Hypoxia – defined as a low level of oxygen – is a common characteristic of the majority of solid tumors and contributes to disease progression and resistance to conventional therapies. Overcoming tumor hypoxia is therefore a promising strategy to improve cancer treatment. Hypoxia-activated prodrugs (HAP) are therapeutic agents that are activated only in hypoxic regions of the tumor and not in healthy tissues. This thesis investigated a novel HAP, called CP-506. CP-506 was found to have potent antitumor effects in a broad range of cancer types, both as a monotherapeutic agent, but even more so in combination with radiotherapy and immunotherapy. In addition, the degree of hypoxia and genetic status of the tumor were strong determinants of the...