PD 130908 is an analogue of RSU 1069 with effective hypoxic cytotoxin, but less potent than RSU 1069. Toxicity toward hypoxic tumor cells in vivo is demonstrated by clamping tumors (for 60 min) following administration of PD 130908. Systemic toxicity is substantially reduced following oral drug administration. Further, doses achievable following fractionated drug treatments are sufficiently high to produce significant levels of radiosensitization.