OBJECTIVES: To estimate the health state utility (HSU) of patients with human epidermal growth factor (HER2)-negative and germline BReast CAncer (gBRCA+) mutation positive metastatic breast cancer (mBC) randomised to olaparib or single-agent chemotherapy in the OlympiAD registration trial (NCT02000622).

METHODS: EORTC QLQ-C30 questionnaires collected at baseline, and every 6 weeks up to progression, were mapped to EQ-5D HSU using a published algorithm from women with locally advanced BC identified via an online mapping registry. HSU were summarised by treatment arm and for baseline, and pre- and post-progression survival (investigator assessment) using descriptive and multivariate linear mixed effects regression (LMER) analysis conducted in R. All analyses were performed on the intention to treat population.

RESULTS: 1665 HSU values were generated from EORTC QLQ-C30 questionnaires collected in OlympiAD. Mean HSU in OlympiAD (0.84) was higher than reported in the algorithm study (0.76), with a greater than 5-point difference in mean emotional, physical and insomnia QLQ scores between studies. Mean HSU at baseline, pre- and post-progression survival were 0.827, 0.848, and 0.812 for olaparib, and 0.810, 0.802 and 0.753 for chemotherapy. The LMER showed that after adjusting for baseline HSU, patients randomised to olaparib experienced a statistically improved HSU versus chemotherapy (+0.048, p-value=0.001) with progression being associated with a statistically significant reduction in HSU (-0.039 (p<0.001)).

CONCLUSIONS: The mapping analysis generated plausible HSU from EORTC QLQ-C30 data in OlympiAD that can be used to inform future cost-effectiveness studies of olaparib in mBC. Key trends include an improved HSU in patients randomised to olaparib, which is consistent with the planned exploratory analysis of EORTC QLQ-C30 in OlympiAD, and a significant negative impact of progression on HSU consistent with other mBC HSU studies. Key limitations include the open-label design of OlympiAD and uncertainty surrounding the extrapolation of a mapping algorithm for locally advanced to mBC.