FDA grants accelerated approval to dostarlimab for dMMR/MSI-H locally advanced rectal cancer

What changed

FDA approved dostarlimab (Jemperli; GSK) for adults with Stage II/III locally advanced rectal cancer that is mismatch-repair deficient (dMMR) or microsatellite-instability high (MSI-H), as determined by an FDA-authorized test. FDA's press release describes use alone, in previously untreated disease. FDA cites published estimates that about 3% of locally advanced rectal cancers are dMMR/MSI-H.

The evidence

AZUR-1 is a single-arm, open-label trial in 154 patients (500 mg IV every three weeks for nine cycles). The primary endpoint was sustained clinical complete response for 12 months (cCR12) on independent central review.

• In the 116 patients evaluable by central review, cCR12 was 47% and objective response was 79%.
• Investigator-assessed cCR12 was 68% in 144 patients.
• At a median follow-up of 26.3 months, FDA reports that no patient with cCR12, cCR or near-CR had progressed.
• A supporting investigator-led study led by Memorial Sloan Kettering (NCT04165772; n=50) reported cCR12 of 93%.

What this establishes

An approved, biomarker-restricted, organ-preserving option for a small, defined group of rectal cancers.

What this does not establish

• It does not establish cure, or that response translates into longer survival.
• It does not apply to rectal cancer that is not dMMR/MSI-H.
• It is not a randomized comparison with chemoradiation and surgery.
• FDA says longer follow-up is needed to understand how long responses last and how often cancer returns. The sponsor must continue follow-up.

Why it matters

Biomarker testing before treatment decides whether the option exists at all. For patients, the immediate consequence is a question to ask: has my tumor been tested for MMR/MSI?

Next decision point

Confirmatory follow-up; FDA documents name no specific confirmatory trial.

Sources

• FDA OCE: accelerated approval dostarlimab LARC Primary · 2026-10-19 · checked 2026-10-19
• FDA press release: dostarlimab rectal cancer Primary · 2026-10-19 · checked 2026-10-19

Related on this site

• Patient Education item P-03
• policy/accelerated-approval-and-confirmatory-trials/
• Records ledger

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