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.