The U.S. Food and Drug Administration (FDA) has approved Foundation Medicine's FoundationOne Liquid CDx as a companion diagnostic for Itovebi (inavolisib), in combination with palbociclib and fulvestrant, for treating adult patients with endocrine-resistant, PIK3CA-mutated, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer. This approval is intended for patients who have experienced recurrence on or after completing adjuvant endocrine therapy.
The approval facilitates the identification of patients who may benefit from this targeted therapy using a simple blood draw. Approximately 70% of all breast cancers are hormone-receptor positive, HER2-negative, and PIK3CA is the most commonly mutated gene in this subtype, found in about 40% of patients.
Significance of PIK3CA Mutation Testing
Mia Levy, M.D., Ph.D., chief medical officer at Foundation Medicine, emphasized the importance of testing for PIK3CA mutations at diagnosis. "This approval reinforces the importance of testing for PIK3CA mutations at the time of diagnosis to help guide decision-making in the first-line setting for metastatic breast cancer patients," said Levy. She added that FoundationOne Liquid CDx enhances broader access to genomic testing, allowing more patients to benefit from this new treatment regimen.
FoundationOne Liquid CDx analyzes over 300 cancer-related genes from a routine blood sample, providing comprehensive genomic insights. It is the only company with an FDA-approved portfolio of both tissue and blood-based comprehensive genomic profiling tests.
Impact on Patient Care
Jean A. Sachs, MSS, MLSP, chief executive officer at Living Beyond Breast Cancer, noted the profound impact of this new treatment option. "Given the high prevalence of PIK3CA mutations in hormone receptor-positive, HER2-negative breast cancer, the introduction of a new targeted treatment regimen in the first-line setting will have a profound impact on this patient population," said Sachs. She also highlighted the importance of biomarker testing in personalized treatment decisions.
With this latest approval, Foundation Medicine now holds seven companion diagnostic indications for breast cancer, solidifying its position as a leader in approved companion diagnostic indications for next-generation sequencing (NGS) testing, accounting for more than 60% of all approved U.S. companion diagnostic indications for NGS testing.
About FoundationOne Liquid CDx
FoundationOne Liquid CDx is a qualitative next-generation sequencing-based in vitro diagnostic test that analyzes 324 genes using circulating cell-free DNA (cfDNA) isolated from plasma. It is designed to identify patients who may benefit from specific therapies, reporting short variants in over 300 genes. The test's utility lies in its ability to provide genomic information from a routine blood sample, making it a less invasive alternative to tissue biopsies. However, the company states that patients who test negative for companion diagnostic mutations should be reflexed to tumor tissue testing and genomic alteration status confirmed using an FDA-approved tumor tissue test, if feasible.
