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Personalis Building Data for High-Sensitivity Residual Cancer Assay

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NEW YORK – Buoyed by a growing dataset showing improved sensitivity compared to other platforms, Personalis said this week that it believes it can make a case for the superiority of its tumor-informed minimal residual disease assay, NeXT Personal, as it prepares to transition it to the clinic. 

NeXT Personal, launched late last year, is similar to existing clinical solid tumor MRD tests, such as Natera's Signatera, using tumor tissue sequencing to derive a patient-specific mutation panel for blood-based MRD assessment. 

Personalis hopes it can distinguish itself in this emerging market, though, via increased sensitivity. Although the company has not published significant clinical data on its test, its proposition is that, by using whole-genome sequencing and deriving broader personalized cancer assays — including, potentially, more than 1,000 targets — it can dramatically increase performance. 

"Our internal data confirms this approach can result in analytical sensitivity down to approximately a few parts per million [which] may translate into much earlier detection of a patient's cancer recurrence, particularly when the amount of tumor DNA in the blood plasma is very low, such as in early-stage cancer after surgical resection, or in patients with complete response of therapy," CEO John West said during a call this week discussing the firm's first quarter financial results

While published data remains thin, Personalis did present a poster at the annual meeting of the American Association for Cancer Research last month, describing two studies it performed to establish the assay's performance. 

Investigators tested a set of cell lines and matched tumor-normal-plasma patient samples at different dilutions, using droplet digital PCR on matched samples as an orthogonal comparator. 

Personalis' assays showed sensitivity as low as one part per million, "with high specificity in normal control samples," company researchers wrote. "We estimate that [approximately] 50 percent of the cases in this set of patients would not have been detected by other commercially available liquid biopsy MRD platforms." 

According to West, Personalis recently received and began processing samples for its first NeXT Personal customer, an unnamed global pharmaceutical company. 

As part of a pilot study, the firm's assay is demonstrating "favorable" sensitivity, among other capabilities, West said, adding that Personalis is in discussions with several other potential pharmaceutical customers and expects new orders to increase throughout the year, converting to initial revenue within 2022, with the "potential for a significant acceleration in 2023 and beyond." 

He added that the company has initiated additional collaborations in Europe, using NeXT Personal to "better understand treatment, response, and resistance" in patients with ovarian and other cancers. 

In the clinical arena, recent debate has focused on questions of clinical utility and the relative merits of tumor-informed versus blood-only MRD assays. 

Although the firm still lacks a cornerstone of published data, West said that Personalis is hoping to leapfrog these concerns as it sees results internally that are "a mile ahead" of others in the space. "What we find when we talk with our customers is that there's almost [an] incredulity, but then we show them some of the data that we have and people get it," he said. 

West argued that existing platforms still struggle with tumor types that are notorious for shedding little, if any, DNA into circulation. On the firm's earnings call this week, he said that these patients, which include early, surgically treated breast and prostate cancers, represent a large proportion of the eligible MRD market. 

"These two cancer types have such low mutational burdens that they can be difficult to detect [and] we realized early on that we may be able to overcome this sensitivity problem," he said. "We have seen cases where we can pick up the fact that the patient still has residual disease quite early when the adjuvant treatment may be just starting." 

For a less sensitive test, "it's all just kind of invisible," West added. "Suddenly there's a lot of new things that we can see, and it's much more informative than just waiting for [recurrence]," he said, adding that the firm believes this increased sensitivity is inspiring "different trial designs" among biopharma partners, "some of which we haven't even thought of ourselves." 

Personalis is currently on the cusp of shifting from a primarily research-focused company to a clinical diagnostics provider, with plans to launch its tissue-based NeXT Dx cancer therapy selection test by the end of this year. On the company's call this week, West said that the firm is on track to submit data to CMS contractor Palmetto's MolDX technology assessment program, hoping to receive a "favorable reimbursement ruling" by the second half of 2022. 

On the heels of that, West said Personalis now also intends to release a laboratory-developed test version of NeXT Personal, following the same reimbursement strategy through MolDX. 

"We do expect to see the clinicians who start ordering our NeXT test are likely to also want to use the NeXT personal test. I think there's a good tie in between those," he said. 

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