Many of you are undoubtedly waking up to the news that GSK finally issued more data from its Phase II trial of Prosensa's Drisapersen. Drisapersen, for any newbies, is a drug considered to be in direct competition with Sarepta. Since Prosensa (RNA)'s IPO many investors became worried that Sarepta would have problems, given that drisapersen was further along in trials. Turns out the worries were overblown. Drisapersen (unlike Sarepta's eteplirsen) simply isn't a very good drug.
The most important piece of news from the data release was that Drisapersen simply isn't as good at generating the key protein dystrophin as Eteplirsen. In fact, by week 25, only 72% of patients on continuous dosing showed increased dystrophin. Only 59% of patients on intermittent dosing showed same. We don't know why the effect is more muted. Possibly due to the low dosing required by drisapersen's dangerous side effects. Possibly due to the larger drisapersen molecule having more difficulty penetrating cells.
Note that the data also reiterated the FAILURE of Drisapersen to attain statistical significance in clinical outcomes as well. I leave off with a direct quote from the data:
At Week 25, no statistically significant treatment benefit (3.51 m) over placebo in 6MWD was observed for the intermittent regimen. At Week 49, a treatment difference (similar magnitude to Week 25 of 35.84 m) over placebo in 6MWD was observed for the continuous regimen, though the results were no longer statistically significant due to increased variability. At Week 49, a treatment benefit (27.08 m) over placebo in 6MWD was observed for the intermittent regimen, although the results were not statistically significant
Sentiment: Strong Buy
GSK/Prosena/RNA, MDA, and most importantly the FDA have all acted mostly with their self interests in mind. It's disgusting, but here too, greed seems to be prevailing over facts. Worse still, it's sick boys who will pay the greatest price, and it didn't have to be that way.
This is the news Sarepta has needed. The stock has been held back ever since Prosensa got buddy-buddy with several investment banks during its IPO. No wonder Prosensa rushed to IPO before this was released.
Hang on. Are we really so thrilled that ONLY 72% of the patients showed an increase of dystrophin? And those on a LOWER imtermittent dose of the competing drug showed a DIRECT CORRELATION of only 59% with an increase in dystrophin?
Doesn't that show a DIRECT RELATION between their drug and dystrophin production? Reducing the drug reduces dystrophin production?
I don't see how this is a good thing.
Bionerd/Red/other in more basic science backgrounds: Would be interested in comments re differences in 'stringency' of measurements of dystrophin between GSK/drisa and SRPT/etep as raised by Brian Skorney of Baird this AM.