Phase I clinical trial of CX-3543, a pro-apoptotic antitumor agent

Abstract

3082 Background: CX-3543 is a novel small molecule specifically designed to target three dimensional nucleic acid motifs, and thus induce apoptosis in cancer cells. Preclinically, CX-3543 demonstrated potency in suppressing xenograft tumor growth with a broad therapeutic window. The objectives of this phase I study are: to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLTs), to establish the pharmacokinetics (PKs), and to determine the recommended dose for further clinical development of CX-3543. Methods: Eligible patients with advanced solid tumors or lymphomas whose tumors progressed on standard therapy or for whom there are no standard therapies receive CX-3543 in successive dose cohorts at: 10, 20, 40, 80 and 160 mg/m2. Dosing is by one hour intravenous infusion daily for five consecutive days repeated on a three week cycle. Therapy is continued until the patient shows signs of intolerance to CX-3543 or evidence of advancing disease. Response by RECIST criteria is determined after every 2 cycles. Results: Ten patients with solid tumors (3–4 per cohort) have received intravenous CX-3543. Doses have been well tolerated. Seven grade 3 adverse events have been reported during the study, but none of these are related to CX-3543. To date no objective responses have been observed. One patient with advanced refractory prostate cancer has stable disease of longer than 4 months duration. CX-3543 has demonstrated good linearity in PK parameters between the dose cohorts with a terminal half life of approximately 12 hours following the first dose. Conclusions: To date, CX-3543 has shown no drug related toxicity and has predictable PKs. No DLTs have yet been observed, and the MTD remains to be defined in this Phase I study. Further enrollment to the planned dose escalation cohorts is ongoing. [Table: see text]