Vertex Pharmaceuticals (VRTX) announced that Kalydeco, its drug for cystic fibrosis (CF), showed potential benefit in patients 18 or older, despite missing a phase 3 study’s primary endpoint. Although not an ideal outcome, expanding Kalydeco’s label into patients with the R117H mutation that are 18+ may still be on the table.
Kalydeco addresses the underlying cause of CF in patients with the G551D mutation and is approved only for patients older than 6 with this mutation. Kalydeco was approved in January of 2012.
Vertex has been looking to expand Kalydeco labeling for both younger patients with the G551D mutation and patients with other forms of the disease. Today’s phase 3 study looked at 69 people 6 years of age and older with cystic fibrosis (CF) who have the R117H mutation. R117H is the most common CF mutation. In North America, Europe and Australia, approximately 1,100 people with CF ages 6 and older have at least one copy of an R117H mutation. In the United States, approximately 300 people have the R117H mutation and are 18 years of age or older.
In the study, the mean absolute treatment difference in the change from baseline in percent predicted FEV1 (ability to force air out of the lungs for 1 second) between treatment with Kalydeco and placebo was 2.1 percentage points (p=0.20). The mean relative treatment difference in percent predicted FEV1 was 5.0% (p=0.06) through the 24-week treatment period among all patients (intent-to-treat analysis).
The study did not meet its primary endpoint across the entire patient population; however, in 50 patients older than 18, the majority of patients in the study, the drug showed a statistically significant improvement in lung function. Vertex believes that this predefined subgroup, patients with the R117H mutation that are older than 18, can benefit from Kalydeco therapy. The company plans to meet with the U.S. Food and Drug Administration (FDA) in early 2014 to discuss these data and the potential submission of a supplemental New Drug Application (sNDA).
While the overall study did not meet its primary endpoints, VRTX continues to make progress in understanding CF. The subset analysis is certainly not ideal, but the positive results in older patients suggest that the FDA may, in fact, be open to expanding Kalydeco’s label to include this small patient population, despite the phase 3 miss. Given the stock’s reaction on Thursday – VRTX is up 2% at the close – investor expectations were not particularly high for this trial.
