# Real-World Utilization of Palbociclib as First-Line Treatment for Canadian HR+/HER2− Women with Metastatic Breast Cancer: Results from PALCAN Study

## TL;DR

This study analyzed how Canadian women with a specific type of breast cancer are using a drug called palbociclib and found differences in treatment duration based on accompanying therapies.

## Contribution

The study provides the first real-world data on palbociclib use in Canadian patients with HR+/HER2− metastatic breast cancer.

## Key findings

- The median duration of palbociclib treatment was 13.8 months in the overall cohort.
- Patients receiving palbociclib with aromatase inhibitors had a longer treatment duration (15.1 months) compared to those with fulvestrant (7.9 months).
- 45% of patients discontinued palbociclib treatment within the first year.

## Abstract

There is limited Canadian real-world data that shows how palbociclib, a first-line treatment for hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer, is being used in Canadian women. Using health administrative data from Alberta, Canada, this study examined the records of 472 female breast cancer patients who were inferred to have received palbociclib as first-line therapy and found that the median duration of treatment was 13.8 months and that the probability that these patients discontinued treatment within the first year was 45%. When patients receive palbociclib, they also receive an endocrine therapy in the form of an aromatase inhibitor (83% of patients in this study) or fulvestrant (14% of patients in this study). The median duration of treatment for patients receiving palbociclib with an aromatase inhibitor was 15.1 months, while the median duration of treatment for patients receiving palbociclib with fulvestrant was 7.9 months.

Canadian real-world data (RWD) regarding palbociclib as a first-line therapy for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) metastatic breast cancer (MBC) is limited. The PALbociclib CANadian (PALCAN) study examined palbociclib utilization patterns as first-line treatment for HR+/HER2− MBC using Alberta health administrative data. The final PALCAN cohort included 472 female patients with a median age of 64 years and a median follow-up time of 22.8 months (IQR: 0.7–88.2). The median (95% CI) duration of treatment was 13.8 (12.7–15.1) months in the overall cohort (IQR: 5.6, 24.8 months), and the probability of treatment discontinuation within the first year was 45%. Aromatase inhibitors (AIs) and fulvestrant were the accompanying endocrine therapies (ETs) in 83% (N = 393) and 14% (N = 64) (15 with unknown accompanying therapy) of patients, respectively. The median duration of treatment for patients receiving an AI as an accompanying therapy was 15.1 (13.6–17.4) months and 7.9 months (5.8–12.6) for patients receiving fulvestrant, which may suggest endocrine resistance in the latter group. The PALCAN data provides insights into practice patterns and the effectiveness of palbociclib as a first-line therapy in female patients with HR+/HER2− breast cancer in the Canadian real-world setting.