The American biotechnology company Guardant Health, which produces liquid biopsy tests to detect cancer from mutations and other modifications in blood samples,[1] was co-founded by Helmy Eltoukhy and AmirAli Talasaz during 2012–2013.

[2][3] According to John Dorfman of the Pittsburgh Tribune-Review, Talasaz and Eltoukhy discovered a technique which "involves detecting and monitoring tumor fragments circulating in the patient's bloodstream", as an alternative to traditional tissue biopsies.

[5] Early in its history, Guardant Health acquired multiple patents by Swiss biochemist Maurice Stroun, who became a founding advisor.

[7] In 2016, the company announced clinical trial results demonstrating the test "detected disease-associated genetic mutations that were also present in 94% to 100% of the solid tissues extracted from the study's subjects".

Bloomberg reported that the results were short of the 85 percent accuracy rate that investors expected, and the company's stock price fell following the news.

[25] The lease agreement was the largest in Silicon Valley for the year to date,[26] and the company has since moved its corporate headquarters to the approximately 250,000-square-foot Palo Alto space.

[25][27] The offices in Torrey Pines, San Diego are Guardant Health's largest outside Palo Alto and Redwood City at 37,000 square feet.

Medicare began covering the test for select lung cancer patients in 2018, prior to Food and Drug Administration approval (which is not required)[7] in 2020.

[39] Japan's Ministry of Health, Labour and Welfare granted regulatory approval of Guardant360 CDx as a companion diagnostic "for identifying patients with metastatic non-small cell lung cancer who may benefit from treatment with Lumakras (sotorasib)" in late 2021.

The test helps oncologists improve the management of early-stage CRC patients by detecting circulating tumor DNA (ctDNA) in blood after surgery to identify patients with residual disease who may benefit most from adjuvant therapy, and by detecting recurrence earlier than current standard-of-care methods like carcinoembryonic antigen (CEA) tests or imaging.

[43] The company partnered with the Vall d'Hebron Institute of Oncology to launch the first blood-based cancer testing services in Barcelona in mid 2022.

[5][52] In response, Guardant Health rejected the claims, accused Illumina of attempting to eliminate competitors, and asked for a suit dismissal.