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Gradientech Launches Clinical Study of AST System to Support Commercial Launch


NEW YORK ─ Swedish microfluidics firm Gradientech has launched a clinical study for its QuickMIC antibiotic susceptibility testing system as it targets a near-term European launch.

The Uppsala-based firm and its collaborators will be testing the system's performance in sepsis, using roughly 100 samples collected prospectively from several European university hospitals along with 350 isolates collected from sites around the world.

The study will last roughly three to four months and will support the company's effort to secure CE-IVD marking for the QuickMIC system, said Gradientech CEO Sara Thorslund. She said the company plans to launch the system this summer starting in Spain, Portugal, and the Nordic region, followed by targeting additional countries in Europe.

The QuickMIC system uses Gradientech's microfluidics technology to establish a series of antibiotic gradients in which clinicians can grow their samples of interest to gauge their susceptibility to these drugs. According to the company, the system generates antibiotic susceptibility data in as little as two hours, significantly faster than the 24 or more hours typically required by the culture-based methods commonly used in clinical AST work.

Gradientech was founded in 2009 as a spinout from Uppsala University and began to develop the QuickMIC system around 2012. It also offers microfluidic-based, cell-based assays on its CellDirector research platform.

The system uses agarose gels embedded with the bacteria of interest and treated with a gradient of different antibiotic concentrations. These gels are then monitored using automated microscopy to assess microcolony growth, allowing clinicians to generate minimum inhibitory concentration, or MIC, values for the microorganism-bacteria pairings to assess susceptibility.

Use of the concentration gradient provides higher resolution data on bacteria growth, which allows the platform to calculate MIC values more rapidly.

The company has looked at a variety of infection types in its QuickMIC development work but will be focusing on sepsis in the clinical study and its forthcoming commercial launch.

"We and other rapid AST companies are focused on sepsis because they are the most time-critical samples, and the willingness to pay for AST rapid testing is highest with sepsis samples," Thorslund said.

A number of companies including Specific Diagnostics, Accelerate Diagnostics, and Q-linea have already received CE-IVD marking for rapid AST testing of positive blood cultures. Accelerate's PhenoTest BC has also received US Food and Drug Administration 510(k) clearance.

Thorslund said that Gradientech believes the QuickMIC system can compete with other vendors based on the system's speed. QuickMIC typically delivers results in two to four hours compared to between three and seven hours for most of its competitors.

She said the company also believes its ability to provide a more precise read of antibiotic resistance will prove attractive in the long term. AST results are typically reported as MICs, a measurement of the lowest dilution of an antibiotic mixture that will inhibit a microbe's growth.

"MIC values are usually reported in two-fold dilution steps, that is, two, four, eight, 16, 32, and so on," Thorslund said. "But you can't get any information in between that."

Because the QuickMIC system is measuring microorganism growth along a gradient of antibiotic concentrations, it is able to provide finer-grain information about a pathogen's susceptibility. Thorslund said that while the majority of doctors still view the question of resistance or susceptibility as a binary, an increasing number of clinicians are interested in more precise MIC values, which she noted can help inform dosing decisions.

She said that demonstrating the clinical utility of more precise MIC values is a research area Gradientech plans to tackle in the future.

To receive CE-IVD mark, the system must achieve 90 percent agreement with conventional AST. Thorslund said Gradientech has already run a version of the current study internally including a wide range of bacteria isolates but also using clinical samples from Uppsala University Hospital and met the required performance.

"We should be successful as we are essentially doing [the same study] again, yet with an increased number of specimens" she said.

In a study published in mBio in 2020 testing 21 clinical isolates, the QuickMIC platform showed agreement of 80 percent, 100 percent, and 80 percent for gentamicin, ofloxacin, and tetracycline, respectively and 100 percent, 82 percent and 74 percent for amikacin, ceftazidime, and meropenem, respectively. The system's very major error rate (meaning when a resistant strain is classified as susceptible) was 26.2 percent, while its major error rate (susceptible strains classified as resistant) was 3.7 percent, and its minor error rate (resistant strains misclassified as sensitive with increased exposure or vice versa) was 9 percent.

The study will test a panel of 12 antibiotics focused on Gram-negative bacteria as a start. Thorslund said that there is a stronger clinical demand for rapid sepsis AST tools for Gram-negative compared to Gram-positive bacteria due to the greater success and availability of molecular tests to address the latter class of organism. She said Gradientech plans to start a clinical study evaluating the QuickMIC panel for Gram-positive bacteria toward the end of 2022.

Gradientech's plans for a CE-IVD mark have been delayed several times. In a 2018 interview, Thorslund said the company hoped to secure the CE-IVD mark by the spring of 2019. In early 2020, she said the company was planning to start clinical performance trials for the system in the fall of that year and expected a CE-IVD mark following those trials.

The European Union's new IVD regulations, which are slated to go into effect in May, are considerations for diagnostic firms operating in the EU, and Thorslund said Gradientech has "done significant preparation to meet the IVDR during the development of QuickMIC," noting, for instance, that the current clinical trial "is harmonized to meet IVDR requirements."

She said the company plans to start the IVDR certification process shortly after receiving the CE-IVD mark.

Gradientech also aims to conduct a clinical study for the system in the US to support a submission with the FDA, though Thorslund said the company has not yet planned it in detail.