Combination of Osimertinib with Concurrent Chemotherapy and Hormonal Therapy for Synchronous NSCLC, Hormone Receptor-Positive Breast Cancer, and Triple-Negative Breast Cancer: Case Report

Patients presenting with multiple primary malignancies remain a growing challenge for physicians due to a lack of data for generalizable guidelines. Identification of driver mutations in carcinogenesis leads to the development of targeted treatment of many different cancer types, but its combination with other anti-cancer therapy is not well understood. We report a case of a 66-year-old woman who presented with triple-negative breast cancer, multifocal hormone receptor-positive breast cancer, primary epidermal growth factor receptor-mutated lung adenocarcinoma, possible primary lung adenocarcinoma of unspecified mutational status in the contralateral lung, and a solitary metastatic lesion in the brain from one of her primary cancers. She was treated with stereotactic radiosurgery and osimertinib in combination with carboplatin/nab-paclitaxel, doxorubicin/cyclophosphamide, and letrozole, with excellent clinical and radiographical response. We did not observe synergistic toxicity or unexpected adverse events from the treatment. To the best of our knowledge, this is the first report of concurrent osimertinib with these chemotherapy and hormonal therapy agents. As large-scale studies are difficult to conduct for these rare cases requiring exceptional treatment, it is important for physicians to build on the community's shared experience via case reports to better predict efficacy and safety of combining targeted agents with other conventional systemic treatments.