Vertex Pharmaceuticals has chosen to advance experimental therapies VX-659 and VX-445 into late stage development as part of two different triple combination regimens for people with cystic fibrosis (CF).

The company said it plans to initiate the first Phase III triple combination programme with VX-659 in the first half of 2018, and a second to evaluate VX-445 in triple combination mid-year.

Regulatory discussions are ongoing to finalise the design of these programmes, the firm noted.

The move follows Phase II data showing mean absolute improvements in ppFEV1 (percent predicted forced expiratory volume in one second) of up to 13.3 and 13.8 percentage points for VX-659 and VX-445, respectively, in triple combination with in CF patients carrying F508del mutation and one minimal function mutation.

The regimens were also generally well tolerated across both studies, with the majority of adverse events considered mild to moderate in severity and the discontinuation rate due to side effects low.

"These results support the selection of both the VX-659 and VX-445 triple combination regimens and underscore the potential for these regimens to provide significant clinical benefits for up to 90 percent of people with CF," said Jeffrey Chodakewitz, Vertex’ chief medical officer.

"Together, all the Phase II data to date provide further evidence that the addition of a next-generation corrector to tezacaftor and ivacaftor has the potential to provide substantial clinical benefits to patients with one F508del and one minimal function mutation who don't currently have a medicine to treat the underlying cause of their CF, as well as to provide additional benefits to patients with at least one F508del mutation who are already eligible for CFTR modulator therapies,” added Jennifer Taylor-Cousar, associate professor of medicine and pediatrics at National Jewish Health, Colorado, and co-chair of Vertex's Triple Combination Steering Committee.