omment re VX-770: Vertex notes planned additional testing for
•Pediatric study: A study of KALYDECO in children ages 2 through 5 with gating mutations, including G551D, is expected to evaluate the safety, tolerability and effect on sweat chloride and other measures of clinical activity using a pediatric formulation of KALYDECO. Comment: This testing cannot use FEV1 because, as I've noted before, you can't measure FEV1 for 2 - 5 year olds. This fact leads me to conclude Vertex has/expects expanded label approval for VX770 based on SC. •Study in people with the R117H mutation: Vertex plans to begin the first clinical study of KALYDECO in people who have at least one copy of the R117H mutation in the CF gene. The R117H mutation causes abnormal function of the CFTR protein at the cell surface. Approximately 3 percent of people with CF in the U.S. have the R117H mutation. •Study in other gating mutations: Vertex also plans to begin the first clinical study of KALYDECO in other gating mutations where CFTR proteins are present at the cell surface but do not function properly. G551D is the most common gating mutation, present in approximately 4 percent of people with CF in the U.S., and was the focus of previous Phase 3 KALYDECO studies. The remaining gating mutations to be evaluated in this study account for an additional approximately 1 percent of people with CF in the U.S.
Comments: These last 2 expanded tests add 4% to the market for VX-770, which would double the market. BUT this is much less than I had predicted/expected based on earlier comments from Vertex indicating that as many as 20% could benefit from VX-770 and I believed 12% a conservative estimate. I'm unsure why there is only another combined 4% that is being targetted. That said, I think there could well be some off-label usage by other mutations (but double deltas).