August 2020 was a groundbreaking month for liquid biopsy technology, with two assays approved by the US Food and Drug Administration (FDA) as companion diagnostics just weeks apart. The Guardant360 CDx assay, approved August 7, was the first liquid biopsy companion diagnostic to also incorporate next-eneration sequencing (NGS). Approved specifically to identify EGFR mutations in patients with NSCLC in order to appropriately select for osimertinib therapy, the assay simultaneously detects mutations in 55 genes. However, mutations outside of EGFR are not validated for use with a specific therapy, and a tissue biopsy is still offiicially recommended if EGFR mutations are not detected via liquid biopsy. On August 26 the FoundationOne Liquid CDx was approved as a ompanion diagnostic for three EGFR inhibitors used in NSCLC—osimertinib, gefi tinib, and erlotinib—as well as one PARP inhibitor for prostate cancer. Th e FoundationOne Liquid CDx is covered for use in all solid tumors by Medicare. Results from FoundationOne Liquid CDx include information about more than 300 cancer-related gene mutations, as well as about microsatellite instability and blood tumor mutational burden, which can help inform immunotherapy selection. “Liquid biopsies are becoming an increasingly important option to inform personalized treatment decisions for physicians treating certain [patients with advanced cancer] who require minimally invasive solutions to genomic testing,” said Mark Socinski, MD, Executive Director Thoracic Cancer and Medical Oncologist at the AdventHealth Cancer Institute, Orlando, Florida, in the company’s press release.