A phase 1 dose finding study of CHR-2797, an inhibitor of M1 aminopeptidases, in patients with advanced solid tumours

Abstract

3053 Background: CHR-2797 is a novel, orally bioavailable inhibitor of the M1 family of aminopeptidases, in particular PuSA, and LTA4 hydrolase. Exposure of cancer cells to CHR-2797 results in the generation of the active metabolite CHR-79888 which is poorly membrane-permeable, resulting in intracellular accumulation. CHR-2797 has shown anti-proliferative activity in syngeneic (rat) and xenograft (mouse) cancer models, and is anti-angiogenic in vitro. Methods: Patients (pts) (ECOG PS ≤ 2) with histologically confirmed advanced solid tumors resistant or refractory to standard therapy were eligible. The accelerated titration design of the trial involved two phases for evaluation of schedule and dose: 1) fixed dose with increasing duration, and 2) dose escalation over a fixed duration (28 days). Results: 16 pts (median age: 64.5 years [range 48.8–80.1], 13M/3F)were treated with once daily doses ranging from 10mg to 130mg. The first four patients received a 10mg dose for 7, 14, 21 or 28 days respectively. Five subsequent cohorts received 28 days continuous dosing, with dose doubling in single patient cohorts until drug-related toxicity ≥ Grade 2. Thereafter dose was escalated in ≤ 40% increments in 3-patient cohorts. The most frequent adverse events were: gr 1–2 thrombocytopenia (44%), gr 1 diarrhea (25%), gr 1–2 transaminitis (19%), gr 1–2 fatigue (13%), gr 1 hot flushes (13%), and gr 1 lightheadedness (13%). There were no DLTs. Five patients continued therapy after 28 days; stable disease has been achieved in 1 pt for 6 months with granulosa cell carcinoma of ovary, who was progressing prior to study entry. CHR-2797 and CHR-79888 demonstrate dose proportional increases in AUC and Cmax. The terminal half-life for CHR-2797 is around 1–2 hours, whereas it is between 9 and 11 hours for CHR-79888. Intracellular (packed blood cells) exposure to both CHR-2797 and CHR-79888 is good, with CHR-79888 accumulating over 28 days, such that by day 28 the intracellular levels are comparable to plasma. Conclusions: CHR-2797 is well tolerated and can be safely administered at doses that reach plasma concentrations associated with activity in pre-clinical models. Accrual into the study continues. No significant financial relationships to disclose.