Long-term survival after immunotherapy and targeted therapy without chemotherapy in an elderly patient with HER2-positive gastroesophageal junction cancer: A case report

A 74-yr-old man underwent thoracic laparoscopy combined with radical gastrectomy, and the postoperative pathological diagnosis was esophageal and gastric cardia cancer pT3N1M0, pStage IIB. Immunohistochemical staining for HER2 (3+) and PD-L1 (<5%) was positive. Adjuvant chemotherapy was not performed because the patient developed severe thrombocytopenia (platelet counts <30 × 10(9)/L), which was never cured throughout the reporting period. At 10.7 months post-surgery, he suffered metastases in multiple organs, including the peritoneum, liver, lung, and bone. Following two cycles of first-line trastuzumab and pembrolizumab (200 mg), he developed immune-related myositis (G2), myocarditis (G2), and hepatitis (G1). Therefore, pembrolizumab was discontinued. Trastuzumab was administered as a monotherapy; meanwhile, adoptive cytokine-induced killer (CIK) cell infusions were initiated. Eight months after the initial immunotherapy, a solitary brain metastasis was detected, and the patient underwent CyberKnife radiosurgery. For second-line therapy, adoptive CIK cell immunotherapy plus trastuzumab was still used. At the time of reporting, the patient had achieved a complete response (CR) in the brain and liver and a partial response (PR) in the ilium, and he had been followed-up for 36.6 months, much longer than the median survival time for patients with advanced GEJ cancer. We suggest that HER2-targeted therapy and immunotherapy with pembrolizumab or CIK adoptive cell infusions prolonged the overall survival of an elderly patient with HER2-positive GEJ cancer with multiple metastases.