Vertex downgrades Kalydeco combo CF data but analysts still positive

Vertex has suffered an embarrassing data blunder, in that it said on 29 May that it has had to correct some previously released interim data from its small Phase II combination trial of its cystic fibrosis drug Kalydeco (ivacaftor) and the experimental agent VX-809 in the most common genetic forms of the disease – making it clear to investors that only 35% of 37 CF patients with the F508del mutation saw an absolute improvement in lung function (FEV1) of 5% or more with the combo, as opposed to the 46% that it previously reported.

The news is a setback, as the initial read out of the data has been associated with a jump in...