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OGT to Commence Clinical Trial for New Array-based Non-invasive Prenatal Test for Down's Syndrome

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NEW YORK (GenomeWeb) — Oxford Gene Technology this week said it will initiate a clinical trial of a new, microarray-based non-invasive prenatal test for Down's syndrome. According to the firm, the assay has "significant advantages" over established, next-generation sequencing-based approaches, including a reduction in turnaround time, as well as cost.

John Anson, executive vice president of R&D at Oxford, UK-based OGT, told BioArray News in an email this week that the planned clinical trial has been designed to support the CE marking of the product as an in vitro diagnostic medical device in Europe. The study will involve more than 700 blood samples run at three "independent and highly respected" laboratories, Anson said. He did not elaborate.

OGT was founded in 1995 by microarray technology pioneer Edwin Southern. Over the past decade, it has developed and launched a series of microarray and next-generation sequencing products and services, including its CytoSure comparative genomic hybridization arrays for cytogenetics research and pre-implantation genetic screening.

The firm's move into the NIPT market, which includes players such as Illumina, Sequenom, Natera, and Ariosa Diagnostics, comes at a time of heightened competition for what is considered to be an attractive prize: a slice of a market estimated to grow to around $3.6 billion by 2019, according to several market research reports.

OGT's NIPT market entry also raises additional questions about which technology is best for NIPT. Though sequencing has been the platform of choice to date, Ariosa Diagnostics recently demonstrated that using Affymetrix microarrays in its NIPT offering produced more accurate results with shorter turnaround time compared to Illumina sequencing.

According to Anson, OGT sees similar benefits in using arrays over sequencing.

"As a leading provider of products and services for molecular genetics, OGT is ideally placed to identify and deploy the optimal technology for novel application areas," said Anson. "When looking at existing sequencing-based NIPT approaches, it was clear that microarray technology could offer some significant advantages, including lower cost, reduced time to result, and ease of analysis," he said. Given these perceived benefits, OGT initiated a project to evaluate the use of microarray technology for NIPT two years ago, Anson noted.

Unlike the potential implementation by Ariosa of an array-based service, OGT intends to make its NIPT offering available as kits, a difference that the firm hopes to use to its advantage, as laboratories will for the first time be able to offer NIPT in house.

"Microarray technology is already a front-line test for research into variety of genetic disorders and, as such, clinical research labs already have the scanners, other equipment, and trained personnel to carry out the work," said Anson. "We envision our NIPT product seamlessly integrating into the existing clinical research workflows, providing faster and much more cost-effective access to results than currently available," he said.

OGT has also been expanding its sales and support infrastructure in recent years, including the opening of an office in New York in 2012, and believes its growing team will allow it to "rapidly and successfully" enter the market with its array kits, Anson said.

"Our hope is that this test, once it is clinically validated, will be widely adopted by clinical testing laboratories to ensure more pregnant women and their clinicians can access this highly sensitive, rapid, and safe procedure," said Anson.

Though he did not provide a timeline for introducing the test in the US, Anson said that the data from the clinical trial as well as generated by European customers could provide the basis for an FDA filing.

While OGT has not entirely divulged its NIPT approach, it has made a few claims so far. In a statement this week, it said that the time to result has been reduced to less than three days from up to 10 days, which includes the time to ship a sample to a company for analysis. The company also said its methodology includes a combination of sample preparation procedures, array design, and analysis software.

"The fetal DNA fraction in maternal blood is very low," Anson said of OGT's approach. "To address this, OGT has developed a proprietary DNA amplification protocol to ensure sufficient quantities of high-quality DNA for accurate analysis," he said.

In terms of array design, Anson said it has been "critical" to ensure that only informative probes are included on the chips. "It is vital that the probe content matches the DNA fraction amplified from the maternal blood sample," said Anson. "This minimizes the potential for background noise and thereby provides clear results," he said.

Agilent Technologies manufactures OGT's arrays, printing eight arrays on each microscope slide. Each array contains about 60,000 probes. "We believe this format strikes the right balance between the needs of both the higher and lower throughput future users of the array," said Anson.
He added that OGT is also designing a new software package for NIPT that will be compliant with International Electrotechnical Commission standard 62304, which provides benchmarks for software to comply with regulatory requirements in both the US and Europe.

OGT has already successfully completed a pre-clinical trial of its new test using 200 samples from three independent sample sets across two different sites, and achieved "exceptionally high sensitivity and specificity" for the detection of Down's syndrome, according to the firm. In addition to detecting Trisomy 21, it is expected that in the future the technology will also identify other chromosomal aneuploidies and microdeletions, Anson said, though he didn't provide further details.

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