Guardant360 Liquid CDx

Guardant360® Liquid CDx detects single nucleotide variants (SNVs), insertions and deletions (indels) in 741 genes, copy number amplifications (CNAs) in two genes, copy number loss (CNL) in one gene, and rearrangements in nine genes. It uses targeted high-throughput hybridization-based capture technology to analyze circulating cell-free DNA (cfDNA) extracted from plasma derived from peripheral whole blood collected in Streck Cell-Free DNA Blood Collection Tubes (BCTs). This approach allows for non-invasive genomic profiling without requiring a tissue biopsy.

Guardant360® Liquid CDx is not intended to be used as a standalone diagnostic. It is designed to be used as a companion diagnostic to identify patients eligible for specific targeted therapies listed in the approved labeling, as well as for tumor mutation profiling in oncology for patients with solid malignant neoplasms. Results must be interpreted in conjunction with other clinical findings and laboratory tests, particularly for patients who test negative for specified biomarkers.

The device requires plasma derived from peripheral whole blood collected in **Streck Cell-Free DNA Blood Collection Tubes (BCTs)**. Since the test analyzes cfDNA from a single plasma specimen, the process inherently involves single-use of the collection tube and associated reagents for each patient sample. The device itself is not physically reusable, as it is designed for one-time use per patient test.

Guardant360® Liquid CDx analyzes circulating cell-free DNA (cfDNA) in plasma, eliminating the need for an invasive tissue biopsy. However, for patients who test negative for the biomarkers listed in the approved labeling, the device recommends reflexing to **FDA-approved tumor tissue testing** if feasible. This hybrid approach ensures comprehensive biomarker assessment while offering a non-invasive option where tissue access is limited or challenging.

Guardant360® Liquid CDx was approved through the **FDA’s Premarket Approval (PMA) pathway**, indicated by the PMA number (P250027). This pathway is typically reserved for high-risk medical devices, ensuring rigorous evaluation of safety and effectiveness. Clinically, this means the device’s intended use—identifying patients eligible for specific targeted therapies and providing tumor mutation profiling—has been validated under strict regulatory scrutiny, though its use remains limited to the biomarkers and therapies explicitly listed in the approved labeling.