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Another Mass Spec Test Moves to Clinic as Sera Launches Preterm Birth Risk Panel


NEW YORK (GenomeWeb) – Sera Prognostics said this week that it will roll out a limited commercial launch of its PreTRM proteomic test this fall for assessing women's risk of preterm birth.

With the launch, the company becomes the second company to bring a multiplexed, MRM mass spec-based proteomic test to market, following in the footsteps of Integrated Diagnostics, which launched its Xpresys Lung cancer test in 2013.

Sera will use the limited launch to collect a variety of data on the test, Gregory Critchfield, the company's chairman and CEO, told GenomeWeb.

"How well it performs, what the turnaround time ends up being — these are all things we are looking at before we do a broader launch" in 2016, he said.

While mass spec throughput will not be a limiting factor during this year's limited launch, the company is currently at work implementing higher-throughput workflows capable of accommodating the large patient population it ultimately hopes to capture, Critchfield said.

"We are working with our vendor [Agilent] and internally on how you scale up, because we will have to get to much larger volumes of testing since the patient population that we are interested in is very large," he said.

Sera is "looking at improvements in chromatography [and] simplification of the front-end [sample prep] with robotics and other things," as it works towards upping throughput, Critchfield said.

In 2013 Sera and Agilent signed a strategic partnership deal under which Agilent was to help Sera develop assays for its test, and, as part of the deal, Sera purchased multiple Agilent 1290 Infinity UHPLC systems, 1260 Infinity LC systems, and 6490 iFunnel triple quadrupole mass spec instruments. Critchfield said this week that Sera will run the PreTRM test on the 6490 instrument out of its CLIA lab.

Another challenge for companies looking to move mass spec assays into the clinic has been developing approaches for correcting both for natural variability in the patient population and portions of the mass spec-based protein quantitation process – perhaps most notably trypsin digestion.

In the case of Indi's Xpresys, the company used a combination of traditional stable isotope-labeled peptide standards along with a set of endogenous protein standards, which allows it to control for both the workflow's analytical variability and pre-analytical variability.

Critchfield declined to go into detail on how Sera controls for similar variability in its assays, noting that the company plans to present on its methods in detail in upcoming scientific meetings. He said, though, that he expects the approach to be "of interest to the scientific community," adding that the company is using a combination of existing approaches adapted to the particular needs of its assays.

Sera is rolling out the early launch in several clinical sites that participated in the company's 5,500-patient Proteomic Assessment of Preterm Risk clinical study. The company said this week that it has completed the PAPR study and plans to present data from it at a scientific meeting in the first quarter of 2016.

Sera has not released any data from the study on the test's performance, but last year Critchfield told GenomeWeb that early feasibility studies had put the specificity and sensitivity of the panel in the 80 percent range.

In a study published in the November 2010 issue of the American Journal of Obstetrics and Gynecology, the test demonstrated sensitivity of 86.5 percent and specificity of 80.6 percent for preterm birth at 28 weeks of pregnancy. In February 2011, the company presented data at the Society for Maternal-Fetal Medicine's annual meeting in which the test predicted preterm birth at 24 and 28 weeks gestation with 94 percent sensitivity and 85 percent specificity.

The PreTRM test, which is intended for use in women with singleton pregnancies, predicts risk of preterm labor at around the midpoint of pregnancy by measuring the levels of nine peptide or protein markers.