Cost-Effectiveness of Ribociclib Plus Endocrine Therapy for Premenopausal or Perimenopausal Women With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer in Thailand.

OBJECTIVES

To evaluate the cost-effectiveness of ribociclib plus letrozole as first-line therapy for premenopausal or perimenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer in Thailand.

METHODS

We developed a state-transition (Markov) model with 5 health states and 2 tunnel states, using 28-day cycles over a lifetime horizon from the public healthcare perspective. First-line progression-free survival was reconstructed from MONALEESA-7 Kaplan-Meier curves and fitted using log-normal parametric survival models. Transition probabilities incorporated progression and death as competing risks. Utilities came from Thai EuroQol 5-Dimension (EQ-5D) data, and direct medical costs were estimated based on primary data collection from tertiary hospitals (2025 US$). Outcomes included costs, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER). Uncertainty was assessed using 1-way and probabilistic sensitivity analyses, whereas scenario analyses varied drug prices and incorporated Asian subgroup efficacy.

RESULTS

Ribociclib plus letrozole yielded 5.42 QALYs at US$75 324, compared with 4.06 QALYs at US$9020 for letrozole alone, with an ICER of US$48 753 per QALY, which is above Thailand's willingness-to-pay threshold of US$4842 per QALY. The ICER was most sensitive to first-line progression-free utility, ribociclib acquisition cost, and the discount rate. Applying MONALEESA-7 Asian subgroup efficacy and a 75% ribociclib price reduction reduced the ICER to US$11 621 per QALY. Sensitivity analyses confirmed the robustness of the ICERs across all scenarios.

CONCLUSIONS

Despite clinical benefits, ribociclib plus letrozole is not cost-effective in Thailand at the current price. Price negotiation and alternative financing or risk-sharing mechanisms are warranted to expand access while preserving budget sustainability.