OBJECTIVES: To evaluate the incremental cost-effectiveness ratio (ICER) of adjuvant olaparib for patients with germline BRCA 1/2-mutated (gBRCAm1/2), high-risk, human epidermal growth factor-2-negative (HER2-negative) early breast cancer (eBC) in the Portuguese setting.

METHODS: A semi-Markov state transition model was used to assess patients’ evolution on a lifetime horizon. The model estimated the cost-effectiveness of olaparib plus hormonal therapy (HT) versus HT alone in people with hormone receptor-positive (HR+) HER2-negative eBC and the cost-effectiveness of olaparib versus watch and wait (W&W) in people with triple-negative breast cancer (TNBC).Transition probabilities were modelled using data from OlympiA trial, complemented with data from additional studies in BRCA-mutated, HER2-negative metastatic BC. Health state utilities were mapped from OlympiA and supplemented by literature estimates. Modelled costs included BRCA genetic test, drug acquisition and administration, subsequent therapies, adverse events, hospitalization, physician-visits, follow-up and end-of-life. Unit costs were based on Portuguese official sources. The analysis was conducted from the Portuguese NHS perspective, assuming an annual 4% discount rate for both costs and consequences. One-way and probabilistic sensitivity analyses were used to assess uncertainty.

RESULTS: In the probabilistic base case, olaparib plus HT was more effective than HT alone with a gain of 1.2 added life years (LY) and 1.0 QALY, associated with an incremental cost of € 39,450/patient. Compared to W&W, olaparib was also more effective with a gain of 1.3 added LY and 1.1 QALY, associated with an incremental cost of € 36,312/patient. ICERs were estimated at €39,468 and €32,095 per QALY, in HR+ and TNBC patients, respectively. Results were mainly sensitive to time horizon, discount rate and utilities.

CONCLUSIONS: In the Portuguese setting treatment with olaparib increased LY and QALY in patients with gBRCAm1/2, high-risk, HER2-negative eBC at a generally acceptable incremental cost. This cost-effectiveness analysis was considered valid to support a reimbursement decision in Portugal.