Most new drugs have only clinical studies focused on a single population at the time of first registration, hence their indications for use are restricted to this population. For clinical conditions when there are no other treatments available, new drugs have higher costs in Brazil. There is no review of prices when these medications broaden their therapeutic areas, and this can have a significant financial impact. This study’s objective is to assess the financial implications of pembrolizumab’s incremental indication after its initial registration.

We calculated the annual cost to treat all Brazilian patients with indications for use in the first registration and all incremental indications of pembrolizumb. Populations were estimated by epidemiological data from the pembrolizumab clinical trials called, KEYNOTE studies, and the INCA 2023 cancer estimate for the Brazilian population. Costs were calculated by CMED-ANVISA price value and considering the dosing of 200mg every 3 weeks.

In 2016, pembrolizumab was granted registration in Brazil was restricted to patients with advanced melanoma. In 2022 the indication was expanded to more than 20 new indications, with several studies in progress that potentially will lead to further inclusions. The estimate of patients eligible for indications increase of 1,796 to 99,544 patients with an increased total cost from BRL625,802,837 to BRL34,685,366,192 (USD121,185,677.4 to USD6,716,763,399.04).

The financial burden of pembrolizumab’s expanded uses after it was first approved could significantly rise, endangering the long-term viability of healthcare systems. In Brazil, where medicine costs are not regularly monitored, the annual inflation adjustment is the only factor that causes prices to change. In order to lower medicine prices in response to the addition of new indications, the expansion of therapeutic options for the same condition, or even obsolescence, regulations are required.