The U.S. Food and Drug Administration on Monday granted accelerated approval to GSK plc (GSK) for Jemperli (dostarlimab-gxly), making it the first and only immunotherapy for adults with stage II and III mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H) locally advanced rectal cancer.

This decision allows eligible patients to bypass traditional treatments that permanently impact their daily lives.

Avoiding Invasive Traditional Interventions

Historically, patients facing locally advanced rectal cancer undergo chemotherapy and radiation before surgery.

These standard interventions frequently cause severe complications, including infertility, secondary cancers, and dysfunction in the bowel, urinary, and sexual systems.

Surgical procedures also carry the risk of life-threatening complications or require a permanent colostomy.

Jemperli monotherapy offers a less invasive alternative for the 3% to 10% of rectal cancer patients whose tumors feature the dMMR or MSI-H biomarker.

Jemperli Mechanism and Clinical Trial Efficacy

The dMMR and MSI-H terms identify a flaw in how cancer cells repair DNA errors. As mistakes accumulate, the immune system can spot these proteins.

Jemperli functions by blocking the PD-1 protein on immune cells, removing the shield cancer cells use to hide.

The FDA based its approval on the AZUR-1 Phase II clinical trial. In the study, 154 patients received Jemperli every three weeks for six months.

After a median follow-up exceeding two years, nearly 75% of participants avoided surgery, chemotherapy, and radiotherapy entirely.

Investigator assessments revealed 68% of evaluable participants sustained a complete clinical response at the 12-month mark. Independent central reviews indicate 47% achieved this response, with data still maturing.

Safety Profile and Future Presentations

An earlier trial at Memorial Sloan Kettering Cancer Center observed 50 patients, finding no detectable signs of cancer post-treatment, with 93% maintaining this status for at least twelve months.

GSK plans to present the complete interim AZUR-1 data at the European Society for Medical Oncology Congress in October 2026.

GSK Price Action: GSK shares were up 0.32% at $49.67 at the time of publication on Monday, according to market data.