TriangleHEALTH PROFESSIONAL · SOURCE READING
Immunotherapy
Source: Rectal Cancer Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: February 12, 2025 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary. Independent clinical review is pending.
Context: Treatment of Stages II and III Rectal Cancer / Treatment Options for Stages II and III Rectal Cancer
Among patients with rectal adenocarcinomas, 5% to 10% of the tumors have mismatch repair deficiency or high MSI. Immune checkpoint inhibitors are efficacious as a first-line therapy for metastatic colorectal cancers, with overall response rates of 30% to 60%.[26-28] These responses proved durable, and prolonged OS was demonstrated in these settings.
Evidence (immunotherapy):
A phase II trial (NCT04165772) studied dostarlimab, an anti-programmed death-1 (PD-1) monoclonal antibody, in 12 patients with locally advanced, mismatch repair–deficient, stage II or stage III rectal adenocarcinoma.[29]
Source links and citations
A phase II trial (NCT04165772) studied dostarlimab, an anti-programmed death-1 (PD-1) monoclonal antibody, in 12 patients with locally advanced, mismatch repair–deficient, stage II or stage III rectal adenocarcinoma.[29]
All 12 patients had clinical complete responses of 100% (95% CI, 74%–100%) after a median follow-up of 12 months. Patients’ cancers did not recur when the follow-up period ranged from 6 to 25 months. At the time of follow-up, chemoradiation therapy and surgery had been avoided.[29][Level of evidence C3]
Source links and citations
A phase II trial (NCT04165772) studied dostarlimab, an anti-programmed death-1 (PD-1) monoclonal antibody, in 12 patients with locally advanced, mismatch repair–deficient, stage II or stage III rectal adenocarcinoma.[29]
Before this approach becomes a new standard, more patients need to be evaluated. A longer follow-up period is required to ensure durability and assess the need for future surgery or chemoradiation therapy.
Studies cited in this source section
Source citation is not a determination that a study applies to you.
Publication references
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Preserved source evidence · Independent clinical review pending · Not medical advice