I am not denying that Etep works, or getting into an argument about +fibers vs. absolute levels of dystrophin, or "making my bets" or suing the FDA or anything like that. I don't care about Dirk's motives or biases or whether he was wrong on GNTA. I don't care that GSK used even worse methodology. I am not a scientist and I just want to know if anyone on this board who knows about IF can tell me how reliable it is. Is he full of #$%$ with his latest post on the problems with IF, or is IF flawed but the best we have? If you are not going to talk about the science, please don't respond. Any on point response will be greatly appreciated. Thank you.
Dirks main point:
"I believe all of us can agree on is that it would be important to determine whether the antisense oligo eteplirsen can restore sufficient Becker-type dystrophin to have a therapeutic effect. "
How much more evidence do you need then the therapeutic effect seen by the children maintaining their strength or even increasing during the trial. No placebo effect would have lasted as long for this population.
Yes, I can explain this very simply. Dirk laid out a case for how it would be possible for an unscrupulous company to manipulate immunofluourescent images. He never at any time adduced even one iota of evidence that Sarepta had actually performed any such manipulations. Go back and read it again, in particular the section about how background levels and so forth could be changed. It isn't a matter of science. It's a matter of having NOTHING TO DO WITH SAREPTA. Sarepta didn't change background levels or manipulate evidence, and Dirk can't find even a hint that they did. Nevertheless, he wants to spread FUD (fear, uncertainty, and doubt) by implying Sarepta did something he can't prove. That's why, my friend wggm, motives do matter. The science here is irrelevant. It consists merely of things Sarepta COULD have done, in theory. It's scientifically possible that you were OJ's killer. You can hold a knife. You are capable of stabbing. Nothing wrong with that science, but the implication is ridiculous. Same here. Sure, Immunofluourescent images can be manipulated. Any images can be altered. But that's not the same as presenting evidence that Sarepta actually did anything. Dirk has moved into wholesale fearmongering and left objective science far behind. Remember, the FDA had no issues at all with Sarepta's quantification methods.
IF is a perfectly appropriate technique, and it is used in a variety of diagnostic settings, and in therapeutic settings as well. For breast cancer pts it is an IF method that is used to determine if pts qualify for use of Herceptin, from a quantitative assessment by IF that is scored 0, 1+, 2+ or 3+. It is used in children with DMD as a means of diagnosis, and thus has a history in this disease.
Finally and importantly the methods as described by Cris use multiple stained sections that are each 'scored' in multiple fields of view to ensure that representative sampling has been done. These are done blinded.
There is nothing wrong with IF, and there is nothing wrong with IF the way it is being employed in this study. The fact is that the AA decision is indeed based on a need to analyze methods. We know that this is exactly what FDA has asked for, an in depth white paper on the methods. The FDA has been handed two packages of methods and data. They will decide ultimately which will become the gold standard. They have accepted and approved IF as method for a commercial application in the past, and for note here Herceptin sells in the 4B / year range, and it's use is decided by IF.
Immunofluorescence (IF) uses an antibody for specificity conjugated to a fluorescein molecule for detection.
Herceptin is a monoclonal antibody that interferes with the human epidermal growth factor-2 receptor.
To say IF is a good measure to determine if the exon-skipping treatment is working for DMD because IF can determine if someone is HER2+ is disingenuous.