Biologics as Replacement of a Deficient or Abnormal Protein.

Insulin has been previously indicated as the prototypical biologic medicine. Treatment by addition of exogenous insulin is the preferred treatment for type I diabetes and is used extensively in type II diabetes. However, other conditions characterised by deficiencies are treated in a similar manner.

Deficiencies in various coagulation factors typify a number of inherited bleeding disorders.  Clotting factor VIII deficiency manifests itself in haemophilia A whilst lack of factor IX results in haemophilia B. Treatment for both of these conditions is by supplementation of the missing proteins using either purified blood products or, more commonly, human recombinant proteins. The development and use of recombinant clotting factors in conjunction with better screening methods has drastically reduced the incidence of infection of haemophiliacs with HIV.

Growth failure caused by growth hormone (somatotropin) deficiency or as symptoms from pathological states such as Prader-Willi disease or Turners syndrome can be treated by exogenous administration of recombinant human growth hormone produced either in E. coli (Genotropin) or from genetically engineered mammalian cells (Saizen).

Gaucher’s disease is a lysosomal storage disease caused by a deficiency in the enzyme β-glucocerebrosidase which hydrolyses glucocerebroside to glucose and ceramide. Deficiency in this enzyme results in an accumulation of the substrate in a variety of tissues including spleen, liver, kidneys, lungs, brain and bone marrow. Types I and III, the adult forms of the disease can be treated by replacement treatment with recombinant β-glucocerebrosidase (Imiglucerase), which, when given intravenously every two weeks, can dramatically decrease liver and spleen size, reduce skeletal abnormalities, and reverse other manifestations.