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Guardant Health Collecting Data to Make Case for 'Blood-First' Cancer Testing Paradigm

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NEW YORK (GenomeWeb) – On the heels of a successful IPO and anticipating several milestones over the first half of next year, Guardant Health is focusing on what it believes will be the major drivers toward increased adoption and recognition of its liquid biopsy testing as not just an adjunct to tumor tissue analysis, but as a first-line choice in cancer diagnostics.

In a conference call discussing its first quarterly earnings report as a public company this week, CEO Helmy Eltoukhy and President AmirAli Talasaz said repeatedly that Guardant believes it can forge a "blood-first paradigm," in which oncologists feel confident that ordering the company's comprehensive liquid biopsy testing will get them results that are at least non-inferior to what they would get from a tissue test, if not superior.

According to Talasaz, the germ of this will come from a study Guardant has been conducting called NILE (Noninvasive vs. Invasive Lung Evaluation), which is designed to determine the "non-inferiority" of cell-free DNA-based genotyping as it pertains to the detection of seven National Comprehensive Cancer Network-recommended biomarkers in first-line, treatment-naïve, non-squamous non-small cell lung cancer.

During the firm's call this week, Talasaz said that the multi-center study has enrolled its planned 300 patients, in which investigators are evaluating whether Guardant's test picks up mutations in a way that is equivalent to tissue sequencing, as well as how treatment linked to mutations detected in blood but not in tissue contribute to patient outcomes.

According to Talasaz, the data from NILE are expected to read out in the first half of 2019. In the meantime, Guardant has already begun to see other positive results in the same vein, from other studies that are not purpose built to assess Guardant360 versus tissue in a first-line setting, but nonetheless address some of the same questions the NILE investigators are studying.

The most recent is a study, published last month in JAMA Oncology, in which a team from the University of Pennsylvania found that the Guardant360 test identified targeted mutations in more patients than did tissue sequencing. Investigators also concluded that patients treated on the basis of Guardant360 results responded comparably to those treated based on tissue mutations.

Talasaz said that Guardant sees the findings as especially persuasive because they reflect real-world application of Guardant360. The UPenn cohort included 323 consecutively tested NSCLC patients, about half of whom were tested at diagnosis versus at progression of therapy.

In nearly a third of the cohort, the patient's physician ordered Guardant360 as the sole genotyping test without any tissue sequencing, something Talasaz said "represents real-world scenarios in which Guardant360 is able to obviate invasive tissue procedures."

Another boon to Guardant in the results, he said, is the fact that UPenn reported that tissue genotyping failed in over 40 percent of those who did have tissue testing ordered, something that represents the potential of Guardant360 to provide "targeted therapy opportunities to patients [who] would have otherwise not benefited."

Finally, Talasaz said, "In those patients for whom both tissue on and plasma results were available, the addition of plasma increased the proportion with standard-of-care actionable biomarkers by 71 percent."

If the company can produce similar results in NILE, it is hoping it can persuade more physicians to order Guardant360 without the fear that they may be missing genetic information that could help them treat their patient, at least in the NSCLC space.

Company officials didn't discuss how Guardant might then try to push this rationale for blood-first testing into the regulatory and reimbursement sphere.

But Guardant is expecting to make progress next year toward at least gaining regulatory approval and associated reimbursement for a pan-cancer indication for Guardant360, which right now is only paid by Medicare for testing of lung cancer patients who doctors believe can't or shouldn't have a tissue biopsy test.

The company received a breakthrough designation from the US Food and Drug Administration last summer, and Eltoukhy said this week that Guardant currently expects to submit a premarket authorization application before the end of the first half of 2019.

"FDA approval traditionally hasn't been something that has been maybe noticed by the medical community as much based on the diagnostic testing side of things … [but] we believe that approval is more important, frankly, in the liquid biopsy space, because of the fact that [this] is a new modality and one that many physicians may not be familiar with," he said. "Having that third-party really put their stamp of quality on [us], we believe is very critical."

"If and when FDA approval is obtained, we believe it will help with the adoption of liquid biopsy testing among those sitting on the sidelines," Talasaz added.

FDA approval for Guardant360 with a pan-cancer label would also then prompt expanded Medicare coverage under the National Coverage Determination for next-generation sequencing tests that FDA and the Centers for Medicare and Medicaid Services finalized earlier this year.

Eltoukhy and Talasaz suggested during the call that doctors' perception of reimbursement challenges for liquid biopsy may actually exceed the reality, highlighting Guardant's achievement of coverage adoptions among more than 70 private payors.

In that light, achieving a pan-cancer NCD  not only offers a path to greater adoption in the Medicare population, but also could help Guardant make headway among privately insured patients by further legitimizing the test in the eyes of oncologists.

Analysts tuning in to the company's financial results call were curious about how Guardant might be preparing to differentiate itself from competitors, at least three of whom also won fast track or breakthrough designation from the FDA this year, but Talasaz said the firm couldn't comment on "where other players are in their roadmap."