The short version
On October 19, 2026, the FDA approved an immunotherapy drug, dostarlimab (Jemperli), for some people with rectal cancer that has not spread to distant organs (Stage II or III). It applies only to tumors that test as "mismatch-repair deficient" (dMMR) or "microsatellite instability-high" (MSI-H). That is about 3 in 100 of these cancers.
Why it matters
Standard treatment for locally advanced rectal cancer often involves chemotherapy, radiation and surgery, which can affect bowel, bladder and sexual function. In the main study, many people with dMMR/MSI-H tumors who took dostarlimab alone had their tumors disappear on exams and scans and stay gone for at least a year. In the main study, after about two years of follow-up, almost three in four people had not needed surgery, radiation or chemotherapy.
What is not yet known
This is an accelerated approval, based on early results from a study without a comparison group. Doctors do not yet know:
- how long the responses last;
- how often the cancer comes back;
- whether this approach helps people live longer than standard treatment.
People treated this way need close, regular checkups.
Questions to ask your care team
- Has my tumor been tested for MMR or MSI? If not, can it be?
- If it is dMMR/MSI-H, is this treatment an option for me?
- What checkups would I need, and how often?
- What would happen if the cancer came back?
This does not apply to rectal cancers without the marker, or to cancer that has spread to the liver or lungs.
About this page
This page is general information and is not advice about your own treatment. It does not create a physician–patient relationship. For a medical emergency, call 911 or go to the nearest emergency department. Medical disclaimer.