Neoadjuvant Immunotherapy With Prolgolimab in Patients With Locally Advanced Microsatellite Instability/Defective...

Area of Science:

• Oncology
• Immunotherapy
• Gastrointestinal Oncology

Background:

• Adjuvant chemotherapy is standard for locally advanced colon cancer.
• Defective mismatch repair (dMMR)/microsatellite instability (MSI) tumors are sensitive to immune checkpoint inhibitors.

Purpose of the Study:

• To investigate the efficacy of the PD-1 inhibitor prolgolimab in patients with locally advanced colorectal cancer (CRC) and dMMR/MSI.
• To assess response rates, safety, and survival outcomes.

Main Methods:

• Phase II, nonrandomized, open-label clinical trial (NCT06428487).
• Patients received prolgolimab (1 mg/kg) every 2 weeks for 6 months followed by surgery.
• Primary endpoint: pathologic complete response (pCR) + clinical complete response (cCR).

Main Results:

• 17 out of 30 patients (56.7%) achieved pCR + cCR.
• Major pathologic response (MPR) observed in 80.8% of operated patients (n=26).
• Radiographic objective response rate (ORR) was 89.7%; 18-month disease-free survival (DFS) was 90%.

Conclusions:

• Prolgolimab demonstrates high pCR and cCR rates in locally advanced dMMR/MSI CRC.
• The findings support further exploration of organ-sparing approaches.
• Immune-related adverse events were infrequent and manageable.