A phase 1 open-label, sequential dose-escalation study investigating the safety, tolerability, and pharmacokinetics of intravenous TLC388 administered to patients with advanced solid tumors.

Purpose: The first-in-human phase 1 trial examined the dose-limiting toxicities (DLT), maximum tolerated dose (MTD), pharmacokinetic profile, and antitumor activity of TLC388, a novel camptothecin with a unique lactone ring modification, in patients with advanced solid tumors.

Experimental Design: TLC388 was administered intravenously to patients with metastatic chemotherapy refractory solid tumors on days 1, 8, and 15 of a 28-day cycle. Patients underwent tumor assessments every other cycle. Pharmacokinetic samples were drawn on days 1, 8, and 15 of cycles 1 and 2.

Results: Fifty-four patients were enrolled at doses ranging from 1.5 to 60.0 mg/m(2) over 12 cohorts. Treatment was generally well-tolerated and no cumulative toxicity observed. Two of six patients treated at 60.0 mg/m(2) developed DLTs of grade 3 neutropenia causing dose delay and grade 3 febrile neutropenia. The next lower dose, 50.0 mg/m(2), was declared as MTD. Treatment-related grade 3-4 hematologic toxicities included neutropenia (19 %), leukopenia (15 %), anemia (9 %), and thrombocytopenia (7 %). Grade 3-4 nonhematologic toxicities included diarrhea (2 %) and hyponatremia (4 %). Pharmacokinetics of both diastereomers (S,R and S,S) of TLC388, a mixture of two diastereomers, was dose independent; mean (SD) values for the volume of distribution at steady-state and clearance were 857 (1122) L/m(2) for S,R and 996 (1333) L/m(2) for S,S, and 2174 (2526) L/h-m(2) for S,R and 2670 (2988) L/h-m(2) for S,S, respectively. The half-life values averaged 0.67 (1.15) hours for S,R and 0.64 (1.11) hours for S,S. The best overall response was stable disease in 21 (39 %) patients. Prolonged (≥ 6 months) stable disease was noted in eight patients.

Conclusions: TLC388 at 50 mg/m(2) on the current treatment schedule is generally safe and well tolerated.