NEW YORK (GenomeWeb) – A clinical evaluation of a multiplexed assay from Enigma Diagnostics for influenza and respiratory syncytial virus has shown that the test might be useful at the point of care.
Published in November in the Journal of Clinical Microbiology, the study evaluated the MiniLab Influenza A/B & RSV assay on a treatment ward in the 154-bed Evelina Children's Hospital in central London.
In the evaluation, 56 staff members were trained to operate the MiniLab and were instructed to test nasopharyngeal swabs from children with signs and symptoms of respiratory tract infection, ultimately examining 567 samples. Duplicate swabs were sent to the virology lab for testing with the Luminex xTAG Respiratory Viral Panel with discrepancies resolved using the Cepheid Xpert Flu/RSV XC assay.
The research was initiated by Simon Goldenberg at the Centre for Clinical Infection and Diagnostics Research of King's College, London, and Guy's and St. Thomas' National Health Service Foundation Trust, and was funded by Enigma Diagnostics.
"We felt that there was a real unmet clinical need for rapid diagnosis of respiratory viruses," Goldenberg told GenomeWeb in an email.
"Our current laboratory-based respiratory test takes just over 24 hours including sample transportation, so we were keen to look at ways of reducing diagnostic delay so that the clinicians could make better informed decisions," he said.
Goldenberg noted that each winter the pediatric hospital is faced with a surge in patients presenting with influenza-like illness, and that deciding where to place these patients and whether they should have the anti-viral drug oseltamivir or antibiotics presents a challenge.
The group had a prior relationship with Enigma, having performed contract work to look at the performance of their test when run in a centralized lab, but it also weighed the options in terms of other commercial solutions.
"We have tried the BioFire FilmArray ... for bloodstream infections, rather than respiratory tract infections ... and I have seen the Alere i in operation," Goldenberg said, noting that the available platforms offer slightly different things in terms of ease of use and complexity, turnaround time, number of targets detected, and cost, and that each of the platforms may be more useful in different situations.
Training the staff to run the Enigma test was "quite straightforward," Goldenberg said. "I think we spent around 20 minutes walking them through how to run a test, then we observed them running a test alone to check they were competent."
Moreover, the assay didn't require any complex skills, such as pipetting, "So it's perfect for nurses and nursing assistants who are not used to performing tests."
The group did experience some test failures early on, which were "a bit of a puzzle," but these resolved and may have been user error, said Goldenberg.
There were 40 discrepant results, and residual material for 30 of these was available for additional testing. For the remaining 10, the xTAG RVP was considered the gold standard.
The positive and negative percent agreement for each of the three targets was around 95 percent or higher, with the exception of influenza A. For that target, the PPA was 79.2 percent, which was considered low, but in line with published results for some other commercial tests.
The study concluded that a partial mismatch between the primers and circulating influenza A strains at the time of testing could explain why an evaluation during the previous flu season, which was published in the Journal of Clinical Virology, showed 100 percent sensitivity for influenza A compared to the Luminex RVP. That evaluation also showed a specificity of 96 percent and a PPA of 86 percent for flu A. Goldenberg further noted that Enigma is developing a new version of the test.
Other commercially available platforms for near-patient or point-of-care molecular influenza testing include the CLIA-waived Roche Liat cobas flu A/B, which was shown in a recent presentation at the Association for Molecular Pathology annual meeting to impact patient care in the emergency room, and the firm is developing a flu/RSV test. Cepheid markets a flu assay for the GeneXpert which has been used near to patients in the turnaround time of an emergency room visit as previously reported, and its Flu/RSV test was submitted for CLIA wavier earlier this year.
On the other hand, syndromic panels, such as the FilmArray Respiratory panel and the Luminex RVP, are constrained to the laboratory.
Thus, the Enigma MiniLab may fill a unique niche in that it can be run near the patient but can also run panels and syndromic assays instead of only a few analytes.
Enigma in the POC space
Indeed, Jessica Barrett, commercial director at Enigma Diagnostics, describes the MinLab system as "the first point-of-care, highly multiplexed PCR platform."
The platform is a table-top unit that gives clinicians results in about an hour, Barrett said.
"It is available 24/7 to give comprehensive, laboratory-quality results from a multiplex PCR panel," she said, noting that other competing products are usually simplexes. Some have faster turnaround times, which would be good in a physician's office, "but for a comprehensive panel, which is what they need for critically ill patients, this system should get some attention."
The firm's strategy is to go after the unmet needs of infectious disease physicians for testing at all hours of the day, to be able to sort through their critically ill patients.
Since launch of the Flu/RSV test in January the firm has set up distribution deals and sales have been increasing, Barrett said.
"We really tried to stay off of people's radar screens, other than customers," she noted. "We wanted to have some content for the platform and to be able to work with early adopters who could give us feedback before we presented the product to a broader audience."
The firm received a $50 million subscription agreement from a Chinese equity firm last year, which helped in the development.
The flu/RSV test is now being expanded further into a respiratory viral panel, and the firm is also working on other highly-multiplexed syndromic panels, Barrett said, adding that the system can detect up to 12 analytes in a single-tube reaction.
The overall platform consists of a controller unit — with a touchscreen interface, barcode reader, integrated printer, and LIS connection — a processing module that contains a robotic arm to perform automated PCR, and shelf-stable test cartridges that store reagents and consumables.
The system is scalable, in that users can link up to six processing modules to each control module, and these are each controlled separately to make the overall system random access.
In fact, Goldenberg said that his group placed an Enigma machine with three modules on the ward in its study in order to run multiple tests at the same time. "If you have a busy emergency department with a high turnover of patients, then having a platform that accepts only one test with a turnaround time of 60 minutes isn't going to cut it," he said.
The single-tube method also uses magnetic bead- and fluidic-based nucleic acid sample preparation, an electrically conducting polymer, or ECP, for direct thermal cycling, freeze-dried reagents, and has high-resolution melting as the endpoint detection.
Barrett joined Enigma in October of last year and was previously director of sales at BioFire Diagnostics.
"The FilmArray was the first time a doctor could get so many targets run in parallel," she said. However, the Enigma system is "at a much lower price point," and targets point of care and critical care with a comprehensive panel.
Specifically, in the UK the control module costs roughly £6,000, and each processing module costs £16,000, with discounts for adding more modules. Each cartridge costs about £25.
In the expanding point-of-care market, three analytes simultaneously detected seems to be the limit, so syndromic panels would be a novelty. To compete with Roche, Cepheid, and Alere, Enigma's strategy will be to differentiate its product, appealing to customer needs for speed as well as comprehensive results.
"We're focusing in on making a range of tests for physicians who are dealing with critical care patients," Barrett said.
The new respiratory viral panel will be more comprehensive, adding rhino/enterovirus as a target, and the firm expects CE marking in March. The test detects a conserved region of influenza A, but the updated panel has changed to a different target area.
Enigma is also developing bacterial and viral meningitis panels, a carbapenamase-producing organisms panel, and it is in testing for a previously described multi-drug resistant tuberculosis panel. The firm is also looking into partnerships for further assay development.
Currently, the manufacturing of cartridges is done at the firm's San Diego site and then shipped to Europe. As for US regulatory intentions, that is still being discussed in house, Barrett said. "It is a very large potential market, and one that I feel is under-served and would be a good adopter of this technology."