DMD Treatments Eteplirsen and Drisapersen in the Spotlight

Duchenne-muscular-dystrophyRecent doubt from the FDA regarding Eteplirsen has caused considerable concern for Sarepta Therapeutics Inc. The pending NDA for Eteplirsen has been effectively put on hold by the FDA, based on concerns regarding Phase 2b study results. Patients suffering from Duchenne muscular dystrophy {DMD} are in dire need of effectual, safe and tolerable treatments to fight the effects of this debilitating disease. There is currently no cure in sight for this extremely degenerative form of muscular dystrophy, which primarily affects males. As one of nine types of muscular dystrophy, DMD is an inherited disease that is marked by an X-linked recessive inheritance pattern.

The current stance from the FDA labels the NDA for Eteplirsen as premature, and calls positive study data about the dystrophin biomarker doubtful. The FDA also questions the efficacy of the results from Phase 2b six minute walking tests. Executives from Sarepta have expressed their great disappointment with the current stall from the FDA. The need for treatment for DMD patients is critical, with patients and their families anxiously awaiting the approval of Eteplirsen. As of mid-November 2013 the current stance of the FDA has delayed the commencement of dosing in the confirmatory study of Eteplirsen until roughly the second quarter of 2014.

Duchenne-Muscular-Dystrophy_XlinkRecessiveEteplirsen has been touted as a plausible and effectual treatment option for patients with DMD. One such trial, conducted in the U.K. involved 19 patients with Duchenne muscular dystrophy. Consequential success from this small, but telling study has led to a current study using Eteplirsen for children, which is being conducted in Columbus, Ohio at the Nationwide Children’s Hospital. Eteplirsen is dispensed intravenously and has been shown in many studies to date to be effective. Eteplirsen works by initiating the dystrophin gene exon 51 from being included in the final genetic instructions that cells use when making the muscle protein dystrophin, leading to the ultimate goal of exon skipping. This exon skipping is believed to induce the production of the partially functional dystrophin protein from the patient’s existing genetic instructions.

In late September 2013 GlaxoSmithKline announced discouraging results from a Phase III trial of Drisapersen, aimed at treating patients with Duchenne Muscular Dystrophy. Also coined DMD, this harsh and degenerative form of Muscular Dystrophy primarily affects boys. As a genetic condition that is characterized by the lack of the protein dystrophin, this rare and debilitating disease destroys the muscle cells. With results revealed from the Phase III clinical trial researchers were hoping to find success with the use of Drisapersen, but were unfortunately disappointed. The primary endpoint of the Phase III study was not met- specifically a significant improvement in the 6 Minute Walking Distance test statistics, as compared to the placebo. There were a total of total of 186 boys in this randomized and double blind study, which was placebo controlled.  The boys were placed in one of two groups, one which received 6 mg/kg of Drisapersen a week subcutaneously, and a placebo group. Dosing was carried out for approximately 48 weeks. Results did not offer statistically different findings, to the great disappointment of researchers, patients and their families. The motor function test of trial participants at the 6 Minute Walking Distance Test was insignificant for both groups, and secondary endpoint results were also dismal. The results from the secondary endpoints, including the 4-Stair Climb, 10 Meter Walk/Run Test and North Star Ambulatory Assessment showed no real statistical difference between the group of boys administered with Drisapersen and the boys who received a placebo. Drisapersen has been indicated in previous studies as being an effectual treatment for patients with DMD. Drisapersen is believed to work by inducing the exon 51 skipping of the DMD gene.

Clearly, further research needs to be done to determine the specific dosing and treatment using Drisapersen to adequately treat patients with DMD.

Ataluren is another DMD drug currently in trials, however there is no new information regarding the status of this experimental treatment.

LGM Pharma supplies Eteplirsen CAS# 173755-55-9, Ataluren CAS# 775304-57-9 and Drisapersen CAS# 1251830-50-8 for research and development purposes. Clients can be assured of quality API products and continuous support throughout the R&D process.


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