Abstract
BACKGROUND: In hormone receptor-positive, human epidermal growth factor 2-negative (HR+/HER2-) metastatic breast cancer (mBC), cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6is) in combination with an aromatase inhibitor (AI) are the preferred first-line (1L) treatment. Although prior cost-effectiveness models comparing CDK4/6is palbociclib, ribociclib, and abemaciclib have used data from placebo-controlled clinical trials, no analyses in the United States have been conducted using real-world evidence (RWE) for a US Medicare-eligible population. OBJECTIVE: To estimate the long-term clinical outcomes and health care costs of 1L CDK4/6i treatment in patients aged 65 years and older using RWE. METHODS: We developed a partitioned survival model to project patient time in progression-free and progressed disease health states. Progression-free survival (PFS) and overall survival (OS) curves for palbociclib + AI were obtained from an analysis of patients aged 65 years and older treated 1L for HR+/HER2- mBC using the Flatiron Health Analytic Database (Flatiron). Adjusted comparative effectiveness estimates vs palbociclib + AI for both ribociclib + AI (PFS hazard ratio = 0.98 [95% CI = 0.86-1.13]; OS hazard ratio = 1.01 [95% CI: 0.87-1.18]) and abemaciclib + AI (PFS hazard ratio = 0.99 [95% CI = 0.86-1.15]; OS hazard ratio = 1.00 [95% CI = 0.84-1.19]) were obtained from the same analysis. All-cause medical costs and CDK4/6i drug costs were based on an analysis of patients aged 65 years and older in Optum Clinformatics DataMart. We used a Medicare perspective over a lifetime horizon for a cohort of patients with mean age of 73.7 years. Sensitivity analyses were performed to assess the robustness of results to plausible variation in input values. RESULTS: Projected life-years (LYs) with palbociclib + AI, ribociclib + AI, and abemaciclib + AI were similar: 5.16 (95% credible range [CR] = 4.94-5.35), 5.12 (95% CR = 4.53-5.82), and 5.16 (95% CR = 4.49-5.90), respectively. Total lifetime health care costs were also similar ($865,000 [95% CR = $807,400-$925,000], $866,800 [95% CR = $786,000-$965,000], and $901,000 [95% CR = $809,000-$1,004,600], respectively). Sensitivity analyses further supported no differences in LYs or total costs between CDK4/6is. CONCLUSIONS: Based on effectiveness and cost estimates from real-world data, our analyses suggest that palbociclib, ribociclib, and abemaciclib produce similar life expectancy and health care costs in US patients aged 65 years and older with HR+/HER2- mBC.