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German Research Project Shows Feasibility of SARS-CoV-2 Testing Using Hologic LDT Functionality

NEW YORK – Investigators at Hannover Medical School in Germany announced Thursday that they have developed a molecular assay for detecting SARS-CoV-2 using the open-access protocol on Hologic's automated Panther Fusion system.

The preclinical assay, described online in the Journal of Clinical Virology, enables random-access, real-time PCR-based detection of SARS-CoV-2 within 3.5 hours from sample to result, the researchers said.

Rapid diagnosis of many infectious diseases, including  SARS-CoV-2, is essential in order to implement therapeutic and infection prevention measures. The Open Access functionality on the Panther Fusion system allows accredited medical laboratories to design and validate laboratory-developed tests to run on the fully automated, high-throughput platform. Laboratories in Europe and elsewhere can run their LDTs along with commercially available IVD assays in a random-access mode, without waiting to batch tests, according to Hologic.

Diagnosis of infections can be achieved more rapidly with a random-access approach than with batch testing in which laboratorians may have to wait until they have accumulated a batch of samples before running tests, Maurice Exner, Hologic's vice president of research and development for diagnostic assay development, said in an interview.

In the context of coronavirus testing, "laboratories can run the US Centers for Disease Control and Prevention assay or their own designs," Exner said.

As a result, the Panther Fusion function that Hologic has called Open Access has the potential to help broaden access to coronavirus screening, Exner added.

"At this point in the outbreak of the coronavirus, it's useful for any lab to have the ability to run tests on one to a few samples alongside samples being tested for other infectious diseases," he said, adding that with this approach, "you don't have to occupy the whole instrument for an extended time to complete a few coronavirus tests."

If the disease spreads and requires high-volume testing, on the other hand, the Panther Fusion has the capability to test about 1,000 samples per day, he said. Further, the company is developing its own SARS-CoV-2 test to run on the Panther system and expects to submit an Emergency Use Authorization application soon with the US Food and Drug Administration.

Other diagnostic tests to detect SARS-CoV-2 are being developed to run on random-access instruments, but only for those that run low volumes, Hologic said.

Random-access testing on the Panther Fusion system permits immediate processing of diagnostic specimens "including RNA extraction, amplification of target sequences, and real-time detection of PCR amplicons," the German researchers said in a letter published in the Journal of Clinical Virology.

The Hannover Medical School investigators adapted two recently published PCR protocols to run them on the Panther Fusion system, using inactivated virus from cell cultures and commercially available control materials. The PCR protocols detect either the E gene of the old 2002 SARS-CoV; SARS-CoV -2 and closely related bat betacoronaviruses; or specifically the RdRp gene of SARS-CoV-2.

For the project, Berlin, Germany-based Tib Molbiol provided positive control RNAs and premixed primer/probe sets, while Hologic provided RNA/DNA extraction and amplification reagents.

The Hannover Medical School investigators said they intend to next validate the assay using clinical samples, but the assay has not received CE-IVD certification in Europe or clearance from the US Food and Drug Administration.

At the American Clinical Laboratory Association's 2020 Annual Meeting Wednesday, representatives from the FDA made the case that the agency's response to the SARS-CoV-2 outbreak may be instructive for the future oversight of laboratory-developed tests.

High-complexity CLIA labs in the US have become eligible under new FDA guidance issued on Feb. 29 to create their own diagnostic test kits to detect the SARS-CoV-2 virus that causes novel coronavirus disease COVID-19. In response to encouragement from a number of stakeholders, the FDA has broadened its emergency use authorization process for tests. High-complexity labs, of which there are approximately 11,000 in the US, are now permitted to develop their own tests.

Robert Boorstein, a Hologic Panther Fusion user and medical director for oncology and esoteric testing at Brooklyn, New York-based Lenco Diagnostic Laboratories, said the Hannover Medical School approach could be useful for labs that already have Panther Fusion systems and have been using the open-access channel. "For labs that have not been using the channel, they might prefer to wait for the [Emergency Use Authorization] reagents to be released," he said.

A random-access test is probably most desirable for a hospital-based lab, he noted. From a reference laboratory perspective, unlike a chemistry platform, most random access molecular diagnostic platforms are unlikely to run 24 hours a day, so that could take away some of its advantage, Boorstein added.

Although recent guidance changes coming from the FDA make applying for Emergency Use Authorization less onerous, "I am not sure how many labs have the experience, expertise, and resources to do an FDA EUA submission," Boorstein added. "Our preference is that manufacturers get the EUA because that makes it far easier for us to launch the test, and manufacturers can support that process to a greater degree."

Hologic launched the Panther system in Europe in 2010 and in the US in 2012. The firm recently announced that it is adding functionality to the Panther fully automated testing platform with sample-to-result automation, adaptable workflow options, and a consolidated testing menu.

In 2018, it formally introduced the Open Access functionality enabled by new software designed to help laboratories create protocols, analyze data, set thresholds, and interpret results.

A number of diagnostic companies are providing systems that consolidate routine laboratory-developed tests with pre-manufactured in vitro diagnostic test kits on a single molecular platform, enabling automation of manual tasks and lab efficiencies.

"There are a number of laboratories out there that do a lot of testing for infectious diseases that are well-prepared to set up lab-developed tests for the coronavirus," Boorstein said. "However, I am not sure that's true for the average lab. Many small- and mid-size labs do not have the resources or skillsets to do this, and people generally underestimate the cost and complexity of doing lab-developed tests."