Panitumumab (pmab) with FOLFIRI as first-line treatment of patients (pts) with metastatic colorectal cancer (mCRC): Resections and curative surgery in a phase II single arm, multicenter study (20060314).

Abstract

3545 Background: Pmab, a fully human monoclonal antibody directed against the epidermal growth factor receptor (EGFR), is approved in Europe as monotherapy for pts with chemotherapy-refractory, EGFR-expressing, KRAS wild-type (WT) mCRC. Methods: Ptsreceived pmab (6 mg/kg) and FOLFIRI every 2 weeks. Eligibility criteria included histologically confirmed mCRC (no prior systemic treatment for metastatic disease), ECOG PS 0–2 and availability of tumor tissue for biomarker analysis. The primary endpoint was objective response rate and secondary endpoints included progression-free survival and safety. All analyses are descriptive, this abstract discusses resections. Results: A total of 154 pts were enrolled. At time of primary analysis (June 09), KRAS evaluable samples were available for 94% (n = 145) of pts: 86 (59%) pts had KRAS WT tumors and 59 (41%) pts had KRAS mutant (MT) tumors. Demographics in the primary analysis set (all KRAS evaluable pts) by KRAS WT and MT were: 78%/54% male; median age (range) 63.5 years (21–84)/65.0 years (37-80); ECOG PS 0-1 95%/93%. Response rate in the KRAS WT group was 56% vs 38% in the MT group and median progression-free survival was 8.9 months vs 7.2 months. Resection rate was 15% (95% CI 8.3%, 24.5%) and 7% (95% CI 1.9%, 16.5%), and the majority of pts that underwent surgery had liver only mets 12 (92%) and 2 (50%), in the KRAS WT and MT groups respectively. One pt in the KRAS WT group had surgery for skin lesion mets and in the KRAS MT group, one pt underwent surgery for ovary and colon mets and another for lung mets. Complete removal was achieved in 8% (95% CI 3.3%, 16.1%) of pts in the KRAS WT group and 5% (95% CI 1.1%, 14.2%) in the KRAS MT group. Adverse events (AEs) were in line with previously reported data and KRAS status did not appear to influence incidence of these AEs. There were 3 treatment-related grade 5 events (haematemesis and rectal haemorrhage in the WT group and vena cava thrombosis in the MT group). Conclusions: Pmab combined with FOLFIRI in the first-line setting appears to be a well-tolerated regimen. These data suggest that pmab may increase incidence of resection in the WT group versus MT group. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Amgen Amgen Amgen Amgen Amgen Amgen