Very exciting results announced today for VX-445
Sounds like they'll review more data at end of 24 weeks and decide between VX-659 and VX-445

From Vertex press release on 3/6:

Two Phase 3 Studies of the Triple Combination of VX-445, Tezacaftor and Ivacaftor Met Primary Endpoint of Improvement in Lung Function (ppFEV1) in People with Cystic Fibrosis

-Mean absolute improvement in ppFEV1 of 13.8 percentage points from baseline at week 4 in people with one F508del mutation and one minimal function mutation (F/MF) compared to placebo (p<0.0001)-

-Mean absolute improvement in ppFEV1 of 10.0 percentage points from baseline at week 4 when VX-445 was added in people with two F508del mutations (F/F) already receiving tezacaftor and ivacaftor compared to control group of placebo added to tezacaftor and ivacaftor (p<0.0001)-

-Safety and efficacy profile reported today supports potential submission of a New Drug Application for the VX-445 triple combination regimen-

-Vertex plans to seek global regulatory approvals for either VX-659 or VX-445 triple combination regimen in both F/F and F/MF patient populations concurrently based on final 24-week data for both regimens expected in the second quarter of 2019-

-U.S. NDA and EU MAA planned for the third and fourth quarters of 2019, respectively-

-Given the similarity of the data for the 4-week primary efficacy endpoint for the VX-659 and VX-445 regimens and the near-term availability of the final 24-week data for both regimens in the second quarter of 2019, Vertex plans to utilize these final 24-week data to choose the best regimen to submit for regulatory approvals globally.

“Both the VX-659 and VX-445 triple combination regimens showed highly consistent and significant improvements in lung function across our Phase 3 programs, underscoring the important clinical benefit that a triple combination regimen may provide to patients with two F508del mutations and to those with one F508del and one minimal function mutation,” said Reshma Kewalramani, M.D., Executive Vice President, Global Medicines Development and Medical Affairs and Chief Medical Officer at Vertex. “We look forward to submitting global regulatory applications for one of these triple combination regimens for both patient populations later this year.”