FDA Grants Accelerated Approval to Jemperli for Rectal Cancer: Immunotherapy Alone, Without Chemo, Radiation, or Surgery

Oct 21

Quick Answers

What happened? On October 19, 2026, the FDA granted accelerated approval to Jemperli (dostarlimab) for adults with stage II or III rectal cancer whose tumors are MSI-H or dMMR and have not spread beyond the local area. It is the first and only immunotherapy approved for this use.
Why is it different? Standard rectal cancer treatment usually means chemotherapy, radiation, and surgery. Jemperli is immunotherapy alone — no chemo, no radiation, no surgery first. Patients whose cancer fully responds may be able to skip those treatments and be watched closely instead.
How well did it work? In the AZUR-1 study of 154 patients, 47% had a clinical complete response — no detectable cancer — that lasted at least 12 months, based on independent expert review. No patient whose cancer responded has had it come back so far, after more than two years of follow-up on average.
Who is it for? Only the roughly 5–10% of rectal cancers that are MSI-H or dMMR. A lab test on the tumor is how doctors find out. Most rectal cancers are not in this group.

What Happened in Rectal Cancer News?

A rectal cancer diagnosis usually comes with a hard road: months of chemotherapy and radiation, then major surgery. For many people, that surgery means a permanent colostomy bag. Even when it doesn't, bowel, bladder, and sexual problems can last for life.

On October 19, 2026, the U.S. Food and Drug Administration (FDA) granted accelerated approval to a different path for a specific group of patients. Jemperli (dostarlimab-gxly), made by GSK, is now approved for adults with stage II or III locally advanced rectal cancer whose tumors are MSI-H or dMMR.

Jemperli is an immunotherapy drug. It does not poison cancer cells the way chemotherapy does. Instead, it helps your own immune system find and attack the cancer.

It is the first and only immunotherapy approved for this group of patients — and it is given on its own, with no chemotherapy or radiation alongside it.

For the first time, some rectal cancer patients may be able to treat their cancer with immunotherapy alone — and, if it works completely, skip surgery altogether.

This approval is a close cousin of the one we covered last week, when the FDA approved immunotherapy plus chemotherapy for stage III dMMR colon cancer. Same family of tumors — dMMR. Same idea — immunotherapy. Opposite recipe: there, immunotherapy was added to chemotherapy after surgery. Here, immunotherapy replaces chemotherapy, radiation, and surgery — at least for patients whose cancer fully responds.

What Is Rectal Cancer, and What Does Treatment Usually Look Like?

The rectum is the last several inches of the large intestine, just before the anus. Rectal cancer is closely related to colon cancer — together they are called colorectal cancer — but its location deep in the pelvis makes it harder to treat.

"Locally advanced" means the cancer has grown through the rectal wall or into nearby lymph nodes, but has not spread to distant organs. Stage II and stage III describe how far it has grown locally.

Standard treatment for locally advanced rectal cancer usually has three parts:

Chemotherapy, often combined with radiation to the pelvis, to shrink the tumor
Surgery to remove the rectum, or part of it
Sometimes more chemotherapy afterward

This approach saves lives. But it can leave lasting effects:

Bowel problems, such as urgency, leakage, or frequent trips to the bathroom
Bladder problems
Sexual dysfunction
Infertility
A temporary or permanent colostomy — an opening in the abdomen where waste leaves the body into a bag
A small risk of a second cancer years later from the radiation

That is why doctors and patients have been looking for a way to cure this cancer while letting people keep their rectum — and their normal body function. It is sometimes called "organ preservation." Jemperli is the biggest step in that direction so far.

What Does MSI-H or dMMR Mean?

These two terms describe the same basic feature of a tumor, found by lab testing.

Your cells have a repair system that fixes small copying mistakes in your DNA. Think of it like spell-check for your genetic code.

In some tumors, that spell-check system is broken. Mistakes pile up. A tumor like this is called dMMR (deficient mismatch repair). Because so many mistakes build up, the tumor's DNA becomes unstable — that is called MSI-H (microsatellite instability-high).

Here is the surprising part: all those mistakes make the tumor look strange to the immune system. A normal tumor can be hard for the immune system to notice. An MSI-H/dMMR tumor is covered in unusual markers, like a car covered in warning stickers. That makes it much easier for immunotherapy to work against it.

About 5–10% of rectal cancers are MSI-H/dMMR. That is a small group — but for that group, this news is major.

