Given that the INAVO120 trial enrolled a predominantly U.S. and Chinese patient population, this study will leverage the updated INAVO120 clinical data to conduct the first cost-effectiveness analysis of the inavolisib-triplet regimen versus palbociclib plus fulvestrant for PIK3CA-mutated, HR+/HER2− advanced breast cancer in the first-line setting after endocrine resistance. This evidence concerns the gene PIK3CA and breast cancer.