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UK Startup LEX Diagnostics Developing Ultra-Fast Low-Cost PCR for Infectious Disease Dx


PHOENIX – UK-based LEX Diagnostics is working on an ultra-fast point-of-care real-time PCR platform for infectious disease diagnostics that can deliver results within five minutes at a price point similar to current antigen tests.

The company, a spinoff from UK technology development firm TTP Group, was founded in early 2020 at the height of the COVID-19 pandemic and is based in the Melbourn Science Park, a few miles south of Cambridge. Last year, GenMark Diagnostics invested an undisclosed amount in the firm through a definite option agreement.

At the Association for Molecular Pathology annual meeting here on Wednesday, Andrew Anyakwo, head of reagent development at LEX — which stands for "low energy extreme" — outlined the firm's technology and laid out its vision for a fast, low-cost, high-accuracy diagnostic. He presented during a workshop sponsored by LGC Biosearch Technologies, LEX's development partner for reagents.

According to Anyakwo, current POC testing devices on the market have several shortcomings. For example, many are not that user friendly, requiring various steps that can result in mistakes. LEX, on the other hand, has developed a cartridge that only requires users to add the sample, which helps avoid human error.

Secondly, existing tests, such as COVID-19 antigen tests, may be low cost but are not extremely sensitive, he said. Alternatively, they may have PCR sensitivity but at a significant cost. "We want accuracy at low cost," he said, and LEX's first test will have a limit of detection comparable to conventional real-time PCR.

Lastly, although existing POC PCR tests can already deliver results within 30 minutes or so, greater speed would still be an advantage. A primary care visit in the UK, for example, only lasts 10 minutes, he said.

To get there, LEX is betting on ultra-fast PCR amplification directly from human samples. According to Anyakwo, the groundwork for this "extreme PCR" was already laid almost 10 years ago by Carl Wittwer and colleagues at the University of Utah, who demonstrated in a 2015 publication that PCR could be performed with temperature cycles that last merely seconds, allowing DNA to be amplified within a minute or less.

Wittwer is also a cofounder of BioFire Diagnostics, now part of BioMérieux, and an adviser to Scope Fluidics, a Polish company whose subsidiary Curiosity Diagnostics is developing a 15-minute sample-to-answer PCR system. Curiosity was acquired this year by Bio-Rad for $170 million.

LEX has been working on reducing the size of ultra-fast PCR reactions with thin and flat reaction chambers that are cheap to manufacture and can change temperature within seconds. This is based on work conducted as part of an internal development program at parent company TTP in 2018. LEX has filed several patents on the technology and was granted a core patent in the US earlier this year, according to its website.

The company has developed a cartridge — and has manufactured tens of thousands of them for internal use — with an opening at the side to insert the sample, for example a nasal swab. From there, the sample goes into a heated chamber where it is lysed in less than a minute. The cartridge, which slides into a small device, also features a buffer-filled blister and lyophilized real-time PCR reagents.

While LEX had originally set out to develop a fast influenza test, it currently plans to bring a combined flu and SARS-CoV-2 test to market as its first product. The test is already well into development — according to the company's website, it already demonstrated the assay's performance a year ago.

One challenge has been that the flu and COVID-19 viruses are enveloped, so conventional lysis to crack them open has taken about five minutes, Anyakwo said, but LEX has been able to reduce that time to one minute.

Another challenge has been that human samples contain molecules that can interfere with the PCR reaction. For example, he said, mucin in nasal fluid is a major PCR inhibitor and has traditionally required lengthy pre-PCR cleanup. However, LEX has come up with novel compounds that make the PCR reaction tolerant to inhibitors, are compatible with lyophilization, and compare favorably to off-the-shelf inhibitor-tolerant RT-PCR mixes, he said.

After developing and testing the reagents on a conventional thermocycler, LEX has put them through their paces on its own cartridge and platform and has achieved amplification in record time, down to three minutes, Anyakwo said.

While LEX plans to develop a respiratory test first, its platform would also be suitable for other rapid infectious disease tests, Anyakwo noted, such as a strep A test or a Chlamydia trachomatis/Neisseria gonorrhoeae (CT/NG) test. The same underlying technology could in principle also be used to enhance high-throughput testing in central laboratories, he noted.

Anyakwo provided no timeline for the commercialization of LEX's platform, but Chris Hole, the company's VP for commercial development, told GenomeWeb that the goal is to obtain clearance from the US Food and Drug Administration first, which could take some time. The company has no plans to release a research use version of the platform, he added.