Enhertu as an effective treatment for metastatic lung cancer with brain metastasis recurrence: a case report.

Background: Metastatic lung cancer with recurrent brain metastasis presents significant treatment challenges. Enhertu (trastuzumab deruxtecan), a targeted therapy for HER2-positive cancers, has shown promise in treating solid tumors, including nonsmall cell lung cancer (NSCLC) with brain metastases. This case report examines the efficacy of Enhertu in a patient with metastatic lung cancer and recurrent brain metastasis. Case presentation: A 39-year-old woman diagnosed with Stage IV adenocarcinoma of the left lung, negative for EGFR, ALK, and ROS-1, but with an ERBB2 mutation, experienced neurological symptoms leading to a diagnosis of brain metastasis in 2019. After multiple lines of therapy, including surgery, irradiation, chemotherapy, and targeted treatments, she presented with recurrent brain metastasis in January 2024. Following progression despite previous treatments, she was started on Enhertu in February 2024. Intervention: The patient was treated with Enhertu, and after six cycles, radiologic evaluation via PET and MRI scans in June 2024 demonstrated significant reduction in the size of cerebral and cerebellar metastases, with no new lesions or abnormal meningeal enhancement. Additionally, there was notable regression in the size and metabolic activity of lung lesions and previously hypermetabolic nodes. Results: Enhertu led to a partial response, with regression of most metastatic sites, including brain and lung metastases, and no evidence of new hypermetabolic lesions. The treatment was well tolerated with minimal adverse effects. Conclusion: Enhertu represents a promising treatment option for HER2-mutant metastatic lung cancer with recurrent brain metastasis. This case highlights the potential of Enhertu in overcoming treatment resistance in complex metastatic settings, warranting further investigation in broader clinical settings.