NEW YORK (GenomeWeb) – Sequenom next month plans to launch in international markets a second noninvasive prenatal test, called VisibiliT, that targets women with average-risk pregnancies and has both lower cost and content than its existing MaterniT21 Plus test,. The firm will also further expand MaterniT21 Plus, which it offers for increased-risk pregnancies, to include three additional clinically relevant microdeletions.
Sequenom revealed earlier this year that it was working on a lower-cost sequencing-based NIPT for average-risk pregnancies, to be launched before the end of this year, and VisibiliT appears to be the fruit of that labor.
VisibiliT will only look for the two most common trisomies, Down syndrome/trisomy 21 and Edwards syndrome/trisomy 18. As an additional option, it will report the fetus' sex.
By comparison, MaterniT21 Plus reports on trisomies 21, 18, and 13, a number of sex chromosomal aneuplodies, and, under the "enhanced sequencing series," on trisomies 16, 22, and various microdeletions.
Unlike MaterniT21 Plus, which provides test results as either positive or negative, VisibiliT will report a risk score that is based on maternal age, fetal fraction, and the relative amounts of chromosomes 21 and 18.
According to Sequenom CEO Bill Welch, VisibiliT is modeled after existing noninvasive first-trimester screening tests. These screens usually combine a blood test for two pregnancy-associated proteins, PAPP-A and hCG, with an ultrasound to measure nuchal translucency and also provide a risk score for trisomy 21, trisomy 18, and sometimes trisomy 13. However, he said, VisibiliT is "much more accurate" than current first-trimester screens.
The list price for VisibiliT is $790, compared to $2,762 for MaterniT21 Plus. Both tests can be performed as early as 10 weeks into pregnancy, and their turnaround times are expected to be similar, approximately five days, according to the company.
While VisibiliT is offered to women carrying a single fetus whose pregnancies are considered average risk, MaterniT21 Plus is available to pregnant women at enhanced risk for fetal chromosomal aneuplodies due to advanced maternal age, personal or family history of chromosomal abnormalities, a fetal abnormality on an ultrasound, or a positive serum screening test. This includes women with multifetal gestations.
Sequenom Laboratories, the company's CAP-accredited and CLIA-certified laboratory, will offer both tests as a service. Initially, VisibiliT, like MaterniT21 Plus, will run on Illumina's HiSeq platform, according to Welch, although it will use a different process and bioinformatics, and shorter reads.
Earlier this year, the company had said that the new test would run on a different platform and that it was exploring a number of technologies. At the time, it also predicted that the new test would be similarly priced to serum screens, on the order of $250 to $300, but the initial price is more than twice as much. Welch said Sequenom will continue to bring down the cost of VisibiliT as test volumes increase.
Sequenom has performed a clinical evaluation study of VisibiliT with more than 1,000 samples, and this week presented a poster on the results, including the risk score analysis, at the International Conference on Prenatal Diagnosis and Therapy in Brisbane, Australia.
According to the poster, 84 percent of the samples, from singleton pregnancies with known outcome, came from a low-risk population, and the remainder from a high-risk population, including women above and below age 35. Circulating free DNA from maternal plasma was sequenced at low depth of coverage on an Illumina HiSeq 2000, and the risk score was calculated based on maternal age and the sequencing results.
Sequenom said the study demonstrated a sensitivity and specificity of greater than 99 percent for trisomies 21 and 18. All 21 trisomy 21-positive samples and all 10 trisomy 18-positive samples in the study were classified as high risk, and all 1,027 non-trisomy 21 samples and 1,038 non-trisomy 18 samples as low risk.
By comparison, the current first trimester combined screen has a sensitivity of less than 90 percent and a specificity around 5 percent.
Sex determination was 99.3 percent accurate: four out of 525 female fetuses were incorrectly classified as male, and three out of 523 male fetuses as female.
Starting next month, Sequenom will offer VisibiliT in several unspecified countries through its international distribution partners, but not in the US because reimbursement for the test is currently unclear. According to the company, it "will continue ongoing discussions with payors in the US and is prepared to offer the test in the US as insurance coverage develops."
"We are going to be very judicious in the US, because while there may be a need, it's unclear what the payment process will be for this year," Welch said.
For MaterniT21 Plus, the company had 140 million lives covered under contract as of June. However, due to changes in reimbursement codes, the company has had trouble collecting reimbursement from both commercial and government payors.
As it prepares to roll VisibiliT out abroad, Sequenom is further expanding the content of MaterniT21 Plus. As part of its "enhanced sequencing series" of additional content that Sequenom started adding last October, the company will "soon begin" to report the presence of three additional sub-chromosomal microdeletions on chromosomes 11, 8, and 4 that cause Jacobsen syndrome, Langer-Giedion syndrome, and Wolf-Hirschhorn syndrome, respectively. It reported study data on the new content at the meeting in Brisbane this week.
Unlike VisibiliT, "the content for MaterniT21 Plus continues to get broader and richer," Welch said, with the ultimate goal of mirroring the content of diagnostic microarrays.