Predictive factors of trastuzumab-based chemotherapy in HER2 positive advanced gastric cancer: a single-center prospective observational study

Purpose Trastuzumab plus chemotherapy is an effective therapy in HER2 positive advanced gastric cancer (AGC). However, the clinicopathologic factors that predict the outcome of routine trastuzumab therapy remain unclear. Methods The outcome and safety profile of trastuzumab therapy in untreated HER2 positive AGC was evaluated in this prospective observational study. Clinical and pathological data including demographics, treatment profiles, expression level of HER2 were analyzed to identify predictive factors of trastuzumab-based first-line therapy for their progression-free survival (PFS). Results Overall, 107 patients were eligible. The median number of treatment cycles was 9 (range 1-44), the median PFS and median overall survival (OS) were 7.7 months (95% CI 6.5-8.9) and 16.0 months (95% CI 13.2-18.8), respectively. The confirmed response rate was 58.9%, and the disease control rate was 82.2%. Patients with liver metastasis (HR 1.616) and poor performance status (PS, HR 2.518) were independently associated with a worse PFS, while the other clinicopathological factors including demographics, treatment profiles and some other clinical characteristics did not predict the survival. Conclusions In routine clinical practice, the addition of trastuzumab to chemotherapy was effective and safe in real-world setting in Chinese patients with HER2 positive AGC, regardless of most of the clinicopathological factors. Further studies are needed to improve the prognosis of HER2 positive patients with liver metastasis or poor PS.