OBJECTIVES: HER2+ breast cancer (BC) management based on chemotherapy and anti-HER2 agents has changed the course of the disease, improving disease-free and overall survival. In Chile, public reimbursement of anti-HER2 agents includes trastuzumab for all indications, pertuzumab for metastatic BC, and trastuzumab emtansine (TDM1) for adjuvant when residual disease. Phesgo® is a subcutaneous combination of trastuzumab and pertuzumab designed to treat HER2+ BC at any stage. This study aimed to determine the potential benefits of incorporating Phesgo® into the Chilean public health system for treating women with HER2+ BC under different coverage scenarios.

METHODS: A stock-and-flow model for HER2+ patients in the Chilean public healthcare system was developed. Net present value (NPV) was calculated in Chilean pesos (CLP) over eight years for three scenarios: 1) Trastuzumab is covered for treating neoadjuvant, adjuvant, and metastatic HER2+ BC. Pertuzumab is covered for metastasis only; 2) Phesgo® is covered in first-line metastasis, while trastuzumab is covered in neoadjuvant and adjuvant; 3) Phesgo® is covered in first-line metastasis and neoadjuvant, while trastuzumab is covered in adjuvant. Under the three scenarios, TDM1 coverage remained constant.

RESULTS: For the current scenario, the total expenditure in 2022 was CLP 21.313.195.891; by 2029, it is estimated to reach CLP 24.706.905.543. Phesgo® in the first-line metastasis-only generates savings from CLP 509.702.97 in 2022 to CLP 756.695.054 in 2029 compared to the current scenario, with an NPV of CLP -4.542.267.624. Phesgo® in first-line metastasis and neoadjuvant generates savings from CLP 472.600.729 in 2022 to CLP 898.318.541 in 2029, with an NPV of CLP -4.972.212.089 compared to the current scenario.

CONCLUSIONS: Regardless of the coverage fund by which Phesgo® treatment is financed, including Phesgo® in metastasis and neoadjuvant generates savings for the Chilean public health system. These come from improved clinical response due to neoadjuvant dual HER2-blockade and a cost-saving option over pertuzumab in metastasis.