Dornase alfa is a highly purified solution of recombinant human deoxyribonuclease I

Deoxyribonuclease I

Deoxyribonuclease I , is an endonuclease coded by the human gene DNASE1.DNase I is a nuclease that cleaves DNA preferentially at phosphodiester linkages adjacent to a pyrimidine nucleotide, yielding 5'-phosphate-terminated polynucleotides with a free hydroxyl group on position 3', on average...

 (rhDNase), an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 which selectively cleaves DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

. Dornase alfa hydrolyzes the DNA present in sputum/mucus of cystic fibrosis

Cystic fibrosis

Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...

 patients and reduces viscosity

Viscosity

Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher 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

Deoxyribonuclease II

Deoxyribonuclease II, or Acid DNase, hydrolyzes deoxyribonucleotide linkages in native and denatured DNA, yielding products with 3'-phosphates. As the name implies, it is more effective at acid pH.There are several known DNases II, including:...

, have therapeutic potential as well, but as of yet no further DNases have been brought to market for cystic fibrosis.

Dornase alfa is an orphan drug

Orphan drug

An orphan drug is a pharmaceutical agent that has been developed specifically to treat a rare medical condition, the condition itself being referred to as an orphan disease...

.