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FDA Clearance of PrimeraDx ICEPlex, C. Diff Assay Opens Doors for Additional Tests

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PrimeraDx said this week that the US Food and Drug Administration has granted 510(k) clearance for its ICEPlex C. difficile assay kit and ICEPlex molecular diagnostics system.

The approval provides PrimeraDx with a runway from which to commercially launch a number of additional multi-analyte in vitro diagnostics in infectious disease and oncology, including companion diagnostics.

PrimeraDx President and CEO Matthew McManus told PCR Insider in an email this week that the company is "very pleased by the FDA clearances of the C. diff kit and also the ICEPlex as a multiplex clinical platform. The agency has been a pleasure to work with, and I strongly believe we have a better platform as a result. The clearances validate our approach to building a full-spectrum diagnostics company, as well as platform itself, and represent a significant step in that process."

The approval also provides a buoy during a challenging time for PrimeraDx, which was recently forced to downsize as it undergoes a restructuring and attempts to put together a new round of financing.

Despite this setback, McManus pledged to move the company ahead in its efforts to develop a broad range of molecular tests for the ICEPlex platform.

"I'm very proud of the work the team at PrimeraDx has done to get us to this point," he said. "We have a broad and deep pipeline of products in development and plan to take a number of them through the FDA. We're currently studying the market to determine which fits best with our business plan."

On the diagnostic development front, PrimeraDx has entered into agreements with Eli Lilly and Quest Diagnostics to develop ICEPlex assays to support multiple targeted therapeutic development programs. The company also won a grant in 2012 from the National Cancer Institute to develop a gene expression profiling assay that can rapidly detect diffuse large B-cell lymphoma subgroups.

ICEPlex runs an assay technology called scalable target amplification routine, or STAR, which integrates standard endpoint PCR with capillary electrophoresis to simultaneously quantitatively measure multiple target nucleic acids.

The platform continuously samples PCR reactions containing fluorescently labeled primers during sequential cycles of amplification. The amplified products can then be detected by size using capillary electrophoresis, and the amplification kinetics can be reconstructed using real-time PCR algorithms to quantify the amount of material in the initial sample. This enables a higher level of multiplexing than is possible with real-time PCR.

PrimeraDx originally developed the ICEPlex platform for infectious disease assays, and still has a number of tests in the pipeline in that area, such as panels for multiple viral loads in transplant patients, fungal infections, and sexually transmitted infections.

The ICEPlex C. difficile Assay Kit is a molecular diagnostic test for the detection of Clostridium difficile in human stool samples. The assay is designed to target the C. difficile tcdB gene (encoding for the toxin B protein), and is performed as a seven-plex PCR reaction including three internal calibration standards, one internal control, and three independent target sites on the toxin B gene.

In a poster presented last month at the Association for Molecular Pathology annual meeting, clinical researchers from the Cleveland Clinic, Nationwide Children's Hospital, Tampa General Hospital, Ohio State University, and PrimeraDx presented a poster detailing data from a multicenter prospective clinical trial of ICEPlex C. difficile.

The researchers compared the ICEPlex test to a cell culture cytotoxicity method for 688 fresh patient samples and found that ICEPlex demonstrated 91 percent sensitivity and 97 percent specificity.

PrimeraDx is also attempting to sell the ICEPlex system in an "open platform mode" so clinical labs can independently develop and validate their own molecular diagnostic assays.

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