Difference between VX-661/VX-770 and VX-809/VX-770 study

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baseballfrank

New member
What is the difference between the 2 clinical trails? I know both are for F508 mutations and both VX 661 and VX 809 are effecitve in moving the defect to the surface of the cell to allow VX-770 or Kalyedeco to work. Can anybody shed any light on other differences? which seems to most effective? Pluses and minues of each?
 
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static

New member
From what has been talked about it is just a different way of deliverance, scientific stuff that would probably need to be answered by a geneticist. From what I understand (and don't quote me) the 661 helps unfold the chromosome so more salt can be delivered to the cells from the sodium chloride channel. However, you need the 770 still to open up the channel.

Basically, the new drugs are trying to move it closer to the sodium chloride channel. The other mutation wasn't as deep down as ours, so theirs was easier to fix.
 
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stranger

Guest
VRTX has put 661 in a different class in their go to market strategy; 661 is the first of this new corrector class. From the preso's I have seen, this next gen of correctors could work with other correctors, as well as 770.

According to the trials.gov info, the dosage of each is vastly different (in particular, this is the moving target with 809 that may be delaying the Ph3 trial -- I support this conclusion by reading through the transcripts of the analysts calls with VRTX).

The 809/770 trial has been granted new status with the FDA; 'Fast Track,' or something like that. What this means to the CF community isn't exactly clear (at least not to me). Does it mean that there is more flexibility in trial design? Interpretation of endpoint success? Quicker / broader access? 661/770 has not had this designation (at least not yet).

809/770 has had Ph2 data reported (somewhat infamously I suppose). 661/770 Ph2 has not.

Maybe there is a question: why one and not the other? This question has been asked a few times on the VRTX earnings call or other calls with analysts (Nov 2012; late May 2012). The science bypasses me at this point but from a business point of view, if I am VRTX, I need 770 E V E R Y W H E R E as quick as possible, whether it is with 809, 661 or anything else. Right now, 809 is furthest down the path.
 
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stranger

Guest
Kalydeco was one of the fastest and I belive was the catalyst for this new bucket with the FDA. The reason why I am still curious is it would be interesting for me to understand if the burden on VRTX has changed / been shifted to something that either tactically and / or strategically benefits the patient population under 'Fast Track' status.
 
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CyrilCrodius

New member
stranger said:
Maybe there is a question: why one and not the other? This question has been asked a few times on the VRTX earnings call or other calls with analysts (Nov 2012; late May 2012). The science bypasses me at this point but from a business point of view, if I am VRTX, I need 770 E V E R Y W H E R E as quick as possible, whether it is with 809, 661 or anything else. Right now, 809 is furthest down the path.
Click to expand...

I think it's simply because VX-661 "came out" later.
 
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albino15

New member
I don't know the technical differences between 661 and 809 but they must be different somehow. Correct me if I'm wrong but didn't they do some early trials with 661 and it wasn't as good as they thought it would be, then they did another trial with 809 combined with 770 and those seemed to work out better so now they're kind of running with it. You don't really hear anything about 661 anymore, it's all about the 809 770 combo.
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stranger

Guest
It went the other way around; there was some initial disappointment with 809 so they modified the molecule to become 661. The 770 + 809 results were controversial because of semantics of 'absolute' and 'relative' with respect to when they disclosed the PhII results. Back to my original reply, they have created a new category that they are calling '2nd Gen' correctors and 661 is the first of those. I think when they presented at the NACFC in October, either van Goor or Mueller spoke about CFTR treatments someday that could combine multiple correctors as well as the conductor, 770. Here is a link from the press release: http://investors.vrtx.com/releasedetail.cfm?ReleaseID=712776
It doesn't talk about the approach of multiple correctors but this was discussed on the webcast (which is taken down after two weeks). There might be a screen shot of that preso somewhere; if I find it, I will post it.
 
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