There's a new player in personalized medicine: molecular allergy testing.

"We're not in the genomic testing business, so it may not be as obvious to the casual observer that we have an important place in personalized medicine," explains Robert Reinhardt, MD, chief medical officer of ImmunoDiagnostics of Thermo Fisher Scientific (formerly Phadia). "Individuals are unique in terms of their sensitization patterns. More sophisticated testing technology in this area will have a positive impact on patients through personalized education, therapies, guidance and outcomes."

The need for more advanced allergy testing was underscored by a 2011 allergy report from Quest Diagnostics' Allergies Across America study, the largest study of allergy testing in the United States to date.

According to Quest Diagnostics' study summary, allergies affect one in five Americans, and result in 17 million physician office visits, 30,000 ED visits and several hundred deaths yearly. The study found that the overall allergen-sensitization rate increased across the four-year study period by 5.8 percent, while the number of patients tested for 11 specific allergens (egg white, milk, peanut, soybean, wheat, ragweed, mold, two types of dust mites, cat skin and dog dander) increased 19 percent -- "significantly faster than growth in laboratory testing in general."

ImmunoDiagnostics' ImmunoCAP® allergy tests for whole allergens have been on the market for 20 years and have grown to a catalogue of about 600 IgE tests. In 2011, the company's first recombinant component allergy tests were cleared by the FDA, among them a highly touted peanut component test (uKnow® Peanut Molecular Allergy Test) . In addition, new microarray tests (ImmunoCAP ISAC) that measure component allergens are now being submitted to the FDA for clearance.

So what do these new recombinant tests bring to the table? They allow unprecedented and heightened insight into the machinations of allergy. "We've had fully quantitative testing for 20 years now and have been able to gather a lot of data around the probability that a given level of specific IgE translates into a likelihood that an allergen is important for a patient, " explains Dr. Reinhardt. "But until recently, we've only been able to work with whole allergens. That's like measuring a soup that contains all of the protein components; you are measuring some that might be more clinically relevant as well as those that might be cross- reactive and not so important in terms of the patient's clinical picture."

The new microarray technology can measure 112 components from roughly 50 allergens (many food-related).  The test can be done on a finger-stick sample and results are available in a couple of hours.

"Results from 112 components would very nicely let us see cross-reactive patterns," says Dr. Reinhardt. "Many allergens share identical or similar proteins so you can see if a patient has a true food allergy or if symptoms are based on cross reactivity. The flip side of that is that the microassay can identify which are the primary sensitizers - what we call storage proteins  -- that might confer a higher degree of risk for systemic or more severe reactions." Furthermore, these test results could help clinicians make decisions about which patients might benefit most from allergy shots and even about which proteins might best be put into the extract for an optimal "recipe" for immunotherapy. Moreover, the results can assist physicians in determining when to do food-challenge testing for patients who show food sensitization.

Dr. Reinhardt says the value of these recombinant tests stretch well beyond the individualized allergen profiles they provide for a patient. "New recombinant drugs are coming on the market (the monoclonal antibody drugs in particular); these are very expensive drugs typically.  However lots of patients develop (or have before initial treatment) anti-drug antibodies. It's important that we figure out personalized therapies with those drugs to make sure the right patient gets the right drug in the right dose at the right time, as the saying goes." He explains that because specific IgE has the potential to identify patients who have drug antibodies, there's tremendous interest in this usage from drug companies,  payers, and the FDA.

"There is huge potential in being able to identify patients for whom the drugs will be most effective, and safe," said Dr. Reinhardt. Also significant, he says, is the fact that the microarray test is almost infinitely customizable. "It all depends what you put on that dot; you can do lots of creative things. Pharmaceutical companies are interested in the possibility of custom microarrays to help them identify the best patient candidates for clinical trials."