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Instrument-Free POC Molecular Coronavirus Test Being Developed by Sense Biodetection

NEW YORK – Sense Biodetection is accelerating the development of an instrument-free molecular platform for SARS-CoV-2, the coronavirus that causes COVID-19, in a bid to provide more sensitive point-of-care tests in the market.  

If successful, the company could have the device available for sale to hospitals, physicians' offices, clinical pharmacies, and community healthcare centers in a few months, said Sense Bio's CEO Harry Lamble.

The Abingdon, UK-based firm believes that its instrument-free molecular test ─ using an alternative to traditional PCR methods ─ may eventually enable people to test for active infections in their homes, Lamble said.

According to Lamble, Sense Biodetection's molecular, point-of-care test for detecting SARS-CoV-2 provides the level of sensitivity and specificity of PCR-based molecular testing. But where real-time PCR uses commercially available fluorescence-detecting thermocyclers to amplify specific nucleic-acid sequences, leading to test results in about one hour for point-of-care instruments, "A crucial aspect of our Veros SARS-CoV-2 test is that it takes less than 10 minutes," Lamble said. "This speed comes from our use of a proprietary isothermal amplification method instead of PCR." 

Sense Bio said that its tests involve "innovation in low-cost fluid handling, temperature control, and mechanical design" to provide rapid diagnostic results, enabling immediate treatment decisions. The sampling process for the test is like that of current point-of-care molecular diagnostic tests in that a nasal swab sample and elution buffer are transferred directly by pipette to the test, Lamble said. Use of isothermal amplification within an enclosed test unit enables rapid and specific amplification of DNA at constant temperature and eliminates the need for thermal cycling.

However, most current molecular point-of-care tests rely on use of a disposable cartridge that contains a sample which is plugged into an instrument. The user waits ─ often for up to an hour ─ for the instrument to complete the test and then initiates the next test run, continuing to use and reuse the instrument in this fashion. 

Sense Bio's test device runs the test in a single hand-held unit and like a pregnancy test, the entire test is thrown away after a single use. It provides a "yes" or "no" answer to whether a pathogen is present in the sample, Lamble said.

If Sense Bio is successful in developing its test, users will be able to take the test straight out of the box, run the test, and receive a result in about 10 minutes. A provider can run as many tests as are needed in parallel, and isothermal amplification and detection is completed in the handheld unit.

The firm refused to disclose specific details of how the test operates within a handheld unit, citing a need to protect its intellectual property.

Last October, Sense Bio raised £12.3 million ($15.9 million) in Series A funding to support the development and clinical validation of its first diagnostic test. At the time, the firm was developing its platform for respiratory infections, including influenza. That, Lamble said, has given it a head-start on developing a test for the coronavirus infection.  

Molecular tests are the go-to platforms in many diagnostic testing applications, including testing for SARS-CoV-2, said Michael Anstey, a partner at UK-based Cambridge Innovation Capital (CIC) and an investor in Sense Bio. "However, until Sense Biodetection, companies have been unable to crack [such a rapid] instrument-free approach for molecular testing," he said.

Because Sense Bio's test is thrown away after a single use,  it is like a lateral flow immunoassay pregnancy or HIV self-test, for example. However, using molecular technology, the test can be expected to provide the same levels of sensitivity and specificity as lab-based and point-of-care machines with instruments, leading to fewer false positives and false negatives than immunoassays, which is crucial in the context of COVID-19 testing, Lamble said.

Seeing opportunity in point-of-care molecular testing, a second startup,  Austin, Texas-based Nuclein, recently announced it was exiting stealth mode with a handheld real-time PCR system and a prototype assay for SARS-CoV-2. Both the system and assay are disposable. Nuclein anticipates providing test results in around one hour and having a test available in the fall.

Mesa Biotech, meanwhile, markets a 30-minute assay that uses the company's handheld Accula system. The system is designed for point-of-care use in screening facilities, physician office labs, urgent care centers, or long-term nursing facilities, but the instrument is not disposable.

"The issue with an instrument, no matter how small, is that it leads to a fundamentally different model of testing," Lamble said. "Machines restrict throughput. For example, to perform two tests at a time on the Mesa Biotech or Abbott ID Now [instruments] requires the purchase of two instruments. As an instrument-free test, Sense’s Veros overcomes this limitation. You simply take a second test out of the box."

In simple terms, with the Sense Bio approach, he said, the test is taken to the patient rather than samples being taken to a machine.

"Perhaps the most significant challenge we have overcome in order to achieve a disposable molecular test over the last six years is the cost of goods of the test device," Lamble said. "It is challenging to get the cost of goods to a point that makes the instrument-free model viable."

That is why Sense Bio recently appointed Phillips-Medisize, a Hudson, Wisconsin-based contract development and manufacturing firm, "to commit to volume production of our product with capacity to achieve many millions of test devices per year," Lamble said.  

The Sense Bio instrument-free platform has potential to make COVID-19 and infectious disease testing more accessible, said Bill Welch, chief technology officer at Phillips-Medisize, which is working with several companies developing different types of tests for SARS-CoV-2 virus detection.

Large lab instruments can take too long to provide results to patients and molecular point-of-care systems require a desktop console for testing, Welch said. "The [Sense Bio test] can make high performance instrument-free testing available where laboratory and console-based molecular systems are not readily available. Additionally, the platform has the potential to decrease the burden on healthcare workers" at a time when they are already overextended.

The FDA has not yet cleared any coronavirus tests for at-home use. However, Lamble said he anticipates seeking FDA Emergency Use Authorization for its SARS-CoV-2 test. The firm will also look to obtain a World Health Prequalification Emergency Use Listing and possibly CE marking.

He added that the clinical validation program for its Veros SARS-CoV-2 test is ongoing.

Lamble said he anticipates that the per-test cost will be comparable to other point-of-care molecular diagnostic tests. He declined to be more specific.

Lamble said that some immunoassay-based tests being developed for coronavirus testing at the point of care may have a role in population screening and "detecting whether someone has developed immunity." Companies are also developing immunoassays that detect virus antigens for active disease testing, Lamble said, but "Molecular chemistry is better technology to achieve that, and the antigen tests will end up having low sensitivity tests in the same way that they have low sensitivity for influenza."

The World Health Organization last week recommended that new point-of-care immunodiagnostic tests for the coronavirus that causes COVID-19, including antigen tests, should not be used for clinical decision-making, and it said that molecular PCR testing of respiratory tract samples is the recommended method for the identification and laboratory confirmation of COVID-19 cases.

A molecular test such as that being developed by Sense Bio detects infection at high levels of sensitivity while it is active, Lamble said, adding, "We'll make our test available as soon as we can, but it may be that when we bring it online, its primary use is to help contain recurring outbreaks."