Updated analysis of HERBIS-1: A phase ll study of trastuzumab (T-mab) in combination with tri-weekly S-1 plus CDDP in HER2-positive advanced gastric cancer.

Abstract

98 Background: The HERBIS study demonstrated the promising antitumor activity and manageable toxicities of S-1 plus cisplatin and T-mab (SPT) regimen in patients (pts) with HER2-positive advanced gastric cancer (AGC) (Sugimoto et al. ASCO GI 2012, Abstract 70). We report the updated time-to event analysis. Methods: Main eligibility criteria were gastric or esophagogastric junction adenocarcinoma, HER2-positive, unresectable or recurrent, measurable lesion, no history of chemotherapy or radiotherapy, ECOG PS of 0-1 and adequate organ function. Pts received S-1(80-120mg / day) on days 1-14, cisplatin 60 mg/m2on day 1 and T-mab 8 mg/ kg on day 1 (6 mg/ kg from 2nd course) repeated every 3 weeks until disease progression. Primary endpoint was response rate (RR) and secondary endpoints were overall survival (OS), progression-free survival (PFS), time to treatment failure (TTF) and adverse events. The planned sample size was 50 pts. Results: A total of 56 pts were enrolled from July 2011 to May 2012. Two pts were ineligible and one patient did not receive any treatment. Therefore, the efficacy and safety analyses were conducted in the full analysis set of 53 pts. The confirmed response rate was 67.9% (95% CI: 53.7-80.1), and the disease control rate was 94.3% (95% CI: 84.3-98.9). Median OS was 16.0 months (95% CI: 13.3 - NaN), median PFS was 7.8 months (95% CI: 6.0 – 8.8) and median TTF was 5.7 months (95% CI: 4.2 - 7.1), respectively at the median follow-up time of 13.5 months. The main grade 3/4 adverse events were leukopenia 8%, neutropenia 36%, anemia 15%, increased creatinine 6%, hypoalbuminemia 9%, anorexia 23%, diarrhea 8% and vomiting 6%. Conclusions: SPT have promising antitumor activity and manageable toxicities in pts with HER2-positive AGC. Clinical trial information: UMIN000005739.