Real-world study of patients with HR+/ HER2- metastatic breast cancer treated with palbociclib and fulvestrant.

Aims: To investigate real-world treatment patterns and outcomes among patients with hormone receptor-positive/human epidermal growth factor 2-negative (HR+/HER2-) metastatic breast cancer (mBC) who initiated first-line palbociclib-fulvestrant.

Patients & methods: Retrospective observational study of iKnowMed electronic health records among patients who initiated first-line palbociclib-fulvestrant between 1 February 2016 and 31 December 2019 and were followed through 30 June 2020. Demographic, clinical, and treatment characteristics were evaluated descriptively. Endpoints including real-world progression-free survival, overall survival, time to chemotherapy, real-world duration of therapy, and time to next treatment were assessed using Kaplan-Meier methods from first-line treatment initiation.

Results: 317 patients were included (median age 67.3 years, 90.5% post-menopausal, 36.9% bone-only disease, 15.9 months median follow-up). Among those with prior adjuvant treatment (n = 269), 66.2% (n = 178) had disease-free intervals less than 12 months. Median real-world progression-free survival was 19.6 months (95% CI 15.2-23.6).

Conclusions: These results suggest favorable real-world clinical outcomes associated with first-line palbociclib-fulvestrant among patients with HR+/HER2- mBC. (clinical trial registration: NCT04498481).