Additionally, these new D/SD measures support the
inclusion of D/SD in the broad group of inflammatory
dermatoses, including psoriasis, atopic dermatitis and
acne. These conditions have different triggering events,
but share the pathophysiology of inflammation, proliferation
and skin barrier impairment. Other inflammatory
dermatoses have been studied in more detail (45) than D/
SD; and the biomarker data reviewed here are especially
useful for demonstrating the commonalities of pathophysiology
with these well-established conditions (49).
Relevance of biomarkers as surrogate clinical measures
The benefits of developing a molecular, biomarkerbased
quantification capability is likely to extend
beyond a more thorough understanding of a disease
condition and include the potential to use biomarkers
as relevant efficacy measures (46). If the biomarkers
reflect disease mechanisms underlying the clinical
pathophysiology, as they appear to in the case of D/
SD, they can be useful tools as measures earlier in the
onset of the condition, and/or as surrogate endpoints
for clinical efficacy of treatments. The FDA recognizes
this advantage of biomarker tools and encourages the
use of biomarkers in a recent white paper “Innovation
or Stagnation?” (47). An example of the use of
biomarker analysis in dermatology exists for atopic
dermatitis (AD) (48). Surface quantification of IL-18
was found to correlate with the severity of the condition
and appeared to be due to Staphylococcus aureus
colonization. This is an example demonstrating both
benefits of this biomarker for AD: generation of new
pathophysiological information and the establishment
of a new clinical measurement endpoint.
A number of biomarkers have been found to be
significantly correlated to the key D/SD symptom of
flaking (see Table I), even when evaluated on the basis
of individuals analyzed. All of these biomarkers have
a specific rationale within the known etiology of the
condition, enabling a greater, more detailed understanding
of the pathophysiology of D/SD. These biomarkers
can also be used as surrogate clinical endpoints for the
detailed assessment of D/SD treatment success, thus
complementing the traditional measures that are mainly
focused on visible signs/symptoms.