Structure and mechanism of Fingolimod


Structure and mechanism of Fingolimod

Journal of Pharmacology and Therapeutic Research is an open access, peer reviewed journal that focuses on the interdisciplinary research offering therapeutic solutions to various neurological, genetics, psychological, and respiratory issues affecting the human beings.

Fingolimod (INN, trade name Gilenya, Novartis) is an immunomodulation drug, mostly used for treating multiple sclerosis (MS).  It has reduced the rate of relapses in relapsing-remitting multiple sclerosis by approximately one-half over a two-year period.  Fingolimod is a sphingosine-1-phosphate receptor modulator, which sequesters lymphocytes in lymph nodes, preventing them from contributing to an autoimmune reaction.

First synthesized in 1992 by Yoshitomi Pharmaceuticals, fingolimod was derived from an immunosuppressive natural product, myriocin (ISP-I) through chemical modification. Myriocin was isolated from the culture broth a type of entomopathogenic fungus (Isaria sinclairii) that was an eternal youth nostrum in traditional Chinese medicine.  Showing positive results in both in vitro (mixed lymphocyte reaction) and in vivo screening (prolonging rat skin graft survival time), myriocin was modified through a series of steps to yield fingolimod, code named at the time FTY720.  A recent review highlights the synthetic methods, mode of action and potential applications of this molecule. Structure activity relationship (SAR) studies on myriocin homologs and partially synthetic derivatives showed that the configuration at the carbon bearing the 3-hydroxy group or the 14-ketone, the 6-double bond, and the 4-hydroxy group were not important for its activity and simplification of the structure of ISP-I was done in an attempt to reduce toxicity and improve drugability.

It is derived from myriocin (ISP-1), a metabolite of the fungus Isaria sinclairii. It is a structural analogue of sphingosine and is phosphorylated by sphingosine kinases in the cell (most importantly sphingosine kinase 2). The molecular biology of phospho-fingolimod is thought to lie in its activity at one of the five sphingosine-1-phosphate receptors, S1PR1. Phospho-fingolimod causes the internalization of S1P receptors, which sequesters lymphocytes in lymph nodes, preventing them from moving to the central nervous system and causing a relapse of multiple sclerosis.

The unphosphorylated moiety of fingolimod, which is the predominant form of the drug in the body, is also an active molecule. Unphosphorylated fingolimod impairs the ability of cytotoxic CD8 T cells to kill their target cells by a different mechanism, which involves the arachidonic acid pathway, which is unrelated to sphigosine phosphate receptors. This has implications both for increasing susceptibility to viral infections as well as enhancing therapeutic efficacy in multiple sclerosis.

Additionally, fingolimod shifts macrophages to an anti-inflammatory M2 phenotype. It modulates their proliferation, morphology, and cytokine release via inhibition of the transient receptor potential cation channel, subfamily M, member 7. (TRPM7).

Finally, fingolimod has also been found to have other molecular targets and functions. Fingolimod has been reported to be a cannabinoid receptor antagonist, a cPLA2 inhibitor and a ceramide synthase inhibitor. It has also been reported to stimulate the repair process of glial cells and glial precursor cells after injury.

With Kind Regards,
Mark Orwell
Managing Editor
Journal of Pharmacology and Therapeutic Research