A first-in-human phase I and pharmacokinetic study of CP-4126 (CO-101), a nucleoside analogue, in patients with advanced solid tumours

Background: CP-4126 (gemcitabine elaidate, previously CO-101) is a lipid–drug conjugate of gemcitabine designed to circumvent human equilibrative nucleoside transporter1-related resistance to gemcitabine. The purpose of this study was to determine the maximum tolerated dose (MTD) and the recommended phase II dose (RP2D) of CP-4126, and to describe its pharmacokinetic profile. Methods: Eligible patients with advanced refractory solid tumours, and adequate performance status, haematological, renal and hepatic function, were treated with one of escalating doses of CP-4126 administered by a 30-min intravenous infusion on days 1, 8 and 15 of a 28-day cycle. Blood and urine samples were collected to determine the pharmacokinetics (PKs) of CP-4126. Results: Forty-three patients, median age 59 years (range 18–76; male = 27, female = 16), received one of ten dose levels (30–1600 mg/m2). Dose-limiting toxicities included grade 3 anaemia, grade 3 fatigue and grade 3 elevation of transaminases. The MTD and RP2D were 1250 mg/m2 on basis of the toxicity and PK data. CP-4126 followed dose-dependent kinetics and maximum plasma concentrations occurred at the end of CP-4126 infusion. Seven patients achieved stable disease sustained for ≥3 months, including two patients with pancreatic cancer who had progressed on or after gemcitabine exposure. Conclusions: CP-4126 was well tolerated with comparable toxicity profile to gemcitabine. Future studies are required to determine its anti-tumour efficacy, either alone or in combination with other cytotoxic chemotherapy regimens