The main objective of this study is to determine whether the employment of fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection (or Phesgo) to treat metastatic HER2-positive breast cancer patients would minimize costs compared to the traditional treatment of separate intravenous doses of pertuzumab and trastuzumab in Peru. To achieve this, we used EsSalud (the social security health insurance) data and assessed it through a mixed strategy, which consisted of a quantitative and a qualitative approach. The first one aimed to calculate the direct (non-drug consumables, drugs, and healthcare professionals) and indirect costs of both treatments to develop a comparison, whilst the second aimed to validate information and internalize the procedure in an EsSalud context.

Overall, we found that the usage of Phesgo would be cost saving in EsSalud’s context. Specifically, we found three main insights. Firstly, the savings produced from switching from the traditional intravenous treatment to the subcutaneous one would allow EsSalud to afford full annual costs of 2 additional treatments, but without increasing their budget. This would cover 7% of the gap of 29 patients who do not have access to full treatment. Secondly, the result of a univariate sensitivity analysis in this work indicates that the price of Phesgo would have to increase by 16% so that both treatments cost the same. Thirdly, to increase the number of patients, the intravenous treatment would have to be totally replace by the Phesgo treatment, since the use of the latter requires less personnel and infrastructure.