Envafolimab as Neoadjuvant Immuntherapy in Resectable Local Advanced dMMR/MSI-H Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignant tumours of human beings. Mismatch Repair-deficient (dMMR)/ Microsatellite Instability-high (MSI-H) CRC is a specific subtype of CRC, which accounts for approximately 15% of all CRC patients, and can not benefit from 5-fluorouracil (5-FU) adjuvant chemotherapy. Once patients have distant metastases, they are not sensitive to traditional palliative chemotherapy, and thus lead to much worse prognosis than that of mismatch repair-proficient (pMMR)/ microsatellite stability (MSS). A phase II clinical study of anti-PD-1 immunotherapy based on mismatch repair (MMR) status published in "N Engl J Med" showed that the objective response rate (ORR) of advanced colorectal cancer patients with dMMR received anti-PD-1 is 40%, and a longer response time can be obtained compared to conventional chemotherapy. Another study (ClinicalTrials.gov, NCT03926338) which investigating the effect of neoadjuvant PD-1 blockade with toripalimab, with or without celecoxib, on mismatch repair-deficient or microsatellite instability-high, locally advanced, colorectal cancer. The result revealed that all 34 patients had an R0 resection. 15 of 17 patients (88%) in the toripalimab plus celecoxib group and 11 of 17 patients (65%) in the toripalimab monotherapy group had a pathological complete response.
In theory, anti-PD-L1 drugs should have fewer immune side-effects than anti-PD-1 drugs. However, there are no reports of anti-PD-L1 neoadjuvant therapy for the dMMR/MSI-H colorectal cancer. Therefore, the aim of this study was to investigate the efficacy and safety of anti-PD-L1 monoclonal antibody (Envafolimab) as neoadjuvant immuntherapy for resectable local advanced colorectal cancer patient with the dMMR/MSI-H.