Reliance of agency-approved and guideline-recommended therapies on surrogate endpoints in triple-negative breast cancer (TNBC).

Abstract

e13085 Background: Surrogate endpoints, such as progression-free survival (PFS) and event-free survival (EFS), are used for accelerated approval in various cancers, including TNBC. Here we review the use of surrogates and clinical outcomes in determining agency approval and guideline recommendation. Methods: Phase 2/3 TNBC trials and trials including TNBC subgroups reporting hazard ratios (HR) for clinical and surrogate endpoints were identified through a systematic search of LARVOL CLIN, PubMed, and conference proceedings. Trials that only evaluated cytotoxic agents and did not report EFS, PFS and/ or overall survival (OS) HR values were excluded. We performed a descriptive analysis of agency and guideline approvals in relation to therapeutic benefit as measured by surrogate outcomes and OS. Results: 21 TNBC cohorts and 1 pooled analysis studying 17 different targeted therapies for TNBC were included. There are 3 targeted therapies that have agency approval and 7 targeted therapies that are recommended by either the NCCN, EMA and ASCO guidelines. Of the two FDA and EMA-approved therapies, pembrolizumab + chemotherapy (PBL + CHT) showed PFS/EFS benefit for early TNBC and PDL1+ metastatic (m) TNBC but only OS benefit for PDL1+ mTNBC, whereas sacituzumab showed significant benefit for both PFS and OS for mTNBC. Four therapies (olaparib for BRCA+ mTNBC, bevacizumab for early TNBC, talazoparib for BRCA+ mTNBC and PBL + CHT for PD-L1+ mTNBC) are recommended by guidelines without having a significant OS benefit. Conclusions: Surrogate outcomes are heavily relied upon for TNBC guideline recommendation. Despite the need for timely access to novel TNBC therapeutics, clinical outcomes should be followed to ensure benefit once they have been reached. An up-to-date digitized trial results repository would ensure expedient review of clinical endpoints. [Table: see text]