Biotech Values

[DewDiligence]

VRTX – Here’s what Werber has to say about
the dropout-related statistics in his report that
just came out (bold-face emphasis is mine):

>>
The PROVE studies are designed to yield end-of-treatment and sustained viral response (SVR) data based on a true intent-to-treat (ITT) basis. That is, if a patient receiving VX-950 or placebo +/- PEG-IFN/ribavirin drops out of the trial, they are encouraged to have their blood drawn at 12 weeks and are included as part of the analysis.

This method can shift the data in either a positive or negative manner with respect to VX- 950. If a patient receives VX-950 for 2 weeks and is taken off of the drug due to tolerability issues, but remains on PEG-IFN/ribavirin for the remainder of the 12 week period and is found to be a responder, then that patient would be counted as a responder in the VX-950 group (despite having only received VX-950 for [only] two weeks). This would obviously benefit of Vertex.

Similarly, if a patient receives VX-950 for only a short period of time and fails what is mostly a PEG-IFN/ribavirin regimen, that patient would be counted as a VX-950 failure, to the detriment of Vertex.

It remains to be seen how the FDA will interpret this approach. It is possible that the FDA may prefer a stricter approach, whereby patients who dropout after receiving VX-950 or placebo are considered failures no matter what the outcome of the patient is at 12 weeks. This approach could skew the statistics of the trial against VX-950.
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