Pharmacokinetic and pharmacodynamic results of a 4-hr IV administration phase I study with EPC2407, a novel vascular disrupting agent

Abstract

3569 Background: EPC2407 is a 4-aryl-chromene single isomer microtubulin inhibitor with vascular disrupting and apoptotic activity at nanomolar concentrations. In an earlier phase I study dosing by 1 hr infusions daily x3 on a 21 day cycle, DLT at 21 mg/m2 was pain at tumor sites and vasoconstriction with increases of BP and QTc. MTD was 13 mg/m2 over 1 hr (ASCO 2008, Abst 2531). All drug-related toxicities resolved within an hour of stopping the infusion. Prolonged infusion of EPC2407 to extend exposure of tumor vasculature was designed with administration of EPC2407 over 4 hrs for 3 consecutive days of a 21 day cycle. Eleven patients have received this schedule and their cancers included leiomyosarcoma, colo-rectal, ovary, hepatocellular (2), NSCLC, pancreas, carcinoid, hemangiopericytoma, larynx and small bowel. Results: Doses escalated from 13 to 30 mg/m2 over 4 hours, with MTD determined to be 24 mg/m2. DLTs at 30 mg/m2 were similar to those seen in the 1 hr infusion, with pain at tumor sites in 1 participant and asymptomatic ST depression in a second. Other toxicities were also similar and included transient hypertension. QTc increases were not significant and no new toxicities were encountered. T1/2 with 4 hr infusion was ∼2hr, also seen with 1 hr infusion. AUC and Cmax values were similar to that predicted from the 1 hr data except AUC at 13 mg/m2 was lower than expected. DCE-MRI was done at baseline and after infusion on day 3, cycle 1. Analysis to date of DCE-MRI data of 4 patients showed a median decrease of 40% in both tumor permeability (Ktrans) and tumor perfusion volume (Vp). The two patients with hepatocellular carcinoma had notable stable disease and clear clinical benefit. Both patients received 18 mg/m2 dose, with one receiving 7 cycles over 5 months, and the other still on study (cycle 6) with stable disease for at least 4 cycles. Conclusions: EPC2407 shows clinical promise, with infusion-associated toxicities characteristic of the VDA drug class but without sustained or cumulative toxicity. Studies combining EPC2407 with conventional cytotoxic/cytostatic regimens are being designed. [Table: see text]