Anti-PD-1-based immunotherapy as curative-intent treatment in dMMR/MSI-H rectal cancer: A multicentre cohort study

• DOI: 10.1016/j.ejca.2022.07.016
• Publication Date: 2022-08-26T19:18:30Z
• Authors: Qiao-Xuan Wang; Bin-Yi Xiao; Yong Cheng; Ai-Wen Wu; Tao Zhang; Hui Wang; Xuan Zhang; Wei-Xin Huang; Jing-Hua Tang; Wu Jiang; Scott R. Steele; Smitha Krishnamurthi; Yuan Li; Jian Cai; Ling-Heng Kong; Dan-Dan Li; Zhi-Zhong Pan; Xiao-Shi Zhang; Pei-Rong Ding
• Keywords: Cohort Studies; 03 medical and health sciences; 0302 clinical medicine; Rectal Neoplasms; Humans; Microsatellite Instability; Immunotherapy; Neoplasm Recurrence, Local; Colorectal Neoplasms; DNA Mismatch Repair; Retrospective Studies; 3. Good health

In a portion of patients with DNA mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) rectal cancer, clinical complete response (cCR) could be achieved after anti-programmed cell death protein 1 (anti-PD-1) immunotherapy. However, no data are available concerning the safety of omitting surgery and adopting immunotherapy as a curative-intent treatment for these patients.We retrospectively collected a series of patients with dMMR/MSI-H rectal adenocarcinoma who had cCR after receiving anti-PD-1 immunotherapy and adopted immunotherapy as curative-intent treatment from six institutions. Survival outcomes were analysed using the Kaplan-Meier method.Nineteen patients were included with a median age of 48 (range 19-63). One patient was diagnosed with stage I disease, four with stage II disease and fourteen with stage III disease. Sixteen patients received anti-PD-1 immunotherapy as the first line of therapy, and eleven patients were treated with single-agent anti-PD-1 antibodies. The median time from the start of treatment to cCR was 3.8 (range 0.7-6.5) months. During a median follow-up of 17.1 (range 3.1-33.5) months since achieving cCR, no local or distant relapse was observed. Two-year local recurrence-free survival, distant metastasis-free survival, disease free-survival and overall survival for the whole cohort were 100%, 100%, 100% and 100%, respectively.For patients with dMMR/MSI-H locally advanced rectal cancer who achieved cCR during anti-PD-1 immunotherapy, adopting immunotherapy as curative-intent treatment might be an alternative option. Longer follow-up and larger cohorts are warranted to verify this innovative treatment approach.