Dornase alfa (proprietary name Pulmozyme from Genentech) is a highly purified solution of recombinant human deoxyribonuclease I (rhDNase), an enzyme which selectively cleaves DNA. Dornase alfa hydrolyzes the DNA present in sputum/mucus of cystic fibrosis patients and reduces viscosity in the lungs, promoting improved clearance of secretions. This protein therapeutic agent is produced in Chinese hamster ovary cells.
Dornase alfa is the most recent therapeutic agent developed with this basic mechanism of action. Prior to the cloning of the human enzyme, bovine DNase I was on the market for many years, though its utility was limited by the inherent antigenic response to a cow protein in the lungs of patients. Other DNases, such as DNase II, have therapeutic potential as well, but as of yet no further DNases have been brought to market for cystic fibrosis.