The Food and Drug Administration in the US has approved the use of a new therapy called Symdeko to treat the underlying cause of cystic fibrosis.

The therapy uses a new drug, tezacaftor/ivacaftor in combination with ivacaftor (Kalydeco) to treat patients aged 12 and over who have two copies of the F508del gene or at least one CF gene that is responsive to the treatment.

Two research trials of the medicine tezacaftor in combination with ivacaftor show the new combination therapy to have comparable effects to Orkambi (which combines ivacaftor with a drug called lumacaftor) for people with two copies of the F508del gene, and significant improvements for those with one F508del and one “residual function” gene.

The EVOLVE study involving those with two copies of the F508del gene, presented in the New England Medical Journal by Professor Stuart Elborn, found that the tezacaftor/ivacaftor combination treatment was more stable than Orkambi, with similar benefits of around four per cent lung function improvement, and with fewer side effects.

The EXPAND study, presented by Professor Jane Davies, found an average improvement in lung function of 6.8 per cent in those with one F508del and one residual function mutation, compared with the group taking placebo medication.

Late last year both the FDA and EMA (European Medicines Agency) announced they would be prioritising the drug for consideration, with the FDA recently Symdeko in February.