The U.S. FDA has approved FoundationOne CDx, a tissue-based companion diagnostic test, to identify patients with PIK3CA-mutated, hormone receptor–positive, HER2-negative advanced or metastatic breast cancer who may benefit from treatment with inavolisib (Itovebi) combined with palbociclib (Ibrance) and fulvestrant (Faslodex). The approval provides an important alternative to the previously authorized blood-based FoundationOne Liquid CDx, helping patients whose tumors release insufficient DNA into the bloodstream for reliable liquid biopsy testing.
The decision is supported by results from the phase 3 INAVO120 trial involving patients with endocrine-resistant breast cancer. Patients receiving the inavolisib combination achieved a median progression-free survival of 15.0 months, compared with 7.3 months for those receiving placebo. The overall response rate was 58% versus 25%, while the median duration of response reached 18.4 months compared with 9.6 months. Early overall survival data also favored the inavolisib regimen, reinforcing its clinical benefit. The study enrolled patients whose disease progressed during or shortly after endocrine therapy and who had not received prior systemic treatment for metastatic disease.