Biologics are treatment derived from a biological process rather than being manufactured chemically. Biologics can be broadly classified into two major groups; Anti-Tumour necrosis factor alpha and others.

Among various cytokines, Tumour necrosis factor alpha is the main target of for many biologics Therefore, will start with the anti-tumour necrosis factor. In the TNFα producing cells such as phagocytes the transmembrane TNFα is detached from the cell membrane by the action of the TNF converting enzyme The free-floating molecule is now called soluble TNFα The soluble TNFα molecules traverse to the TNFα responsive cells Where they bind to specific receptors called TNF receptors abbreviated as TNFR. There are two subtypes of TNF receptors TNFR1 And TNFR2 Soluble and transmembrane TNF could bind to either TNFR1 or TNFR2

But transmembrane TNFα prefer binding to TNFR2 TNFR1 are expressed in almost all body cells except erythrocytes Whereas TNFR2 are strictly expressed in the immune cells. Generally, activation of TNFR1 lead to sequences of biological reactions end up with cell apoptosis. On the other hand, activation of TNFR2 promotes cell proliferation. Both soluble and transmembrane TNFα are the main targets for many biologics The anti-TNFα biologics can be functionally divided into two groups Anti TNFα antibodies And Soluble TNFα receptors. The anti TNFα antibodies can be further divided into Chimeric antibodies Fully humanized antibodies Fully humanized with Poly Ethylene Glycol antibodies Infliximab drug is an example of chimeric antibodies produced from mouse myeloma. Adalimumab and golimumab are biologics generated completely from human antibodies The certolizumab is a unique biologic where polyethylene glycol Fab segment is connected to the human monoclonal antibody

Etanercept drug contains soluble TNFR2 receptors that bind and inactivate TNFα. Over the last twenty years the biologics have significantly improve the remission rates in many rheumatoid arthritis patients However, 40% of patients do not respond to biologics treatment To enhance the effectiveness of biologics in resistant patients The next generation of biologics should work more selectively They should block TNFR1 and activate the TNRF2 Now we will go through the other biologics These biologics attack either cytokines or cellular targets

The targeted cytokines include IL-6 IL-1 And IL-17 Whereas T cell and B cells are the main cellular targets IL-6 is attacked by tocilizumab antibodies While IL-1 receptors are blocked by anakinra biologic. Secukinumab is IL-17 antibody. T cell are deactivated by abatacept Whereas B cells are depleted rituximab biologics. Unfortunately, the cost of biological treatment is very expensive The one-year treatment course for one patient can cost up to £10 000 Therefore, after the end of patency of famous biologics many biosimilars have been introduced to the clinical practice Biosimilars Have similar structures, mechanism of actions, clinical efficacy and side effects of original biologics Fortunately, they cost much less than the original biologics Dozens of biosimilars have been licenced for clinical practice worldwide and hundreds are tested in clinical trials