ATC Group: L04AA Selective immunosuppressants

Abatacept is a fusion protein that consists of the extracellular domain of human cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) linked to a modified Fc portion of human immunoglobulin G1 (IgG1). Abatacept selectively modulates a key costimulatory signal required for full activation of T lymphocytes expressing CD28.

Abetimus is a selective immunosuppressive agent (a compound that selectively dampens down the immune system). Most patients with SLE have antibodies in their blood that are directed against double-stranded DNA (deoxyribonucleic acid). These antibodies are thought to be linked to the development of lupus kidney disease. Abetimus is a small piece of double-stranded DNA that has been designed to reduce circulating levels of these antibodies. When Abetimus is injected, the levels of these antibodies in the blood are lowered and this is expected to help reduce the patient’s likelihood of experiencing a ‘flare’.

Alefacept interferes with lymphocyte activation by specifically binding to the lymphocyte antigen, CD2, and inhibiting LFA-3/CD2 interaction. Activation of T lymphocytes involving the interaction between LFA-3 on antigen-presenting cells and CD2 on T lymphocytes plays a role in the pathophysiology of chronic plaque psoriasis. Also causes a reduction in subsets of CD2+ T lymphocytes as well as CD4+ and CD8+ T lymphocytes.

Equine anti-thymocyte globulin is composed of purified gamma globulin containing primarily IgG against human thymus lymphocytes. It is formed by inoculating a horse with an antigen (human thymoyctes) which then induces the horse immune system’s B-lymphocytes to produce IgG immunoglobulins specific for that antigen. The result is polyclonal IgG that is then purified from the horse’s serum to produce a usable drug product that can be used for immunosuppression. Although the exact mechanism of action is unknown, equine anti-thymocyte globulin targets a variety of immune system proteins including lymphocyte surface proteins, granulocytes, platelets, bone marrow cells, and other cell types. Equine ATG is currently indicated for the suppression of the immune system to prevent renal transplant rejection and in the treatment of aplastic anemia. Induction of T cell apoptosis and resulting T-cell lymphopenia found in vivo is credited for its therapeutic effect in these conditions.

There are currently various ATG products available, which differ in the source of inoculated animal (rabbit, horse, or pig) and in the type of antigen product used to produce immunoglobulin (thymocytes, peripheral T cells, etc.).

Antithymocyte immunoglobulin is a selective immunosuppressive agent mostly acting on T lymphocytes. Antithymocyte immunoglobulin is used for the prevention and treatment of graft rejection after solid organ transplantation, usually in combination with other immunosuppressive drugs.

Apremilast, an oral small-molecule inhibitor of phosphodiesterase 4 (PDE4), works intracellularly to modulate a network of pro-inflammatory and anti-inflammatory mediators. PDE4 is a cyclic adenosine monophosphate (cAMP)-specific PDE and the dominant PDE in inflammatory cells. PDE4 inhibition elevates intracellular cAMP levels, which in turn down-regulates the inflammatory response by modulating the expression of TNF-α, IL-23, IL-17 and other inflammatory cytokines.

Belatacept, a modified form of CTLA4-Ig, binds CD80 and CD86 more avidly than the parent CTLA4-Ig molecule from which it is derived. This increased avidity provides a level of immunosuppression that is necessary for preventing immune-mediated allograft failure and dysfunction. Belatacept blocks CD28 mediated co-stimulation of T cells inhibiting their activation.

Belumosudil is a serine/threonine kinase inhibitor indicated for the treatment of chronic graft-versus-host disease (chronic GVHD). Specifically, it is an inhibitor of Rho-associated coiled-coil kinase 2 (ROCK2; ROCK-II). Belumosudil binds to and inhibits the serine/threonine kinase activity of ROCK2. This inhibits ROCK2-mediated signaling pathways which play major roles in pro- and anti-inflammatory immune cell responses.

Cladribine is a nucleoside analogue of deoxyadenosine. In resting cells cladribine causes DNA single-strand breaks, rapid nicotinamide adenine dinucleotide consumption, ATP depletion and cell death.

Efgartigimod alfa is a human IgG1 antibody fragment engineered for increased affinity to the neonatal Fc Receptor (FcRn). Efgartigimod alfa binds to FcRn, resulting in a reduction in the levels of circulating IgG including pathogenic IgG autoantibodies. Efgartigimod alfa does not affect the levels of other immunoglobulins (IgA, IgD, IgE or IgM), or those of albumin.

Imlifidase is a cysteine protease derived from the immunoglobulin G (IgG)-degrading enzyme of Streptococcus pyogenes that cleaves the heavy chains of all human IgG subclasses but no other immunoglobulins. The cleavage of IgG leads to elimination of Fc-dependent effector functions, including CDC and antibody-dependent cell-mediated cytotoxicity (ADCC). By cleaving all IgG, imlifidase reduces the level of DSA, thus enabling transplantation.

Mycophenolate mofetil is the 2-morpholinoethyl ester of mycophenolic acid (MPA). MPA is a potent, selective, uncompetitive and reversible inhibitor of inosine monophosphate dehydrogenase, and therefore inhibits the de novo pathway of guanosine nucleotide synthesis without incorporation into DNA.

Mycophenolic acid is a potent, selective, uncompetitive and reversible inhibitor of inosine monophosphate dehydrogenase, and therefore inhibits the de novo pathway of guanosine nucleotide synthesis without incorporation into DNA. Mycophenolic acid has more potent cytostatic effects on lymphocytes than on other cells and is indicated in combination with ciclosporin and corticosteroids for the prophylaxis of acute transplant rejection in adult patients receiving allogeneic renal transplants.