Phase I study of LY573636-sodium, an acylsulfonamide anti-cancer compound with a novel mechanism of action, administered as 24-hour continuous infusion in patients with advanced solid tumors
2542 Background: LY573636 -sodium (hereafter referred to as LY573636 ) is a novel anti-cancer compound that induces apoptosis by a mitochondrial-mediated mechanism. Methods: A phase I study was conducted to determine the maximum tolerated dose and pharmacokinetic (PK) profile of LY573636 administered as a 24-hour continuous intravenous (IV) infusion every 28 days. Results: 26 patients (pts) were enrolled on study, 12 males and 14 females, with a median age of 57 (range: 41–74). LY573636 was dose-escalated using a flat dosing-based schema. No dose limiting toxicity (DLT) was observed until the 2,000 mg cohort, when 1 pt developed CTCAE grade 3 hyperbilirubinemia. PK analysis revealed that LY573636 had a low total plasma clearance (CL = 0.02L/hr) and a terminal elimination half-life of approximately 340 hours due to high-albumin binding (∼99%). One additional pt in the 2,000 mg flat dose cohort developed grade 4 thrombocytopenia in cycle 2, possibly due to the accumulation of albumin-bound drug. Based on these PK and clinical data, the dosing strategy was revised to a flat loading/maintenance dose regimen of 2,500 mg/1,750 mg every 28 days by 24-hour continuous IV infusion. Thirteen pts were treated at this dose level, with 1 pt experiencing a DLT of grade 4 leukopenia. Overall, 8/26 pts had stable disease (SD) after 2 or more cycles, with 2 pts still on study. Five pts received ≥ 4 cycles (SD ≥ 4 mos), including heavily pre-treated pts with ovarian cancer, soft tissue sarcoma, and uterine cancer. Conclusions: LY573636 is a novel anti-cancer compound with a unique mechanism of action. The most common DLT was BM suppression. Because of the long half-life of LY573636 , and the encouraging findings of a separate IV bolus phase 1 study, an IV bolus-based regimen will be taken forward into phase 2 study. No significant financial relationships to disclose.