FDA Approves 4th-Generation Latent TB Blood Test

Troy Brown, RN

June 08, 2017

The US Food and Drug Administration (FDA) has approved QuantiFERON-TB Gold Plus (QFT-Plus); (QUIAGEN NV), a fourth generation latent tuberculosis (TB) blood test that combines CD4/CD8 ratio design to complete comprehensive immune response detection with the most adaptable blood collection workflow, according to a company news release.

The product is the newest generation  of the market's leading blood test for detecting latent TB infection, according to the company.

The decision follows consideration of a premarket approval supplement in late 2016, and commercialization of the test is planned to begin in the United States in late 2017.

 "We are pleased by the timely FDA approval for QuantiFERON-TB Gold Plus and that we can now bring a range of very attractive clinical and workflow benefits to customers who have helped us to create the market-leading latent TB testing franchise," Thierry Bernard, senior vice president and head of QIAGEN's Molecular Diagnostics Business Area, said in the company news release.

"Tuberculosis is a global disease that is having an impact in the United States as well, where up to 13 million people are infected and nearly 10,000 people are currently suffering with active disease," he added.

The company previously launched the test in 2016 in more than 75 countries across Africa, Asia, Europe, Latin America, and the Middle East. Almost 2 million of the new tests have been used there to date.

The addition of the proprietary new technology is an important milestone in diagnostic test development for latent TB infections, according to the company. It is the first time a test has the potential to capture a much more complete picture of an individual's immune response to the infection. This is a critical advancement to elucidating how the immune system reacts to the infection, and could set a new standard for disease management in the future.

The test's new features include advances supporting research into the risk stratification of latent TB infections that develop into active disease on the basis of the first-time incorporation of CD8+ T cell response data; this gives researchers valuable new information by measuring a more extensive range of immune response.

Published scientific evidence emphasizes the future potential of CD8+ T cells in distinguishing active from latent TB, identifying recent compared with old infections, and revealing TB in high-risk populations including HIV coinfection and young children, as well as assessing patient response to TB treatment.

"Workflow flexibility that allows for even more efficient implementation, especially in large-scale TB screening programs. These include a standard single-tube blood collection option which allows blood samples to be processed up to 53 hours after venipuncture without affecting the accuracy of the test. This adds to the existing, unique 'assay in collection tube' design allowing for immediate stimulation of the blood sample," the company said in the release.

Task Force Support

QFT-Plus expands on the foundation of the third-generation version of the world's leading interferon gamma release assay (IGRA), QuantiFERON-TB Gold (QFT). It is well proven, has a large body of clinical evidence, and has shown to be cost-effective and efficient, the company states.

A task force society supported by the American Thoracic Society, the US Centers for Disease Control and Prevention, and the Infectious Diseases Society of America released updated evidence guidelines in 2016 recommending the use of IGRA tests in larger groups of those with high risk for TB infections. This recommendation followed those by the US Preventive Services Task Force 3 months prior that urged primary care physicians to screen adults with high risk for latent TB infection. Both groups referred to the QFT as an FDA-approved IGRA at the time that was preferable to the century-old tuberculin skin test in certain patient groups.

Additional trials are currently taking place in 22 countries involving more than 30,000 patients and, to date, nine independent peer-reviewed publications have voiced support of the test. The first trials studied sensitivity in patients with active TB and close contacts, and on laboratory precision and correlation to flow cytometry. The test is currently the only IGRA TB test under evaluation by the World Health Organization included in its global campaign to eradicate TB.

The World Health Organization estimated that in 2015 there were 10.4 million new cases of active TB worldwide and 1.8 million deaths from TB. Latent TB infection (LTBI) causes infection but produces no symptoms unless it progresses to the active disease. Globally, about one in three people have latent TB, which will progress to approximately 5% to 10% of those individuals if they are untreated. Screening of high-risk individuals and treating those with LTBI are critical to curbing TB in the United States, European countries, and developing regions.

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