Cost-Effectiveness Analysis of Adjuvant Neratinib Following Trastuzumab in Early-Stage HER2-Positive Breast Cancer

BACKGROUND: Disease-free survival (DFS) in early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer is significantly greater with the addition of neratinib after adjuvant trastuzumab versus no additional therapy. However, it remains uncertain whether these survival gains represent good value for the money, given the substantial cost of neratinib. OBJECTIVE: To evaluate clinical and economic implications of adding neratinib after adjuvant trastuzumab based on results from the phase III ExteNET trial. METHODS: A 3-state Markov model was developed to estimate the cost-effectiveness of neratinib for women with early-stage (I-III) HER2-positive breast cancer. Five-year recurrence rates were derived from the ExteNET trial. Mortality and recurrence rates after 5 years were derived from the HERceptin Adjuvant (HERA) trial. Outcomes included life-years, quality-adjusted life-years (QALYs), and direct medical expenditures. The analysis was performed from a payer perspective over a lifetime horizon. One-way sensitivity and probabilistic analyses were conducted to evaluate uncertainty. RESULTS: Total cost of neratinib following adjuvant trastuzumab was $317,619 versus $152,812 for adjuvant trastuzumab alone. A gain of 0.4 QALYs (15.7 vs. 15.3) and 0.1 years of projected life expectancy (18.3 vs. 18.2) favored neratinib after trastuzumab versus trastuzumab alone. The neratinib cost per QALY gained was $416,106. At standard willingness-to-pay thresholds of $50,000, $100,000, and $200,000 per QALY gained, neratinib has a probability of 2.8%, 16.7%, and 33.9% of cost-effectiveness, respectively. The cost per QALY gained in a scenario analysis only including patients with hormone-receptor positive disease was $275,311. CONCLUSIONS: Based on 5-year data from ExteNET, neratinib following adjuvant trastuzumab is not projected to be cost-effective, even among those patients shown to derive the greatest clinical benefit. Future analyses should reassess the cost-effectiveness associated with neratinib treatment as trial data mature. Copyright (C) 2019, Academy of Managed Care Pharmacy. All rights reserved.