U.S. Approves Immunotherapy Offering Alternative to Surgery for Certain Rectal Cancer Cases

The U.S. Food and Drug Administration (FDA) has given the green light to a new application of an immunotherapy that could enable certain rectal cancer patients to forgo surgery, chemotherapy, and radiation.

This decision introduces a novel treatment option for a specific group of patients, although further research is necessary to determine whether its benefits are sustainable over the long term.

On October 19, the FDA announced the approval of this new use for the drug Jemperli, also known as dostarlimab, developed by the pharmaceutical company GSK.

Previously utilized for other cancer types, Jemperli can now be administered in the U.S. to specific rectal cancer patients who have not yet undergone treatment.

Eligible Patients for the Treatment

Not every rectal cancer patient is a candidate for this immunotherapy. The approval targets adults with stage II or III rectal cancer, meaning the tumor has penetrated certain areas but hasn't spread to distant organs.

The treatment is particularly effective for cancers that exhibit specific characteristics, which are identified through medical tests. Known as dMMR or MSI-H, these terms suggest that cancer cells struggle to repair certain errors in their genetic material.

Simply put, these errors can make the tumor more easily recognizable and attackable by the body's natural defenses.

The FDA estimates that around 3% of patients with locally advanced rectal cancer exhibit these characteristics. Thus, before considering this treatment, doctors must perform specific tests to determine if a patient qualifies.

Mechanism of Jemperli

Unlike chemotherapy, which employs drugs to destroy cancer cells, this immunotherapy engages the body's defense mechanisms to combat the tumor.

Some cancer types manage to evade the body's defenses. Jemperli helps by blocking a signal that these cancers use to avoid detection and attack.

The aim is to control or eliminate visible signals of the tumor without immediately resorting to more aggressive treatments.

Traditional rectal cancer treatments can include chemotherapy, radiation, and surgery to remove the tumor. While these methods can be necessary, they often come with significant side effects, such as impacting bowel function and, in some cases, necessitating a colostomy.

Chemotherapy and radiation can also lead to discomfort and affect urinary, sexual, or reproductive functions.

The possibility of avoiding these procedures, when medically safe, is one of the most promising aspects of the drug.

FDA Findings

The FDA's decision was primarily based on results from a study called AZUR-1, which involved 154 rectal cancer patients with the necessary characteristics.

Participants received Jemperli intravenously over approximately six months. According to the FDA, 110 of the 154 patients, or 71%, did not require additional surgery, radiation, or chemotherapy, and their cancer did not progress during the evaluation period.

This result is significant as it suggests that, for some individuals, immunotherapy can manage the disease without other treatments.

However, this does not guarantee that 71% of the patients are permanently cured. Researchers still need to monitor whether the cancer reoccurs and for how long the medication’s benefits last.

In the same study, 26 patients required surgery, and 13 others received additional treatments like cancer drugs or radiation. One patient's cancer progressed without further treatment, while four participants dropped out or couldn't continue under observation.

The monitoring period lasted approximately two years and two months, during which tests were conducted to determine if the tumor remained or showed signs of returning. These tests included MRIs, CT scans, and exams to view inside the rectum.

Patients who displayed no detectable signs of cancer could continue under medical observation without immediate surgery. However, this decision requires regular monitoring since avoiding surgery doesn't mean discontinuing treatment or neglecting the disease.

If the cancer returns or doesn't respond adequately to the drug, doctors may consider surgery or other options.

The FDA also took into account a prior study at a specialized cancer center in New York, involving 50 patients with similar characteristics. Although this research showed promising results, it differed from the AZUR-1 study of 154 participants, which served as the primary basis for the new approval.

Understanding the Approval's Implications

The FDA has granted accelerated approval, a process that allows promising treatments for serious conditions to be authorized sooner. This indicates that the current findings are encouraging enough for use in selected patients, but further confirmation of long-term effectiveness is needed.

GSK will need to continue evaluating patients and provide additional long-term data.

It’s important to note that Jemperli can cause serious side effects. As the drug stimulates the body's immune response, it may mistakenly attack healthy organs and tissues in some individuals, potentially leading to severe health issues and, in rare cases, being life-threatening.

Common side effects include fatigue, diarrhea, itching, and skin rashes. Reactions during drug administration and complications requiring immediate medical attention can also occur.

Thus, choosing this immunotherapy should be under the guidance of cancer specialists. Rectal cancer patients should consult their oncologists to determine if they need tests to identify the dMMR or MSI-H characteristics and whether they could benefit from this treatment.

The approval does not imply that all patients should abandon surgery, radiation, or chemotherapy. Nor should any ongoing treatment be changed without consulting the medical team.

The new approval is for the United States and does not mean the drug is approved for the same use in other countries. The FDA noted that other regulatory bodies, including those in Canada, Israel, Switzerland, and the United Kingdom, participated in the international review, though their assessments were ongoing when the U.S. decision was made.

The agency did not confirm whether all health insurance plans would cover the treatment or guarantee its availability in specific hospitals.

For Cuban patients residing in the U.S. who meet the medical criteria, this new option may represent an alternative to discuss with their specialists.

This approval adds to recent developments in cancer drug advancements. On October 19, it was reported that Russia authorized the registration of a cancer drug developed in Cuba, known as nimotuzumab.

This is a separate product, created by the Center of Molecular Immunology in Havana, targeting specific signals that promote tumor growth. It should not be confused with Jemperli, which aims to assist the body's natural defenses in fighting cancer cells and whose new U.S. approval specifically applies to certain rectal cancer cases.

In April 2025, Cuba also announced trials of another experimental immunotherapy in advanced cancer patients at the Hermanos Ameijeiras Hospital in Havana. This research focused on individuals who had not achieved desired results from other treatments.

However, access to cancer treatments continues to face challenges in Cuba. In May 2025, Dr. Jorge Álvarez Blanco, head of Medical Oncology in Sancti Spíritus, warned about late diagnoses and the lack of necessary medications to complete treatments.

The specialist noted that some patients require multiple drugs for chemotherapy, which are not always available, while issues with radiotherapy equipment also impact cancer care.