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PhasiQ Awarded NSF Grant to Develop Multiplex Protein Biomarker Test for DVT

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NEW YORK (GenomeWeb) – Immunoassay developer PhasiQ this week received a two-year grant from the National Science Foundation to develop and commercialize an ELISA-based multiplex protein biomarker test for identifying patients with deep vein thrombosis (DVT).

The effort marks the company's ongoing effort to expand its offerings beyond do-it-yourself immunoassay kits and into pre-designed research tests for disease biomarkers and, ultimately, point-of-care diagnostics, John Dishinger, PhasiQ's director of product development, told GenomeWeb.

PhasiQ's core technology involves simultaneously measuring the expression of multiple proteins while preventing the antibody crosstalk that can result in false positives and false negatives using a technology dubbed micropatterned phase separation, or MPS. This approach, according to the company, uses proprietary solutions to allow antibody pairing where needed while eliminating unwanted binding.

MPS compartmentalizes the reagents for a given assay into specific regions of a multiwell plate, Dishinger explained. "Essentially, we are doing many independent immunoassays without any antibody crosstalk or mixing of antibodies, so we can theoretically multiplex any combination of proteins."

Shuichi Takayama, PhasiQ's founder, CEO, and CSO, and a professor at the University of Michigan, has published a number of reports describing the MPS technology, including a 2014 paper detailing its use in identifying protein biomarkers in patients with acute graft-versus-host disease (GVHD).

According to that study, antibody cross-reactions were eliminated in multiplex ELISA assays through the use of aqueous two-phase systems composed of the phase-separation-promoting polymers polyethylene glycol (PEG) and dextran (DEX), which confine detection antibody solutions in a fully aqueous environment to regions where complementary capture antibodies are immobilized.

The method, the paper states, works because droplets of the denser DEX solution sink in the PEG solution and remain in contact with the assay plate during incubation. Further, interfacial tensions between DEX-PEG and the DEX assay plate cause the DEX droplets to form domes that remain in place, and detection antibodies are retained without diffusive dispersion in the DEX phase due to partitioning effects.

Also in 2014, Takayama and UMich colleagues reported the use of the MPS approach for multiplexed immunostaining of cell monolayers and tissues, showing that "multiple antigens can be detected on a single fixed sample by incorporating antibodies within dextran solutions, which are then patterned by micropipetting at specific sites on the sample in a solution of PEG."

PhasiQ currently sells a number of user-customized ELISA immunoassay kits based on the MPS approach, but sees greater promise for in-house designed kits for research and clinical use.

Dishinger said that PhasiQ is currently pursuing development of a GVHD biomarker test, but declined to provide specific details citing ongoing changes in the firm's intellectual property strategy around that program.

Meanwhile, work is proceeding apace with the DVT test, for which PhasiQ has secured $750,000 in Small Business Innovation Research funding from the NSF.

Under a now-completed Phase I grant, the company developed a working prototype of the DVT test, which it now aims to refine to detect nine undisclosed biomarkers for DVT.

Once this optimization is complete, PhasiQ will clinically validate the device in approximately 200 banked and de-identified patient blood samples in a collaboration with UMich researcher Jose Diaz, Dishinger said.

He declined to comment on which biomarkers are being evaluated, but said that they relate to work conducted in Diaz's lab. Among Diaz's published work are studies examining established and novel DVT biomarkers including soluble P-selectin, D-dimer, CRP, VWF, MPO, and ADAMTS13.

PhasiQ hopes that this validation work will be sufficient for the introduction of a DVT test for research use only, potentially within two years, Dishinger noted. The end goal for the firm, however, would be a bedside test to rule in or rule out DVT, he said.

He added that additional clinical testing would be required before such a diagnostic could be launched.

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