Cost Effectiveness of Ribociclib Plus a Nonsteroidal Aromatase Inhibitor in Pre-/Perimenopausal, HR+ and HER2− Advanced Breast Cancer: A Canadian Healthcare Perspective

Background and Objectives The MONALEESA-7 trial demonstrated the efficacy and safety of ribociclib plus a nonsteroidal aromatase inhibitor (NSAI) [with goserelin] for pre-/perimenopausal women with hormone receptor-positive and human epidermal growth factor receptor 2-negative advanced breast cancer. This analysis evaluated the cost effectiveness of ribociclib plus NSAI vs NSAI monotherapy and tamoxifen monotherapy from the perspective of the Canadian healthcare system. Methods The incremental cost-effectiveness ratio expressed as incremental costs per quality-adjusted life-year (QALY) gained for ribociclib plus an NSAI vs an NSAI and vs tamoxifen was estimated using a semi-Markov cohort model developed in Microsoft Excel with a 15-year time horizon and states for progression-free survival, post-progression survival, and dead. Survival distributions for progression-free survival, post-progression survival, and time to discontinuation as well as health-state utilities were estimated using data from MONALEESA-7. Direct costs of advanced breast cancer treatment were based on Canadian-specific values from published sources. Costs ($CAN 2019) and QALYs were discounted at 1.5% annually. Results Ribociclib plus an NSAI was estimated to yield gains of 1.42 life-years and 1.17 QALYs vs an NSAI, and 2.61 life-years and 2.12 QALYs vs tamoxifen, at incremental costs of $209,701 and $220,836, respectively. In probabilistic analyses, the incremental cost-effectiveness ratio for ribociclib plus an NSAI was estimated to be $178,872 per QALY gained vs an NSAI and $104,400 per QALY gained vs tamoxifen. Results of deterministic analyses were similar (incremental cost-effectiveness ratios of $177,245 and $103,316 vs NSAI and tamoxifen, respectively). Results were sensitive to parametric distributions used for projecting progression-free survival and the time horizon. Conclusions At its current list price, ribociclib used in combination with NSAI is likely to be co-effective relative to an NSAI alone or tamoxifen alone if the willingness-to-pay threshold is less than approximately $178,000 per QALY. These results have informed deliberations regarding reimbursement and access to this treatment in Canada and may be useful for decision makers in other settings.