Vertex on Monday announced a Phase 3 trial of its experimental cystic fibrosis drug, VX-661 in combination with ivacaftor, was stopped early due to lack of efficacy in a hard-to-treat patient population.
The biotech is currently testing the drug combination in three other patient populations and expects to test VX-661 plus ivacaftor in roughly 850 patients across those studies.
Analysts were unfazed by the failure, due to the high-risk nature of the patient population and the low expectations set by the company for that specific trial.
Vertex announced late Monday its Phase 3 clinical trial of VX-661 in combination with ivacaftor in patients with one copy of the F508del mutation and one copy of a mutation that results in minimal CFTR protein function will be stopped due to lack of efficacy.
The trial was reviewed during a planned interim analysis by a Data Safety Monitoring Board, which recommended the trial end. The DSMB did note that there were no safety concerns with the drug combination.
"While we recognize that people with CF with minimal function mutations have a form of the disease that is particularly difficult to treat, we believed it was important to evaluate whether a dual combination of VX-661 and ivacaftor could provide some benefit to these patients given they do not today have a medicine to treat the cause of their disease," said Jeffrey Chodakewitz, chief medical officer at Vertex.
While a failure is always a hit to a development program, at least one analyst doesn't see the trial as a problem for Vertex.
"The effects of this failure on VRTX’s expected entry into additional CF populations will likely be small: expectations were low, and VRTX is continuing with plans to investigate their next-generation triplet therapies in this patient population, with a launch potentially as early as 2019," wrote Evercore ISI analyst Mark Schoenebaum in a note to clients, adding that success of this trial could have meant an early entry into this market for Vertex.
In more important news for the therapy, Vertex also disclosed it has fully enrolled a trial of VX-661 plus ivacaftor in patients with two copies of the F508del mutation—one of the largest subgroup populations of cystic fibrosis. This trial is expected to report out at the end of the year.
Vertex expects to file VX-661 plus ivacaftor for approval in the second half of 2017. The company is also pursuing a triple combination therapy including VX-661, ivacaftor and a next-gen corrector.