Phase I trial of imexon, Inj. plus gemcitabine in patients with advanced previously untreated pancreatic adenocarcinoma

Abstract

15058 Background: Imexon for inj. (Amplimexon®, AMP) is an aziridine-containing iminopyrrolidone which causes G2 arrest, accumulation of reactive oxygen species, and induction of apoptosis in pancreatic cancer cells. AMP demonstrated synergy with gemcitabine (GEM) in preclinical pancreatic cancer models. This phase I study of AMP plus GEM was undertaken to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT). Secondary endpoints were pharmacokinetics for both agents (PK) and tumor response. Methods: Patients (pts) with previously untreated advanced pancreatic adenocarcinoma received one of two dosing regimens. The first 19 received 30 minute AMP IV days 1–5 and 15–19 followed by 30 minute GEM IV days 1, 8 and 15 Q4 wks (Regimen A). Dosing was modified after 19 pts to administer both AMP and GEM over 30 minutes days 1, 8 and 15 every 4 weeks (Regimen B). Dose levels (AMP/GEM, in mg/m2) for Regimen A: 200/800, 280/800, 200/1000, and 280/1000, and for Regimen B: 280/1000, 335/1000, 390/1000, 540/1000, and 750/1000. The current cohort is 1000/1000. Pts were assessed for response after cycles 2, 5 and 8. PK and pharmacodynamic (plasma thiol depletion) measurements were obtained during cycle one. Results: Forty-six pts have been treated to date, with 36 having complete toxicity data and evaluable. Pt characteristics: M/F (24/12), Age (mean 60.4 years, range 43–75), ECOG PS 0/1 (56%, 44%), metastatic/locally advanced (91%, 9%). The 36 pts have completed 122.5 cycles of therapy (median 2, range 0.5–12). Common toxicities: anemia (77%), fatigue (71%), nausea (60%), fever (54%), and leukopenia (54%). DLT were 1/6 at 280/1000 (Regimen A - febrile neutropenia), 1/6 at 280/1000 (Regimen B - gr 3 hypotension, gr 4 renal failure), and 1/9 at 390/1000 (gr 3 hyperbilirubinemia). Accrual continues at 1000/1000. Of 36 pts, 4 have had partial responses and 14 stable disease. PK and plasma thiol analysis are ongoing. Conclusions: Imexon can be administered safely with full dose gemcitabine. Accrual continues to define the combination MTD. The response rate in this phase I study compares favorably with historical gemcitabine monotherapy, and further phase II evaluation of this combination in advanced pancreatic cancer is warranted. No significant financial relationships to disclose.