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Guardant Health Sues Natera for False Advertising, 'Misleading' Oncologists About MRD Tests

This story has been updated to include comments from Natera.

NEW YORK – Guardant Health said Friday that it has filed a lawsuit in federal court against Natera for false advertising, unfair competition, and unlawful trade practices, relating to what it argues are misleading statements about the companies' products for minimal residual disease detection.

The complaint specifically focuses on the recently launched Guardant Reveal assay, and alleges that Natera is misleading healthcare providers about the performance of the assay by suggesting it is "inaccurate and/or insensitive" and inferior to Natera's Signatera test in advertising that Guardant said was "carefully timed" to coincide with Reveal's launch earlier this year.

Guardant has asked the US District Court for the Northern District of California for an injunction preventing Natera from continuing to make such statements and requiring the firm to take corrective actions.

Guardant Reveal is a blood-only liquid biopsy test to detect residual and recurrent disease in early-stage cancer patients treated with curative intent. Currently marketed for colorectal cancer, the test detects epigenetic signals in circulating tumor DNA and is performed after surgery to identify patients with residual disease who may benefit most from adjuvant therapy. Guardant has also demonstrated that the assay, if performed serially, can detect emerging recurrence earlier than current standard-of-care methods.

Natera, meanwhile, has been marketing Signatera since 2019. It begins with analysis of a tissue sample taken from a patient's tumor. This is then used to create a personalized assay which is used for the same MRD and recurrence detection purposes as Guardant Reveal.

"With little or no concern for the CRC patients who could be harmed, Natera has undertaken a campaign of misinformation to convince customers and potential customers, including oncologists and other physicians, cancer researchers, healthcare institutions, biopharmaceutical companies, and genetic laboratories, to avoid using Reveal in favor of Natera's own Signatera," the company's complaint reads.

"In its commercial advertising and promotion, Natera makes literally false and misleading statements that disparage Guardant's new assay, and falsely asserts that Signatera is superior to Reveal across a variety of metrics, including sensitivity, failure rate, negative predictive value, and hazard ratio, among other categories," it continues.

Describing the alleged misinformation further, Guardant cited a "Dear Colleague" advertisement dated March 2, 2021, which it writes was widely emailed and urged recipients to review the evidence for new assays "rushing into the clinical MRD market."

Guardant alleges that in accompanying data attached to that advertisement, published in a white paper no longer available on the company's website, and highlighted in a subsequent investor presentation, Natera used "outright misrepresentations" and "scientifically unfounded comparisons based on cherry-picked metrics, data artifacts, and noncomparable clinical studies" to support claims of superiority of Natera's own test over Guardant Reveal.

Among issues raised, Guardant argued that Natera inappropriately compared a recent study of Reveal with other studies of Signatera that had different test protocols, analysis methods, and patient populations. Such a comparison can't scientifically support a claim of superiority of one test over another, the firm said.

In making its comparisons, Guardant also argued that Natera cherry-picked data that elevates its own test while ignoring or mischaracterizing data that supports Guardant's.

Guardant has asked the court to prevent Natera from continuing to make or disseminate such statements, to retract and/or correct the claims it has already made, and to award it damages and other relief for the harm inflicted on its business.

"Guardant Health believes it is vital that clinicians receive accurate and truthful information, as this impacts potentially lifesaving patient treatment decisions. We also believe that companies in the cancer diagnostics business must have patient care as their central mission and should not misrepresent medical science. When they do, we believe that immediate corrective action is required," John Saia, Guardant Health senior VP, general counsel, and corporate secretary, said in a statement.

Natera's response

Natera responded to Guardant by filing its own suit on Friday in the US District Court for the Western District of Texas, alleging that Guardant used false and misleading claims to deceive physicians about the performance capabilities of its MRD test, in violation of the Lanham Act.

The company said in an email that it views Guardant’s lawsuit as meritless and "an attempt to stop Natera from exposing Guardant’s true test performance and the clinically relevant differences between their tumor-naïve test and the tumor-informed Signatera test."

Natera said that it views Guardant's own statements about its assay as false and misleading. Among other details, the company highlighted Guardant's promotion of 91 percent sensitivity for its Reveal Assay, based on its recently published study, arguing that that calculation was made with seven false negative cases excluded from the analysis "without clinical justification."

"Test specificity was also not evaluated in this setting, since 'surveillance' samples were not analyzed from the patients who remained relapse-free," Natera wrote, adding that it views it as "inappropriate" to claim test sensitivity without evaluating specificity in the same population.

Natera believes the only valid sensitivity claim Guardant can make for its MRD test is for serial longitudinal samples, which would be 69 percent, a number it has cited in the promotional material at the heart of Guardant's suit.

Natera further argued that Guardant's sales material and recent presentations have paired a 91 percent sensitivity calculation with a claim of 100 percent specificity taken from two different analyses, calling the practice "highly deceptive."

"It is also inappropriate for Guardant to claim 100 percent specificity without clarifying that this analysis excluded two false positive cases where a full year of clinical follow-up information was not collected, despite having time to do so. This commercial promotion significantly misrepresents the study’s findings and puts patients at risk," the firm wrote.

"Natera is committed to free and open dialogue about data that directly impacts clinical decision making and patients' safety. We look forward to working with the medical and academic community to advance the science of MRD testing in a transparent manner," the company said.