Testing matters. The FDA approval requires an FDA-authorized test to confirm the tumor is MSI-H or dMMR. If you or a loved one has rectal cancer, asking "Was my tumor tested for MSI and MMR?" is one of the most important questions you can ask. Our recent post explains the same testing for colon cancer: FDA Approves Immunotherapy Plus Chemotherapy for Stage III Colon Cancer.

What Is Jemperli and How Does It Work?

Jemperli's medical name is dostarlimab-gxly. It is a type of immunotherapy called a PD-1 blocker.

Here is a simple way to picture it. Your immune system has T cells that patrol the body looking for threats. Some cancer cells survive by pressing a "brake pedal" called PD-1, which tells T cells to stand down. Jemperli blocks that brake pedal. With the brake released, T cells can recognize the cancer — especially an MSI-H/dMMR tumor covered in unusual markers — and attack it.

For this rectal cancer use, Jemperli is given through an IV (a drip into a vein):

500 mg every 3 weeks
9 doses over about 6 months
No chemotherapy or radiation given with it

After treatment, doctors check the tumor carefully — with exams, scopes, scans, and biopsies — to see whether the cancer is still detectable.

If no cancer can be found, that is called a clinical complete response. Patients who reach that point may choose close monitoring — often called "watch and wait" — instead of surgery. The close monitoring is not optional or casual: it means regular exams, scopes, and scans for years, so any return of the cancer is caught early.

What Did the AZUR-1 Study Find?

The approval is based on AZUR-1, a global phase 2 study of 154 patients with stage II or III MSI-H/dMMR locally advanced rectal cancer, all treated with Jemperli alone.

One important detail: AZUR-1 had no comparison group. Everyone in the study got Jemperli. That means we know how patients did on Jemperli, but the study cannot directly prove how it compares with standard chemotherapy, radiation, and surgery. Keep that in mind as you read the results — they are genuinely exciting, and genuinely early.

The study's main measure was a clinical complete response sustained for 12 months — no detectable cancer, still gone a full year later.

The key results

47% of patients (54 of 116 evaluated) had a clinical complete response sustained 12 months, based on independent central review — outside experts who checked the results. This is the study's official main result (95% confidence interval: 37–56%). The number is still maturing: 38 more patients whose cancer had already fully responded were still inside their 12-month follow-up window when the data was reported.
When the study doctors assessed their own patients, the 12-month complete response rate was 68% (98 of 144). Independent review is stricter, which is why its number is lower — and why the 47% figure is the one to lead with.
76% of patients (110 of 144) had no evidence of cancer one year or more after treatment in an exploratory analysis — including 12 patients whose complete response was confirmed by tissue examination after surgery.
No disease recurrences have been reported among patients whose cancer responded, after a median follow-up of more than two years.
Roughly 71% of treated patients received Jemperli alone, with no chemotherapy, radiation, or surgery afterward.

Nearly half of patients had no detectable cancer a full year after Jemperli alone — and, so far, none of the responders has had the cancer come back.

Earlier evidence pointed this way. In a well-known Memorial Sloan Kettering study published in The New England Journal of Medicine in 2022, the first 12 patients treated with dostarlimab for this type of rectal cancer all had a complete response. AZUR-1 is the larger study that put the approach on the FDA's desk.

GSK is presenting the full AZUR-1 results at the ESMO Congress in Madrid on October 25, 2026. We will be watching for longer follow-up numbers.

What Does "Accelerated Approval" Mean?

This part matters, so let's be clear about it.

Under accelerated approval, the FDA allows a drug on the market based on early results that suggest a real benefit — here, complete responses lasting 12 months — instead of waiting years for proof that patients live longer or stay cancer-free longer. In return, the company must keep studying the drug, and continued approval can depend on those follow-up results. If the benefit does not hold up, the approval can change.

Three honest caveats for this approval:

Single-arm study. AZUR-1 had no comparison group, so there is no direct head-to-head proof against standard chemoradiation and surgery.
Long-term durability is unknown. The FDA label notes that the long-term risk of the cancer coming back is not yet known. Two-plus years without a recurrence among responders is encouraging — it is not the same as "cured forever."
Small eligible group. Only the 5–10% of rectal cancers that are MSI-H/dMMR qualify. For everyone else, standard treatment remains the path.

None of this cancels the news. It frames it: a real breakthrough, at an early stage of proof.

What Side Effects Can Jemperli Cause?

"Immunotherapy alone" does not mean "no side effects." In AZUR-1:

Fatigue — 32% of patients
Rash — 22%
Diarrhea — 18%
Itching (pruritus) — 17%
Serious side effects occurred in 20% of patients
3% of patients stopped treatment permanently because of side effects

Because Jemperli releases the immune system's brakes, it can also cause immune-related side effects: the immune system can inflame healthy organs, including the bowels (colitis), lungs, liver, kidneys, skin, or hormone glands such as the thyroid. These can appear during treatment or even after it ends.

