. This data further supports the efficacy and potential of this treatment.

Importantly, the safety of Jemperli combined with chemotherapy was confirmed, with no new safety concerns identified. Dr. Stephanie Cinthu Stephen Ambrose, Medical Director at GSK Singapore, remarked that the expanded regulatory approval in Singapore redefines the treatment landscape for patients with primary advanced or relapsed dMMR/MSI-H endometrial cancer. Until now, chemotherapy has been the standard treatment for many patients with this progressive disease. In the GSK RUBY trial, the combination of Jemperli and chemotherapy showed a 72% reduction in the risk of disease progression or death compared to chemotherapy alone, offering both statistically and clinically significant benefits. These results emphasize Jemperli's potential to become a foundational immunotherapy in cancer treatment.