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Linear Diagnostics Eyeing 2022 Launch for Point-of-Care STD Testing Platform


NEW YORK – Linear Diagnostics is moving ahead with plans to debut a new point-of-care platform for sexually transmitted disease testing, with the aim of having it available for clinical use in Europe sometime next year. 

CEO Brendan Farrell said that the Birmingham, UK-based firm is working with Cambridge, UK-based R&D consultancy firm Sagentia to develop the cartridges and reader for its first assay, a duplex test for gonorrhea and chlamydia. Linear Diagnostics is also raising money to support its efforts, and recently secured £800,000 ($1.1 million). The firm intends to raise more, Farrell said. Linear Diagnostics is also seeking partners to help it market its test platform worldwide.

"We are going to raise a significantly larger sum of money because the development of the cartridge and instrument is certainly not going to be done for £800,000," said Farrell. "We are probably looking at a figure closer to £3 or £4 million sterling," he said. "We are starting to go out and raise funds from venture capital firms, but, importantly, we are looking for partners who would work on test development and may be interested in marketing the product ultimately." 

Linear Diagnostics' story stretches back a decade to 2011, when the company spun out of the University of Birmingham's School of Biosciences. Its core technology revolves around linear dichroism, which relies on the use of polarized light to detect the presence of molecules in solutions. The platform can use antibodies, antibodies, or oligonucleotides to capture target DNA sequences, and is capable of detecting multiple infections in a sample in about 15 minutes by using different colored dyes.

More specifically, the technology relies on the arrangement of nanometer-sized molecules arrayed in a microfluidic chamber within a test cartridge. The firm's cartridges are self-contained, sterile, and include all reagents necessary to carry out an assay. With the help of a handheld external optical device, users can detect the molecules' alignment in the chamber by shining polarized light from different angles into the test cartridge. They can also modify the molecules with detection probes that bind to targets in solution.

If bacteria are present, the probes in the cartridge will bind to bacterial targets, and the alignment of the attached molecules in the microfluidic flow will shift. Attached probes can be antibodies that can recognize markers, for instance, or smaller segments of DNA, such as genetic sequences that recognize specific transcripts or genes that code for antibiotic resistance.

According to the company, its use of dyes for multiplexing allows it to use inexpensive optical components for detection as well as to miniaturize the system, so that it can be portable and run using an internal rechargeable battery.

In Farrell's words, Linear Diagnostics' team – which numbers about 10 full-time employees plus numerous ad hoc contributors – excels at chemistry, but is not versed in platform technology development, which is why it has partnered with Sagentia. He said the company's most recent financing will help move Linear Diagnostics' test onto a point-of-care platform.

"We can do linear dichroism fine in the lab, but we want to be able to test people in a sexual health clinic or in a hospital, in front of the patients themselves," said Farrell. "To do that, we need a single use cartridge and a reader."

Carl Hewitt, design and innovation manager at Sagentia, said the company is using its diagnostic development experience to "converge on a low cost per test proposition" for Linear Diagnostics.

"We have deployed a team to augment Linear's own in-house expertise with assay, mechanical, systems, and human factors engineers," Hewitt said via email. "This multidisciplinary approach is crucial when considering CLIA-waiver use experiences," he said. "Point-of-care applications are challenging with many development tensions between commercial viability, functionality, and usability," Hewitt added.

Farrell said that Linear Diagnostics decided to target sexually transmitted diseases because the company believes that it is an underserved market insofar as point-of-care platforms are concerned, with just a handful of rivals.

Two potential competitors are Binx Health and Cepheid. Binx provides a point-of-care test for chlamydia and gonorrhea on a PCR amplification and electrochemical detection-based platform. The test achieved a CE-IVD mark and US Food and Drug Administration clearance in 2019. Cepheid, part of Danaher, offers a real-time PCR-based test called GeneXpert CT/NG for the same indications. Turnaround time varies between the tests. While Linear Diagnostics claims its platform will produce a result in about 15 minutes, Binx's test takes 30 minutes, and Cepheid's about an hour and a half. Farrell declined to discuss pricing for Linear Diagnostics' test at this time.

According to Farrell, there is room for new platforms in the field. "It's a significantly sized market and underserved in the point-of-care segment, which is what made us decide to go after that market."

He also noted that patients presenting with symptons of sexually transmitted diseases often do not return to learn of their results, either out of fear or just because they forget, and therefore having a point-of-care platform that can produce a result while the patient is at a clinic or hospital is imperative.

"Our purpose is to have the patient in front of the practitioner, take a sample, run the test, see if it is positive or negative, and, if positive, put the patient on an antibiotic if necessary," said Farrell. "It's a much better way of practicing medicine and certainly in the sexually transmitted infection area."

The UK left the European Union last year and is transitioning to a new regulatory regime administered via its Medicines and Healthcare Products Regulatory Agency. However, UK companies can still obtain a CE-IVD mark and offer them for clinical use throughout Europe until June 2023, which Farrell said Linear Diagnostics intends to do. "By getting the marking by that time, we won't have to go a separate regulatory pathway," he said.

Yet there is no question that the US is on Linear Diagnostics' horizon. "For a point-of-care system like this, the US would be a very attractive market," said Farrell. The company's strategy is to find a partner to take its platform into the American market, assisting with necessary regulatory submissions along the way.

The product is being designed to obtain a CLIA waiver, meaning that it will be so simple to administer that even untrained personnel can carry out testing. "That way, it doesn't have to be used by a healthcare professional or run in a laboratory environment," he said. Farrell did not provide a timeline for US entry. He also said that Asia-Pacific and Europe are also significant opportunities for the company. In these geographies, the company will also court partners.

"We are a small company and wouldn't have the muscle to market this worldwide," said Farrell. We are looking for people who would be interested in working with us as development partners, marketing partners, or to take the product out into the market."

Sexually transmitted diseases are not Linear Diagnostics's only interest. Farrell said the company is currently looking into other potential applications. "Linear dichroism is very flexible," he said. "We are using a molecular technology, but it can support immunoassays using antibodies and antigens as well," said Farrell. Technically, he noted, the platform could enable antigen and antibody testing in the same immunoassay. "You can mix and match both," he said.