"In what researchers are calling a breakthrough two preliminary trials have found that either of two tripledrug regimens could potentially benefit  percent of people with cystic fibrosis. The trials were shortterm finding that the drug combinations improved adult patients lung function over four weeks. But experts said they were optimistic the results will hold up in the larger longerterm trials already underway. Whats most exciting they said is that the tripledrug approach could open up new options to nearly all cystic fibrosis patients. This is not a cure for cystic fibrosis stressed Dr. Steven Rowe who led one of the trials. But it could be gamechanging. Cystic fibrosis CF is a genetic disorder that causes persistent lung infections. Over time extensive lung damage leads to respiratory failure. At one time children with CF usually died before they reached school age. But with improved treatments the typical life expectancy is now about  years according to the Cystic Fibrosis Foundation. Cystic fibrosis is caused by various mutations in a gene called CFTR. In the past several years drugs that target those underlying genetics have become available. Known as CFTR modulators they were heralded as a major advance in treating the disorder. However they work well only for a small number of people with certain CFTR mutations explained Rowe director of the Cystic Fibrosis Research Center at the University of Alabama at Birmingham. The most common mutation that causes cystic fibrosis is called Fdel  and it has proven tougher to tackle Rowe said. About half of people with CF carry two copies of the mutation one inherited from each parent. For them a combination of two existing CFTR modulators can ease breathing problems  but the overall effects are only modest Rowe said. Then theres the  percent of CF patients who carry only one copy of Fdel plus another defect known as a minimalfunction mutation. For them the existing CFTR modulators do not work at all. Both new trials focused on those two groups of patients. The results are published in the Oct.  New England Journal of Medicine to coincide with the researchers presentation at a North American Cystic Fibrosis meeting in Denver. Rowes team tested a combination of two available CFTR modulators  tezacaftor and ivacaftor  plus an experimental one known as VX. The other trial used the same existing drugs along with a similar new drug dubbed VX. Rowes team randomly assigned  adults with cystic fibrosis to either take the tripledrug regimen or be in a comparison group. In the comparison group patients with one Fdel mutation took placebo pills while patients with two copies of the mutation took tezacaftor and ivacaftor alone. After four weeks the trial found the tripledrug therapy had improved lung function in patients with both types of mutations. Their performance on a test called FEV rose by as much as  percentage points on average  what Rowe described as a pronounced improvement. The other trial had nearly identical results. This is the first time Rowe said that CFTR modulator therapy has pushed the needle for patients with one Fdel mutation. An editorial published with the studies said they represent a major breakthrough. Now the questions are whether the improved lung function can be sustained and whether the drugs prevent symptom exacerbations and other complications wrote Dr. Fernando Holguin of the University of Colorado Aurora. Vertex Pharmaceuticals Inc. is developing both experimental drugs. The ability of these potential drugs to treat individuals with a single Fdel mutation means that more people than ever before could benefit said Dr. Michael Boyle senior vice president for therapeutics at the foundation. This is very exciting news for our community. Rowe agreed there are still important questions about the tripledrug regimens. One is how well do they work for younger patients Patients as young as  are included in the larger ongoing trials Rowe said. So far the treatments appear safe. Most side effects in the fourweek trials were mild to moderate the researchers said and included cough headache and increased sputum. If the experimental drugs are ultimately approved there will be the realworld issue of price. Vertex currently markets the combination of tezacaftor and ivacaftor as Symdeko  at a reported list price of  a year. In the United States more than  people have cystic fibrosis according to the foundation. More information For an overview of cystic fibrosis visit the Cystic Fibrosis Foundation https SOURCES Steven Rowe M.D. M.S.P.H. director Gregory Fleming James Cystic Fibrosis Research Center University of Alabama at Birmingham Michael Boyle M.D. senior vice president therapeutics Cystic Fibrosis Foundation Bethesda Md. Oct.   New England Journal of Medicine"