Dr. Emma Guttman-Yassky announced help is at hand. While efforts to identify blood biomarkers have proved deeply disappointing, skin biomarkers are another story. She and her coinvestigators have identified a set of reliable skin biomarkers of therapeutic response in atopic dermatitis patients.
"We believe that these biomarkers represent the molecular fingerprints of the disease and might be key to future development of targeted treatments," said Dr. Guttman-Yassky, director of occupational and contact dermatitis at Mount Sinai Medical Center, New York.
She and her coinvestigators took lesional and nonlesional skin biopsies from 12 atopic dermatitis patients before and after undergoing narrow-band UVB phototherapy three times weekly for 12 weeks, a regimen the patients responded to with a mean 81% reduction in SCORAD index scores. Reversal of epidermal hyperplasia and abnormal keratinocyte differentiation – the histologic hallmarks of atopic dermatitis – was associated with elimination of inflammatory leukocytes and Th2-associated cytokines and chemokines (J. Allergy Clin. Immunol. 2011;128:583-93).
Among the skin biomarkers of atopic dermatitis that reversed with effective therapy were inflammatory dendritic epidermal cells, myeloid and plasmacytoid dendritic cells, CD3+ T cells, and interleukins-4 and -13.
This study, as well as another by Dr. Guttman-Yassky and her colleagues (in press), demonstrated a major role for interleukin-22 in atopic dermatitis. The cytokine was markedly overexpressed in lesional skin, with resultant upregulation of the antimicrobial protein’s S100A7, S100A8, and S100A9. After narrow-band UVB therapy, expression of IL-22 expression was downregulated, as were the IL-22-induced chemokines S100A7-9.
Expression of the three antimicrobial proteins in lesional skin also appears to be useful as a biomarker defining acute disease. Their levels jump within 3 days after onset of acute atopic dermatitis, according to Dr. Guttman-Yassky.
"Are we there yet in terms of biomarkers in atopic dermatitis? That’s the million-dollar question. Regarding biomarker availability, I think yes. We now have biomarkers that are highly informative on the reversal of disease pathology with treatment," she said. "I believe that the next step is clinical trials with specific immune antagonists that incorporate biomarkers of response. I think biomarkers are key if we want to know if new therapies really work. This will enhance early decisions and reduce the cost of developing new treatments."
An important implication of the narrow-band UVB/biomarker study in terms of atopic dermatitis pathogenesis is that the data argue against a fixed genetic phenotype, since the atopic dermatitis epidermal phenotype was shown to be reversed with broad-based immune-targeted phototherapy. Instead, the study results argue in favor of what Dr. Guttman-Yassky called "the inside-out hypothesis" of atopic dermatitis, which postulates that the epidermal abnormalities that define the disease are caused by underlying immune activation.
Her studies were supported by the National Institutes of Health.
HOME Project Seeks Standardization
During the same session, Dr. Hywel C. Williams provided an update on a major international project called Harmonising Outcome Measures for Eczema (HOME). The goal of the HOME project is to develop a consensus on a core set of outcome measures to be used in all atopic dermatitis clinical research. This should make future studies easier to compare, contrast, and synthesize in meta-analyses.
A minimum set of core outcome measures in atopic dermatitis is needed because the situation can be chaotic, noted Dr. Williams, professor of dermatology and director of the Center for Evidence-Based Dermatology at the University of Nottingham (U.K.).
"There are more than 20 named scales for atopic dermatitis, including SCORAD, POEM, SASSAD, ADASI, ADAM, EASI, and the FSSS. Some have been only partly tested. Many have not been tested at all. At international meetings I see people shouting at each other, trying to communicate what the results of their studies mean. Some people are in the SCORAD camp, some are in the SASSAD camp, others are in the EASI camp. How can we possibly communicate? This is a shameful situation which we really have to put right if we are to progress," he said.
The HOME project is modeled after Outcome Measures in Rheumatology, or OMERACT, an international consensus group that meets every 2 years with the goal of raising the quality of rheumatologic research. HOME comprises atopic dermatitis researchers, clinical experts, journal editors, patient advocates, and representatives from the European regulatory agency. The FDA was invited but didn’t attend last year’s HOME meeting in Amsterdam, where working groups were formed to identify the best evidence-based instruments for assessing atopic disease signs, symptoms, flares, quality of life, and treatment efficacy and safety. The HOME group will meet next year in San Diego on April 6-7.
Aside from Dr. Graham, a Regeneron employee, the other speakers in the special session reported receiving research grants from various sources but declared having no conflicts of interest with regard to their presentations.