OBJECTIVES: The economic impact of treatment-related adverse events (AEs) associated with PARP inhibitor (PARPi) and chemotherapy treatment in aBC is unknown. This study aimed to characterize AE costs associated with olaparib, talazoparib and chemotherapy treatment of physician choice (TPC) in patients with gBRCA-mutated, HER2-negative aBC who had received ≤3 lines of prior chemotherapy using safety data from randomized controlled trials (RCTs).

METHODS: Commonly reported CTCAE grade ≥3 AE probabilities were extracted from the publications of two Phase III RCTs, OlympiAD and EMBRACA. Per-patient costs were calculated from the US third-party payer and German statutory health insurance system perspectives, using RCT data and AE unit costs sourced from the literature and adjusted to 2018 prices. A within-study comparison of the total AE costs for PARPi (olaparib or talazoparib) versus TPC was performed and supplemented by a direct comparison of AE costs for olaparib versus talazoparib, modelled using the results of an indirect treatment comparison (ITC) applied to the AE risk of TPC pooled across RCTs.

RESULTS: In within-study comparisons, from the US and German perspectives, olaparib and TPC were estimated to have AE costs of $3,151/€320 and $4,595/€380, respectively. Talazoparib was estimated to have AE costs of $7,939/€807, and TPC was estimated to have AE costs of $4,345/€433. Consistent with the within-study comparisons, the ITC analysis predicts a mean per-patient cost of $4,291/€404 for olaparib and $10,719/€904 for talazoparib.

CONCLUSIONS: Olaparib’s safety profile appears to translate into lower costs for managing grade ≥3 AEs versus chemotherapy and talazoparib. This should be interpreted with caution due to uncertainty in AE management and costs and the heterogeneity of AE reporting across the RCTs. Confirmation of these results in future real-world studies is required.