OBJECTIVES: The KEYNOTE-522 trial demonstrated that addition of pembrolizumab to neoadjuvant chemotherapy provided a significant improvement in event free survival and a favorable trend in overall survival for high-risk early-stage triple-negative breast cancer.

The objective of the model was to evaluate the cost-effectiveness of neoadjuvant pembrolizumab + chemotherapy followed by adjuvant pembrolizumab after surgery in patients with high-risk early-stage triple negative breast cancer (TNBC) in Costa Rica. The comparator was neoadjuvant chemotherapy alone, which was the control arm of the KEYNOTE-522 trial.

METHODS: A multistate transition model was developed using efficacy and safety data from KEYNOTE-522 trial considering Costa Rica third-party payer perspective. The model included 4 mutually exclusive health states: event-free, locoregional recurrence, distant metastasis, and death. Quality-adjusted life years (QALYs) were calculated based on EuroQoL-5 Dimensions utility data collected in KEYNOTE-522. Direct costs for drug acquisition, administration, adverse events, disease management, and subsequent therapies were reported in local currency (CRC 645.4 = $1.00 USD in September 2022). A 3% annual discount rate was applied to costs and outcomes. Sensitivity and scenario analyses were performed to test the robustness of the “base case” results.

RESULTS: Over a lifetime horizon, total costs were CRC 52,257,029 (USD 80,968) for pembrolizumab + chemotherapy and CRC 14,805,746 (USD 22,940) for chemotherapy. Total QALYs were estimated as 14.04 for pembrolizumab + chemotherapy and 11.28 for chemotherapy. Total LYs were estimated as 18.06 and 14.51 for the pembrolizumab + chemotherapy Vs chemotherapy arm, respectively. The ICER for pembrolizumab + chemotherapy compared to chemotherapy was CRC 13,617,906 (USD 21,100) per QALY gained and CRC 10,550,371 (USD 16,347) per LY gained.

CONCLUSIONS: Pembrolizumab in combination with chemotherapy is projected to be cost-effective compared to chemotherapy, at a WTP threshold of CRC 24,148,286 (3 GDP) per QALY (USD 37,416/QALY) for high-risk, early-stage TNBC in Costa Rica.