Vertex has reported positive phase 2b data for its kidney disease prospect inaxaplin, boosting its efforts to expand beyond the population targeted in a pivotal trial.
The phase 2b Amplified clinical trial recruited two groups of people with APOL1-mediated kidney disease (AMKD). Vertex enrolled 22 people with AMKD and modest proteinuria, plus 17 patients with the kidney disease and Type 2 diabetes. The populations are distinct from that enrolled in the phase 2/3 Amplitude trial, which recruited people with severe proteinuria and no other kidney disease-causing comorbidities.
Vertex chose UACR, a measure of proteinuria, as the primary endpoint for Amplified. At Week 13, Vertex reported a mean reduction of 42.7% in UACR in people with AMKD and modest proteinuria. UACR fell 17.3%, on average, in the AMKD with Type 2 diabetes population.
The biotech reported similar results on a secondary endpoint that looked at UPCR, another measure of proteinuria. UPCR fell 44.7% in the modest proteinuria cohort and declined 25.4% in the Type 2 diabetes arm.
Inaxaplin’s effect on patients with AMKD and modest proteinuria is “remarkable,” Carmen Bozic, M.D., chief medical officer at Vertex, said in a statement. Bozic acknowledged that the magnitude of effect in the Type 2 diabetes population was smaller, but said Vertex is excited by the result.
Vertex plans to discuss the data with regulators in the context of the pivotal Amplitude trial, Bozic said. The company has completed enrollment in Amplitude and expects to share data from a preplanned interim analysis early next year. If positive, the analysis could support a filing for accelerated FDA approval.
Amplitude could unlock a population with about 150,000 patients in the U.S. and Europe, Susie Lisa, senior vice president of investor relations at Vertex, said at a Wells Fargo event this week. An FDA label covering the two arms in Amplified would add about 100,000 patients to the target population.
In an Aug. 3 note to investors, Guggenheim Securities analysts put the probability of success in primary AMKD at 65%. The analysts see the Type 2 diabetes population as a longer shot, ascribing a 45% chance of success to the indication.
Inaxaplin, a small-molecule inhibitor of APOL1 channel function, could compete with Maze Therapeutics’ MZE829. Maze reported phase 2 data on a mixed population of kidney disease patients, including people with diabetes. Analysts hailed MZE829’s “best-in-class potential,” but the biotech’s share price fell.