In Vitro: Piclamilast (RP 73401, 1 μM, 30 min) significantly inhibits the changes in 23 genes via mechanisms involving AP-1 activation and c-Jun phosphorylation at Ser63. ?Piclamilast (RP 73401) exhibits IC50 values >100 μM, 40 μM, >100 μM, 14 μM for PDE1, PDE2, PDE3 and PDE5. Respectively.
In Vivo: Piclamilast (RP 73401, 10 mg/kg, 30 min) alone does not affect the MST of leukemia-bearing animals. Piclamilast combined with ATRA (HY-14649) significantly more effective than ATRA alone in increasing the MST (40 days; interval 34–45 days) of leukemia-bearing animals.