Neoadjuvant Pembrolizumab in Stages I-III Deficient Mismatch Repair Colon Cancer: A Clinical Trial.

Area of Science:

• Oncology
• Gastroenterology
• Clinical Trials

Background:

• Neoadjuvant immunotherapy significantly improves pathological complete response in dMMR colon cancer.
• Optimal treatment duration and regimen for this patient group remain under investigation.

Purpose of the Study:

• To evaluate the safety and efficacy of a single cycle of neoadjuvant pembrolizumab in localized dMMR colon cancer.
• To determine pathological complete response rates following single-cycle pembrolizumab treatment.

Main Methods:

• Phase II, single-arm, multicenter clinical trial (NCT05662527) involving 42 patients with stage I-III dMMR colon cancer.
• Patients received one cycle of pembrolizumab (4 mg/kg) followed by surgery within 3-5 weeks.
• Primary outcomes assessed safety and pathological complete response (pCR) rates.

Main Results:

• 46% (19/41) of evaluable patients achieved pCR; 61% had a major pathological response.
• 39% of patients experienced surgical complications, with three events above Clavien-Dindo grade 2 (two grade 3b, one grade 5).
• Three grade 3 adverse events were reported; no grade 4 or 5 events occurred.

Conclusions:

• Single-cycle neoadjuvant pembrolizumab demonstrates good tolerability and effectiveness in localized dMMR colon cancer.
• The study's positive interim results led to continued patient enrollment.
• This regimen represents a potential treatment option for dMMR colon cancer.