Other names: Targretin
Bexarotene is being tested for its ability to boost myelin repair. It is taken as tablets once daily.
Bexarotene for myelin repair: Phase II
Bexarotene is being tested for its potential to repair myelin. It is currently used to treat certain types of skin cancer and is taken as tablets once daily.
- Bexarotene targets the retinoid X receptor on oligodendrocytes and stimulates myelin production
- In laboratory studies, bexarotene has shown the potential to repair myelin
- Side effects of bexarotene include increased levels of fats in the blood (cholesterol and triglycerides), reduced numbers of white blood cells, lower levels of thyroid hormones (hypothyroidism), itchy rash, headaches, vomiting and diarrhoea
How does bexarotene work?
Myelin is a fatty protein that forms a sheath around the axons of nerve cells - the part of the cell that transmits messages to other nerve cells. Myelin acts as insulation to the axon and helps maintain the speed of transmission of messages. In the central nervous system, myelin is produced by cells called oligodendrocytes.
Damage to myelin (or demyelination) caused by multiple sclerosis interrupts or blocks nerve messages. In the earlier stages of MS, oligodendrocytes can often repair areas of damaged myelin - a process known as remyelination. As MS becomes more established, these cells stop functioning or are killed off and myelin is not repaired, resulting in increasing disability.
Bexarotene binds to special locations (receptors), called retinoid X receptors, on oligodendrocytes. Laboratory studies have found that drugs which act on these receptors can encourage oligodendrocytes to remyelinate, offering the potential to reverse damage caused by MS and improve symptoms.
Bexarotene is currently used as a treatment for certain types of skin cancer.
How is bexarotene taken?
Bexarotene is taken as tablets, once daily.
What are the results so far?
So far, laboratory studies have identified a role for the retinoid X receptor in the control of myelin repair. Animal studies have suggested that bexarotene, a drug which acts on these receptors, may promote remyelination, offering the potential to reverse damage caused by MS and improve symptoms. Bexarotene has not previously been tested in multiple sclerosis.
What further research is planned?
- Bexarotene compared to placebo
This phase II study is recruiting 50 people with relapsing remitting MS who are currently taking a “first-line” disease modifying drug, which includes Avonex, Betaferon, Extavia, Plegridy, Rebif, Copaxone, Brabio, Aubagio and Tecfidera. Half of the participants will take bexarotene and half will take placebo for six months, in addition to their current disease modifying drug. The main aim of the study is to monitor the safety of taking bexarotene in people with RRMS. In addition, the study will assess whether bexarotene can promote remyelination by comparing MRI scans, measuring EDSS and visual evoked potentials.
Further details of this study.
All participants have now completed their treatments. Results of the study are expected in September 2019.
In a series of blogs and vlogs, Hellie, a person with MS, chronicles her journey taking part in this clinical trial.
The most common side effects of bexarotene include changes in levels of fats in the blood (cholesterol and triglycerides), reduced numbers of white blood cells, lower levels of thyroid hormones (hypothyroidism), itchy rash, headaches, vomiting and diarrhoea.