Breast Cancer Therapy, Tamoxifen, May Promote Myelin Repair in MS

Tamoxifen (brand name, Nolvadex), a widely used treatment for breast cancer, can also be used to treat myelin loss in patients with multiple sclerosis (MS), a new study suggests.

The finding, by a team of researchers at the University of Cambridge, U.K., was published in a study titled “Tamoxifen accelerates the repair of demyelinated lesions in the central nervous system” in the journal Scientific Reports.

Researchers used both  in vitro cultures and a mouse model with reduced levels of myelin to analyze how six existing drugs might effect the repair and recovery of cells able to produce myelin, called oligodendrocytes.

“We’re very excited about our findings,” said Mark R.N. Kotter, the study’s senior author, in a news release. “What we discovered was that Tamoxifen can enhance myelin repair in MS by encouraging the brain’s own stem cells to regenerate myelin.”

Stem cells are unspecialized cells that are capable of becoming any other type of cell in an appropriate environment. The team found that tamoxifen, which targets the estrogen receptors (ERα, ERβ, and GPR30) present in these cells, stimulated the stem cells to become oligodendrocytes, the brain cells responsible for producing myelin. Estrogen receptors play an important role in oligodendrocyte differentiation and in remyelination.

Investigators also observed that mice with reduced myelin levels, when treated with tamoxifen, had increased numbers of brain oligodendrocytes, showing that, in vivo (in a living organism), tamoxifen may well induce remyelination in the brain. Together, these results support the use of tamoxifen to help repair myelin loss, a hallmark of MS.

“Considerable efforts are currently being made to develop remyelination-enhancing drugs. The use of tamoxifen has several advantages over the development of new drugs. For example, it has an excellent safety profile that has undergone the test of time by exhaustive application in the clinic,” the researchers wrote.

The team believes that tamoxifen is a good candidate for future clinical trials that will assess its potential ability to effect myelin repair in people with MS.

Myelin loss occurs in several neurological disorders. In the most prominent demyelinating disease, MS, myelin sheaths in neurons are damaged by an autoimmune process.