Economic Evaluation of Inavolisib Combined With Palbociclib–Fulvestrant for PIK3CA-Mutated, HR+/HER2− Advanced Breast Cancer in USA

ObjectiveInavolisib, a novel highly selective PI3Kα inhibitor, is approved for treating PIK3CA-mutated, hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer (PIK3CA-mutated, HR+/HER2- ABC). Given its significant efficacy, as confirmed by the updated INAVO120 III trial, but also its high price, a comprehensive evaluation of its value is warranted. The purpose of this study was to investigate whether inavolisib plus palbociclib-fulvestrant is cost-effective for patients with PIK3CA-mutated, HR+/HER2- ABC from the U.S. healthcare system perspective.MethodsA Markov model comprising three health states was developed to simulate the progression of PIK3CA-mutated, HR+/HER2- ABC. Parametric survival models, fitted to and extrapolated from survival data, were used to estimate long-term clinical outcomes. Lifetime costs and health outcomes were calculated. Willingness-to-pay (WTP) thresholds were set at $100,000, $150,000, and $200,000 per quality-adjusted life year QALY to reflect general and more affluent regional standards. One-way and probabilistic sensitivity analyses were conducted to assess model robustness, and subgroup analyses explored the variation in benefits across patient clinical characteristics.ResultsCompared with placebo, inavolisib provided an additional 0.6 QALYs while increasing costs by $160,490.07, resulting in an incremental cost-effectiveness ratio (ICER) of $268,457.82 per QALY. Sensitivity analysis identified the utility of the progression-free state as the most sensitive factor in the model. Within the WTP threshold range of $100,000 to $200,000 per QALY, the inavolisib regimen was not considered cost-effective. To achieve cost-effectiveness at WTP thresholds of $100,000, $150,000, and $200,000 per QALY, the per-cycle price of inavolisib would need to be reduced to 59.5%, 72.0%, and 86.5% of its current price, respectively.ConclusionFor patients with PIK3CA-mutated HR+/HER2- ABC, the inavolisib regimen is not cost-effective in the U.S. healthcare setting. Negotiating price reductions and adjusting decision thresholds based on patient characteristics may be viable strategies to meet the extensive treatment demand in the U.S.