Long-term response to treatment of metastatic HER2-positive gastric cancer. Clinical case

Metastatic gastric cancer remains a disease with unfavorable prognosis, median overall survival with standard chemotherapy is less than 1 year. In 15–20 % of patients, the tumor is characterized by HER2 hyperexpression/amplification which allows to use targeted therapy. Results of the ToGA trial showed that addition of trastuzumab to the 1st line chemotherapy in HER2-positive patients statistically significantly increased median overall survival to 16.0 months in the high expression (immunohistochemistry 3+) group, and this regimen remains the standard treatment in these patients in the 1st line. A clinical case of a 46-year-old female patient with disseminated HER2-positive (immunohistochemistry 3+) stage IV (primary tumor, metastases in the liver, ovary, carcinomatosis) is presented. During 1st line therapy (XELOX + trastuzumab), partial and later complete regression of the tumor lesions was achieved. After 10 courses of induction therapy, supportive therapy with capecitabine and trastuzumab was started which has been going for more than 9 years with overall survival of 123 months and duration of complete response 116 months. Results of the observation show the possibility of exceptionally long and deep response to chemotherapy and trastuzumab combination in individual patients with HER2-positive metastatic gastric cancer which emphasizes significant heterogeneity of this patient subgroup. Optimization of metastatic gastric cancer treatment requires further study aimed at identification of predictive biomarkers of response to anti-HER2 therapy.