Safety and pharmacokinetics (PK) of AMG 706 with panitumumab plus FOLFIRI or FOLFOX for the treatment of patients (pts) with metastatic colorectal cancer (mCRC)

4081 Background: AMG 706 is an oral, investigational multikinase (MKI) inhibitor with antiangiogenic and direct antitumor activity, selectively targeting VEGF, PDGF and Kit receptors. Methods: This is an ongoing phase 1b, open-label, dose-finding study of AMG 706 with panitumumab plus FOLFIRI or FOLFOX in pts with mCRC. Objectives are to establish safety, PK, and the maximum tolerated dose of AMG 706 with this regimen. Pts =18 yrs with mCRC, ECOG 0–1, =1 prior chemotherapy for advanced disease and no prior oral VEGFr MKIs or anti-EGFR therapy, received either FOLFIRI or FOLFOX (based on prior therapy) plus panitumumab (6mg/kg IV day 1 of each 2-wk cycle), and escalating doses of AMG 706 (50, 75, 125mg QD; 75mg BID) given continuously from day 3 of cycle 1. Assessments included dose-limiting toxicities (DLT) during the first 2 cycles and tumor response (every 6–8 wks from wk 6). Results: As of Nov 2006, 45 pts were enrolled and received at least 1 dose of AMG 706 (FOLFIRI/FOLFOX n=33/12); 64% had prior chemotherapy. There were 6 DLTs: FOLFIRI n=4, all grade 3 (diarrhea n=2: 50mg QD, 75mg BID; deep vein thrombosis n=1: 75mg QD; high GI output n=1: 75mg BID); FOLFOX n=2 (all fatigue, grade 3: 50mg QD). Treatment-related adverse events (AE) occurring in =10% of pts included: any AE, FOLFIRI/FOLFOX 88/92% of pts (grade 3, 21/58%); fatigue 55/58% (12/33%), anorexia 24/50% (0/0%), diarrhea 24/33% (0/8%), epistaxis 27/0% (0/0%) and hypertension 15/8% (0/0%). There were no grade 4/5 AEs. 2 cases of cholecystitis (grade 3, n=1) occurred. Preliminary data showed that AMG 706 PK at 50mg QD (FOLFOX) and 50–125mg QD (FOLFIRI) was comparable to data from monotherapy studies at the same dose levels. AMG 706 did not markedly alter the PK profiles of irinotecan or its metabolites. Objective tumor response per RECIST is shown in the table . Conclusions: In this study of pts with mCRC, AMG 706 was tolerable when combined with panitumumab and FOLFIRI or FOLFOX, with little effect on AMG 706 PK. [Table: see text] No significant financial relationships to disclose.