Raxone (idebenone) is being investigated by Santhera Pharmaceuticals as a therapy for primary progressive multiple sclerosis (PPMS) and Duchenne muscular dystrophy (DMD).

Raxone is currently approved in Europe for the treatment of Leber’s hereditary optic neuropathy (LHON). It is not approved for any use in the U.S.

How Raxone works

The symptoms of multiple sclerosis (MS) are caused by damage to the myelin sheath, the protective layer that surrounds the nerve fibers, and eventual permanent nerve damage. This damage is caused by the immune system mistakenly attacking myelin and causing inflammation in the tissue. However, there is evidence to suggest that oxidative stress may also contribute to the damage in progressive forms of MS, including PPMS.

Energy is produced in the mitochondria, called the “powerhouses” of the cells, through a process called the electron transport chain. This process can produce reactive oxygen species (ROS), which cause oxidative stress and can lead to cell death.

Raxone is a man-made equivalent of the naturally occurring antioxidant, coenzyme Q10. Antioxidants can reduce the level of free ROS, and research has suggested that patients with progressive MS have significantly lower levels of naturally occurring antioxidants, which could be contributing to the progression of the disease.

Based on this, Santhera is studying whether Raxone can protect the brain and spinal cord from damage that leads to worsening disability in PPMS patients. However, previous preclinical studies of Raxone in a mouse model of MS showed no benefit.

Raxone in clinical trials 

A randomized, placebo-controlled, double-blind Phase 1/2 clinical trial (NCT00950248), sponsored and conducted by the National Institute of Neurological Disorders and Stroke (NINDS), is currently ongoing but no longer recruiting participants.

This study aims to assess the safety, effectiveness, and mechanism of action of Raxone in 85 patients with PPMS over a study period of two years.

Initially, a baseline for each patient will be established through five clinic visits over one year, followed by two years of treatment with Raxone or a placebo. Throughout the three years, the patients will undergo various tests to assess neurological and general health using techniques such as magnetic resonance imaging (MRI) and blood testing.

Patients who complete the trial will be invited to participate in an open-label extension study (NCT01854359), where they will be given Raxone for one year. These two trials are expected to be completed by August 2018 and August 2019, respectively.

The safety profile of Raxone in MS is currently unknown. However, in patients with LHON the treatment is well tolerated. The most common side effects are the common cold, cough, mild to moderate diarrhea, and back pain.

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