A new phosphodiesterase 4 B inhibitor, BI 1015550, which is under phase 3 trials for IPF, might be a candidate [39] because it has been shown to inhibit tumor necrosis factor-α and interleukin-2 release from peripheral mononuclear cells in vitro and lipopolysaccharide-induced neutrophil influx into the bronchoalveolar lavage in an in vivo rat model [40]. Here, PDE4B is linked to idiopathic pulmonary fibrosis.