Anacor Pharmaceuticals (now Pfizer) was developing AN-2898, a boron-containing, small-molecule inhibitor of type 4 cyclic nucleotide phosphodiesterase (phosphodiesterase IV), as a topically applied therapy for psoriasis and atopic dermatitis. AN-2898 inhibits the release of tumore necrosis factor-alfa (TNFα), interleukin (IL)-12, and IL-23. AN-2898 also inhibits the activity of phosphodiesterase (PDE) 4 and 7. AN-2898 IC50 values for inhibition of PDE4 and PDE7 activity is 0.06 and 0.21 uM, respectively. AN-2898 is a competitive, reversible inhibitor of PDE4 with a Ki of 65 nM. AN-2898 has been studied in clinical trials for atopic dermatitis and psoriasis. The development of AN-2898 appears to have been discontinued.