Evaluation of HER2-targeted Therapy for Gastric Cancer and Establishment and Verification of Monitoring System

The positive rate of HER2 in Chinese patients with gastric cancer is about 12-13%. HER2 positive gastric cancer has strong invasion, high metastasis rate and poor prognosis. The effective rate of chemotherapy combined with anti-HER2 targeted therapy for HER2 positive advanced gastric cancer was 47%, and the median survival time was extended to 13.8 months. However, the status of HER2 in advanced gastric cancer has obvious temporal and spatial heterogeneity, and the heterogeneity of HER2 directly affects the outcome of anti-HER2 treatment. Therefore, compared with biopsy pathology, it is urgent to explore noninvasive, systemic and repeatable methods to evaluate HER2 status of systemic lesions. 68Ga-HER2 Affibody-BCH, a HER2 imaging agent, was independently prepared by the Department of nuclear medicine of our center. According to the results of preclinical studies, in patients with HER2 positive advanced gastric cancer, the imaging effect was the best 2 hours after intravenous injection of 68Ga-HER2 Affibody and there was no adverse reaction. 68Ga-HER2 Affibody PET/CT imaging can directly reflect the HER2 heterogeneity within the same lesion and between the primary and metastatic lesions. In order to solve the clinical problems, this study intends to further explore the imaging of 68Ga-HER2 Affibody-BCH in patients with advanced gastric cancer and the amplification of HER2 in the peripheral blood of this population, so as to overcome the heterogeneity of HER2, explore the potential beneficiaries of anti HER2 treatment, and provide the basis for the evaluation of anti-HER2 treatment efficacy.