GSK’s top-selling cancer product is expanding its approval to include advanced cases of rectal cancer, bringing eligible patients the option of treatment with an immunotherapy that could avoid the need for chemotherapy, radiation, and surgery.
The drug, dostarlimab, brand name Jemperli is now approved for treating rectal cancer in adults who have stage II or III disease that is locally advanced, the FDA announced Monday afternoon. The drug was initially approved five years ago for endometrial cancer.
Jemperli is a checkpoint inhibitor, part of a class of antibody drugs designed to block PD-1, a protein on immune cells that keeps them from recognizing and fighting cancer cells. In both endometrial cancer and rectal cancer, the drug is approved for treating disease that is microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), genetic characteristics that make a cancer cell unable to properly repair DNA damage. To determine whether a patient is eligible for the drug, the genetic signature must be first be identified by an FDA-authorized test for solid tumors.
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Patients with advanced cases of rectal cancer typically receive chemotherapy or radiation before undergoing surgery to remove the malignancy. These treatments come with a range of complication risks. Jemperli started to show its potential in rectal cancer in a small study conducted at Memorial Sloan Kettering Cancer Center. Preliminary results were the talk of the 2022 annual meeting of the American Society of Clinical Oncology. Full results showed treatment with Jemperli alone led to no detectable signs of cancer in all 50 patients; 93% of these patients remained cancer free at one year.
GSK’s FDA submission for Jemperli in rectal cancer was based on a pivotal Phase 2 test it conducted evaluating the immunotherapy in 154 previously untreated rectal cancer patients. After a median follow-up of more than two years, almost three-fourths of patients had not needed surgery, radiation, or chemotherapy. These patients continue to be followed to better understand the durability of the Jemperli. GSK reported preliminary Phase 2 data in July. Full results are scheduled for presentation later this week during the European Society of Medical Oncology annual meeting in Madrid.
“People facing rectal cancer are often thinking not only about treating their disease, but also worrying about what life will look like afterwards,” Colorectal Cancer Alliance CEO Michael Sapienza said in GSK’s Jemperli approval announcement. “The possibility of avoiding chemotherapy, radiation and surgery represents a meaningful advance for patients and their families.”
Jemperli received particularly speedy FDA consideration, reviewed under an FDA pilot program that shortens the review time for drugs that meet a national health interest, such as cancers with limited treatment options. The regulatory decision in rectal cancer is an accelerated approval based on the interim results. GSK must submit additional clinical data to demonstrate lasting clinical benefit.
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Jemperli was initially discovered and developed by AnaptysBio, which then licensed it to Tesaro. GSK bought Tesaro in 2018 and continued the drug’s development. Since Jemperli’s 2021 approval in endometrial cancer, it has grown to become GSK’s top overall cancer product. For 2025, GSK reported £861 million (about $1.1 billion) in sales for the drug. For the first half of this year, GSK reported £480 million (about $644 million) in Jemperli revenue. GSK sees additional growth opportunities for the product. Clinical trials are underway evaluating Jemperli in colorectal and head and neck cancers.
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