Dear FDA,

I am writing to you about the forthcoming meeting to consider the marketing application for eteplirsen, a morpholino-oligo that induces exon-skipping to generate functional dystrophin protein and therefore, it is hoped, improved outcomes for patients with Duchenne Muscular Dystrophy (DMD).

I should, before continuing, declare my conflict of interest. DMD is a terrible disease, and understandably the prospect of a first treatment able to slow or arrest the progress of the disease arouses strong emotions among patients and their families. In voicing their support for the approval of eteplirsen, the conflict of interest of these patient advocates is clear. Similarly, the vested interest of the company that owns the rights to eteplirsen, Sarepta Therapeutics (NASDAQ:SRPT), is straight-forward and obvious. Less clear, but nonetheless relevant, are the strong links between doctors who have been treating DMD patients with eteplirsen and the company behind the drug. In writing to voice their support, these doctors did not fully disclose this conflict, so in setting out the case against approval I do not want to make the same error. My conflict of interest is that I am a taxpayer, and it will fall to me, and people like me, to pay for the use of this drug should it be approved.

My concern is that eteplirsen may be granted an accelerated approval because of the undue pressure being brought to bear by those parties with an understandable interest in seeing it approved for use: patients (and their families) and the company (and its consultants), despite not meeting the usual requirements for such an approval.

Let me be absolutely clear: I do not oppose approval of eteplirsen because I believe it is either unsafe or that it does not work. Indeed, the available data is encouraging on both counts. Crucially, however, the studies that have been performed to date do not reach the generally accepted bar for demonstrating efficacy. It is possible, but far from certain, that when further data has been collected this agent will prove to be the long-sought-after breakthrough for DMD patients.

The key data that supporters of this agent point to is a year-long study in 12 boys with DMD. This study has the gold-standard double-blind placebo-controlled design, although the placebo patients were randomized to drug after 24 weeks complicating the assessment.   While small studies are unavoidable in rare genetic diseases, approving a drug on the basis of just eight treated patients would set a new precedent.

The study had two key end-points: the first was levels of dystrophin protein in muscle biopsies, and the second (and more important) was the change in …

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