=Vertex (VRTX) to seek marketing approval for new 'teza/iva' combination therapy for cystic fibrosis

Vertex Pharmaceuticals said that a combination of two of its medicines had successfully treated cystic fibrosis in a closely watched clinical trial, paving the way for regulators to approve a new option for sufferers of the deadly genetic illness.

The treatment had fewer side-effects than another drug combination already sold by Vertex, known as Orkambi, which became the first medicine able to treat a large proportion of cystic fibrosis patients when it was approved in 2015.

Vertex is announcing successful outcomes from two clinical trials involving tezacaftor, a second-generation "corrector" used in combination therapies to treat the underlying cause of cystic fibrosis. Importantly, the new efficacy and safety data reported from the tezacaftor studies improves upon the performance of Vertex's existing products.

Tezacaftor is a crucial drug for Vertex because it will enable the company to treat more cystic fibrosis patients and potentially blunt competitors racing to catch up.

Vertex shares closed Tuesday at $89.67 but rose 19% to $107 following the release of the trial news. The stock is up 45% year to date, factoring in Tuesday's night after-market reaction.

The larger of the two clinical trials announced today -- which Vertex calls EVOLVE -- enrolled just over 500 cystic fibrosis patients with two copies of a genetic mutation known as F508del. These patients represent about 40% of all cystic fibrosis cases.

Over 24 weeks, the combination of tezacaftor with an already approved Vertex drug ivacaftor (sold as Kalydeco) improved lung function by four percentage points compared to a placebo. The outcome was statistically significant, achieving the primary endpoint of the trial, Vertex said Tuesday.

The four percentage point improvement in lung function attributed to "teza/iva" compares well against Orkambi, Vertex's currently approved combination therapy for the same group of cystic fibrosis patients. Orkambi increases lung function by three percentage points, according to data from its own clinical trials included in the FDA label.

The safety profile of teza/iva also improves upon Orkambi. Thirteen percent of the patients treated with teza/iva in the EVOLVE clinical trial reported respiratory adverse events including shortness of breath, chest tightness or abnormal breathing. The comparable respiratory adverse event rate for placebo patients was higher at 16%.