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ImmunArray Launches Multimarker Platform With Test to Rule Out Lupus

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NEW YORK (GenomeWeb) – Israel-based ImmunArray is launching a microarray platform along with the SLE-Key Rule out, a multiplex molecular diagnostic test to rule out lupus, which will be the firm's first of several planned tests for the new platform.

The SLE-Key Rule Out test uses microarray technology to detect antibodies against certain antigens that are indicative of the disease. ImmunArray has come up with a six-antigen classifier test that so far can only rule out a diagnosis of systemic  lupus erythematosus (SLE), but has the potential to affirm a diagnosis in a patient and maybe even help physicians monitor disease progression, ImmunArray CEO Scott Batty told GenomeWeb.

The firm is launching SLE-Key and the iChip microarray platform on which the test is based in the US this week.

The iChip platform is based on technology developed by Irun Cohen of the Weizmann Institute of Science in Rehovot, Israel. "It's a basic microarray on a glass slide with microprinting," Batty said, "but unlike proteomics chips or genomics chips, we print a much broader category of molecules that serve as antigen to bind antibodies in the serum of the patient in question."

The iChip platform can print proteins and peptides, short sequences of nucleotides and DNA, as well as cell surface receptors, cytokines, chemokines, and even lipid or carbohydrate-based molecules, he said. In addition to lupus, the firm is also pursuing iChip applications for brain injury and immunoncology.

The firm, he said, has "taken what was a very good but basic research tool and turn it into a commercial-grade manufacturing platform," which has been designed to run on an Agilent Technologies instrument, including the G2565 Series C microarray scanner.

The SLE-Key will be processed at a reference lab the firm is building in Richmond, Virginia. It's not quantitative, but it offers 94 percent sensitivity and 75 percent specificity for ruling out a diagnosis of lupus, Batty said. The test itself is blood-based and requires no special handling or preprocessing. Because the firm has yet to fully scale its operation, Batty said it only runs the test one day per week with a turnaround time of seven to 10 days, but as volume rises, it hopes to reduce turnaround time down to 24 to 48 hours. ImmunArray has currently signed up 15 rheumatology centers in the US to work with the firm in launching the diagnostic testing service.

Batty said the cost of the test is "still to be determined," but it could be priced at a premium to Exagen Diagnostics' Avise test, another multimarker test already on the market. The SLE-Key not only combines some ELISA-based antibody tests that can be ordered individually, but also provides supplementary information that may be of interest to doctors, Batty said. "We're showing they can get the same information and more from our testing platform as they can now."

With the number of potential patients ImmunArray has identified, it estimates that market size at about $300 million in the US. "It's not a billion-dollar market," ImmunArray Chairman Donna Edmonds told GenomeWeb, "but it's an important market." And based on the rheumatology practices already signed up, Edmonds said ImmunArray estimates uptake will outpace previously released lupus tests.

After the test launches in the US, she said the firm expects to go after the European market.

In conversations with rheumatologists, Batty said ImmunArray discovered that the doctors were more troubled by the thought of lupus diagnoses they might have missed than cases that they did catch. "They lose sleep over missing a diagnosis," Batty said. "There might be more value in positive affirmation as opposed to excluding it, but with a disease state as complex as lupus, the ability to exclude that and focus more in other areas is an unmet need."

Lupus is notoriously difficult to diagnose because it probably isn't one disease, but rather a constellation of interrelated or overlapping diseases that closely resemble each other.

Finding the right biomarkers for the different types of lupus and printing them all on the same microarray chip was a great challenge for ImmunArray. The firm selected biomarkers in concert with studies conducted by Irun Cohen, as well as based on a review of the literature from basic science, drug discovery, and clinical trials. It included existing antigens that doctors can currently use to diagnose lupus with ELISA-based tests, like rho proteins, but came up with new ones as well.

ImmunArray has included several proprietary oligonucleotide sequences as antigens on the array, developed after Cohen studied how patients with lupus came to create antibodies against single-stranded and double-stranded DNA.

Getting the different antigens onto the same glass slide provided a special hurdle. ImmunArray was able to get some of the same information about antibodies using peptide reductions, rather than the parent protein, which made it easier to print on a glass slide, Batty said.  

"There's a lot we've learned about using a common chemically activated surface background and being able to print antigens on that in a reliable format," he said. "A number have to be print in different conditions," he added, and steps have to be taken in between the conditions to obtain stability so that the antigens won't be altered by the next round of printing. Because of the complexity in ironing out the specifics of printing the various types of molecules on the chips, ImmunArray has opted to keep the information as a trade secret rather than seek out patents.

The firm devised a six-antigen classifier to create an exclusionary test that provides a high degree of sensitivity to separate cases of lupus from healthy controls, the firm claims. "A number of the existing tests are known to be associated with lupus and can have either high specificity or sensitivity, but the corollary to that particular statistical measure is usually no better than a coin toss," Batty said. ImmunArray's set of classifiers is "very reliable to the point in time when the patient is sitting in the office and the doctor."

That ability to capture the antibodies at the time of the test greatly expands the potential use of the test in the future.

"The next step in development is to make an affirmative diagnosis of lupus in the context of similar diseases like psoriasis and rheumatoid arthritis," Batty said. In addition, ImmunArray could develop the test so that it not only classifies general subsets of disease, but also helps predict specifics about a patient's individual case.

"Can we measure changes in antibody signature? Can we project progression to renal involvement for a patient not known to have that currently?" The answer is "yes," as Batty sees it.

"We have a real ability to monitor the disease dynamically over time and watch the biology of disease change over time," he said.

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