LBA4000 Background: EGFR overexpression occurs in 27-50% of esophagogastric adenocarcinomas (OGA), and correlates with poor prognosis. The REAL3 trial evaluated the addition of the anti-EGFR antibody panitumumab (P) to epirubicin, oxaliplatin and capecitabine (EOC) in advanced OGA.
METHODS
Patients with untreated, metastatic or locally advanced OGA were randomised to EOC (E 50mg/m2, O 130mg/m2, C 1250mg/m2/day) or mEOC+P (E 50mg/m2, O 100mg/m2, C 1000mg/m2/day, P 9mg/kg). Primary endpoint was overall survival (OS); secondary endpoints were progression-free survival (PFS), response rate (RR), toxicity, and biomarker evaluation. Response was evaluated by RECIST after 4 and 8 cycles. Following IDMC review in October 2011 trial recruitment was halted and panitumumab withdrawn. Data for patients on treatment were censored at this timepoint.
RESULTS
553 patients were recruited (EOC 275, mEOC+P 278), with median follow-up 5.0 and 5.2 months respectively. Median OS was 11.3 months with EOC compared to 8.8 months with mEOC+P (HR 1.37: 95% CI 1.07-1.76, p=0.013). Median PFS was 7.4 and 6.0 months respectively (HR 1.22: 95% CI 0.98-1.52, p=0.068), with RR being 42% compared to 46% (odds ratio 1.16: 95% CI 0.81-1.57, p=0.467). mEOC+P was associated with ↑ G3/4 diarrhoea (17% vs 11%), skin rash (14% vs 1%) and thrombotic events (12% vs 7%), but ↓ haem toxicity (>G3 neutropenia 14% vs 31%). In the mEOC+P arm, OS was significantly improved in patients with G1-3 rash (77%, n=209) on treatment compared to those without (23%, n=63); median OS 10.2 vs 4.3 months (p<0.001), with similar significant improvements seen in RR and PFS. Biomarker analysis in the first 200 patients has not identified other predictive markers associated with P therapy. Multivariate analysis for OS in these patients demonstrated a negatively prognostic role for KRAS mutation (HR 2.1: 95% CI 1.10-4.05, p=0.025) and PIK3CA mutation (HR 3.2: 95% CI 1.01-10.40, p=0.048).
CONCLUSIONS
Addition of P to EOC chemotherapy was associated with worsening of OS in an unselected advanced OGA population. This may be in part due to lowered doses of O and C in the mEOC+P regimen. Outcomes in patients treated with P varied by grade of skin toxicity.