SMA clinical trial update

Promising news has been released from clinical trials of two possible treatments for spinal muscular atrophy (SMA) in recent weeks. This is encouraging news for families affected by SMA and the pharmaceutical companies are now in a race to be the first to prove that their drug is safe and effective.

Olesoxime clinical trial preliminary results

A European Phase 2 trial of olesoxime was recently completed and promising preliminary results were released this week. Olesoxime is a cholesterol-like compound being developed by Trophos, a French pharmaceutical company. In mice with SMA, olesoxime protects nerve cells from damage and improves neuronal growth and function, effects that could prove beneficial to SMA patients.

The phase 2 trial involved 165 people with SMA type 2 and 3 aged between three and 25 years. Two thirds of the participants received olesoxime oral liquid daily for two years and the remaining participants took a placebo. It was a “double-blind trial” which means that the participants and the clinicians didn’t know who was taking olesoxime or placebo until the end of the trial when the results were analysed.

The trial showed that loss of motor function was prevented in those taking olesoxime while those taking the placebo had the typical progressive loss of motor function. Trial participants taking the olesoxime also had fewer of the medical complications that are normally associated with SMA. Detailed results will be published and presented at upcoming conferences in Europe and the USA.

Dr. Enrico Bertini, the principle investigator of the study said “Olesoxime has the potential to be the first ever approved treatment specifically developed for SMA patients. Its neuroprotective effect combined with fewer adverse events caused by the disease itself is encouraging.”

Christine Placet, chief executive officer of Trophos commented on the next steps for the development of the drug: “Our focus now is on the regulatory steps needed to bring this important product to patients as quickly as possible. We are currently exploring a number of options, including potential industry partnerships and identifying new sources of funding.”

ISIS-SMNRX clinical trial interim results

In the US, Isis Pharmaceuticals is currently testing a potential drug called ISIS-SMNRx in two clinical trials and some results part-way through the trials have recently been announced. ISIS-SMNRx is a therapy based on antisense oligonucleotides (AONs) – small pieces of genetic material that can specifically manipulate the way that the genetic code is read. The aim of using AONs for SMA is to encourage the cells to produce more of the SMN protein that is missing in people with SMA. Administration of ISIS-SMNRx to mice with SMA was shown to target many neuromuscular symptoms leading to a large increase in survival.

The first of the ongoing trials aims to test two different doses of the drug in about 20 infants with SMA type 1. All four infants in the lower dose (6 mg) group have received the scheduled three initial doses of the drug which was injected into the fluid around the spinal cord. They have now been in the study for over six months and are approximately nine and a half to 16 months in age with an average age of approximately 12 and a half months. All four infants are alive and none have required permanent respiratory assistance. It appears that these infants are doing better than the typical course of the disease because it is known that approximately half of infants with Type I SMA die or need permanent ventilation by about 10 months of age. However, given the small number of infants treated so far, this will need to be confirmed with detailed analysis of the full results of the study. In the higher dose (12 mg) group of infants, ten have received at least one dose of ISIS-SMNRx. Of these 10 infants, nine still remain in the study. One infant succumbed to pneumonia early in the treatment portion of study.

The second Isis study aims to test four different doses (3, 6, 9 and 12 mg) of ISIS-SMNRx in children with Type 2 or Type 3 SMA. The drug will be injected into the fluid around the spinal cord two or three times over a three month period. This study is also still ongoing but some interim results have been released for the lowest three doses. By nine months after the first dose, muscle function was measured to have improved; the higher the dose, the greater the improvement. Dosing has just started for the highest dose group (12 mg).

Importantly, in all of the trials so far, ISIS-SMNRx has been well tolerated. Isis plans to enroll all of the participants in these trials into extension studies where they will receive 12 mg of ISIS-SMNRx every six months. This will allow the longer term effects of the drug to be monitored and also give the participants access to the promising treatment.

The ISIS-SMNRx trials involve only a small number of participants and assessments have only been made over a short time period, so further clinical trials will be needed to further assess the safety and effectiveness. The results so far are encouraging enough though for plans to already be in place to start larger Phase 3 studies in the middle of this year. More information about the ISIS clinical trials is available on the website.

Further information

• The MDA spinal muscular atrophy factsheets contain more information about the condition including a research summary
• More SMA research news: A plant extract – quercetin – has been tested in a mouse model of SMA
Clinical trials – your questions answered.
• Information about patient registries
• You can get regular updates by becoming a friend of the MDA Facebook page

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