Neoadjuvant envafolimab in a patient with MSI-H/dMMR colon cancer: a case report and literature review.

Clinical evidences of neoadjuvant immunotherapy in patients with mismatch repair deficient/microsatellite instability-high status (dMMR/MSI-H) colorectal cancer have not been well received. A 36-year-old man complained of recurrent right upper quadrant pain for more than 1 year, and the symptoms were not significantly relieved after 10 days of oral Changyanning tablet. The patient was finally diagnosed as dMMR/MSI-H colon cancer. Tumor regression was achieved after seven cycles of envafolimab treatment, and the patient obtained postoperative pathological complete response (pCR). Here, we report a case of MSI-H/dMMR transverse colon cancer, who obtained pCR after neoadjuvant envafolimab (a novel subcutaneous single-domain anti-PD-L1 antibody) with a favorable safety profile, aiming to enhance the experiences of comprehensive diagnosis and treatment of colon cancer.