Cost-Utility Analysis of Trastuzumab-Emtansine Versus Trastuzumab for the Treatment of Residual Invasive HER-2-Positive Breast Cancer in Iran.

Background: Breast cancer is one of the most common types of cancer in women, and its incidence is increasing in Iran. HER-2-positive breast cancer is invasive and often associated with poorer outcomes. Patients with this type of breast cancer can develop resistance to medications like trastuzumab. Trastuzumab-emtansine (TDM1) is a medication developed to reduce cancer cell resistance to trastuzumab. The TDM1 has been shown to decrease the incidence of death and recurrence in breast cancer.

Objectives: This study aimed to evaluate the cost-utility and calculate the budget impact of TDM1 versus trastuzumab for the treatment of residual invasive HER-2-positive breast cancer.

Methods: A Markov model with a lifetime horizon was developed, incorporating four health states. Women aged 45 with residual invasive HER-2-positive breast cancer entered the model. The study adopted a healthcare system perspective, with costs reported in 2021 US dollars. Discount rates of 7% for costs and 3% for utility values were applied. Utility values and transition probabilities were derived from published literature. Costs were estimated based on guidelines, expert opinions, and Iranian tariffs. Iran's pharmacoeconomic threshold of 1085$ was used for comparison. The incremental cost-effectiveness ratio (ICER) and budget impact of TDM1 were calculated, and sensitivity analyses were conducted to assess the robustness of the model.

Results: The model indicated that treatment with TDM1 resulted in a 1.59 quality-adjusted life year (QALY) increase, with an additional cost of 1408$. This was deemed cost-effective, considering Iran's pharmacoeconomic threshold of 1085$ (calculated ICER: 886$ per QALY gained). One-way sensitivity analysis revealed that the model was sensitive to the costs of TDM1 and trastuzumab, the discount rates for utility values and costs, and the probability of achieving invasive disease-free survival (IDFS). Probabilistic sensitivity analysis showed that 59.61% of simulations fell below Iran's pharmacoeconomic threshold, supporting the model's robustness. The budget impact analysis revealed that the additional budget required for TDM1 treatment over a three-year period was 1,120,546$ compared to trastuzumab.

Conclusions: Although TDM1 imposes higher costs, it is more cost-effective than trastuzumab for the treatment of residual invasive HER-2-positive breast cancer in Iran.