Safety, pharmacokinetic, and clinical activity profiles of ramucirumab in combination with three platinum/fluoropyrimidine doublets in Japanese patients with chemotherapy-naive metastatic gastric/gastroesophageal junction cancer

Background We evaluated the safety, tolerability, pharmacokinetics, and tumor response of ramucirumab in combination with one of three platinum/fluoropyrimidine regimens in Japanese patients with chemotherapy-naive metastatic gastric/gastroesophageal junction cancer. Methods In this phase 1b study, patients received 8 mg/kg ramucirumab on days 1 and 8 every 3 weeks, following one of three regimens: capecitabine + cisplatin, XP; S-1 + cisplatin, SP; or S-1 + oxaliplatin, SOX. The primary objective was to assess safety and tolerability; the secondary objectives were to evaluate pharmacokinetics and tumor response. Results Six patients were treated in each cohort. All regimens were generally well tolerated, although 1 patient in SOX was associated with grade 3 enterocolitis, which was considered a dose-limiting toxicity. Common grade 3 or higher adverse events included neutropenia (1 in XP, 3 in SP, and 2 in SOX), decreased appetite (1 in SP), and hypertension (2 in XP). The mean trough ramucirumab concentrations were consistent across all cohorts, and those of most patients exceeded target levels, which were estimated from previous studies of the approved ramucirumab dose (8 mg/kg every 2 weeks). Among the 11 patients with measurable disease, overall response rate and disease control rate were 45.5% and 100.0%, respectively. Median progression-free survival (95% CI) was 7.6 months (6.0 to not estimable). Conclusion Ramucirumab 8 mg/kg on days 1 and 8 every 3 weeks in combination with XP, SP, or SOX was generally well tolerated and demonstrated preliminary anti-tumor activity in chemotherapy-naive Japanese metastatic gastric/gastroesophageal junction cancer patients.