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Neoadjuvant immunotherapy in mismatch-repair-proficient colon cancers.

Abstract

Immune checkpoint blockade (ICB) has led to paradigm shifts in the treatment of various tumour types1-4, yet limited efficacy has been observed in patients with metastatic mismatch-repair proficient (pMMR) colorectal cancer5. Here we report clinical results and in-depth analysis of patients with early-stage pMMR colon cancer from the phase II NICHE study (ClinicalTrials.gov: NCT03026140). A total of 31 patients received neoadjuvant treatment of nivolumab plus ipilimumab followed by surgery. The response rate was 26% and included six patients with a major pathological response (≤10% residual viable tumour). One patient with an ongoing clinical complete response did not undergo surgery. Circulating tumour DNA (ctDNA) was positive in 26/31 patients at baseline, and clearance was observed in 5/6 responders prior to surgery, while 19/20 non-responders remained ctDNA+. Responses were observed despite a low tumour mutational burden in all tumours, while chromosomal genomic instability scores were significantly higher in responders compared to non-responders. Furthermore, responding tumours had significantly higher baseline expression of proliferation signatures and TCF1, and imaging mass cytometry revealed a higher percentage of Ki-67+ cancer and Ki-67+ CD8+ T cells in responders compared to non-responders. These results provide a comprehensive analysis of response to neoadjuvant ICB in early-stage pMMR colon cancers and identify potential biomarkers for patient selection.

More about this publication

Nature
  • Publication date 20-10-2025

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