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Dostarlimab is a PD-1 blocker famous for making rectal cancer disappear without surgery in every patient with a mismatch-repair-deficient tumour.
Dostarlimab is a humanised IgG4 antibody against PD-1 that releases exhausted tumour-reactive T cells, given at 500 mg every 3 weeks for four doses and then 1,000 mg every 6 weeks. It is approved in dMMR endometrial cancer with carboplatin and paclitaxel (RUBY, with an overall survival benefit), in all-comer primary advanced or recurrent endometrial cancer with chemotherapy (2024), and for dMMR solid tumours. Its fame comes from the MSK rectal cancer study (Cercek, NEJM 2022), in which every patient with dMMR rectal cancer achieved a clinical complete response, sustained in more than 40 patients by 2025, without surgery, chemotherapy or radiation. That result led to an organ-preservation paradigm, a Breakthrough Therapy designation in 2025 and the AZUR-1 registrational trial. The durability of organ preservation is the open question.
Backbone ribbon from PDB 7WSL. RCSB PDB 7WSL. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
Humanised IgG4 anti-PD-1. Connects to PD-1.
1.Antibody binds PD-1
Source: www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications. Doses are for orientation; the current label governs.
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies.
Covered under the medical benefit with prior authorisation confirming diagnosis, biomarker status and line of therapy; site-of-care policies may steer infusions away from hospital outpatient departments. Plans generally require documented dMMR/MSI-H status for the endometrial and tumour-agnostic uses.
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B). Not medical or financial advice; verify with your plan.
Sources: NICE TA1189 · SMC advice: dostarlimab. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
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Adult patients with mismatch repair deficient (dMMR) recurrent or advanced endometrial cancer (EC), as determined by an FDA-approved test, that has progressed on or following prior treatment with a platinum-containing regimen.
Accelerated approval, dMMR recurrent/advanced endometrial cancer after platinum source
Treatment for adult patients with mismatch repair deficient (dMMR) recurrent or advanced solid tumors, as determined by an FDA-approved test, that have progressed on or following prior treatment and who have no satisfactory alternative treatment options
dMMR solid tumours (tumour-agnostic, accelerated) The confirmatory requirement was still open 5.1 years later, when the FDA's table was read. source
Adult patients with mismatch repair deficient (dMMR) recurrent or advanced endometrial cancer (EC), as determined by an FDA-approved test, that has progressed on or following prior treatment with a platinum-containing regimen.
Confirmed: the accelerated approval of 2021 converted to traditional approval 1.8 years after it was granted.
dMMR primary advanced/recurrent endometrial cancer with chemotherapy (RUBY) source
All-comer primary advanced/recurrent endometrial cancer with chemotherapy source
Breakthrough Therapy designation, dMMR locally advanced rectal cancer (organ preservation) source
| Region | Year | Indication |
|---|---|---|
| US | 2021 | dMMR recurrent/advanced endometrial cancer; dMMR solid tumours |
| US | 2024 | Primary advanced/recurrent endometrial cancer with chemotherapy (all-comers) |
| Adverse event |
|---|
| Fatigue |
| Anaemia |
| Rash |
| Nausea |
| Diarrhoea |
| Hypothyroidism |
| Transaminase increase |
Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
| Country | Reimbursement | List price | Assistance |
|---|---|---|---|
| United States | Medicare Part B (physician-administered); commercial plans per formulary | not disclosed | - |
| United Kingdom | NICE: recommended with chemotherapy for dMMR/MSI-H advanced endometrial cancer (TA1068) | not disclosed | - |
List prices are manufacturer or Medicare figures where publicly disclosed; net prices after rebates are usually lower. Reimbursement changes; check the payer.
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For mismatch repair-deficient rectal cancer, six months of a single antibody now replaces chemotherapy, radiotherapy and an operation, and the same appears to be true for early-stage mismatch repair-deficient cancers of other organs.
Women with newly diagnosed advanced or recurrent endometrial cancer should receive a PD-1 antibody (dostarlimab or pembrolizumab) with their chemotherapy, and mismatch repair testing is now essential because women with dMMR tumours gain a very large and durable benefit. The gain in mismatch-repair-proficient tumours is real but smaller, and molecular classification (POLE, p53, MMR) is increasingly used to decide who benefits most.
Cercek's dostarlimab study is the clearest demonstration that immunotherapy can replace surgery in a solid tumour: patients with dMMR rectal cancer can keep their rectum and avoid the permanent effects of pelvic radiotherapy and surgery. Non-operative management after PD-1 blockade is now in guidelines for this group, and MMR testing before treatment of rectal cancer is essential. The approach applies only to the 5-10% of rectal cancers that are dMMR.
Dostarlimab was approved for previously treated mismatch repair-deficient endometrial cancer on these data, before moving into first-line combination in RUBY.
This paper established a new regulatory paradigm: a drug approved for a molecular feature regardless of organ. It made MSI/MMR testing standard across advanced cancers and remains the clearest example of a biomarker that works across histologies. It also anchored the idea that mutation load, via neoantigens, is what makes tumours visible to T cells.
Query for this drug: (TITLE:"Dostarlimab" OR ABSTRACT:"Dostarlimab" OR TITLE:"Jemperli" OR ABSTRACT:"Jemperli") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Dostarlimab, not a curated reading list.
Shares Nonoperative management of mismatch repair-deficient tumors, Cercek 2022: six months of dostarlimab alone made rectal cancer disappear in every patient with mismatch-repair deficiency, Le 2017: mismatch-repair deficiency predicts response to PD-1 blockade across twelve tumour types, leading to the first tissue-agnostic drug approval, MSI and mismatch-repair testing.
Shares Luis A. Diaz Jr., Cercek 2022: six months of dostarlimab alone made rectal cancer disappear in every patient with mismatch-repair deficiency, Le 2017: mismatch-repair deficiency predicts response to PD-1 blockade across twelve tumour types, leading to the first tissue-agnostic drug approval, MSI and mismatch-repair testing.
Shares Luis A. Diaz Jr., MSI and mismatch-repair testing, dMMR (mismatch repair deficiency by IHC), MSI-high (microsatellite instability by PCR or sequencing).
Shares VENTANA MMR RxDx Panel, MSI and mismatch-repair testing, dMMR (mismatch repair deficiency by IHC), MSI-high (microsatellite instability by PCR or sequencing).
Shares Chemotherapy + PD-1/PD-L1 blockade, first-line advanced endometrial cancer, GOG Foundation, Endometrial cancer with no specific molecular profile, Mismatch-repair-deficient endometrial cancer.
Shares VENTANA MMR RxDx Panel, MSI and mismatch-repair testing, Endometrial cancer with no specific molecular profile, MSI-high (microsatellite instability by PCR or sequencing).
Shares VENTANA MMR RxDx Panel, POLE-ultramutated endometrial cancer, p53-abnormal endometrial cancer, including uterine serous carcinoma, Endometrial cancer with no specific molecular profile.
Shares MSI and mismatch-repair testing, dMMR (mismatch repair deficiency by IHC), MSI-high (microsatellite instability by PCR or sequencing), Mismatch repair deficient (MSI-high) pancreatic ductal adenocarcinoma.