Supplementary Material for: Combination of osimertinib with concurrent chemotherapy and hormonal therapy for synchronous NSCLC, hormone receptor positive breast cancer and triple negative breast cancer.

Patients presenting with multiple primary malignancies remains a growing challenge for physicians due to a lack of data for generalizable guidelines. Identification of driver mutations in carcinogenesis lead 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 EGFR mutated lung adenocarcinoma, likely primary lung adenocarcinoma of unspecified mutational status and a solitary metastatic lesion in the brain from one of her four 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 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.