1182 – Potential clinical impact of pembrolizumab incorporation for triple-negative breast cancer in Brazil’s public health system: a 5-year survival modeling study

Abstract

Introduction: Triple-negative breast cancer (TNBC) is an aggressive subtype associated with poor outcomes and limited treatment options. Although pembrolizumab has demonstrated an overall survival benefit in early-stage TNBC, it
has not yet been incorporated into Brazil’s Unified Health System (SUS).
Objective: To estimate the potential clinical impact of pembrolizumab incorporation into the SUS for early-stage TNBC.
Methods: This retrospective observational modeling study used secondary DATASUS records to build a real-world SUS
cohort and compared it with a counterfactual pembrolizumab cohort derived from published survival data. After deterministic linkage of hospitalization and outpatient datasets, 4,404 eligible patients composed the SUS cohort. For the 5-year
survival analysis, 705 patients with adequate follow-up were included. A synthetic pembrolizumab cohort (n=784) was
generated based on the phase III KEYNOTE-522 overall survival results. The primary outcome was 5-year overall survival.
Cumulative mortality, absolute risk reduction, number needed to treat, and the number of additional lives preserved per
1,000 treated patients were also estimated.
Results: Five-year overall survival was 56.9% in the SUS cohort and 88.0% in the pembrolizumab cohort. The corresponding 5-year cumulative mortality was 43.1% versus 13.4%. Mean survival was 45.4 months in the SUS cohort and 55.1 months
in the pembrolizumab cohort. The absolute reduction in mortality was 31.1%, with an estimated number needed to treat
of 3.2. In a simulation per 1,000 treated patients, 570 patients were alive at five years under the current SUS scenario versus 864 with pembrolizumab, corresponding to 294 additional lives preserved over five years. Benefits were observed in
both age subgroups.
Conclusion: The incorporation of pembrolizumab for TNBC in the SUS could substantially improve 5-year survival and
translate into a major population-level survival gain, with nearly 300 additional lives preserved per 1,000 treated patients.
Ethics: Public data.