Capecitabine/Oxaliplatin Chemotherapy and Cemiplimab With or Without Fianlimab or REGN7075 in Locally Advanced Rectal Cancer

Inclusion Criteria: * Age ≥18 years. * Eastern Cooperative Oncology Group (ECOG) performance status 0 - 1. * Rectal cancer (with tumor tissue present at or below the peritoneal reflection) as determined by MRI pelvis or endoscopic ultrasound. * Have histologically proven mismatch repair proficient (pMMR) or microsatellite stable (MSS) rectal adenocarcinoma. * Must not have received any prior systemic treatment or radiation. * Candidate for sphincter-sparing surgical resection after neoadjuvant therapy according to the primary surgeon. * Patients have the following clinical staging: * cT2 node-positive: * T: Tumor is invading the muscularis propria but has not grown through it to the serosa * N: At least 1 perirectal lymph node ≥5 mm and no more than 4 perirectal lymph nodes \>10 mm in short axis * M: No evidence of metastasis * cT3 node-negative * T: Tumor has grown through the muscularis propria into the serosa but has not invaded nearby organs * N: No perirectal lymph nodes ≥ 5 mm in size that suggest tumor involvement * M: No evidence of metastasis * cT3 node-positive * T: Tumor has grown through the muscularis propria into the serosa but has not invaded nearby organs * N: At least 1 perirectal lymph node ≥ 5 mm and no more than 4 perirectal lymph nodes \> 10 mm in size in short axis * M: No evidence of metastasis * Absence of distant metastases on CT or MRI imaging * Patients must have adequate organ and marrow function defined by study-specified…