Treatment patterns and overall survival in HER2+ metastatic breast cancer at US community oncology practices

Aim: To describe real-world treatment patterns/outcomes among patients with HER2+ metastatic breast cancer (MBC). Materials & methods: Real-world treatments and overall survival (OS) were evaluated among adult women diagnosed with HER2+ MBC, with and without brain metastases (BMs), between 1 June 2012 and 31 May 2018 using electronic medical records from the Definitive Oncology Dataset. Results: Among 372 patients, 69% initiated first-line trastuzumab plus pertuzumab-based therapy; many therapy combinations were utilized in the second- to fourth-line. During follow-up (median 24.8 months), 18% of patients died (22% with and 16% without BMs). Mean OS was shortest among patients with BMs at MBC diagnosis in the third- and fourth-line. Conclusion: OS was poor, and no clear standard of care was observed among patients with HER2+ MBC progressing on trastuzumab-based therapies.