A Phase I Dose-Escalation and Pharmacokinetic Study of Brostallicin (PNU-166196A), A Novel DNA Minor Groove Binder, in Adult Patients with Advanced Solid Tumors

Purpose: This study was performed to determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetics of brostallicin, a nonalkylating DNA minor groove binder and a synthetic derivative of distamycin A, given as a weekly i.v. infusion. Experimental Design: Using an accelerated dose escalation design, patients with advanced solid tumor malignancies were treated with brostallicin administered as a 10-min i.v. infusion on days 1, 8, and 15 of a 28-day cycle. The starting dose of brostallicin was 0.3 mg/m²/week. To study the pharmacokinetic behavior of brostallicin, serial blood samples were obtained before and after the first and last infusions during cycle 1, and in cycles 2 and 4 in a limited number of patients. Results: Fourteen patients received 32 complete cycles of brostallicin. Dose-limiting toxicity was febrile neutropenia and was observed in 3 of 5 patients treated at 4.8 mg/m ²/week. The maximum tolerated dose and recommended Phase II dose was 2.4 mg/m²/week. The mean ± SD terminal half-life at the maximum tolerated dose was 4.6 ± 4.1 h. There was moderate distribution of brostallicin into tissues, and the clearance was ∼20% of the hepatic blood flow. The area under the concentration time curveo_0-∞ of brostallicin increased in a dose-linear fashion. No significant relationship was observed between any plasma pharmacokinetic parameter and clinical toxicities. There were no objective responses during the trial, but 5 patients had stable disease after two cycles of treatment. Conclusions: The dose-limiting toxicity of weekly brostallicin was neutropenia. Systemic exposure increases linearly with dose. The recommended dose for Phase II studies is 2.4 mg/m² on days 1, 8, and 15 of a 28-day cycle.