Aim: To describe treatment journey and clinical outcomes after palbociclib initiation in HR+/HER2- breast cancer patients across multiple lines. Materials & methods: Adult patients (n = 559) were identified in a population-based study between January 2018 and June 2020. Results: Median follow-up time was 41.2 months. The starting dose was 125 mg for more than 85% of patients, and a third had dose reduction. Median time on treatment was 30.5 months for palbociclib + aromatase inhibitors for patients that received first-line treatment after metastatic diagnosis, and 12.6 months for palbociclib + fulvestrant across multiple lines, and longer for patients that had a dose reduction during treatment. At 48 months, 59.3 and 27.3% of patients were still alive, respectively. Subsequent lines resulted in median time on treatment of 4.4-7.7 months in both groups. Conclusion: Time on treatment for palbociclib was comparable to data from clinical trials, and follow-up allowed us to examine subsequent treatment after initial treatment failure. Dose reduction was common in the real-world setting and did not adversely affect efficacy.
Trial registration: ClinicalTrials.gov NCT04671615.
Keywords: CDK4/6 inhibitors; HR+/HER2- breast cancer; observational study; palbociclib.
We used healthcare data from Israel to study the outcomes of adults (mostly women) who had breast cancer that spread (metastatic) and who started treatment with anticancer medications in the form of palbociclib in combination with either aromatase inhibitors (as first treatment after metastatic disease diagnosis) or fulvestrant (after having been treated with a different medication) between January 2018 and June 2020. Patients treated with palbociclib with aromatase inhibitors (52%) were on average 63 years old, and most had medium to high socioeconomic status (63%) and functioned independently (60%). Patients were treated on average for 30.5 months, and just over a third switched to a different treatment after their disease worsened. Four years after starting treatment, 59% of patients were still alive. Patients treated with palbociclib and fulvestrant, after having been treated with a different medication (48%), were on average 66 years old, and 61% had medium to high socioeconomic status and 50% functioned independently. These patients were treated on average for 12.6 months, and over two-thirds switched to a new treatment. Four years after starting this treatment, 27% of patients were still alive. Overall, most patients included in this study started treatment with the recommended dose of palbociclib (125 mg), and a third had to change to a lower dose to continue treatment (probably due to side effects). Clinical trial registration: NCT04671615 (ClinicalTrials.gov).