4018 Background: Gemcitabine/platinum combination is considered as globally acceptable standard care in patients with ABTC. Two recently published randomized trials showed adding EGFR antagonist, either erlotinib or cetuximab, does not further improve the clinical outcomes of gemcitabine/oxaliplatin (GEMOX)-treated ABTC patients. However, the impact of KRAS mutation status on the results of both studies was not properly addressed. Methods: A prospective, multicenter randomized, phase II trial to evaluate the therapeutic efficacies of adding cetuximab to GEMOX in patients with ABTC, in which eligible patients were stratified by status of KRAS mutation and ECOG PS, and tumor location then randomized to receive either GEMOX (gemcitabine 800 mg/m2, fixed-rate infusion and oxaliplatin 85 mg/m2, i.v., Q 2 weeks) or GEMOX plus cetuximab (500 mg/m2, i.v., Q 2 weeks, C-GEMOX). The primary endpoint was overall response rate (ORR). As an exploratory trial, 120 (60 per arm) patients was estimated to detect a two-tailed 10% difference in ORR (20% in GEMOX and 30% in C-GEMOX) with a significant level of a=0.2 and b=0.5. Results: Between Nov 2010 and May 2012, a total of 122 patients were accrued. The demography was male: 47.5%, median age: 60 y/o, ECOG PS 0/1: 28.7%/71.3%, IHCC/EHCC/GBC: 71.3%/16.4%/12.3%, KRAS mutation: 36.1%, with locally advanced/metastatic diseases: 32.0%/68.0%, and prior surgical resection: 41.8%. On intent-to-treat analysis, the ORR and DCR in the C-GEMOX (N=62) and GEMOX (N-60) arms was 27.3% vs 15.0% (p=0.1223) and 82.2% vs 60.0% (p=0.0090), respectively (Fisher’s exact test); while the median PFS was 7.1 vs 4.0 months (p= 0.0069) and median OS was 10.3 vs 8.8 months (p=0.4057), respectively (log-rank test). Planned subgroup analysis showed the 43 patients with KRAS mutated tumors benefited more from cetuximab therapy, with a DCR of 78.3% vs 38.1% (p=0.0132), median PFS of 7.0 vs 1.9 months (p=0.0351) and median OS of 10.3 vs 6.6 months (p=0.6924). Conclusions: Adding cetuximab significant improves the DCR and PFS of GEMOX in ABTC patients, notably in subpopulation with KRAS mutated tumors. Larger-scale phase III trial is warranted. Clinical trial information: NCT01267344.
