**Author details**

Terry W. Chin

tor150 mg twice a day for 28 days. Interim results found decreases in sweat chloride with both treatments. However, significant increases in FEV1 were found in both doses 100 mg and 150

[20] There were significant improvements in the mean absolute change in percent predicted of FEV1 and BMI after 24 weeks. Because there appeared to be no difference in two doses studied, the submission to the FDA selected lumacaftor 400 mg BID plus ivacaftor 250 mg BID. An open label roll-over study is still in progress and expected to continue for another 24 weeks.

Patients receiving just VX-661 monotherapy in the Phase 2 study also did not show any improvement, further supporting the strategy of combining a corrector and potentiator in treating patients with F508del mutation. In 2015, Vertex is starting a series of large-scale Phase 3 studies examining the efficacy of the combined therapy with VC-661 and ivacaftor in patients

The capability of molecules to enhance CFTR protein activity offers potential new treatment options for patients with CF. Long-term follow-up studies on ivacaftor, the first CFTR modulator to obtain FDA approval, look very promising. However, the drawback with these targeted therapies is the wide range of CFTR dysfunction seen in CF. Expanding the use of ivacaftor to nine other gating mutations only benefit about 10% of the total CF patient

mg of VX-661 with ivacaftor at 9% and 7.5% over baseline, respectively. [19]

**Figure 4.** Please Add Caption

**Figure 3.** Structural formula of lumacaftor (VX-809)

136 Cystic Fibrosis in the Light of New Research

**5. Conclusions**

population.

with one or two copies of the F508del mutation.

Address all correspondence to: tchin@memorialcare.org

Miller Children's Hospital, Long Beach, University of California, Irvine, USA
