Summary: Interstitial lung diseases (ILD) constitute a heterogeneous group of diseases whose common pathophysiological feature is the presence of an inflammatory and/or fibrotic component. Over the past 25 years, the field of ILD has undergone a dynamic evolution, from understanding the pathobiology of these diseases to the development of new pharmacological options and approaches to patient care. Although currently available antifibrotic drugs do not completely halt the progression of ILD, their introduction into clinical practice has improved prognosis and prolonged survival. Furthermore, it is worth noting that the use of antifibrotic drugs is associated with possible adverse effects, which may limit treatment tolerance and lead to discontinuation, ultimately resulting in a lack of benefits in improving long-term prognosis. Therefore, in the case of progressive ILD, there remains an unmet need for more effective and better tolerated therapies. Phosphodiesterase 4 (PDE4) is a very attractive and potential target in the treatment of various diseases associated with inflammation and fibrosis. Nerandomilast is a new, oral, preferential PDE4B inhibitor with a reduced number of adverse effects compared to non-selective PDE4 inhibitors, which has been recently evaluated for its usefulness in ILD therapy. This article presents the drug's mechanism of action, discusses preclinical and clinical data, and the FIBRONEER study program, which formed the basis for the application for drug registration in the treatment of progressive forms of ILD.