Abstract CT070: Innovative design for a phase I trial with intra-patient dose escalation: The Crotoxin study

INTRODUCTION. Crotoxin is a bipartite South America rattle snake neurotoxin. It has broad spectrum antitumor activity in vivo in addition to exerting analgesic effects. Prior clinical reports using i.m. injections resulted in local immune reactions with erythema, itching or pain, in addition to anaphylaxis though encouraging responses were recorded. A clinical study was designed incorporating i.v. administration, dose escalation and pre-treatment antihistamine use, aimed at improving dose limiting toxicity (DLT) and local tolerance. METHOD. This trial was performed in patients with stage IV cancer with the primary endpoints to assess safety and tolerability, measured by Dose-Limiting Toxicity (DLT) and to define the Maximum Tolerated Dose (MTD). The secondary objectives were to document anti-tumor efficacy, evaluated according to radiological RECIST criteria 1.0 and analgesia. Baseline pain assessments were completed for each patient. Cohort I included 6 patients with advanced solid tumors (no further therapy options), with dose escalation from 0.04 to 0.32 mg/m2/day administered IV by saline drip over 2h daily (Mon to Fri) over 54 days. RESULTS.One male and 5 females (pts) with prior heavily-treated advanced tumors were enrolled: colorectal adenocarcinoma, epithelioid mesothelioma, non-small-cell lung cancer, carcinoma of unknown primary site, invasive breast ductal carcinoma and ovarian papillary adenocarcinoma. Three patients reached the highest target dose level. DLT or MTD were not attained. In Cohort I grade 1 to 2 drug-related events occurred in 3/6 patients: anorexia, diplopia and nystagmus. There were no drug-related serious adverse events. Tumor assessment was performed after 8 weeks of dose escalation (day 54) and all subjects were determined to have progressive disease. At baseline, pain was reported for 5/6 subjects, surveys revealed a diminution of analgesic scores. CONCLUSION: Crotoxin i.v. dose escalation protocol allowed administering 0.32 mg/m2/day without unexpected toxicity. Lack of anti-cancer benefit might be related to the long period of 6-8 weeks to reach this dose. A redesign of the protocol to escalate faster and to higher doses, without weekend breaks, is required. Citation Format: Jacques Medioni, Mara Brizard, Reza Elaidi, Paul F. Reid, Benlhassan5 Khadija, Dorothy Bray. Innovative design for a phase I trial with intra-patient dose escalation: The Crotoxin study [abstract]. In: Proceedings of the American Association for Cancer