A study of the combination of oxaliplatin, capecitabine, and trastuzumab and chemo-radiotherapy in the adjuvant setting in operated patients with HER2+ gastric or gastroesophageal junction cancer (TOXAG study).
26 Background: We evaluated the safety and tolerability of trastuzumab (T) in combination with oxaliplatin (O), capecitabine (C) and chemo-radiotherapy in the adjuvant setting in operated, HER-2 positive gastric or gastroesophageal junction adenocarcinoma patients. Methods: We have screened 212 and enrolled 34 patients who were curatively resected (R0, R1 with partial or total gastrectomy, with D2 lymph node dissection) and were HER2-positive (IHC 2+/FISH+ or IHC 3+). The primary objectives were safety and tolerability of the treatment combination and secondary objectives were disease-free and overall survival rates. Patients received T 8 mg/kg intravenously (iv) on Day 1 of cycle 1 and 6 mg/kg iv on day 1 of every following 3-weekly cycle for 1 year as 17 cycles, O 100 mg/m2 iv on Day 1 of cycles 1-3 and C 850 mg/m2 orally twice daily on days 1-14 of cycles 1-3 and 5 days per week during chemo-radiotherapy. Radiotherapy was given at a total dose of 45 Gy divided into 25 doses 5 treatment days per week for 5 weeks starting from the 1st day of cycle 4. Results: The median age was 57 years and 73.5% were male, 97.0% had an ECOG PS score ≤ 1,33, 97.0% had D2 lymph node resection. Staging was 3A or higher at the time of diagnosis in 76.4% of patients. Patients had high rate of tolerability to the combination regimen (90.3%) and successfully completed 3 cycles of O+C+T plus chemoradiotherapy followed by continuation with T, achieving the primary goal of the study by showing a better tolerability rate as compared to tolerability reported for INT0116 study (p = 0.0068). After 25 months of follow-up confirmed through a telephone visit, 59.8% patients were still alive and median overall survival was not yet reached. Twelve patients died secondary to disease progression. There were no deaths due to toxicity and 6 dose reductions overall (1 for T, 2 for O and 3 for C). T was stopped in one patient; C was temporarily interrupted 11 times (mostly during radiotherapy) and stopped in 1 patient. Conclusions: T in combination with C, O and radiotherapy in the adjuvant setting for gastric or gastroesophageal junction adenocarcinoma seems safe and tolerable. Clinical trial information: NCT01748773.