FDA Clears Jemperli for Rectal Cancer, Offering Some Patients a Path Without Surgery

Imagine being told your cancer treatment plan involves months of chemotherapy, weeks of radiation, and then major surgery that could permanently change how your body functions. That has long been the standard path for people diagnosed with locally advanced rectal cancer. This week, for a specific subset of those patients, that path got an alternative.

The FDA announced Monday afternoon that it has expanded approval of dostarlimab, sold by GSK under the brand name Jemperli, to include adults with stage II or III rectal cancer that is locally advanced. The approval applies only to tumors with a particular genetic fingerprint, but for patients who qualify, the implications are significant. Instead of the grueling three-part regimen that has defined rectal cancer care for decades, some patients may be able to treat their disease with immunotherapy alone.

Jemperli belongs to a class of drugs called checkpoint inhibitors. Think of PD-1, the protein these drugs target, as a kind of off-switch that cancer cells learn to flip in order to hide from the immune system. By blocking PD-1, Jemperli essentially disables that off-switch, allowing a patient's own immune cells to recognize and attack the cancer. It is not a new mechanism. GSK has used it before.

The drug first won approval five years ago for endometrial cancer, also in patients whose tumors carry specific genetic markers. Those markers are called microsatellite instability-high, or MSI-H, and mismatch repair deficient, or dMMR. Both describe cancer cells that have lost the ability to properly fix errors in their own DNA. That flaw, oddly enough, makes these tumors easier targets for immunotherapy, because the DNA damage tends to make the cancer cells look more foreign to the immune system. Before a patient can receive Jemperli, doctors must confirm this genetic signature using an FDA-authorized test designed for solid tumors.

From a Small Study to a Pivotal Trial

The idea that immunotherapy alone might replace surgery for rectal cancer did not emerge overnight. It traces back to a small study at Memorial Sloan Kettering Cancer Center that became one of the most talked-about presentations at the 2022 annual meeting of the American Society of Clinical Oncology. The results were striking. All 50 patients in that study saw their cancer become undetectable after treatment with Jemperli alone, and 93% remained cancer free a year later.

That early signal was promising enough to justify a larger, pivotal Phase 2 trial, which became the basis for GSK's FDA submission. The trial enrolled 154 previously untreated rectal cancer patients. After a median follow-up of more than two years, almost three-fourths of those patients had avoided surgery, radiation, and chemotherapy entirely. GSK reported preliminary data from this trial back in July, and the full results are scheduled for presentation later this week at the European Society of Medical Oncology annual meeting in Madrid.

Researchers are continuing to track these patients, since the central open question is durability. Avoiding treatment is only meaningful if the cancer stays away. That is also why the FDA granted this an accelerated approval rather than full approval. GSK must still submit additional clinical data demonstrating that the benefit holds up over time, a standard condition for drugs cleared through this faster pathway.

Speed mattered here in more ways than one. Jemperli received expedited review under an FDA pilot program designed to shorten review timelines for drugs addressing a national health priority, a category that includes cancers with limited treatment options. For a disease where standard care can mean lasting changes to bowel function, sexual health, or the need for a permanent colostomy, getting an effective alternative to patients faster carries real weight.

Michael Sapienza, CEO of the Colorectal Cancer Alliance, captured that stakes in GSK's approval announcement. "People facing rectal cancer are often thinking not only about treating their disease, but also worrying about what life will look like afterwards," he said. "The possibility of avoiding chemotherapy, radiation and surgery represents a meaningful advance for patients and their families." That sentiment reflects something clinicians have long understood: cancer treatment decisions are never just about survival. They are about what kind of life a patient gets to return to afterward.

It is worth being clear about scope, though. This approval does not apply to all rectal cancer patients, only those whose tumors carry the MSI-H or dMMR genetic signature. That is a minority of rectal cancer cases overall. For patients without that marker, standard treatment involving chemotherapy, radiation, and surgery remains the appropriate path. Genetic testing to identify eligible patients becomes the critical first step, and expanding access to that testing will matter just as much as the drug itself.

Jemperli's journey to this point has been a long one. The drug was originally discovered and developed by AnaptysBio, which later licensed it to Tesaro. GSK acquired Tesaro in 2018 and carried the drug through continued development. Since its 2021 approval in endometrial cancer, Jemperli has grown into GSK's top overall cancer product by sales. The company reported £861 million, about $1.1 billion, in Jemperli sales for 2025, and £480 million, roughly $644 million, in revenue for just the first half of this year.

GSK is not stopping at rectal and endometrial cancers. The company has clinical trials underway testing Jemperli in colorectal and head and neck cancers, suggesting the drug's role in oncology could continue expanding in the years ahead.

Why It Matters

Treatment decisions in cancer care are rarely just about eliminating disease. They are about the years that follow, and whether patients can return to something resembling normal life. An immunotherapy option that spares eligible rectal cancer patients from chemotherapy, radiation, and surgery does not just shorten treatment. It potentially preserves bowel function, sexual health, and quality of life in ways that matter deeply to patients and their families. The accelerated approval comes with real conditions attached, and GSK still needs to prove the benefit lasts. But for a group of patients who previously faced few alternatives, this approval represents a genuine, if carefully bounded, step forward.