Phase I dose-escalation study of a novel antitumor agent, SR271425, administered intravenously in split doses...

SR271425 is a novel DNA-binding cytotoxic agent with a broad spectrum of antitumor activity in preclinical models,across a variety of the schedule of administration. In toxicological studies, it has been reported to prolong QTc proportionally to C (max). In order to circumvent this C (max)-related QTc prolongation, 5 phase I studies were initiated to investigate 1-h, 24-h, weekly, and split iv infusions. This phase I study assessed a split-dose regimen (a 1-h infusion on each of Days 1 to 3, repeated every 3 weeks) to establish the dose limiting toxicities (DLT), to recommended a phase II dose, and to characterize PK/PD.

Patient with advanced solid tumors, adequate bone marrow, hepatic, renal function and on specific cardiac criteria were eligible and "3 + 3" design was used for dose escalation. That dose escalation was guided by PK data, toxicities observed and information from other ongoing phase I studies with SR271425. SR271425 plasma levels (PK samples) were measured using a validated LC-MS/MS method. Careful monitoring of ECGs was done, and ECGs were read centrally.

Three centers enrolled 19 heavily pretreated patients to six dose levels, from 75 to 450 mg/m(2)/day (i.e., 225-1,350 mg/m(2)/cycle): 12 males and 7 females. Median age 56. Median ECOG, PS = 1. Main tumor types were brain, breast, gynecological, and urological. Patients received a median of 2 cycles (range: 1-6). NCI-CTC Grade 1-2 toxicities included nausea, vomiting, asthenia, rash, and yellow skin discoloration. No DLTs were reported, and there were no dose-limiting prolongations of QTc. Both C (end) and AUC increased in a dose-related manner, with no evidence of accumulation between Day 1 and Day 3, consistent with the mean (+/-SD) terminal elimination half-life of 5.11 +/- 1.21 h. Stable disease was observed in five cases.

Split doses allow high cumulative exposure to SR271425 without significant toxicity, especially without QTc prolongation. MTD was not reached due to the early termination of the SR271425 program by the sponsor.