DRF-1042

The purpose of this bridging phase I study was to characterize the toxicity, pharmacokinetics, and antitumor effects of a capsule formulation of DRF‐1042, a novel camptothecin analog, in refractory solid tumor patients. DRF‐1042 was given daily for 5 consecutive days for 2 weeks, repeated every 3 weeks at 81 mg/m2. Adverse events were monitored following NCI‐CTC. Blood samples were processed for bioanalysis using a validated high‐performance liquid chromatography method. The pharmacokinetics of lactone and total (lactone + carboxylate) forms was determined on days 1 and 12 using a noncompartmental pharmacokinetic method. Pharmacokinetic data with the capsule formulation were compared with previously reported pharmacokinetic parameters with a suspension formulation. Efficacy was evaluated by applying World Health Organization criteria. Six patients received 10 courses of therapy. Thrombocytopenia and diarrhea were dose‐limiting toxicities. The upper limit of the area under the curve of DRF‐1042 (lactone and total) with the capsule formulation was higher than a suspension formulation at a similar dose on day 1 (lactone: capsule = 8.53 μM•h, suspension = 5.33 μM•h; total: capsule = 393 μM•h, suspension = 176 μM•h) and day 12 (lactone: capsule= 22.1 μM•h, suspension = 6.1 μM•h; total: capsule = 1302 μM•h, suspension = 309 μM•h). The upper limit of the area under the curve of DRF‐1042 (lactone and total) was higher under fed conditions (lactone = 15.9 μM•h, total = 605 μM•h) relative to fasted conditions (lactone = 8.53 μM•h, total = 393 μM•h) on day 1. One patient experienced stable disease. The toxicity and pharmacokinetics of the capsule correlated well with the suspension. The recommended phase II dose is 81 mg/m2.