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Luminex Readying Next-Generation Respiratory Viral Panel for 2015 FDA Submission


Luminex is developing a new version of its xTAG PCR chemistry that it believes will improve the ease of use of its technology while maintaining its high-multiplex and high-throughput capabilities.

The Austin, Texas-based company intends to apply the new chemistry to its US Food and Drug Administration-approved Respiratory Viral Panel, with plans to commence clinical trials on the updated assay in 2014 and submit it to the FDA the following year.

Jeremy Bridge-Cook, the firm's senior vice president of R&D, discussed Luminex's new chemistry and the next-generation RVP during the firm's annual investor invent, which was webcast last week from the Association for Molecular Pathology meeting in Phoenix, Ariz.

According to Luminex's website, its xTAG approach consists of several steps. Multiplexed PCR is performed to amplify regions of interest in target genes. The reaction is then treated to remove excess nucleotides and primers, followed by a primer extension step that is specific for the allele or the infectious agent that is being analyzed. The 5' end of the primers is attached to an xTAG universal tag sequence and the 5' universal tag sequence is then hybridized to the complementary anti-tag sequence coupled to a particular xMAP bead set. The hybridized beads are then read by the Luminex xMAP system.

The company's xTAG technology forms the basis for its bead array-based tests. In addition to the RVP, the company offers a Gastrointestinal Pathogen panel, as well as assays for cystic fibrosis carrier screening and CYP2D6, which enables clinicians to assess an individual's ability to metabolize certain drugs. The FDA has cleared all four xTAG assays for in vitro diagnostic use. Luminex most recently saw its GPP cleared for clinical use earlier this year.

Bridge-Cook said that the new xTAG chemistry in development incorporates the approach's primers, enzymes, and fluorescent reporters all into a single mix in the wells of a sealed 96-well plate. Luminex customers using the new technology will only need to pipette their nucleic acid samples into the plate's wells, re-seal it, and run it in a thermal cycler. When the PCR program is complete, the plate is transferred to the company's benchtop MagPix instrument to be read out.

Bridge-Cook said that the assay's hand-on time has been reduced from approximately two hours to a few minutes, and that the risk of contamination has been eliminated, because the plate is never unsealed after the samples are added.

"Our goal is to achieve as close as possible to [a] sample-to-answer workflow while maintaining the throughput advantages of plate-based batch processing," he said.

Bridge-Cook noted that the updated version of the RVP that will rely on the new chemistry will also contain new content. The current RVP tests for eight viruses and subtypes, including influenza A, influenza A subtype H1, influenza A subtype H3, influenza B, respiratory syncytial virus, human metapneumovirus, rhinovirus, and adenovirus. Bridge-Cook said that the company will add several new targets, including bacterial pathogens, to the next-generation RVP.

He said that Luminex expects to achieve FDA clearance for the assay by the first half of 2015.

It is unclear if Luminex intends to move its other xTAG-based IVDs to the new chemistry in the future. A company spokesperson said that Luminex will make such decisions based on the needs of its customers.

"The new chemistry will be well suited for higher volume laboratories, so some assays may be more aligned to those types labs," the spokesperson told BioArray News. "When it makes sense and based on the customer need, we will pursue those opportunities."

Aries update

Bridge-Cook's discussion of the new xTAG chemistry and next-generation RVP was overshadowed somewhat by the company's introduction of its cartridge-based, sample-to-answer molecular diagnostics platform. Dubbed Project Aries, the system combines the real-time PCR chemistry that Luminex gained through its acquisition of EraGen Biosciences with the sample-to-answer molecular testing instrument it obtained when it bought startup GenturaDx. Luminex closed both deals last year.

At AMP, Luminex discussed the initial test menu for the new system, which includes assays for Clostridium difficile, herpes simplex virus I and II, and a combined panel for influenza A, influenza B, and respiratory syncytial virus. The firm plans to launch the system and its accompanying test menu in Europe in the second half of 2014, and aims to see it cleared by the FDA the following year.

Bridge-Cook said during the investor event that the company has two other assays in development for the Aries system, but did not provide more information about them for competitive reasons. While the availability of the new system will mark Luminex's entry into the market for lower-multiplex molecular tests, the company sees its RT-PCR and higher-multiplex microarray-based tests as complementary.

Specifically, Bridge-Cook said that some Luminex customers would like to use its forthcoming influenza A/influenza B/respiratory syncytial virus assay together with its RVP.

"Some labs have told they want use RVP on inpatients and a flu A/B/RSV on outpatients," said Bridge-Cook. "Others want to use RVP for their central lab testing but want to use the simpler flu A/B/RSV test for their satellite labs."

Luminex's GPP customers imagine combining that panel with the C. difficile assay in a similar way, Bridge-Cook noted.

"Some customers have told us they want to use GPP on all patients and use a C. difficile test to confirm positives," said Bridge-Cook. "But other customers want to perform a C. difficile test upfront on all in-patients and use the GPP on C. difficile-outpatients."

Having a menu of complementary tests could help Luminex reach customers in the infectious disease testing segment, which the firm has been eyeing, Russell Bradley, senior vice president of corporate development and global marketing, said during the investor event.

Bradley called infectious disease testing "one of the largest segments" in the global IVD market, adding that the segment is estimated to swell to a market value of $4 billion by 2017, driven by increased demand for tests to diagnose hospital-acquired and respiratory infections.

Luminex believes that hospital labs that have already implemented the company's RVP and GPP tests could also lead the adoption of the new Aries tests, Bradley noted.

"We believe it is this customer segment that will benefit most" from the new platform, Bradley said. "The small footprint, sample-to-result automation, the IVD menu, and the ability to automate and standardize [laboratory-developed test] assays are capabilities that make this system highly attractive to this customer segment," he said.