Diarrhea deserves special attention with this drug. It can be a simple side effect — or an early sign of immune inflammation of the colon, which needs prompt medical treatment. Either way, ongoing diarrhea also drains water and electrolytes from the body. Report it early, do not just wait it out.

Three Myths to Avoid

Myth 1: "Accelerated approval means it is fully proven." No. It means the early results were strong enough to make the drug available while confirmatory studies continue. The complete-response numbers are real; the long-term picture is still being written.

Myth 2: "If the cancer disappears, you're done with doctors." No. A clinical complete response is the start of years of close surveillance — regular rectal exams, endoscopies, and MRI scans. That watch-and-wait plan only works if you keep every appointment.

Myth 3: "Immunotherapy is gentle, so side effects don't matter." Most patients in AZUR-1 had manageable side effects, but 1 in 5 had a serious one. Fatigue, rash, diarrhea, and immune-related inflammation are real, and new symptoms during or after treatment should always be reported promptly.

What Should Patients and Caregivers Watch For?

During and after Jemperli treatment, contact your care team promptly if you notice:

Diarrhea that is new, worse than usual, or lasts more than a day — or any blood or mucus in the stool
Severe stomach pain or tenderness
A new or spreading rash, blistering, or severe itching
Cough, shortness of breath, or chest pain
Yellowing of the skin or eyes, or dark urine
Unusual tiredness, weight change, mood change, or feeling cold all the time (possible hormone-gland effects)
Headaches that won't go away, or vision changes
Signs of dehydration: dry mouth, dizziness, urinating much less than usual, muscle cramps, or a racing heartbeat

Because immune-related side effects can appear even after treatment ends, keep reporting new symptoms at follow-up visits too.

Why Supportive Care Still Matters — Even Without Chemotherapy

This approval is about avoiding harsher treatment, not about avoiding care. Learn more in our post: Cancer Treatment Is More Than Fighting the Tumor: Why Supportive Care Matters

For patients on Jemperli, supportive care looks like this:

Diarrhea and hydration. With 18% of patients getting diarrhea, fluids and electrolytes still matter. Losing water, potassium, and magnesium day after day leaves you weak and can strain the heart and kidneys. Keep up with fluids, and ask your team whether your electrolytes should be checked.
Fatigue. Nearly 1 in 3 patients felt significant fatigue. Rest planning, light activity, and good nutrition support are part of treatment, not extras.
Life under surveillance. Skipping surgery means years of scopes, scans, and "scanxiety" — the worry that comes with each check. That is its own quality-of-life topic, and it is worth discussing openly with your team and family.
Bowel, bladder, and sexual health. The whole point of organ preservation is protecting these functions. If something changes, say so — your team can only help with what they know about.

That is the supportive-care space HuMOLYTE was made for. HuMOLYTE is a medical food for use under medical supervision, designed to support hydration and electrolyte balance — including magnesium, which many standard drinks do not replace — and gut health during cancer treatment. HuMOLYTE does not treat cancer, and it does not replace Jemperli, surgery, or care from your oncology team. Talk with your oncologist before starting any new product during treatment, including HuMOLYTE.

Practical steps that help during immunotherapy:

Keep a simple symptom diary: energy, appetite, bathroom habits, skin changes.
Report diarrhea, rash, or a new cough early — do not wait for the next infusion.
Ask whether you need lab checks for thyroid and other hormone levels.
Keep every surveillance appointment, even when you feel perfectly well.

Questions to Ask Your Oncologist

Was my tumor tested for MSI and mismatch repair (MMR)? Is it MSI-H or dMMR?
Am I a candidate for Jemperli instead of chemotherapy, radiation, and surgery?
What does "accelerated approval" mean for my situation, and what follow-up studies are planned?
If I have a complete response, what would the watch-and-wait schedule look like — how often would I need exams, scopes, and scans?
What happens if the cancer comes back during surveillance? Is surgery still an option then?
What side effects should I watch for, and which ones mean I should call right away?
How long would I be on Jemperli, and what happens if side effects force us to stop early?
How will my thyroid and other hormone glands be monitored?
What is our plan for fluids and electrolytes if I develop diarrhea?
If I am not MSI-H/dMMR, what standard treatment do you recommend, and are there clinical trials for me?

