The United States Food and Drug Administration (FDA) approved a new use of an immunotherapy that could allow certain rectal cancer patients to avoid surgery, chemotherapy, and radiation therapy.
The decision opens a new treatment possibility for a specific group of patients, although more studies are still needed to determine if the benefits are sustained in the long term.
On October 19, the FDA announced the approval of this new use for the Jemperli medication, also known as dostarlimab, developed by the pharmaceutical company GSK.
The medication was already used to treat other types of cancer. The new development is that it can now be used in the United States for certain patients with rectal cancer who have not yet received treatment.
Who could benefit?
Not all patients with rectal cancer can receive this immunotherapy.
The authorization is aimed at adults with stage II or III rectal cancer, meaning when the tumor has progressed within that area of the body or to nearby tissues, but has not yet spread to distant organs.
It is also necessary for cancer to have certain characteristics that allow the medication to be more effective.
These characteristics are identified through medical tests and are known as dMMR or MSI-H, two terms that indicate that cancer cells have difficulties repairing certain errors in their genetic material.
In simple terms, those errors can make the tumor easier for the body's natural defenses to recognize and attack.
The FDA estimates that approximately 3% of patients with locally advanced rectal cancer exhibit these characteristics.
Therefore, before considering the treatment, doctors must conduct specific tests to determine if the patient meets the necessary criteria.
How does Jemperli work?
Unlike chemotherapy, which uses drugs to destroy cancer cells, this immunotherapy helps the body's own defense system to fight the tumor.
Some types of cancer manage to go unnoticed by the body's defenses. Jemperli blocks one of the signals they use to evade attack.
In this way, the immune system can better recognize cancer cells and act against them.
The goal is to control or eliminate the detectable signals of the tumor without immediately resorting to more aggressive treatments.
In rectal cancer, traditional options may include chemotherapy, radiotherapy, and surgery to remove the tumor.
Although these treatments may be necessary to combat the disease, they can also cause significant side effects.
For example, some surgeries affect the functioning of the intestine and, in certain cases, require creating an opening in the abdomen to expel waste into a bag, a procedure known as colostomy.
Chemotherapy and radiotherapy can also cause discomfort and affect urinary, sexual, or reproductive functions.
The possibility of avoiding these procedures, when it is medically safe to do so, is one of the most promising aspects of the medication.
FDA Results
The FDA's decision was primarily based on the results of a study called AZUR-1, which involved 154 patients with rectal cancer who met the necessary criteria.
Participants received Jemperli intravenously, through multiple administrations over a period of approximately six months.
According to the results released by the FDA, 110 out of 154 patients, which is 71%, did not require additional surgery, radiation therapy, or chemotherapy, and their cancer showed no signs of progression during the evaluation period.
It is an important result because it suggests that, in certain individuals, immunotherapy can control the disease without resorting to other treatments.
However, this does not mean that 71% of patients are definitively cured.
Researchers still need to verify over a longer period whether the cancer reoccurs and how long the benefits of the medication last.
In the same study, 26 patients required surgery and another 13 received additional treatments, such as cancer medications or radiation therapy.
There was also a patient whose cancer progressed without receiving any further treatment, while four participants dropped out of the study or were unable to continue under follow-up.
The doctors observed the participants over a follow-up period with a central duration of approximately two years and two months.
During that time, they conducted tests to check if the tumor was still present or if there were signs of it returning.
Among those tests were MRI scans, CT scans, and examinations that allow for viewing the interior of the rectum.
Patients who did not show detectable signs of cancer were able to continue under medical surveillance without undergoing immediate surgery.
But this decision requires regular monitoring, because avoiding surgery does not mean abandoning treatment or neglecting to monitor the disease.
If cancer reappears or does not respond adequately to the medication, doctors may consider surgery or other alternatives.
The FDA also took into account a previous study conducted at a cancer specialty center in New York, which involved 50 patients with similar characteristics.
That research also showed encouraging results, although it is different from the AZUR-1 study, which involved 154 participants and served as the main basis for the new authorization.
Does approval mean that the medication has already demonstrated all its benefits?
The answer is no.
The FDA granted accelerated approval, a process that allows for the early authorization of certain promising treatments aimed at serious diseases.
This means that the available results are encouraging enough to allow for their use in selected patients, but it is still necessary to confirm how long their effectiveness lasts.
The company GSK must continue to evaluate patients and provide additional information on long-term results.
It is also important to clarify that Jemperli can cause serious side effects.
Since the medication stimulates the body's immune response, in some individuals it may cause the immune system to mistakenly attack healthy organs and tissues.
These reactions can cause significant health problems and, in exceptional situations, can even be fatal.
Among the most common side effects are fatigue, diarrhea, itching, and skin rashes.
Reactions may also occur during the administration of the medication, as well as complications that require immediate medical attention.
Therefore, the choice of this immunotherapy should be made under the supervision of cancer specialists.
Patients diagnosed with rectal cancer may ask their oncologist whether they need tests to identify dMMR or MSI-H characteristics and if they could benefit from this treatment.
Approval does not mean that all patients should abandon surgery, radiotherapy, or chemotherapy. It is also not advisable to stop or modify an already prescribed treatment without consulting the medical team.
The new authorization pertains to the United States and does not imply that the medication is approved for this same use in all countries.
The FDA reported that other regulatory agencies, including those from Canada, Israel, Switzerland, and the United Kingdom, participated in the international review of the application, even though their assessments were ongoing when the U.S. decision was announced.
The organization also did not indicate that the treatment would be covered by all health insurance plans nor guaranteed its availability in specific hospitals.
For Cuban patients living in the United States who meet the medical requirements, the new indication may represent an alternative that they should evaluate with their specialists.
The approval adds to other recent advancements in the development of drugs against various types of cancer.
On October 19th, it was announced that Russia had authorized the registration of a cancer medication developed in Cuba, known as nimotuzumab.
It is a different product, created by the Molecular Immunology Center in Havana, that acts on certain signals that promote the growth of some tumors.
Therefore, it should not be confused with Jemperli, which aims to help the body's natural defenses combat cancer cells and whose new U.S. approval specifically pertains to certain cases of rectal cancer.
In April 2025, Cuba also reported on trials of another experimental immunotherapy for patients with advanced cancer, developed at the Hermanos Ameijeiras Hospital in Havana.
That research was aimed at individuals who had already undergone other treatments without achieving the expected results.
However, access to cancer treatments continues to face difficulties on the island.
In May 2025, Dr. Jorge Álvarez Blanco, head of Medical Oncology in Sancti Spíritus, raised concerns about late diagnoses and the lack of necessary medications to complete treatments.
The specialist explained that some patients need multiple medications for chemotherapy, but these are not always available, while issues with radiation therapy equipment also impact oncological care.
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