Angela DeMichele1, Massimo Cristofanilli2, Adam Brufsky3, Xianchen Liu4, Jack Mardekian4, Lynn McRoy4, Rachel M Layman5, Birol Emir4, Mylin A Torres6, Hope S Rugo7, Richard S Finn8. 1. Abramson Cancer Center, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA, 19104, USA. Angela.DeMichele@uphs.upenn.edu. 2. Robert H. Lurie Cancer Center of Northwestern University, Feinberg School of Medicine, Chicago, 710 N Fairbanks Ct, Suite 8-250A, Chicago, IL, 60611, USA. 3. UPMC Hillman Cancer Center, University of Pittsburgh Medical Center, 300 Halket Street, Pittsburgh, PA, 15213, USA. 4. Pfizer Inc, 235 42nd St, New York, NY, 10017, USA. 5. The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 1354, Houston, TX, 77030, USA. 6. Winship Cancer Institute, Emory University School of Medicine, 1365 Clifton Rd. NE, Building A, 1st Floor, Rm. 1307A, Atlanta, GA, 30322, USA. 7. University of California San Francisco Helen Diller Family Comprehensive Cancer Center, 1825 4th Street, 3rd Floor, Box 1710, San Francisco, CA, 94158, USA. 8. David Geffen School of Medicine at University of California Los Angeles, 2825 Santa Monica Blvd, Suite 200, Santa Monica, CA, 90404, USA.
Abstract
BACKGROUND: Findings from randomized clinical trials may have limited generalizability to patients treated in routine clinical practice. This study examined the effectiveness of first-line palbociclib plus letrozole versus letrozole alone on survival outcomes in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor-negative (HER2-) metastatic breast cancer (MBC) treated in routine clinical practice in the USA. PATIENTS AND METHODS: This was a retrospective observational analysis of electronic health records within the Flatiron Health Analytic Database. A total of 1430 patients with ≥ 3 months of follow-up received palbociclib plus letrozole or letrozole alone in the first-line setting between February 3, 2015, and February 28, 2019. Stabilized inverse probability treatment weighting (sIPTW) was used to balance baseline demographic and clinical characteristics. Real-world progression-free survival (rwPFS) and overall survival (OS) were analyzed. RESULTS: After sIPTW adjustment, median follow-up was 24.2 months (interquartile range [IQR], 14.2-34.9) in the palbociclib group and 23.3 months (IQR, 12.7-34.3) in those taking letrozole alone. Palbociclib combination treatment was associated with significantly longer median rwPFS compared to letrozole alone (20.0 vs 11.9 months; hazard ratio [HR], 0.58; 95% CI, 0.49-0.69; P < 0.0001). Median OS was not reached in the palbociclib group and was 43.1 months with letrozole alone (HR, 0.66; 95% CI, 0.53-0.82; P = 0.0002). The 2-year OS rate was 78.3% in the palbociclib group and 68.0% with letrozole alone. A propensity score matching analysis showed similar results. CONCLUSIONS: In this "real-world" population of patients with HR+/HER2- MBC, palbociclib in combination with endocrine therapy was associated with improved survival outcomes compared with patients treated with letrozole alone in the first-line setting. TRIAL REGISTRATION: Clinicaltrials.gov; NCT04176354.
BACKGROUND: Findings from randomized clinical trials may have limited generalizability to patients treated in routine clinical practice. This study examined the effectiveness of first-line palbociclib plus letrozole versus letrozole alone on survival outcomes in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor-negative (HER2-) metastatic breast cancer (MBC) treated in routine clinical practice in the USA. PATIENTS AND METHODS: This was a retrospective observational analysis of electronic health records within the Flatiron Health Analytic Database. A total of 1430 patients with ≥ 3 months of follow-up received palbociclib plus letrozole or letrozole alone in the first-line setting between February 3, 2015, and February 28, 2019. Stabilized inverse probability treatment weighting (sIPTW) was used to balance baseline demographic and clinical characteristics. Real-world progression-free survival (rwPFS) and overall survival (OS) were analyzed. RESULTS: After sIPTW adjustment, median follow-up was 24.2 months (interquartile range [IQR], 14.2-34.9) in the palbociclib group and 23.3 months (IQR, 12.7-34.3) in those taking letrozole alone. Palbociclib combination treatment was associated with significantly longer median rwPFS compared to letrozole alone (20.0 vs 11.9 months; hazard ratio [HR], 0.58; 95% CI, 0.49-0.69; P < 0.0001). Median OS was not reached in the palbociclib group and was 43.1 months with letrozole alone (HR, 0.66; 95% CI, 0.53-0.82; P = 0.0002). The 2-year OS rate was 78.3% in the palbociclib group and 68.0% with letrozole alone. A propensity score matching analysis showed similar results. CONCLUSIONS: In this "real-world" population of patients with HR+/HER2- MBC, palbociclib in combination with endocrine therapy was associated with improved survival outcomes compared with patients treated with letrozole alone in the first-line setting. TRIAL REGISTRATION: Clinicaltrials.gov; NCT04176354.
Entities:
Keywords:
Comparative effectiveness; HR+/HER2−; Letrozole; Metastatic breast cancer; Palbociclib; Real-world data
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