What are biologics (Biologic response modifiers)?
DMARDs (Methotrexate, Leflunomide, hydroxychloroquine, sulphasalazine) are immunomodulators. They modulate the immune system i.e. they modulate the immune system’s abnormal behavior & the attack on the joints. Immune system attacks the joints with the help special chemicals called the cytokines. The immune cells release cytokines that are then responsible for the inflammation in the joints.
Biologics are synthetic molecules that either neutralize these cytokines or block their action. Once the cytokines are neutralized, joint inflammation settles. Since there are multiple cytokines involved in the inflammatory process, different biologic molecules have been developed.
Remicade & Enbrel block the TNF-alpha.
Mabthera/ Reditux (Rituximab) block the CD-20 molecule in the B cells & prevents cytokine production by the B cells.
Tocilizumab (Actemra) blocks the action of Interleukin-6 cytokine.
Abatacept (Orencia) attaches to a protein present on the T cells (One of the immune system cells). This blocks the activation of these T cells thereby blocking the production of new T cells & release of cytokines.
Since there are many cytokines involved in the rheumatoid inflammatory process, hence one biologic agent need not work in all the patients.