- •Real-world treatment patterns and outcomes of first-line palbociclib were evaluated (n = 813).
- •Palbociclib was initiated at the recommended dose of 125 mg in 87% of patients.
- •Of 813 patients, 43% discontinued palbociclib; 11% because of toxicity.
- •Median rwPFS and time to chemotherapy were 20.0 and 36.6 months, respectively.
- •Palbociclib initiation at 125 mg was more effective than lower doses.
To describe real-world treatment patterns and effectiveness of first-line palbociclib plus an aromatase inhibitor (PAL+AI) and examine the association between PAL initial dose and effectiveness among patients with hormone receptor–positive/human epidermal growth factor receptor 2–negative metastatic/advanced breast cancer (HR+/HER2– MBC) in routine clinical practice.
Patients and Methods
This retrospective analysis used Flatiron Health's database of electronic health records from >280 cancer clinics representing >2.4 million actively treated cancer patients in the United States. Women with HR+/HER2− MBC who received first-line PAL+AI were included. Real-world progression-free survival (rwPFS) was defined as the time from starting PAL+AI to death or disease progression. Real-world best tumor response (rwBTR) was assessed based on the treating clinician's assessment of radiologic evidence for change in disease burden.
Of 813 eligible patients, median age was 65.0 years, and median follow-up was 21.0 months. PAL was initiated at 125 mg/d and 75/100 mg/d in 86.5% and 13.5% of patients, respectively. Median duration of PAL+AI was 16.3 months. 43.0% of patients discontinued PAL+ AI; 11.0% discontinued because of toxicity. Median time to subsequent therapy and chemotherapy was 24.6 and 36.6 months, respectively. Median rwPFS was 20.0 months, and best rwBTR rate was 51.9%. Patients starting PAL at 125 versus 75/100 mg/d had longer median rwPFS (27.8 vs. 18.6 months) and higher rwBTR rate (54.0% vs. 40.4%).
These data demonstrate the benefit of PAL+AI in routine clinical practice and may support the initiation of palbociclib at the recommended dose of 125 mg/d for HR+/HER2− MBC.
Trial Registration Number and Date of Registration
NCT04176354, November 25, 2019
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Clinical Breast Cancer
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Management of adverse events due to cyclin-dependent kinase 4/6 inhibitors.Breast Care (Basel). 2019; 14: 86-92
- The cyclin-dependent kinase 4/6 inhibitor palbociclib in combination with letrozole versus letrozole alone as first-line treatment of oestrogen receptor-positive, HER2-negative, advanced breast cancer (PALOMA-1/TRIO-18): a randomised phase 2 study.Lancet Oncol. 2015; 16: 25-35
- Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up.Breast Cancer Res Treat. 2019; 174: 719-729
- Palbociclib and letrozole in advanced breast cancer.N Engl J Med. 2016; 375: 1925-1936
- IBRANCE® capsules. In. palbociclib.Pfizer Inc, New York, NY2019
- Palbociclib in hormone-receptor-positive advanced breast cancer.N Engl J Med. 2015; 373: 209-219
- Real-world evidence - what is it and what can it tell us?.N Engl J Med. 2016; 375: 2293-2297
- Analysis of time-to-treatment discontinuation of targeted therapy, immunotherapy, and chemotherapy in clinical trials of patients with non-small-cell lung cancer.Ann Oncol. 2019; 30: 830-838
- Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+/HER2- metastatic breast cancer in US real-world clinical practice.Breast Cancer Res. 2021; 23: 37
- Progression-free survival for real-world use of palbociclib in hormone receptor-positive metastatic breast cancer.Clin Breast Cancer. 2020; 20: 33-40
- Real-world clinical outcomes and toxicity in metastatic breast cancer patients treated with palbociclib and endocrine therapy.Breast Cancer Res Treat. 2019; 176: 429-434
- Real-world palbociclib use in HR+/HER2- advanced breast cancer in Canada: the IRIS study.Curr Oncol. 2021; 28: 678-688
- Treatment patterns and clinical outcomes of palbociclib-based therapy received in US community oncology practices.Future Oncol. 2021; 17: 1001-1011
- Treatment patterns and clinical outcomes among patients receiving palbociclib in combination with an aromatase inhibitor or fulvestrant for HR+/HER2-negative advanced/metastatic breast cancer in real-world settings in the US: results from the IRIS study.Breast. 2019; 43: 22-27
- Evaluating eligibility criteria of oncology trials using real-world data and AI.Nature. 2021; 592: 629-633
- Development and validation of a high-quality composite real-world mortality endpoint.Health Serv Res. 2018; 53: 4460-4476
- Real-world tumor response of palbociclib plus letrozole versus letrozole for metastatic breast cancer in US clinical practice.Target Oncol. 2021; 16: 601-611
Brufsky A, Liu X, Li B, McRoy L, Layman RM. Real-world tumor response of palbociclib plus letrozole vs letrozole for metstatic breast cancer in US clinical practice. Paper presented at: European Society for Medical Oncology Breast Cancer Virtual Meeting: Milan, Italy; May 23-24, 2020.
- CDK4/6 inhibitors in HR+/HER2- advanced/metastatic breast cancer: a systematic literature review of real-world evidence studies.Future Oncol. 2021; 17: 2107-2122https://doi.org/10.2217/fon-2020-1264
- Retrospective analysis of treatment patterns and effectiveness of palbociclib and subsequent regimens in metastatic breast cancer.J Natl Compr Canc Netw. 2019; 17: 141-147
- Real-world evidence analysis of palbociclib prescribing patterns for patients with advanced/metastatic breast cancer treated in community oncology practice in the USA one year post approval.Breast Cancer Res. 2018; 20: 37
- Palbociclib with letrozole in postmenopausal women with ER+/HER2- advanced breast cancer: hematologic safety analysis of the randomized PALOMA-2 trial.Oncologist. 2019; 24: 1514-1525
- Hematologic adverse events following palbociclib dose reduction in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: pooled analysis from randomized phase 2 and 3 studies.Breast Cancer Res. 2020; 22: 27
- Palbociclib in combination with fulvestrant in women with hormone receptor-positive/HER2-negative advanced metastatic breast cancer: detailed safety analysis from a multicenter, randomized, placebo-controlled, phase III study (PALOMA-3).Oncologist. 2016; 21: 1165-1175
Published online: May 04, 2022
Accepted: May 1, 2022
Received in revised form: March 11, 2022
Received: December 21, 2021
© 2022 Elsevier Inc. All rights reserved.