Final results of a dose escalation (DE), pharmacokinetic (PK), and pharmacodynamic (PD) study of two schedules of OSI-930 in patients (pts) with advanced solid tumors

Abstract

3564 Background: OSI-930 is an oral TKI with potent activity against Kit, VEGFR2, and PDGFR. Preclinical studies demonstrate tumor regression with long-term remissions across multiple xenograft models. Methods: Sequential cohorts of pts with advanced solid tumors received continuous daily OSI-930 to determine the maximum tolerated dose (MTD) and to evaluate safety, PK/PD and efficacy of OSI-930 with both QD and BID dosing. An expansion cohort was enrolled for detailed PD analysis including sVEGFR2 plasma levels, PET imaging in GIST pts or DCE-MRI in selected pts. Results: A total of 58 pts were treated (20M/38F; median 60 years (range 19–83)). OSI-930 was dosed up to 1600 mg QD without reaching MTD. 46 pts received BID dosing [mg(# pts treated)]; 400(7), 500 (31) and 600(8). DLT's were seen in 3/8 pts at 600 mg BID; G3 rash (2 pts) and G4 GGT; and 3/31 at 500 mg BID; G3 myalgia, G3 fatigue and G3 lipase. G3 hypertension was noted in 3/46 pts but not dose-limiting. Common G1/2 toxicities were fatigue (37%), diarrhea (27%), nausea (31%), and rash (24%). Objective (CA125) responses were seen in platinum-resistant ovarian cancer (2 PR/8) while in heavily pretreated GIST (median 4 prior therapies including imatinib/sunitinib), 8/18 pts achieved SD ≥12 w. Median therapy duration in the BID arm was 9 w and 18/46 pts with SD ≥12 w. PK indicated that Css were achieved after ∼7d with BID dosing. PET scans showed reduction in glycolytic activity in 4/9 pts and DCE-MRI response was seen in 4/6 pts. A trend in decreased sVEGFR levels was seen at higher doses. Conclusions: At the MTD level of 500 mg BID OSI-930 is an active, well-tolerated compound with clinically relevant antitumor activity and exposure levels consistent with antitumor activity in preclinical models. PD data indicate mechanistic proof of concept for OSI-930. OSI-930/erlotinib combination phase I study is currently enrolling. [Table: see text]