Economic Evaluation of First-Line Pertuzumab Therapy in Patients with HER2-Positive Metastatic Breast Cancer in Japan

OBJECTIVE: The purpose of this analysis was to evaluate the cost effectiveness of the combination of pertuzumab, trastuzumab, and docetaxel (PTD) for the treatment of patients with human epidermal growth factor receptor-2 (HER2)-positive breast cancer in Japan. METHODS: A partitioned survival analysis model was developed to predict costs and quality-adjusted life-years (QALYs) in a PTD arm and a trastuzumab plus docetaxel (TD) arm. Direct medical costs were considered from the perspective of the Japanese healthcare system. The time horizon of the model was set to 20 years. Data on overall survival and progression-free survival were derived from the CLEOPATRA trial. Cost parameters were estimated using a real-world claims database. Utilities were derived from published sources outside Japan. The incremental cost-effectiveness ratio (ICER) of PTD therapy compared with TD therapy was estimated. Sensitivity analysis was conducted to assess the uncertainty in parameter settings. RESULTS: Compared with TD therapy, PTD therapy incurred an additional cost of $US174,479 and conferred an additional 0.949 QALYs. This resulted in an ICER of $US183,901 per QALY gained. Utility weights for progression-free survival and progressed disease had a relatively large impact on the base-case result, but the ICERs remained higher than $US75,000 per QALY over the full range of model parameters. Based on a probabilistic sensitivity analysis, the probability that PTD is cost effective was estimated to be 3.3%. CONCLUSIONS: Applying a willingness-to-pay threshold of $US75,000 per QALY, PTD therapy as first-line therapy would not be cost effective. Further research is required on utilities and clinical benefits for Japanese patients with breast cancer. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s41669-020-00254-3.