Real-world survival outcomes associated with use of pertuzumab and trastuzumab emtansine (T-DM1) for HER2-positive (HER2+) metastatic breast cancer (MBC) in Brazilian private healthcare setting.

e13022 Background: Breast cancer is a leading death cause of women in Brazil. There are increased concerns with limited access to innovative therapies and the effectiveness of these agents outside clinical trials. This study aims to assess practice patterns and real-world outcomes of patients with HER2+ metastatic breast cancer (MBC) treated in the largest network of community oncology practices of Brazil after the introduction of pertuzumab and T-DM1 in routine care. Methods: De-identified electronic medical records from Oncoclínicas Group were aggregated in a cloud-based central database that allows technology-based abstraction, whereby trained data curators qualify the information using mCODE standards. We included data from all patients with a confirmed diagnosis of HER2+ MBC treated from 2014 to 2021. The primary objective was median overall survival (OS) from diagnosis of metastatic disease and other endpoints included adoption of pertuzumab-based regimen and T-DM1 in the palliative setting and their median Time to Treatment Discontinuation (TTD) in a real-world scenario. Results: Out of 21,559 patients with BC in our database, 6,215 had HER2+ disease and 1,250 had MBC treated with at least one palliative anti-HER2 therapy. Median age at diagnosis was 56 years, 29% had de novo metastatic disease, 81% received 2nd line therapy and 47% a 3rd line or beyond. With a median follow-up of 2 years, median OS was 49 months (CI95% 44-59). We found a ten-fold increase in the proportion of patients receiving pertuzumab or T-DM1 in the last two years when compared to 2014-2015. Overall, 62% received a pertuzumab-based regimen, mostly in the 1st line (76%), with median TTD of 9.9 months (CI95% 9-13). T-DM1 was accessible to 22% of the patients, mostly in 2nd (28%) or 3rd line and beyond (50%), with median TTD of 10.2 months (CI95% 9-13). Conclusions: In the largest Brazilian real-world study of patients with HER2+ MBC treated in the private health system, we found similar outcomes as those reported in North-American and European cohorts, both in terms of OS and TTD with standard-of-care therapies. Adoption of pertuzumab and T-DM1 was fast, but there are still gaps in access and the need to optimize clinical positioning of new anti-HER2 therapies recently approved for clinical use.