Yesterday, Unger (I believe), said that IF assays could be relied on, if they were done correctly, which was a separate question. Given the FDA's doubts about Sarepta's dystropin data and their request for a fourth biopsy, do you take this to mean that they think that lab Sarepta used was unreliable or failed to follow proper procedures to insure accuracy?
Hector, I'm sure JRRT won't mind if I answer…Sarepta's use of only one quantification assay seems to be of concern for the FDA . Eventhough immunofluorescence is the most sensitive assay they would probably want at least Western Blot too. GSK used all three [RNA] and picked the highest protein # out of the three. The variability of oligo induced truncated dystrophin quantification occurs not because of the test method but because the new, different biopsied sample is from a different muscle, different muscle tissue and different muscle cells . I'm starting to believe that all non-peptide oligos only enter muscle cells via myogenesis, not the leaky membrane theory. Muscle cells are very difficult for any complex molecule to enter. This theorem explains the delay in new dystrophin and myogenesis occurs in approx. 1-2% of muscle cells per annum. Itt occurs in mature muscle cells only when they are under "stress" or they are "injured", like in the DMD pathology. I really wish these FDA putative scientists evaluating eteplirsen take a refresher course on the DMD pathology, quantitative assays and oligo chemistry. There concerns via the notes released were pretty scary from a scientific perspective. Factor in the 2012 FDASIA law and it goes from "scary" to malfeasance.