# Cost-effectiveness of inavolisib plus palbociclib-fulvestrant versus palbociclib plus fulvestrant as first-line treatment in HR+/HER2-advanced breast cancer

## TL;DR

This study compares the cost-effectiveness of two breast cancer treatments, finding that adding inavolisib is not cost-effective in the U.S. and China at current prices.

## Contribution

The study introduces a dynamic hazard ratio to model changing drug efficacy over time in cost-effectiveness analysis.

## Key findings

- Inavolisib triple regimen had an ICER of $249,487.22/QALY in the U.S. and $43,812.01/QALY in China, exceeding willingness-to-pay thresholds.
- Price reductions to $133.19/9 mg in China and $421.13/9 mg in the U.S. would make inavolisib cost-effective.
- Subgroup analyses identified specific patient groups in China where inavolisib could be cost-effective.

## Abstract

This study aims to evaluate the cost-effectiveness of inavolisib plus palbociclib-fulvestrant versus palbociclib-fulvestrant for treating advanced HR+/HER2-breast cancer patients with PIK3CA mutations from both United States (U.S.) and Chinese healthcare system perspectives.

A partitioned survival model was used, with survival data from the INAVO120 clinical trials. Primary outcomes assessed were costs, life-years, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER). Sensitivity analysis was performed to explore the uncertainty of model inputs. Changes in treatment efficacy were modeled to assess their impact on cost-effectiveness. Subgroup analysis was also conducted to refine the findings.

In the base-case analysis, the inavolisib triple regimen showed an ICER of $249,487.22/QALY in the U.S. and $43,812.01/QALY in China, both exceeding their respective willingness-to-pay thresholds. Price simulation indicated that the inavolisib-based combination would be preferred in China if the price were reduced to $133.19/9 mg, while a price of $421.13/9 mg would be required to achieve cost-effectiveness in the U.S. Sensitivity analysis demonstrated robust results from the U.S. perspective, while for China, variations in the price of inavolisib and utility of progression-free-survival influenced the conclusions. Subgroup analyses suggested certain patient subgroups could be cost-effective in the Chinese context.

Compared with palbociclib-fulvestrant, the inavolisib triple regimen is not cost-effective at its current price. A substantial price reduction or careful selection of the target patient may be required for the regimen to be economically viable.

•Inavolisib improved survival outcomes in patients with breast cancer, but was not cost-effective in the U.S. and China.•Long-term outcomes were projected using partitioned survival models with splines and proportional hazards extrapolations.•Comprehensive subgroup analyses explored treatment efficacy based on baseline characteristics and prior medication history.•We employed a dynamic hazard ratio to model the change in drug efficacy over time.

Inavolisib improved survival outcomes in patients with breast cancer, but was not cost-effective in the U.S. and China.

Long-term outcomes were projected using partitioned survival models with splines and proportional hazards extrapolations.

Comprehensive subgroup analyses explored treatment efficacy based on baseline characteristics and prior medication history.

We employed a dynamic hazard ratio to model the change in drug efficacy over time.