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Tamoxifen breast cancer drug could at least help slow down an incurable hereditary muscular disease. Researchers at the University of Geneva report with colleagues that the drug has extended the life of mice with the disease.
Myofilactic myopathy is a serious inherited disease that affects one in 50,000 newborn boys. A genetic defect causes muscle atrophy. In particular, due to the weakness of the respiratory muscles, this rare illness usually leads to death in the first two years of life.
Treatment does not yet exist, but at least it could slow the progression of the disease: Researchers at the Universities of Geneva and Strasbourg report promising results in animal experiments with tamoxifen.
Tamoxifen has been used for years in the treatment of breast cancer and has some interesting properties in terms of muscle fiber protection, as announced by the University of Geneva. In a previous study, the researchers had already successfully tested the drug for its effect on the most common muscular disease, Duchenne muscular dystrophy. This concerns one of the 3500 boys. life expectancy is 30 years. Clinical trials are now being conducted.
Based on these promising past results, scientists around Leonardo Scaezza have now looked at the efficacy of tamoxifen in mouse myopathy myopathy models. The results are reported in the journal Nature Communications.
However, the two diseases lead to muscle weakness in a number of ways: In myofibrillary myopathy there is no enzyme called myotubularin. Without this, a protein called dynamin 2 accumulates, causing muscle atrophy. Tamoxifen starts with Dynamin 2.
Mice with the same symptoms as babies with myofibrillary myopathy lived twice as much with the lowest dose tested, with the highest dose being seven times greater than the untreated mouse. The higher dose was – equivalent to the mouse organism – used in breast cancer.
Additionally, the drug slowed the progressive muscle paralysis or even put it to rest. Muscle strength also increased significantly from the treatment.
Timely approach prevents paralysis
The researchers started tamoxifen therapy when the first symptoms occurred in mice about three weeks old. A Canadian research team from Toronto started even earlier and the mice did not show paralysis, the University of Geneva wrote.
Meanwhile, there are also research efforts to treat severe hereditary disease through gene therapy. However, its effectiveness and safety should last for years, according to the rapporteur, Olivier Dorchies, of the University of Geneva.
Since tamoxifen has already been authorized for human use and as clinical trials for Duchenne muscular dystrophy are already under way, researchers hope that tamoxifen therapy will acquire much faster approval for myofibrillary myopathy.