Imexon is an aziridine-derived iminopyrrolidone which has synergy with gemcitabine in pancreatic cancer cell lines. Gemcitabine is a standard therapy for pancreatic cancer. We performed a phase I trial of imexon and gemcitabine to evaluate safety, dose limiting toxicity (DLT), and maximum tolerated dose (MTD) in patients with advanced pancreatic cancer.
Patients with untreated locally advanced or metastatic pancreatic adenocarcinoma received therapy in sequential cohorts on regimen A (n=19; imexon 200 or 280 mg/m2 intravenously (IV) over 30 minutes days 1–5, 15–19 and gemcitabine 800 or 1,000 mg/m2 IV over 30 minutes on days 1,8,15 every 28 days) or regimen B (n=86; imexon 280–1,300 mg/m2 IV over 30–60 minutes days 1, 8, and 15 and gemcitabine 1,000 mg/m2 IV over 30 minutes on days 1, 8, and 15 every 28 days).
One hundred-five patients received 340 treatment cycles (median 2, range 1–16). Patient characteristics: median age 63, 61% male, ECOG PS 0/1 50%/50%, 93% metastatic. DLT was abdominal cramping and pain, often with transient, acute diarrhea. Best response was confirmed partial response (PR) in 11.4%, 8.9% unconfirmed PR, and 48.1% with stable disease. There was a dose proportional increase in imexon AUC across the doses tested with terminal half-life 69 minutes at the MTD and no alteration of gemcitabine pharmacokinetics.
The recommended phase II dose of imexon is 875 mg/m2 with gemcitabine 1,000 mg/m2. DLT was acute abdominal pain and cramping. Encouraging antitumor responses support further evaluation of this combination in advanced pancreatic cancer.