Colon Cancer Stage II/III

The RESET C2 trial aims to introduce organ sparing treatment or watch-and-wait (WW) to patients with localized deficient mismatch repair (dMMR) colon cancer through use of neoadjuvant pembrolizumab. Patients will be divided into four treatment arms based on their surgical and oncologic risks. Each arm provides different intensity neoadjuvant immunotherapy regimens. Patients with complete response at disease restaging procedures will be offered non-operative management, whereas those with non-complete response will proceed to surgery ± adjuvant chemotherapy as standard of care. A WW protocol with regular disease surveillance continues over survivorship. If there is recurrence, surgery and/or appropriate oncologic therapy will be offered determined by multi-disciplinary teams. This is a national, non-randomised, investigator-initiated trial including patients from 13 hospitals across Denmark. The rationale, design, and clinical response metrics are derived from the RESET C study (NCT05662527) showing efficacy, safety and feasibility of neoadjuvant pembrolizumab in this cohort.