Cost-effectiveness of trastuzumab biosimilar combination therapy and drug wastage as first-line treatment for HER2-positive metastatic breast cancer

Background: The rising cost of cancer drug therapy threatens the long-term sustainability of Taiwan National Health Insurance. Cost savings can be achieved through various strategies, e.g., using smaller vial sizes, sharing vials, weight-based dosing, or switching to biosimilars. Here we aimed to examine the cost-effectiveness of a trastuzumab biosimilar combined with docetaxel (TDbiol) for treatment-naive HER2(+) metastatic breast cancer (MBC), and the financial impact of drug wastage. Methods: A Markov model with three health states was developed to assess the cost-effectiveness of trastuzumab biosimilars plus docetaxel over a 40-month time horizon in patients with HER2(+) MBC. Based on the literature and our expert opinion, we assumed similar efficacy between the trastuzumab biosimilar and its reference product. The primary clinical input for the biosimilar was the same as for the reference product in the Cata-strophic Patient Database (HV). Health state utilities were derived from the literature, and direct medical costs were obtained from the National Health Insurance Administration (NHIA). Results: In the base-case scenario, the incremental cost-effectiveness ratio (ICER) was NTD 811,050 per QALY gained. One-way sensitivity analyses showed that the model was sensitive to utilities and transition probabilities, but not particularly sensitive to the wastage assumption. In scenario analyses, the ICER was higher when applying the price for trastuzumab reference biologic (branded), than for trastuzumab biosimilar. Conclusion: The trastuzumab biosimilar combination regimen is cost-effective and offers significant drug cost savings in Taiwan.