Objective: To evaluate progression free survival (PFS) in patients with advanced or metastatic, hormone receptor positive (HR+), HER2-negative (HER2-) breast cancer treated with palbociclib in combination with fulvestrant as second or later lines of treatment.

Method: Observational, descriptive study with a retrospective cohort was carried out in 11 sites in Colombia. The data was extracted from the medical records of women who beginning treatment between February 2018 to August 2019. The index date was defined as first prescription and the follow up was performed until patient has experienced disease progression, death, treatment discontinuation, lost for other causes, or until 12 months of follow up, whichever occur first. Kaplan Meier were used to estimate PFS.

Results: Sixty-nine patients who received at least one dose of the drugs were included in the analysis. The median follow-up was 9.44± 2.48 months, mean age was 61.2 ± 11.14 years and 79.8% of the women were postmenopausal. At the start of the treatment, 54 of the women were in stage IV, with 46 of the women with >2 sites of metastasis. Fourteen patients reported discontinuation, 11 transitory suspension and 23 reduction of the dose. Neutropenia caused 17 cases of transitory suspension and 14 cases of dose reduction. The clinical benefit rate was 66.66%, the median PFS had not been achieved after 12 months being Hazard Ratio 0.69 (95% CI 0.58-0.82); 68.11 % of patients have not progressed. One death was reported due to progression.

Conclusion: Colombian patients diagnosed with HR+/HER2- advanced or metastatic breast cancer treated with palbociclib in combination with fulvestrant as second or later lines of treatment was found to be effective treatment in terms of PFS and maintained the safety profile observed in the pivotal and observational studies.