AWD 12-281 is a potent (IC(50) = 9.7 nM) and highly selective inhibitor of the
phosphodiesterase 4 (PDE4)
isoenzyme with low affinity to the high-affinity
rolipram-binding site. The compound was optimized for topical treatment of
asthma,
chronic obstructive pulmonary disease (
COPD), and
allergic rhinitis. The aim of the present study was to assess the effect of
AWD 12-281 in human inflammatory cells. Peripheral blood mononuclear cells (PBMCs), diluted whole blood, and human
nasal polyp cells derived from surgically resected
nasal polyps from patients with polyposis comprise sources of target tissue cells that can be used to predict anti-inflammatory effects in patients.
AWD 12-281 was capable of suppressing the production of
cytokines in stimulated PBMCs:
interleukin-2 (IL-2,
phytohemagglutinin stimulation),
IL-5 (
concanavalin A stimulation),
IL-5 and
IL-4 (anti-CD3/anti-CD28 costimulation), and
lipopolysaccharide-stimulated release of
tumor necrosis factor alpha (
TNF alpha). The corresponding values for half-maximum inhibition, EC(50), for
AWD 12-281 were within a narrow range (46-121 nM). Comparing the effect of
AWD 12-281 with
roflumilast,
cilomilast (
SB 207499),
rolipram (RPR-73401), and 1-(3-nitrophenyl)-3-(4-pyridylmethyl)pyrido[2,3-d]pyrimidin-2,4(1H,3H)-dione (RS-25344-000), it could be shown that the PDE4 inhibitory activity was closely correlated with inhibitory potential as measured by the above-described assays.
AWD 12-281 was also shown to suppress
TNF alpha release in dispersed
nasal polyps (EC(50) = 111 nM) and in diluted whole blood (EC(50) = 934 nM). The reduced activity in human blood may be related to high
plasma protein binding. Currently, phase II clinical studies are under way to evaluate the therapeutic potential of
AWD 12-281 in
asthma,
COPD, and
allergic rhinitis.