Summary
HR+/HER2- mBC treatment has traditionally relied on endocrine therapy (ET) in early lines of treatment. The approval of cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors improved both progression-free (PFS) and overall survival (OS) for these patients (pts). Traditional chemotherapy (CT) is often utilized in later lines of therapy with limited effectiveness, increase in adverse events, and deterioration in quality of life. Here, we assess the unmet need among heavily pretreated HR+/HER2- mBC pts.
Methods
The study is a retrospective, observational study using U.S. oncology electronic medical record data available to ConcertAI through data sharing agreements, and referred to the ConcertAI Patient360™ breast cancer dataset. Definitions and algorithm to create the HR+HER2- cohort were based on NCCN approved treatment. Pts were included after discontinuing at least one CDK4/6 inhibitor and ET prior to starting their second CT in the metastatic setting. The index date is the start of second, third, fourth and fifth CT in the metastatic setting between January 1, 2015, through September 30, 2019 (for second CT) and September 30, 2020 (for all other lines). The outcomes included are OS and PFS (defined as time to next treatment).
Results
Of 4,483 pts identified with HR+/HER2- mBC, 2,704 pts (60%) received at least one CDK 4/6 inhibitor and ET. Of these, 266 pts (10%) received at least one CDK 4/6 inhibitor, ET and at least two CT in the metastatic setting. The rest of the pts (90%) either died or received less than 2 CT in the metastatic setting. Mean age at the beginning of 2nd CT was 59 years. The median OS after initiation of 2, 3, 4 and 5 CT was 13.5 months (CI 10.7-16.3), 9.1 months (CI 7.6-11), 6.8 months (CI 4.6-11) and 7.2 months (CI 2.9-13), respectively. PFS was 7.6 (CI 6.4-9.4) months, 4.8 months (CI 4.1-6.1), 4.2 months (CI 2.4-5.8) and 3.2 months (CI 2-3.9), respectively.
Conclusions
Outcomes for heavily pre-treated pts with HR+/HER2- mBC who have had prior CDK4/6 inhibition remain limited. Novel, efficacious therapies are needed to overcome limitations of existing treatment options in this setting.
