Cost-effectiveness of one-year adjuvant trastuzumab therapy in treatment for early-stage breast cancer patients with HER2+ in Vietnam

Background: In Vietnam, trastuzumab is included in social health insurance’s benefits package with a reimbursement rate of 60%, but policymakers have been concerned about its cost-effectiveness. The research aims to evaluate the cost-effectiveness of one-year adjuvant trastuzumab therapy for early-stage breast cancer patients with human epidermal growth receptor 2 (HER2+) from a societal perspective. Method: A Markov model was developed and validated to estimate the lifetime cost and effectiveness (using life year and quality-adjusted life year) of one-year adjuvant trastuzumab therapy compared to chemotherapy (using paclitaxel) alone. Treatment efficacy and transition probabilities were estimated based on published trials (i.e., N9831, NSABP B-31, HERA, and BCIRG 006). Local cost and utility data were employed to capture the Vietnam context. One-way sensitivity analysis, probabilistic sensitivity analysis, threshold, and scenario analysis were also performed. Results: One-year adjuvant trastuzumab therapy combined with chemotherapy compared to chemotherapy alone yielded an additional cost of 888,453,971VND (39,062 US$) with an additional 3.09 LYs and 1.61 QALYs, resulting in an ICER of 287,390,682 VND (12,635 US$) per LY gained, or 519,616,972 VND (22,845 US$) per QALY gained. The ICER exceeds the cost-effective threshold of 1- and 3-time GDP per capita by 6.3 and 2.1 times. The probabilistic sensitivity analysis shows similar results. According to one-way sensitivity analysis, ICERs were driven mainly by transition probabilities and trastuzumab price. One-year adjuvant trastuzumab therapy would be cost-effective at the 3-time GDP per capita threshold if the cost of Herceptin 150mg and 450mg vials were reduced by 56% and 54%, correspondingly. Conclusion: In Vietnam, one-year adjuvant trastuzumab therapy for early-stage breast cancer with HER2+ is not cost-effective. The research provided reliable and updated evidence to support policymakers in revising the health insurance benefit package. The policymakers should consider the options to reduce the cost of trastuzumab (e.g., regarding the use of trastuzumab biosimilars, price negotiation options, and options of optimizing the use of Herceptin vials among concurrent hospitalized breast cancer patients).