This is purely speculation on the part of my CF doc, but he says that VX 770 may have some benefit to delta 508s even without VX 809, which is why some clinics (mine included) are undergoing testing on it. Apparently, some of our CFTR may make it to the edge of the cell and then the VX 770 could correct this small number of CFTR and help our FEV1 to some extent. This MAY be possible. It is only a theory. It is really hard to predict and that is why we need the study.