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NX Prenatal Data Suggests Test Could Assess Preterm Birth Risk as Early as 10 Weeks Gestation


NEW YORK (GenomeWeb) – Prenatal diagnostics firm NX Prenatal presented findings at last week's Society for Maternal-Fetal Medicine's Annual Pregnancy Meeting in Atlanta that indicated the company's exosome-based proteomics approach might be able to identify pregnant women at risk of preterm delivery earlier in pregnancy than previously thought.

In the study, researchers associated with the company found that a panel of two markers was able to identify women who would go on to deliver prior to 34 weeks using plasma specimens collected at between 10 and 12 weeks gestation. The pair of markers identified these women with a sensitivity of 80 percent and a specificity of 78 percent.

In fact, NX Prenatal CEO Brian Brohman, told GenomeWeb, this panel represented early-stage work and the company believes that, ultimately, a panel of around 8 to 12 proteins will be optimal for identifying women at risk of preterm delivery. However, he also noted the significance of the study in demonstrating the possibility of identifying these women as early as 10 weeks gestation.

"The feedback we have from physicians, is that the earlier we can help them risk-stratify these patients, the better chance they have to intervene and cause positive feedback," Brohman said.

In previous work, the company identified an 18-protein panel that could distinguish between women who would deliver preterm and at-term with accuracy in the 80 percent range. That panel used samples taken at between 15 and 17 weeks gestation. 

"So this is a striking finding, to be able to take the same approach and move the analysis backwards to week 10 to 12 and be able to find a statistically significant signal at that time," Brohman said. "That is a compelling move in the right direction."

Being able to move the time of diagnosis back to this earlier point could be particularly important given that NX Prenatal will be at best the second company to market a proteomic test for assessing risk of preterm birth. Sera Prognostics, which also presented at the SMFM meeting last week, did a limited launch of its PreTRM preterm birth test last year and is now preparing for wider release.

In data presented last week, the test, which uses multiple-reaction monitoring mass spec to measure the levels of the proteins insulin-like growth factors binding protein 4 (IBP4) and sex-hormone binding globulin (SHBG), was able to identify women who gave birth at or before 35 weeks gestation with an area under the receiver operating curve (AUC) of .93. It identified women who gave birth at or before 37 weeks with an AUC of .75.

The PreTRM test, however, is intended for use at 19 weeks gestation, which is significantly later than the 10 to 12 weeks the recent NX Prenatal study suggests could be possible.

"Early detection is what we are focusing on, and that is an advantage if we can commercialize the test at that time period," Brohman said, discussing what advantages might allow his company's test to make inroads despite coming to market after the PreTRM test.

There are other differences, as well. While the Sera test is validated for predicting risk of delivery prior to both 35 weeks and 37 weeks gestation, the NX Prenatal data released thus far has looked only at women delivering prior to 34 weeks gestation.

In any case, the NX Prenatal test is still in the development stage. And while Sera's PreTerm test ultimately consisted of only two markers (early versions of the test included as many as nine), Brohman said he and his colleagues believed that their assay would ultimately require up to a dozen proteins.

"Pregnancy is a network of interrelated systems between the mom and the baby, and those systems have to stay in balance for a pregnancy to proceed all the way to its natural 40-week delivery outcome," he said, noting that these systems include things like adaptive immunity, inflammatory processes, and coagulation functions.

"So what we feel our approach is picking up are the nodes in that network of important biological functions that need to stay in balance [for a full-term pregnancy]," he said. "And in order to pick up the appropriate number of signals we believe the ultimate test will be an 8- or 10- or 12-plex.

Like Sera with PreTRM, NX Prenatal is using MRM mass spec for its test. Somewhat uniquely, the company is focusing not on protein biomarkers circulating in the blood but rather on proteins contained in exosomes, which it hopes will help with sensitivity.

Exosomes are membrane-bound particles released by cells that contain molecular content including proteins and nucleic acids from their cell of origin. A number of researchers are exploring these vesicles as part of biomarker development work, the idea being that their contents could shed light on the function and status of their source tissue.

Based in Louisville, Kentucky, the firm is a spinout of parent company NX Pharmagen, which Brohman and Co-founder and CSO Alan Ezrin launched to commercialize exosome-based diagnostics more generally, with a focus on oncology and prenatal medicine. They established NX Prenatal to house NX Pharmagen's prenatal assets after deciding that a more focused entity would help with commercialization efforts.

Brohman declined to provide a timeline for development of a final panel or launch of the test, though he did note that the company has a peer-reviewed publication forthcoming detailing its recently completed work.

He declined as well to specify how the company planned to commercialize any test resulting from its work, whether through an internal CLIA lab or a partnership with a larger diagnostics firm or by taking it through US Food and Drug Administration clearance.

"All of those options are available to us," he said.