Spiroplatin was investigated in a multicenter phase II study, during which the drug was given over 4 h. 64 Patients with nine different solid tumors received 141 cycles of spiroplatin at a dose of 30 mg/m2 every 3 weeks. Most important side effects included nausea, vomiting, myelosuppression, and renal toxicity. Four of 11 evaluable patients with prior cisplatin developed increases in serum creatinine (3 transient, 1 died of renal failure). Of 51 patients without prior cisplatin 2 had a transient increase in serum creatinine levels, and 2 showed persistent changes, in 1 of them leading to hemodialysis. Pre- and posthydration did not reduce drug-induced nephrotoxicity. Only 3 patients showed a response; 1 with renal cell carcinoma, 1 with ovarian carcinoma, and 1 with malignant melanoma. Based on the absence of striking antitumor activity and on the presence of severe unpredictable renal toxicity, the study was stopped prematurely.