Cost-effectiveness of Pembrolizumab in Combination with Chemotherapy as Neoadjuvant Treatment and Continued as a Single Agent Adjuvant Treatment for High-Risk Early-Stage Triple-Negative Breast Cancer in Hong Kong.

Abstract

The phaseIII randomized KEYNOTE-522 trial demonstrated that pembrolizumab in combination with chemotherapy as neoadjuvant treatment followed by adjuvant pembrolizumab (pembrolizumab + chemotherapy) provided significant improvements in event-free survival (EFS) and overall survival (OS) for patients with high-risk early-stage triple-negative breast cancer (eTNBC). The objective was to assess the cost-effectiveness of pembrolizumab + chemotherapy compared to neoadjuvant chemotherapy alone (chemotherapy) in patients with high-risk eTNBC from a Hong Kong third-party payer perspective. A multistate transition model with four health states (event-free), locoregional recurrence, distant metastases, and death) was developed to assess the lifetime medical costs and health outcomes (3% annual discount), along with incremental cost-effectiveness ratios (ICERs) using efficacy and safety data from the KEYNOTE-522 trial. The health state utilities were derived from KEYNOTE-522 Euro-QoL-five-dimension five-level questionnaire (EQ-5D-5L) data. Costs were expressed in 2022 Hong Kong dollars (HKD).Scenario and sensitivity analyses were performed to assess the robustness of results. Over a 32-year time horizon, base case results showed that pembrolizumab + chemotherapy was associated with a 3.42year longer EFS and expected gains of 3.05 lifeyears (LYs) and 2.45 quality-adjusted lifeyears (QALYs) compared to chemotherapy. The resultant ICERs were HKD135,200 per QALY gained and HKD108,463 per LY gained, which were lower than the World Health Organization (WHO) cost-effectiveness threshold of three times gross domestic product (GDP) per capita for Hong Kong of HKD1,171,308 per QALY. The one-way sensitivity analyses (OWSA) and probabilistic sensitivity analysis (PSA) showed the results were robust across various inputs and alternative scenarios. On the basis of the analysis conducted for a 56-year-old cohort with high-risk eTNBC and assumptions in the model, pembrolizumab + chemotherapy represents a cost-effective proposition (as the ICER is approximately 35% of the GDP per capita in Hong Kong) for patients with high-risk eTNBC in Hong Kong.