The Bottom Line

On October 19, 2026, the FDA granted accelerated approval to Jemperli (dostarlimab) — immunotherapy alone — for adults with stage II or III MSI-H/dMMR locally advanced rectal cancer:

In AZUR-1 (154 patients), 47% had a complete response sustained 12 months by independent review — with results still maturing — and 68% by investigator assessment.
No responder has had the cancer come back so far, after a median follow-up of more than two years.
About 71% of patients avoided chemotherapy, radiation, and surgery entirely.
The most common side effects were fatigue (32%), rash (22%), and diarrhea (18%); serious side effects occurred in 20%, and immune-related inflammation is the key risk to watch.
Only 5–10% of rectal cancers are MSI-H/dMMR — tumor testing decides eligibility.

This does not mean rectal cancer is cured without surgery for everyone, or that the long-term results are settled. It does mean that for a well-defined group of patients, there is now an FDA-approved path that starts with immunotherapy alone — and that sparing people chemo, radiation, and life-changing surgery, when it is safe to do so, is a goal worth building treatment around. If you or a loved one has rectal cancer, the first step is a simple question: Was the tumor tested?

Frequently Asked Questions

What is Jemperli? Jemperli (dostarlimab-gxly) is an immunotherapy drug called a PD-1 blocker. It helps your immune system recognize and attack cancer. On October 19, 2026, the FDA granted it accelerated approval — as the first and only immunotherapy — for adults with stage II or III MSI-H/dMMR locally advanced rectal cancer.

How is Jemperli different from standard rectal cancer treatment? Standard treatment usually combines chemotherapy, radiation, and surgery, which can cause lasting bowel, bladder, and sexual problems or a permanent colostomy. Jemperli is given alone, by IV, every 3 weeks for about 6 months. Patients whose cancer completely responds may skip chemo, radiation, and surgery and be monitored closely instead.

What does MSI-H/dMMR mean, and how do I know if I have it? It means the tumor's DNA spell-check system (mismatch repair) is broken, so mistakes pile up and the tumor looks unusual to the immune system — which makes immunotherapy work especially well. About 5–10% of rectal cancers are MSI-H/dMMR. An FDA-authorized lab test on the tumor tells you which group you are in.

How well did Jemperli work in AZUR-1? In the 154-patient AZUR-1 study, 47% of patients had no detectable cancer that lasted at least 12 months by independent review (the main result, still maturing), and 68% by investigator assessment. No patient whose cancer responded has had a recurrence so far, after a median follow-up of more than two years.

What does "accelerated approval" mean? It means the FDA approved the drug based on promising early results — here, complete responses lasting 12 months — rather than waiting years for long-term survival data. Continued approval depends on confirmatory results. The long-term risk of the cancer returning is not yet known.

If my cancer disappears, can I skip follow-up? No. A clinical complete response leads to a "watch and wait" plan: frequent exams, scopes, and scans for years. Skipping surveillance removes the safety net that makes organ preservation safe.

What are Jemperli's side effects? The most common in AZUR-1 were fatigue (32%), rash (22%), diarrhea (18%), and itching (17%). Serious side effects occurred in 20% of patients. Jemperli can also cause immune-related inflammation of the bowels, lungs, liver, kidneys, skin, or hormone glands — during or even after treatment.

Can Jemperli be used for colon cancer too? This approval is for rectal cancer. A related immunotherapy approach — atezolizumab plus chemotherapy after surgery — was approved on October 8, 2026 for stage III dMMR colon cancer. The tumor feature (dMMR) is the same; the treatments and settings differ.

What if my rectal cancer is not MSI-H/dMMR? Then this approval does not apply, and standard treatment — chemotherapy, radiation, and surgery — remains the recommended path. Ask your oncologist about clinical trials, which exist for many rectal cancer situations.

Should I ask about Jemperli before starting standard treatment? Yes — timing matters. Once chemotherapy, radiation, or surgery has already happened, the organ-preservation path may no longer be available in the same way. If you have newly diagnosed stage II or III rectal cancer, ask about MSI/MMR testing and Jemperli eligibility before treatment begins.

Sources

For more information on how HuMOLYTE can support your gut health during chemotherapy, visit our product page or consult your health care provider.

This blog was reviewed by Dr. Sourabh Kharait.

This blog is for educational purposes only and is not intended as medical advice. Always consult with your healthcare provider before making any changes to your treatment plan, hydration strategies, or diet. The information provided here is based on general insights and may not apply to individual circumstances.

Rectal CancerJemperliDostarlimabImmunotherapydMMRMSI-HFDA Approval

Rich Foreman