Neoadjuvant Immunotherapy in Localized dMMR/MSI-H Colon Cancer: A Systematic Review of Pathological Response and Surgical Outcomes.
Rathin Gosavi, Baxter Smith, Hanumant Chouhan et al.
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In 30 seconds
This systematic review assessed prospective interventional studies of neoadjuvant immune checkpoint inhibition in adults with localized, non-metastatic dMMR/MSI-H colon cancer. Six studies were included. Pathological complete response (pCR) ranged from 44 to 78.4%, while major pathological response ranged from 57 to 95%; rates varied by regimen, denominator, and definition. Most patients proceeded to colectomy, with high R0 resection rates where reported. Severe treatment-related or immune-related adverse events occurred, including rare grade 5 events. Recurrence was uncommon during reported follow-up, but survival outcomes remain immature.
Key findings
- Across six studies, pCR ranged from 44 to 78.4% and major pathological response from 57 to 95%.
- NICHE-based dual-checkpoint studies reported pCR rates of 60-68% and major pathological response rates of 92-95%.
- Most patients proceeded to colectomy, with high R0 resection rates where reported.
- Severe treatment-related or immune-related adverse events occurred, including rare grade 5 events; recurrence was uncommon and survival outcomes were immature.
Why it matters
The review suggests that neoadjuvant checkpoint inhibition can produce substantial pathological responses in selected localized dMMR/MSI-H colon cancer while allowing surgery in most patients. However, pathological response is not yet evidence of durable oncological benefit, and serious toxicity is possible. These findings help frame the promise and uncertainty of this approach pending longer follow-up and comparative evidence.
What to keep in mind
Evidence remains immature; follow-up ranged from 8.1 to 26 months, and recurrence and survival outcomes were limited. Response rates varied by regimen, denominator, and definition.