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Notes: Abstract Background: The oral bis (acetate) ammine dichloro cyclohexylamine platinum (i.v.) analogue (BMS-182751) was brought into clinical development because it was shown to be cytotoxic against some human tumour cell lines and to have an antitumor activity in murine tumours at least comparable to that of parenteral cisplatin and carboplatin. In early clinical studies in which the optimal schedule of treatment was daily for five consecutive days, dose-dependent nausea and vomiting occurred in about two-thirds of patients. Patients and methods: To evaluate if the use of lower daily doses for longer periods of time could result in a better tolerability, JM216 was given once daily for 14 consecutive days every four to five weeks to adult patients with solid tumors. Oral antiemetics were given prophylactically only at the highest doses. The pharmacokinetics of total and ultrafiltrable platinum were studied on days 1 and 14 of the first cycle by Inductively Coupled-Mass-Spectrometry (ICP-MS). Results: Forty-six patients were treated at doses ranging from 10 mg/m2/d to 50 mg/m2/d and 39 were evaluable for hematologic toxicity over 74 cycles. MTDs were reached at 45 mg/m2/d and 50 mg/m2/d × 14 repeated every five weeks in patients with extensive, or limited/no prior treatment, respectively. The dose-limiting toxicity was neutropenia which was delayed and variable among patients. Other non-hematological toxicities were severe vomiting (22% of cycles), diarrhea (28% of cycles) and drug-associated fever (32% of patients), controlled with paracetamol. Subjective improvement with disappearance of tumour-related pain was observed in one patient with chemotherapy-resistant metastatic prostate cancer and in one previously untreated patient with malignant mesothelioma. Cmax and AUC values of both total and ultrafiltrable platinum on days 1 and 14 were highly variable among patients. Only Cmax on day 1 was linearly related to the dose. Total and ultrafiltrable platinum were still detectable two weeks after the last dose. No relationship could be established between AUC values and toxicities. Conclusions: Daily doses of JM216 of 40 mg/m2 and 45 mg/m2 for 14 consecutive days every five weeks with oral antiemetic prophylaxis are selected for phase II evaluation of single agent in patients with extensive or limited/no prior treatment, respectively. The administration of JM216 on a day × 14 schedule produced nausea and vomiting comparable to that observed with the day × 5 regimen but of longer duration. The variability of pharmacokinetics and pharmacodynamics, even though limited at the doses proposed for phase II evaluation of JM216 as single agent, recommend a careful monitoring of the patients.