The US Food and Drug Administration (FDA) expanded the approval of FoundationOne Liquid CDx as a companion diagnostic for the detection of genetic alterations that indicate a patient is a candidate for treatment with alpelisib, rucaparib, or alectinib, according to a press release from the company.1

FoundationOne Liquid CDx was previously approved by the FDA as a companion diagnostic for detecting EGFR mutations in lung cancer to select for EGFR-targeting tyrosine kinase inhibitors, and BRCA1/2 mutations in prostate cancer for selection of rucaparib.2

The expanded approval includes detection of PI3KCA mutations in hormone receptor–positive, HER-negative advanced breast cancer among men or postmenopausal women for selection of second-line alpelisib in combination with fulvestrant, detection of BRCA1/2 mutations in ovarian, fallopian tube, or primary peritoneal cancer for selection of third-line rucaparib, and detection of ALK rearrangements in metastatic non-small cell lung cancer for selection of first-line alectinib.1

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FoundationOne Liquid CDx is a liquid biopsy that uses cell-free DNA (cfDNA) from plasma that uses next-generation sequencing with high-throughput hybridization-based capture technology to evaluate over 300 genes. The test also detects genomic alterations that fall outside of FDA approval for a specific use.

Editor’s note: This post was updated on 11/4/20.


  1. Foundation Medicine. FDA approves new FoundationOne® Liquid CDx companion diagnostic indications for three targeted therapies that treat advanced ovarian, breast and non-small cell lung cancer [press release]. Published October 27, 2020. Accessed November 2, 2020.
  2. Foundation Medicine, Inc. FoundationOne Liquid CDx technical information. Cambridge, MA: Accessed November 2, 2020.