809 vs 661


New member
My husband has been thinking of getting on the phase three trial of lumacaftor plus ivacaftor. However we both have some reservations. His mutations are both delta F508. He is 28 years old. He has an FEV1 of 75%. This has been stable for the last decade. And his enzyme levels were in the normal range last time they were checked (the center still suggested he take one enzyme pill with each meal).

When I read the phase 2 results for this combo, the results are dismal. There was no FEV benefit. So now for the phase III, they triple the 809 dose. This seems to be somewhat grasping at straws. Like maybe his FEV will go up 2% however all the visits are a lot of work and stress (he works full time and his work doesn't know he has cystic fibrosis) for just 2%. And we won't have enough vacation days to do other fun stuff if he does this trial.

Most of those concerns are pretty trivial. However what really makes me want to suggest he not do this trial is that there has been such promising results in the phase 2 661 and ivacaftor trial and if he participates in this 809 trial, he may miss out on the opportunity to be on a phase 3 661 trial when it comes around.

Anyone research these things in more detail? What do you think?


Super Moderator
I'm sorry, but I think you have several pieces of misinformation. The Phase 2 results were not dismal and FEV did benefit about 6% absolute and 10% relative if I remember correctly. Either way, the results are more than sufficient to justify approval if they bear out in Phase 3. (And are about the equivalent of Pulmozyme but come in a pill). The higher dose is not triple the original dose. Originally they dosed at 600 mg 1x a day for 809 and they added an arm of 400 2x a day which is only 200 more, but might prove even more promising. It is true that the benefit is not as good as Kalydeco, but it gets functioning CFTR to about the 30-35% level (kalydeco to 50%). And by being in the study he can continue on the drug after he is finished until approval, so he could get the drugs a year earlier. I'd jump at this chance in a second. Also, 661 was not more promising--many including me thought it would be. In fact, it seemed in my view slightly less effective than 809. Plus, Vertex is not sure at this point whether they will move 661 on for those with ddf508. In short, I'd call the research coordinator today and say "I want in" if it were me.


Look closely at the dosing of 809 PII, then look at the details on the trials.gov site.

Waiting for 661 also means that you will be waiting for the 661 v 983 decision, which has not been made (at least public).