In colorectal cancer (CRC), ICIs show strong therapeutic associations with microsatellite instability-high (MSI-H) status, while patients with proficient mismatch repair/microsatellite stable (pMMR/MSS) tumors exhibit poor responses. Dual immunotherapy may represent a promising strategy for MSS populations. The Dutch NICHE trial reported a 27% pathological response rate (4/15) in MSS CRC patients with clinical stage I-III disease treated with neoadjuvant ipilimumab plus nivolumab. In advanced or metastatic CRC, a study by Jin Li et al. demonstrated that iparomlimab/tuvonralimab combined with bevacizumab and the XELOX regimen achieved an objective response rate of 70.6% (95% CI: 56.2%-82.5%).
Radiotherapy may synergize with ICIs through multiple immunomodulatory mechanisms. For pMMR/MSS LARC, combining CRT with ICIs holds promise to overcome the "immune-cold" tumor microenvironment and improve therapeutic efficacy. In this clinical trial, the investigators aim to evaluate the efficacy and safety of integrating immunotherapy with CRT as a novel total neoadjuvant therapy for pMMR/MSS rectal cancer.
Age 18-75 years old, male and female
Histologically confirmed pMMR/MSS rectal adenocarcinoma, defined by MRI as clinical stage II (T3-4, N-) or stage III (any T, N+)
Tumor within 12 cm of the anal verge with at least one of the following high-risk factors: cT4, cN2, extramural vascular invasion [EMVI+], mesorectal fascia involved [MRF+], lateral lymph node [LN+], tumor deposit, or low rectal cancer (≤5 cm from the anal verge)
Eastern Cooperative Oncology Group performance status (ECOG PS) score of 0 or 1.
dMMR or MSI-H patients
Myelosuppression without obvious causes
Locally advanced rectal cancer without high-risk factors
Prior or concurrent other malignancies (except cured basal cell carcinoma of the skin and carcinoma in situ of the cervix)