Vertex tumbles despite good final data on combo cystic fibrosis therapy

USA-based Vertex Pharmaceuticals (Nasdaq: VRTX) saw its shares tumble 16% to $51.18 last week, after the company announced final data from a Phase II study of VX-809 and Kalydeco (ivacaftor) that showed statistically significant improvements in lung function among adults with cystic fibrosis (CF) who have two copies (homozygous) of the most common mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, F508del.

It appears that analysts found difficulty in comparing the data with interim results released in May, which was followed by a clarification saying there was less benefit than initially thought, causing Vertex shares to plunge 19% to $52.85 (The Pharma Letter May 30). Kalydeco was approved in the USA in February 2012, for treating CF patients aged six years and above. Vertex recorded sales of $18.4 million for Kalydeco in the first quarter of 2012.

The study randomized homozygous F508del patients to three treatment groups that evaluated increasing doses of VX-809 (200mg, 400mg or 600mg; QD) alone for 28 days, followed by VX-809 in combination with Kalydeco (250mg; q12h) from Day 28 to 56. When patients received the two medicines in combination (Day 28 to 56), there was a statistically significant improvement in lung function (percent predicted forced expiratory volume in one second, FEV1) in each of the homozygous treatment groups compared to placebo.