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T2 Aims for December Start of Clinical Trial for Bacterial Blood Infection Test


NEW YORK (GenomeWeb) – While T2 Biosystems has been focused in recent months on ramping up its sales efforts around the recently approved sepsis fungal pathogen diagnostic T2Candida, the company is also planning for a December start of a clinical study for a complementary sepsis bacteria test.

The two tests are expected to be used in conjunction, enabling clinicians to identify nearly all the pathogens that cause sepsis infections, including ones that typically do not respond to first-line treatment.

Meanwhile, T2 is also gearing up to initiate in the first half of next year a clinical trial of T2HemoStat, a point-of-care hemostasis assay that marks the company's first step beyond its core infectious disease focus.

Last September, the US Food and Drug Administration approved T2Candida for the whole-blood detection of five fungal pathogens — Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, and Candida krusei — that are a common cause of bloodstream infections and sepsis. The agency also cleared the company's T2Dx instrument that runs the panel.

The agency also cleared the company's T2Dx instrument that runs the panel. The bench-top system uses the company's core T2MR magnetic resonance (T2MR) technology, a non-optical detection method that measures how water molecules react in the presence of magnetic fields.

Since then, much of T2's business activities have centered on expanding its commercial infrastructure and marketing efforts to support the test. But T2Candida is only one half of the firm's overall plan to tackle the sepsis market, and T2 is just months away from the start of clinical study for a panel designed to identify bacterial pathogens responsible for the condition.

Of the nearly 1.6 million patients in the US who are diagnosed with sepsis each year, about 40 percent do not respond to first-line treatment with broad-spectrum antibiotics, T2 CSO Tom Lowery told GenomeWeb this week.

Fungal infections account for about 10 percent of these treatment-resistant infections and can be accurately diagnosed with T2Candida, he added. The remaining 30 percent of infections that can't be treated with broad-spectrum antibiotics are due to bacterial infections.

"That is the segment of patients T2Bacteria is going to address," Lowery said. When the two tests are used together in patients suspected of having sepsis, "they will cover over 95 percent of all septic infections."

T2 has not disclosed all of the pathogens on the T2Bacteria panel, but it has said it will include Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus.

At last year's American Society for Microbiology annual meeting, T2 presented preliminary data showing that T2Bacteria was able to detect these three pathogens in spiked whole blood samples at levels as low as 3 colony-forming units per milliliter (CFU/mL). This level of detection, Lowery noted, is in line with what is achieved with T2Candida.

To validate these findings and generate the data needed for regulatory approval, T2 is now preparing to begin a clinical study of T2Bacteria in December — a timeline included in an overview of the study on and one that Lowery called "generally accurate."

That study will include blood samples from about 1,800 individuals suspected of having sepsis. In one arm of the trial, the sensitivity and specificity of T2Bacteria will be compared with blood culture results in about 1,300 patients. In the other arm, T2Bacteria's performance will be evaluated in spiked samples from the remaining 300 patients.

This "just helps ensure that we have enough positive patient samples for the performance of the test to be evaluated," Lowery explained.

He noted that in the T2Candida trial, the company had to include an arm of spiked samples because "the actual number of positive patient samples in the prospective arm was very low." To avoid this issue again, T2 is including a so-called contrived arm in the T2Bacteria study.

Lowery did not provide any guidance on when T2Bacteria might reach the market, assuming a positive outcome to the upcoming clinical study. He did, however, note that the test is expected to have a shorter route to commercialization given that it runs on the T2Dx instrumentation, which has already been approved by the FDA.

As this work continues alongside an early-stage Lyme disease test, T2 is also beginning to expand outside of infectious diseases with T2HemoStat.

Notably, this test is based on T2MR technology, but will run on a different instrument that is designed to be small, simple to use, and provide a number of hemostasis measurements including clotting time, fibrinogen, fibrinolysis, and platelet activity.

For T2HemoStat, "the reagent is simply an activator [for a] coagulation cascade in a blood sample," Lowery said. And unlike T2Candida and T2Bacteria, which require a 4-mL blood sample, T2HemoStat works with 40 microliters of blood — the equivalent of a finger stick of blood.

T2HemoStat is being aimed at healthcare providers in trauma and emergency department environments, he noted. T2 expects to begin a pivotal clinical study of the test in the first half of 2016.