). In the report, Zhang noted, “Vertex's remarkable c $7.2bn (62%) increase in market capitalisation last week, on the back of VX-661 Phase IIa top-line data in cystic fibrosis (CF) patients with two copies of F580del mutations, poses a difficult question for investors. While the valuation reflects the market's confidence in the strength of its potential franchise in CF – possibly worth up to $10bn in peak sales – it also assumes a high probability of success. Vertex is now the undisputed leader in CF with one approved (Kalydeco, ivacaftor) drug and three clinical candidates (VX-809, -661 and -983) in the pipeline, but Edison cautions that the risk is now asymmetric to the downside.” Vertex Pharmaceuticals closed on Thursday at $80.32.