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T2 Biosystems Preps Clinical Trial for Candida Test in Anticipation of FDA Submission

By Tony Fong

NEW YORK (GenomeWeb News) – Molecular diagnostics firm T2 Biosystems is set to begin a clinical trial for its first assay targeting Candida fungal infections as it prepares to seek regulatory approval in the US next year.

Founded in 2006, the company has largely stayed out of the spotlight, but recently on the sidelines of the 30th Annual JP Morgan Healthcare Conference in San Francisco, its President and CEO John McDonough told GenomeWeb Daily News that the firm anticipates filing for clearance of its Candida assay with the US Food and Drug Administration in about a year, addressing a market that he valued at $1.3 billion in the US alone.

T2's technology, which comes out of research done at the Massachusetts Institute of Technology, uses superparamagnetic nanoparticles made up of a superparamagentic metal core, a polymer layer, and analyte-specific binding agents. Essentially, the technology called T2MR measures the reaction of water molecules in the presence of magnetic fields. This reaction is commonly referred to as the T2 signal.

When a binding event occurs inside of a sample, the T2 signal changes, which makes it possible to detect the presence of an analyte. Additionally, because the T2 signal is a time-based signal, calibration curves can be created, allowing the analyte to be quantified.

The advantage of this approach, McDonough said, is that unlike most other diagnostic detection methods, which are optically based, T2 Bio's method skips sample preparation, resulting in greater sensitivity.

If a researcher is detecting for DNA, for example, the DNA needs to be pulled from the sample, and then amplified. This process, however, can result in the loss of as much as 90 percent of the targeted analyte, compromising sensitivity, according to McDonough.

"What we're able to do, which has never been done before, is we can detect directly in clinical samples," such as whole blood, sputum, urine, and other fluids, he said, adding that T2 Bio's technology improves sensitivity over other technologies already on the market by as much as two orders of magnitude.

T2 Bio's first application of T2MR is for sepsis with an initial focus on Candida.

In the US, Candida affects about 90,000 people each year with a 40 percent mortality rate. While other firms such as Bruker, BlackBio, and Miacom have or are developing kits and instruments for detecting sepsis, Candida is mainly diagnosed by blood culture testing.

A drawback of blood culture is that it has a turnaround time of between two to five days, though, and studies have suggested that if detection can be lowered to 12 hours, the 40 percent mortality rate can be reduced to 11 percent, McDonough said. At the same time, hospitalization costs for each patient can be lowered to $80,000 from $130,000.

T2 Bio has developed an assay that can detect Candida in two hours, "and we're hopeful that we can reduce that mortality rate below the 11 percent number by being able to detect in two hours instead of 12," McDonough said.

Importantly, T2 Bio's assay can detect each of the five species of Candida, important because the treatment a patient receives depends on the species of the fungus.

In an internal study using spiked clinical isolates, T2 Bio found that its Candida assay had a 95 percent positive correlation and a 98 percent negative correlation with culture-based tests. In a follow-up study with patient samples, the company found similar "excellent concordance" with blood-culture based methods, it said in a poster presented at the 2011 Interscience Conference on Antimicrobial Agents and Chemotherapy.

The assay also has a lower level of detection — and thus greater sensitivity — than blood culture, according to McDonough. While blood culture can detect Candida at a level of 10 colony-forming units, or CFU, per milliliter, internal data indicates T2 Bio's test detects Candida at 1 CFU per milliliter, which he said is unprecedented.

Most molecular platforms have a level of detection of about 100 CFU per milliliter, which is why other molecular diagnostic makers haven't yet developed a Candida test, he added.

T2 Bio has also developed an instrument to run the assay. Called T2 Dx, the platform, which also can run immunodiagnostic tests, is in the second iteration of its beta version, and the company is setting up a clinical trial for the instrument and the assay in preparation of a submission to the US Food and Drug Administration seeking both 510(k) and de novo clearance.

The company has identified 15 infectious disease centers nationwide to conduct the trial and will begin collecting patient samples in the current quarter and place its instruments in the centers in the third quarter. The trial is anticipated to enroll about 400 patients.

T2 Bio expects to file for FDA clearance of its Candida test in the first part of 2013, McDonough said.

In addition to the $1.3 billion US market, he estimated the global market for the test at about double that. When it goes to market, T2 Bio will use a direct sales force in the US and distributors outside of the US. It has begun discussions with distributors in Europe and Asia-Pacific, McDonough said.

The company also is developing a bacterial panel, which by design, is about 12 to 18 months behind the Candida panel in development. That panel is for the detection of the bacterial pathogens for sepsis, though McDonough declined to identify specific species because of competitive concerns.

The bacterial panel along with the Candida panel would be able to detect 99 percent of all causes of sepsis, he said.

In addition, T2 Bio is eyeing development of tests for infectious diseases, such as Clostridium difficile, and for therapeutic drug monitoring. Some of that work will be done solely by the company, but other tests may be developed through partnerships.

While the firm's technology can be eventually engineered for point-of-care tests, it initially is being designed to handle "reasonable throughput" in a hospital setting, McDonough said.

During the summer the Lexington, Mass.-based firm said it raised $23 million in a Series D financing round, which McDonough said will get T2 Bio to its FDA submission for the Candida assay. Since its inception, the firm has raised about $50 million.