A Phase I-II Study to Test the Safety and Efficacy of PD1 (AB122) and Adenosine Receptor (AB928) Antagonists With Chemotherapy After Short-Course Radiation for Rectal Cancer.

Patients will receive a radiation therapy dose of 25Gy in 5 fractions in combination with etrumadenant 150 mg orally, once daily as part of a continuous dose regimen.

Patients will receive a radiation therapy dose of 25Gy in 5fx

After completing the radiation therapy, patients will receive FOLFOX regimen for 9 cycles in combination with etrumadenant and zimberelimab. All patients will be offered adjuvant zimberelimab for up to one year.

After completing the radiation therapy, patients will receive FOLFOX regimen for 9 cycles in combination with etrumadenant and zimberelimab. All patients will be offered adjuvant zimberelimab for up to one year.