Vertex Pharmaceuticals (NASDAQ:VRTX) said to expect data from two clinical trials testing its cystic fibrosis drugs midyear. It's June. Doesn't get much more midyear than that.

The two trials, dubbed Traffic and Transport, are testing VX-809, at two different doses, plus the already-approved Kalydeco in patients with F508del mutation in the CFTR gene, the most common mutation seen in cystic fibrosis patients.

The combination therapy is revolutionary because it fixes the underlying problem -- CFTR not being able to transport chloride across the cell membrane -- while current treatments only treat the symptoms. Gilead Sciences' (NASDAQ:GILD) Cayston and Novartis' (NYSE:NVS) Tobi, for instance, are antibiotics that treat lung infections caused by buildup of mucus in cystic fibrosis patients.

While the phase 2 data for the combination therapy was positive, it was complicated by the low number of patients, making the error bars fairly substantial. Vertex hopes that, with more patients and longer dosing, the effect of VX-809 and Kalydeco will be clearer.

Investors seem to agree, although they're not completely convinced. As senior biotech specialist Brian Orelli and health-care analyst David Williamson discuss in the video below, there's plenty of upside if the trials are successful. If they fail, Vertex could be cut in half.

Watch the video for more thoughts from Brian and David.