Cystic Fibrosis – Newer agents

Initial U.S. Approval:  2015

Mechanism of Action: The CFTR protein is a chloride channel present at the surface of epithelial cells in multiple organs. The F508del mutation results in protein misfolding, causing a defect in cellular processing and trafficking that targets the protein for degradation and therefore reduces the quantity of CFTR at the cell surface. The small amount of F508del-CFTR that reaches the cell surface is less stable and has low channel-open probability (defective gating activity) compared to wild-type CFTR protein.
Lumacaftor improves the conformational stability of F508del-CFTR, resulting in increased processing and trafficking of mature protein to the cell surface. Ivacaftor is a CFTR potentiator that facilitates increased chloride transport by potentiating the channel-open probability (or gating) of the CFTR protein at the cell surface. In vitro studies have demonstrated that both lumacaftor and ivacaftor act directly on the CFTR protein in primary human bronchial epithelial cultures and other cell lines harboring the F508del-CFTR mutation to increase the quantity, stability, and function of F508del-CFTR at the cell surface, resulting in increased chloride ion transport. In vitro responses do not necessarily correspond to in vivo pharmacodynamic response or clinical benefit.

INDICATIONS AND USAGE:  ORKAMBI is a combination of lumacaftor and ivacaftor indicated for the treatment of cystic fibrosis (CF) in patients age 12 years and older who are homozygous for the F508del mutation in the CFTR gene. If the patient's genotype is unknown, an FDA-cleared CF mutation test should be used to detect the presence of the F508del mutation on both alleles of the CFTR gene.

Limitations of Use
The efficacy and safety of ORKAMBI have not been established in patients with CF other than those homozygous for the F508del mutation.

HOW SUPPLIED: Tablets: 200 mg lumacaftor and 125 mg ivacaftor; supplied as pink, oval-shaped, film-coated, fixed-dose combination tablets containing 200 mg of lumacaftor and 125 mg of ivacaftor. Each tablet is printed with the characters "2V125" in black ink on one side and plain on the other.