Guardant Health Ordered to Pay $245.2 Million for Willfully Infringing Cancer-Test Patents

A federal judge handed Guardant Health one of the biggest patent bills in biotech history.

Judge Gregory B. Williams of the U.S. District Court for the District of Delaware entered final judgment on August 21, 2026, ordering Guardant to pay TwinStrand Biosciences and the University of Washington more than $245.2 million. The ruling formalizes a November 2023 jury verdict that found Guardant willfully infringed two patents covering Duplex Sequencing technology, according to Bloomberg Law.

What Guardant Actually Did

Duplex Sequencing was developed at the University of Washington and increases DNA sequencing accuracy by more than 10,000-fold compared to standard methods, according to Times of India and TwinStrand's own statements as reported by Yahoo Finance. That precision matters because it lets doctors catch ultra-rare genetic mutations tied to early cancer detection.

TwinStrand spun out of the university in 2015 to commercialize the tech. Jurors found Guardant used it anyway, without a license, across 11 products and services, including its flagship Guardant360 CDx test used to detect tumor DNA in patients with advanced solid cancers, according to grafa and Yahoo Finance. Marketchameleon reports those 11 product lines represent roughly 90% of Guardant's total revenue during the infringement period.

How the $245 Million Adds Up

BigGo Finance breaks down the total: an $83.4 million jury verdict from 2023, $19.5 million in post-trial damages, $119.4 million in accrued royalties at a 6% rate, and $22.9 million in interest. Bloomberg Law notes the original jury award applied that 6% royalty rate to a $1.39 billion revenue base, with $106 million of the initial verdict tied to Guardant's services alone.

Yahoo Finance adds a specific detail: the $119.4 million royalty chunk covers sales between February 5, 2024, and May 31, 2026. Guardant kept selling these products for more than two years after the jury already found it liable, and the bill kept growing the whole time.

Guardant now owes a 6% royalty on those same products going forward, paid quarterly, until the patents expire on March 15, 2033. Any unpaid balance keeps accruing interest, according to grafa.

Guardant's Defense

Guardant isn't rolling over. John Saia, the company's chief legal officer, told Yahoo Finance: "We strongly disagree with this decision and will promptly be appealing for its overturn." BigGo Finance reports Guardant argues many of the affected products have since been discontinued or upgraded, which the company presumably will argue limits its future exposure even if the appeal fails on liability.

If Guardant has genuinely moved to next-generation versions of these tests that don't rely on the infringing method, the forward-looking royalty bill could shrink over time regardless of how the appeal goes. Marketchameleon notes that patent proceedings are still active before the U.S. Patent and Trademark Office and the Patent Trial and Appeal Board, and neither patent has been invalidated. Guardant could still get relief there, though nothing has happened yet on that front.

TwinStrand's Side

Chad Waite, TwinStrand's board chair, put it bluntly in a statement carried by Yahoo Finance and BigGo Finance: "Duplex Sequencing solved an accuracy problem the sequencing field had worked on for years, and this judgment affirms the jury's finding that Guardant Health built products on that invention without a license." He added, "We remained steadfast in our conviction that the facts would prevail, and they have."

The court didn't just side with TwinStrand on damages. It also dismissed all of Guardant's counterclaims and rejected the company's post-trial requests to overturn the verdict or get a new trial, according to grafa. TwinStrand and the university won a clean sweep at the trial court level.

One Wrinkle in the Coverage

There's a discrepancy worth flagging. BigGo Finance and Yahoo Finance both describe the ruling as coming from "the U.S. District Court for the District of Columbia," while Times of India, grafa, Bloomberg Law, and Marketchameleon all identify it as the U.S. District Court for the District of Delaware, matching where the original 2021 complaint was filed. Delaware is almost certainly correct given the case's history and the consistency across the majority of sources.

Where This Leaves Guardant

Guardant's stock dipped 3.6% on the news, according to BigGo Finance, before Yahoo Finance later noted shares were up 1.07% in subsequent trading. The appeal is the next concrete step, and it will determine whether Guardant pays the full $245.2 million or gets some relief on liability, damages, or the ongoing royalty rate. Until an appeals court rules, the 6% quarterly royalty clock keeps running on products that make up roughly 90% of Guardant's revenue, according to Marketchameleon.