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Quanterix Asserts Tau Patent Claims as AD Testing Market Heats Up, but IP Defensibility a Question


NEW YORK – As the market for blood-based Alzheimer's disease testing heats up, immunoassay firm Quanterix is signaling it may begin more aggressively protecting what it says is its intellectual property in this space.

Specifically, Quanterix CEO Masoud Toloue said during a recent investor call that companies offering tests for the Alzheimer's protein biomarkers tau and phosphorylated-tau may infringe on the firm's IP if the tests measure levels of those proteins in blood or blood-derived samples at certain levels of sensitivity.

Arti Rai, professor of law at Duke Law and an expert in intellectual property, raised questions, however, about the enforceability of Quanterix's claims, especially in the case of blood-based tau tests that don't use immunoassay technology.

Quanterix's assertion of its IP protection comes as one blood protein in particular, phosphorylated-tau 217 (p-tau 217) has emerged as an important biomarker for helping doctors assess whether individuals have the brain amyloid pathology characteristic of Alzheimer's disease. In addition to Quanterix, Laboratory Corporation of America, Alzpath, and C2N Diagnostics have recently brought clinical p-tau 217 blood tests to market, while Quest Diagnostics said it plans to launch a plasma p-tau 217 assay later this year. Roche has also indicated interest in developing a p-tau 217 blood test.

At the same time, blood-based Alzheimer's testing has received a boost from US Food and Drug Administration drug approvals — in particular of Eisai's Alzheimer's drug Leqembi (lecanemab) — that have raised the possibility that physicians will in the near future need easily scalable Alzheimer's screening methods to identify patients who may benefit from these and/or future treatments.

At last year's Alzheimer's Association International Conference in Amsterdam, a working group brought together by the Alzheimer's Association and the US National Institutes of Health's National Institute on Aging (NIA), proposed that blood-based markers be included in clinical guidelines for Alzheimer's testing.

Toloue said that p-tau 217's growing momentum as an Alzheimer's marker drove the company's decision to broadcast its IP claims.

"As other tests are emerging… we believe it is now the appropriate time to address any potential infringement," he said. He added that the company's IP applies to research, in vitro diagnostic, and laboratory-developed test products.

Duke Law's Rai suggested, however, that the company's position is likely weaker than Toloue represented during the recent investor call.

More than a decade ago, Supreme Court decisions in the cases AMP v Myriad and Mayo v Prometheus established that many commonly used biomarker relationships (isolated gene sequences and cancer risk in the case of AMP v Myriad and drug metabolite levels used for drug dosing in the case of Mayo v Prometheus) are "products of nature" and as such not patent eligible.

Quanterix does not claim that its patent covers all p-tau 217 Alzheimer's testing, only testing above a certain threshold of sensitivity. Specifically, Toloue said, tests that measure p-tau in blood at concentrations of less than 5 pg/mL and with limits of quantitation of less than .2 pg/mL may infringe the company's patent US patent No. 11,275,092.

Of the clinical tests currently on the market, two — Alzpath's Alzpath Dx test and Quanterix's LucentAD p-Tau 217 test — use Quanterix's Simoa high-sensitivity immunoassay technology. Labcorp's p-tau 217 test uses Fujirebio's Lumipulse chemiluminescent enzyme immunoassay and offers a limit of quantification of .06 pg/mL, putting it in the range that Quanterix claims put it at risk of infringing its IP. C2N has not published limit of quantitation figures for its mass spec-based PrecivityAD2 test, but given the test's clinical performance it also likely measures p-tau 217 in the range specified by Quanterix's patent.

On the research side, Alamar Biosciences offers a research-use-only p-tau 217 assay and says that its assays generally are able to measure proteins with attomolar sensitivity.

Rai said that basing patent infringement claims on the level at which the assay quantifies tau protein would be challenging as this is akin to a law of nature, which is not patentable.

Laboratory methods are still patentable, however, and Rai suggested that Quanterix might have more success defending its IP on those grounds. She highlighted claim 12 of the '092 patent, which details steps used in the company's immunoassay.

The method as described in the patent "is not particularly inventive in the sense of being non-obvious, but given where the Federal Circuit has taken some of these cases on laboratory techniques, it does seem like it could pass muster as a sufficiently detailed laboratory technique," Rai said.

Rai said, however, that the '092 patent would not cover a mass spectrometry-based test like C2N's.

"There's absolutely no way," she said.

During the call, Toloue maintained, however, that the company's patent covers any test measuring tau at the specified concentrations "irrespective of immunoassay or mass spec platform." Quanterix declined to comment on questions from 360Dx regarding the defensibility of its IP claims. C2N also declined to comment on Quanterix's IP claims, while Labcorp did not respond to a request for comment.

It remains unclear whether Quanterix will take legal action to enforce its claims or whether it is simply hoping to either deter potential competitors or encourage them to license its technology. Toloue said that the company is not currently planning litigation against any competitors and noted multiple times during the call that it hopes to provide other testing firms non-exclusive licenses to its IP.

Several of Quanterix's potential competitors — Labcorp, Quest, and Roche — are large companies with the resources for a lengthy legal battle.

Alamar Biosciences, on the other hand, is a relatively small startup that is already involved in a patent dispute with proteomics firm Olink. The company's assays are immunoassay-based.

Alamar, which declined to comment on Quanterix's IP claims, has also recently won some p-tau 217 research business away from Quanterix. Researchers at the University of Gothenburg are studying whether self-collected finger prick-blood samples can be used for p-tau 217 testing as part of the Predictom Alzheimer's research project. Nicholas Ashton, associate professor of neurochemistry at the University of Gothenburg and leader of the self-collection project, said that while he and his colleagues had used the Alzpath assay run on Quanterix's technology for their initial pilot study, they have since moved to Alamar's NULISA platform, which he said offers greater sensitivity and multiplexing.

Ashton is also participating in a 4,000-subject UK-based study looking at the utility of blood-based markers for Alzheimer's and other causes of dementia. According to Vanessa Raymont, senior clinical researcher at the University of Oxford and one of the leaders of the study, Alamar's p-tau 217 assay will be used in this effort, as well.