Abstract: Disclosed are formulations for the treatment of cancer including inosine or a related compound in combination with an immune checkpoint inhibitor including but not limited to immune checkpoint inhibitor binding agents (including anti-CTLA4, anti-PD1, anti-LAG-3, anti-TIM-3, anti-TIGIT, anti-CD47, anti-VISTA, and anti-PD-L1), and optionally also including a reinforcing agent to boost immune response, including CAR-T, CAR-NK, tumor vaccine, oncolytic virus vaccine, TLR7/8 agonist, anti-CD47 or IL-2 receptor agonist, and optionally also including other pharmacologically immune-boosting active agents.