Therapeutic Enzymes

Enzymes can be applied therapeutically both externally, orally and intravenously, or even inhaled. In addition to the long-established application of animal, plant, and microbial enzymes for nutritional support, their mostly supportive therapeutic use in infectious and cancerous diseases, in connection with blood clotting and in various rare genetically caused metabolic diseases, is becoming increasingly important. In contrast to many drugs, enzymes generally show few or no side effects, but on the other hand, intravenous application places very high demands on their purity and quality in order to avoid allergenic reactions, for example. This chapter describes the use of enzymes as therapeutics for a wide variety of applications ranging from nutritional support to the treatment of cancer and of rare genetic diseases. An overview is given on production and use of various animal, plant, and microbial enzymes for nutritional support and of human enzymes and their therapeutic use in cancerous diseases and in various rare genetically caused metabolic diseases. In all cases, enzymes should be non-toxic and non-allergenic or themselves meet the requirements placed on food, if ingested orally by patients. Microbial enzymes should be derived from GRAS (generally regarded as safe) organisms. Classical production methods for enzymes of human origin for intravenous use start with their isolation from human urine or from blood plasma, modern methods use animal cell cultures for their production. Intravenous application of enzymes of human origin or recombinantly produced by animal cell culture requires the highest enzyme purity and quality in order to avoid allergenic reactions. PEGylation of therapeutic enzymes can be used to influence their solubility, immunogenicity, and pharmacokinetics, e.g., by reducing proteolysis and increasing stability in serum.