Demonstrating long-term value in older patients (pts): Cost-effectiveness of ribociclib (RIB) in hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2−) early breast cancer (EBC).

16 Background: Adjuvant RIB + a nonsteroidal aromatase inhibitor (NSAI) was approved by the Food and Drug Administration in 2024 for pts with HR+/HER2− stage II/III EBC at high risk of recurrence, including select node-negative and all node-positive pts. The clinical benefit of RIB was observed in the overall pt population and pts aged ≥65. Previous modeling analyses showed long-term benefit and economic value of adjuvant RIB + NSAI vs NSAI in the overall pt population. Given the notable proportion of older pts with EBC and the unmet need, this study aimed to assess long-term cost-effectiveness among pts aged ≥65 from a US Medicare perspective. Methods: A Markov model was developed to estimate the cost-effectiveness of RIB + NSAI vs NSAI over a lifetime horizon, including 4 health states: invasive disease–free (IDF), locoregional recurrence (LR), distant recurrence (DR), and death. Transition probabilities between health states were estimated using NATALEE data observed over 4.5y for the ≥65 subgroup and parametric extrapolation afterwards. Treatment (tx) effect waning was applied (starting at 10y and ending at 15y), informed by clinical opinion and literature. Drug acquisition costs associated with adjuvant, LR, and DR tx; adverse event (AE) costs; disease management costs; and terminal care costs were estimated based on publicly available data sources, NATALEE, and literature. Health state utilities were based on EQ-5D-5L data in NATALEE; AE disutilities were obtained from literature. Lifetime costs, life years (LYs), quality-adjusted LYs (QALYs), and equal value of LYs (evLYs) that reflect gains in LYs at the full value of a healthy year of life irrespective of age, disability, or illness, were considered. Incremental cost-effectiveness ratios (ICERs) between RIB + NSAI vs NSAI were calculated. Sensitivity analyses explored variability in key parameters. Results: Compared with NSAI, RIB + NSAI was estimated to extend survival by an average of 0.81y and evLYs and QALYs by 0.85y and 0.77y, respectively. Pts receiving RIB + NSAI incurred higher adjuvant tx costs offset by lower costs for LR tx, DR tx, disease management for LR and DR, and terminal care. Lifetime total costs for pts receiving RIB + NSAI were lower ($607,735) than for those receiving NSAI ($610,975), per-pt savings of $3,240. Thus, RIB + NSAI was dominant vs NSAI. Scenario analyses supported the base-case findings, with either dominant results or ICERs below $150,000. Conclusions: Among pts aged ≥65, RIB + NSAI extended survival and demonstrated cost-effectiveness over a lifetime horizon compared with NSAI alone, consistent with the overall pt population. Early use of RIB + NSAI offered substantial clinical and economic benefits for older pts with HR+/HER2− EBC by reducing risk of recurrence.