Biologic agents are made from biological (human or animal based) proteins rather than artificial chemicals, much in the way that insulin was made from animal sources in the past. Biologic agents are different from other psoriasis medications in that they are designed to block the condition in the immune system rather than waiting to treat the symptoms of the disease.
It is thought that overactive cells in the immune system set off a series of events in the body, eventually causing psoriasis to develop on the skin surface, with skin cells piling up and inflammation at the base. Biologic agents work by blocking the action of specific immune cells that cause these cells to misbehave, by either reducing the number of these cells in the skin and blood or by blocking the activation of the immune cells or the release of chemicals from them.
Biologic agents target overactive cells in the body. Some target a type of immune cell called a T cell, while others target the chemical messages they release.
In psoriasis, certain T cells are mistakenly activated, producing TNF-alpha (tumour necrosis factor alpha) in excessive amounts, and move into the skin. Once in the skin they begin to act as if they are fighting an infection or healing a wound; the messages the TNF-alpha communicates leads to a rapid growth of skin cells – much faster than normal. This overproduction is what causes cells to pile up at the skin’s surface. Some biologic agents act by preventing the activation and/or migration of T cells, by reducing the number of psoriasis-involved T cells in the body, or both.
For those prescribed one of these treatments, there is a certain level of commitment required as biologic agents need to be stored correctly (in a refrigerator between 2°C and 8°C). Regular and frequent monitoring, such as blood tests, are also required. Biologic agents are given by injection. Once educated and instructed on how to self-inject, most people are able to manage this on their own, but a nurse service is often available to help some individuals.
The long-term safety of biologic agents has not yet been established. As a result they are not considered first-line therapy. There is a pathway criteria outlined by NICE so that patients can access biologic agents after they have tried phototherapy and other systemic therapies such as treatments taken orally.