Fulvestrant and palbociclib combination in heavily pretreated hormone receptor-positive, HER2-negative metastatic breast cancer patients.

Purpose: We report the results of a retrospective analysis of the fulvestrant and palbociclib combination within a temporary authorization of use (TAU) program in 77 heavily pretreated patients with hormone receptor-positive (HR+), HER2-negative metastatic breast cancer.

Methods: All patients who received the fulvestrant and palbociclib combination within this TAU program were included. Toxicities were graded using the CTCAE v5 scale.

Results: The majority of patients (62.3%) were previously treated with the mTOR inhibitor everolimus. The median number of previous treatments for their metastatic disease was 4. With a median follow-up of 14 months, the median progression-free survival (PFS) was 7.6 months. The median PFS significantly (p < 0.0001) decreased with the number of previous treatment lines in the metastatic setting. The median PFS was 5.5 months in patients who had previously progressed on everolimus compared to 9.3 months in the everolimus non-pretreated subgroup. No significant difference in median PFS was detected in patients according to age. The median overall survival rate was not reached. The clinical benefit rate was 64%, including 4% of complete responses, 26% partial responses, and 34% stable diseases for the entire cohort.

Conclusions: The fulvestrant and palbociclib combination exerts an appreciable effect on metastatic heavily pretreated patients with a tolerable toxicity profile.