- Vertex Pharmaceuticals (NASDAQ:VRTX) is down 3% after hours on increased volume in response to its announcement that it has terminated clinical development of lead pipeline candidate VX-661, in combination with Kalydeco (ivacaftor), for the treatment of cystic fibrosis (CF) patients with only one copy of the F508del mutation and one copy of a mutation that results in minimal CFTR protein function (F508del het/min). Its decision was based on the results from a planned interim futility analysis by the independent Data Safety Monitoring Board that showed an insufficient improvement in lung function in these difficult-to-treat patients.
- The company believes a triple combination of a next-generation CFTR corrector + VX-661 + ivacaftor may have potential in this population. A clinical trial is on tap for later this year after Phase 1 data in healthy volunteers is collected.
- The clinical development of VX-661 will continue in three populations of CF patients: those with two copies of the F508del mutation, those with one copy of the F508del mutation and a second mutation that results in residual CFTR function and those with one copy of the F508del mutation and a second mutation that results in a gating defect in the CFTR protein.
- The company says it still expects to file a New Drug Application (NDA) with the FDA seeking approval of VX-661, in combination with ivacaftor, in H2 2017. The filing will include data from the study in patients with minimal CFTR function mutations.
- VX-661 is CF transmembrane conductance regulator (CFTR) corrector. CF is caused by loss-of-function mutations in the CFTR protein. A CFTR corrector addresses the defects in the cellular processing and chloride channel function of CF-causing mutant CFTR alleles, thereby producing a clinical benefit.