RecruitingPhase 2NCT07279077

Node-Sparing Low-Dose Radiotherapy Concurrent With Chemotherapy and PD-1 Inhibitor in pMMR/MSS High-Risk Locally Advanced Colon Cancer: A Prospective, Single-Arm, Phase II Trial

Sponsor

Sixth Affiliated Hospital, Sun Yat-sen University

Enrollment

38 participants

Start Date

Nov 26, 2025

Study Type

INTERVENTIONAL

Conditions

Colon Cancer Radiation Therapy Neoadjuvant Therapies Immune Checkpoint Therapy

Summary

Most colorectal cancers belong to the microsatellite stable (MSS) or proficient mismatch repair (pMMR) subtypes, with limited response to PD-1 inhibitors. Radiotherapy can increase the release of tumor-associated antigens, thereby improve responsiveness to PD-1 blockade in MSS/pMMR rectal cancer. Tumor-draining lymph nodes are important sites for PD-1 inhibitors to exert antitumor effects, and studies have reported that direct radiation-induced damage and fibrosis can inhibit lymph node drainage and anti-tumor function. Accumulating evidence indicates that low-dose radiotherapy reprograms the tumor microenvironment (TME), transforming immunosuppressive 'cold' tumors into immunostimulatory 'hot' tumors. This transition is mediated by modulating the gut microbiota, eliciting innate and adaptive immune responses, inhibiting immunosuppressive cells, and promoting the infiltration of T and B lymphocytes.Therefore, this study aims to evaluate whether node-sparing low-dose radiotherapy (1Gy/8f) concurrent with chemotherapy and PD-1 inhibitor can improve the pathological complete response (pCR) rate, enhance tolerability, and improve prognosis in patients with pMMR/MSS high-risk locally advanced colon cancer.

Eligibility

Min Age: 18 YearsMax Age: 75 Years

Plain Language Summary

Simplified for easier understanding

This trial is testing a new treatment approach for high-risk locally advanced colon cancer — combining low-dose radiation focused away from lymph nodes, with chemotherapy and a PD-1 immunotherapy drug — before surgery, for cancers that don't have defects in their DNA repair system (called pMMR/MSS). **You may be eligible if...** - You are 18–75 years old - You have been confirmed to have locally advanced colon cancer (Stage IIB–III, T4 and/or lymph node positive) by imaging - Your cancer biopsy shows it is pMMR/MSS (the standard type of colon cancer, NOT the MSI-H type) - Doctors have confirmed that surgery with intent to cure is possible - You have not received any prior treatment for colon cancer - Your blood counts, liver, kidney, and heart function are adequate **You may NOT be eligible if...** - You have MSI-H or dMMR colon cancer (a different genetic type) - You have had any prior cancer treatment - You have active serious infections, uncontrolled heart disease, or autoimmune conditions - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

Interested in this trial?

Get notified about updates and connect with the research team.

Interventions

COMBINATION_PRODUCTNode-Sparing Low-Dose Radiotherapy Concurrent With Chemotherapy and PD-1 Inhibitor

Patients will receive 4 cycles of neoadjuvant therapy: In D1, D2: node-sparing low-dose radiotherapy (1Gy\*2d), concurrent with CAPOX chemotherapy and PD-1 inhibitor(200mg). After that, patients will undergo partial colectomy at the site of tumor.