ZD0473 is new platinum agent that was rationally designed to circumvent platinum resistance and reduce the potential for nephro-and neurotoxicity. This Phase I dose-escalating study investigated the pharmacokinetics, tolerability and efficacy of ZD0473 in Japanese patients with solid, refractory tumours. ZD0473 was administered as a 1-h intravenous infusion every 3 weeks. Nine patients received a total of 16 cycles of ZD0473 (median 1 cycle/patient), with 3 patients treated at each of 3 doses (60, 90, 120 mg/m2). The maximum plasma concentration (C(max)) and the area under the concentration-time curve to infinity (AUC(0-infinity)) increased with dose in a linear fashion for both total platinum and ZD0473 in plasma ultrafiltrate, suggesting that the pharmacokinetics of ZD0473 are linear. Haematological and non-haematological toxicities such as nausea and vomiting were mild (grade 1 or 2) and transient. No clinically significant nephro-, oto- or neurotoxicity was observed. Dose-limiting toxicity (DLT) was not observed and the maximum tolerated dose (MTD) was not identified. ZD0473 treatment showed evidence of disease stabilisation in 3 patients (33%). In conclusion, ZD0473 appears to have linear pharmacokinetics, and an acceptable tolerability profile at doses up to 120 mg/m2 in Japanese patients with refractory solid malignancies. Following evaluation of the data from all the Western trials, the ZD0473 development programme changed and this Japanese trial was stopped.