Combining DCSZ11 With Radiation and Chemotherapy as Neoadjuvant Treatment for pMMR Locally Advanced Rectal Cancer

The purpose of this study is to evaluate the safety and clinical activity of combining DCSZ11 with radiation and capecitabine/oxaliplatin (CAPOX) for the neoadjuvant treatment of patients with mismatch repair proficient (pMMR) high risk 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. * Patients have the following clinical staging: * cT4 any node status * Any T stage cN2 node status * Any T or N status, evidence of suspicious lateral lymph nodes \> 10 mm in size in short axis * Evidence of extramural vascular invasion on MRI pelvis * Absence of distant metastases on CT or MRI imaging * Patients must have adequate organ and marrow function defined by study-specified laboratory tests and procedures. * Left ventricular ejection fraction (LVEF) assessment with documented LVEF ≥ 50% by either TTE or Multigated Acquisition (MUGA) (TTE preferred) within 6 months from first study drug administration. * For both Women and Men, must use acceptable form of birth control while on study. * Ability to understand and willingness to sign a written informed consent document. Exclusion Criteria: * Have received an investigational agent or used an investigational device within 28 days of the first dose of study drug. * Have expected to require any other form of systemic or localized antineoplastic therapy while on study. * Have had surgery within 28 days of dosing of investigational agent, excluding minor procedures (dental work, skin biopsy, etc.). * History of severe hypersensitivity reaction to any monoclonal antibody. * History of encephalitis, meningitis, dementia, Parkinson's or uncontrolled seizures within 1 year prior to the first dose of study drug. * Uncontrolled infection of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), or Tuberculosis. * Uncontrolled intercurrent illness including, but not limited to, uncontrolled infection, symptomatic congestive heart failure, unstable angina, cardiac arrhythmia, metastatic cancer, or psychiatric illness/social situations that would limit compliance with study requirements. * Any tissue or organ allograft, regardless of need for immunosuppression, including corneal allograft. * Patient has a pulse oximetry of \