Sarepta have been asked by the FDA to put on temporary hold their clinical trial looking at the safety and efficacy of their gene therapy treatment.

In an open letter to the community, Chief Exec of Sarepta Therapeutics explained the Phase 1/2a clinical trial has been put on hold due to an ‘out-of-specification production lot’. To understand what this means, we need to know a little about how materials for administration of the drug are produced for the trial.

Sarepta produce the actual gene therapy material - the ‘active’ part of the drug.However, this can’t be given straight to a patient and must be integrated with a carrier plasmid (a piece of neutral genetic material that acts as a transport and delivery device). This component of Sarepta’s product was sourced from an FDA approved company at what is known as ‘Research grade’. This is a highly-purified form and would normally be more than suitable. However, a very small piece of unwanted DNA was found in one of the plasmid samples. Sarepta immediately carried out some experiments: they know the structure of this DNA and have shown that this piece of DNA doesn’t make any unwanted protein and is very rapidly and harmlessly removed from the body. It does not appear to cause any unwanted side effects as far as can be seen but clearly this issue has to be addressed.

Sarepta have so far dosed 4 patients in the trial. Following tests on the patients’ biopsies, it appears none of them have been affected by this out-of-specification production lot.

Sarepta have a firm plan in place, the first element being to use a much more refined plasmid (called GMP grade – the highest grade possible, and the standard for fully authorised human medicines). Sarepta are addressing the other points in the FDA hold and will submit their plan to the FDA very soon. The FDA will then have 30 days to respond to the plan. Sarepta will need to show the FDA that there is no difference in drug safety and efficacy when patients are dosed with Research Grade vs GMP plasmids. Sarepta are confident that they have this fully under control.

We hope that our explanation, combined with the official releases, will help you to understand the FDA hold and set minds at rest as to the future of the trials, which Sarepta expect to stay on schedule. 

The next presentation of data from Sareptas gene therapy trial will be at a scientific meeting. We will keep the community updated on the results. 

Read our Gene Therapy Overview for more information about gene therapy. 

READ SAREPTAS PRESS RELEASE: http://investorrelations.sarepta.com/news-releases/news-release-details/sarepta-therapeutics-announces-phase-12a-duchenne-muscular 

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