Ado-trastuzumab emtansine in the treatment of lung adenocarcinoma with ERBB2 mutation: a case report and literature review

The erb-b2 receptor tyrosine kinase 2 (ERBB2), also known as HER2, has long been recognized as an oncogenic driver in some breast and gastroesophageal cancers, and ERBB2-targeted therapies are standard for ERBB2-positive breast and gastric cancer. However, there are currently no standard therapies targeting the ERBB2 pathway in non-small cell lung cancer. Recently, somatic mutations in ERBB2 have been reported in 2–3% of patients with advanced lung adenocarcinoma, these mutations are trans-forming in lung cancer models and result in kinase activation, conferring some in-vitro sensitivity to trastuzumab. The ado-trastuzumab emtansine (T-DM1) is an antibody-drug conjugate composed of trastuzumab joined via a stable linker to DM1. In this report, a 67-year-old male patient was diagnosed with advanced lung adenocarcinoma with multiple lymph node metastases, and multi-chemotherapy and immunotherapy were not effective. The results of genetic testing indicated a non-frameshift insertion mutation in exon 20 of the ERBB2 gene. The patients received T-DM1 at a dose of 3.6 mg/kg by intravenous infusion every 21 days until for 12 cycles. Partial response appeared in the tumor lesions after treatment for four cycles, and PET-computer tomography showed the tumor lesions were effectively controlled, and the efficacy evaluation was complete response after treatment for six cycles. Although the patient experienced second degree of thrombocytopenia during the treatment, the corresponding symptomatic treatment was taken, and the platelets could return to normal before the next cycle of T-DM1. Follow-up review showed the patient is in good health and the tumor has not recurred.