PDE7A and chronic obstructive pulmonary disease: The discovery of BRL 50481 (N, N, 2-Trimethyl-5-nitro-benzenesulfonamide), a sulfonamide-based selective PDE7 inhibitor, represented a significant advancement in targeting alternative cAMP phosphodiesterases to alleviate chronic inflammation in chronic obstructive pulmonary disease (COPD) (Smith et al., 2004).