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Personalis to Broaden Liquid Biopsy Footprint With Minimal Residual Disease Testing

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NEW YORK – Personalis plans to expand its activities in the liquid biopsy space significantly this year, adding to its existing exome-scale mutational profiling assay and recently announced collaboration with Natera a new product called NeXT Personal for minimal residual disease detection and longitudinal patient monitoring.

Personalis CEO John West, said during a call discussing the firm's Q4 2020 earnings that the company believes its combined ability to analyze both tissue and liquid biopsy samples will be an important driver in making oncology a larger part of its revenue mix going forward.

"Although we have not provided revenue estimates for our liquid biopsy offerings, we believe that with multiple time points per patient, we have a tremendous opportunity to grow revenues in this area," he added.

Launched last August, Personalis' core blood-based testing product is NeXT Liquid Biopsy, a circulating tumor DNA-profiling assay for advanced-stage solid tumor cancer patients that covers the whole exome, offering dramatically broader content than most other commercial panels on the market.

In a poster presentation at November's European Association for Cancer Research virtual conference on liquid biopsies, company researchers described the assay as similar to its tissue-based NeXT panel, incorporating chemistry to augment hard-to-sequence genomic regions such as those with high GC content, and adding sequencing depth (5000x instead of 2000x) for 247 specific, clinically relevant oncogenic and tumor suppressor genes.

The investigators also wrote that they developed a specific error-correction algorithm for the liquid biopsy assay, called Silencer, to improve the accuracy of somatic mutation detection without compromising sensitivity in the plasma.

In serial dilution experiments using SeraCare reference samples, NeXT LB successfully and consistently detected almost all known SNVs, missing only one or two targets on average in the lowest 0.5 percent allele frequency samples.

In a small clinical cohort of nine head and neck cancer plasma samples, NeXT LB detected 1,334 somatic SNVs, 31 of which were in clinically relevant immuno-oncology genes. According to the researchers, comparing this to what would be expected with a targeted liquid biopsy panel, there was a clear added value, including the identification of specific alterations relevant to immuno-oncology-related pathways that would otherwise go undetected.

In a final experiment applying the assay to two independent colorectal cancer and head and neck cancer cohorts, the group found that NeXT LB consistently detected both tumor-concordant and plasma-distinct mutations from patient samples.

The test was also able to measure dynamic allele frequency changes in cancer driver genes in patients receiving checkpoint blockade, highlighting potential utility in non-invasive response monitoring.

According to West, because the assay is so much broader than other tests on the market, Personalis can also tune its offering toward increased sensitivity or toward sample efficiency.

"The more places across the genome you can sample, the more molecules there are to look at … so even when there's a relatively low amount of plasma, which might lead to not very many whole genome equivalents [we can] be more sensitive for the amount of plasma," he explained. "You can either use the same amount of plasma as others would if that's available and be way more sensitive, or you have the other possibility, which is to maintain sensitivity but do it with a lot less plasma. And when we work with customers, we do find that the amount of plasma is just really a limiting factor in many cases.

With NeXT LB less than a year on the market, Personalis is now moving quickly to expand further, announcing this week its plans to launch a second product called NeXT Personal this year, which will combine tumor-informed content and a fixed gene panel for blood-based residual disease detection and monitoring.

According to West, the company believes this paired approach can maximize sensitivity for minute signals of residual or recurring cancer while also enabling detection of new mutations that may emerge as a tumor progresses. Although the initial customer base for NeXT Personal is the biopharma sector, Personalis believes it will also be applicable for the diagnostic market in the future.

The move to launch an MRD product is notable coming soon after Personalis and Natera announced a deal under which Natera is using Personalis' NeXT tissue exome as the backbone for its own Signatera MRD assays.

West called the deal a "great opportunity for us to showcase the strengths of our technology and capabilities."

Under the agreement, Natera is paying Personalis directly to perform tissue exome sequencing, while revenue from the sales of the resulting Signatera MRD or monitoring assays remains under its own umbrella, West said this week.

If Personalis is successful in advancing its own personalized assay platform for clinical MRD testing, it will compete not only with Natera, but also Inivata, which has taken a similar approach with its RaDaR technology.

Guardant Health also just launched an MRD product, in its case a universal blood-only assay that does not require tissue sequencing to derive patient-specific mutation panels.

West said that while NeXT Personal will initially be for research use only, Personalis could soon take its first step to transition to a clinical laboratory-developed test.

"Ultimately, I could imagine that this would be something we might even want to take through the FDA, although obviously that process is much more extended," he added.

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