Vertex’s Kidney Disease Drug Succeeds in Phase 2b Trial, Reducing Proteinuria by Up to 44.7%

U.S. pharmaceutical company Vertex Pharmaceuticals reported positive results from a phase 2b trial of inaxaplin, a candidate treatment for kidney disease.

According to Fierce Biotech on the 23rd local time, Vertex said proteinuria measures decreased significantly in the phase 2b AMPLIFIED trial of inaxaplin in patients with APOL1-mediated kidney disease (AMKD).

The AMPLIFIED trial enrolled 22 patients with AMKD and mild proteinuria and 17 patients with AMKD and concurrent type 2 diabetes. This population differs from that of the phase 2/3 AMPLITUDE trial, which enrolled only patients with severe proteinuria.

The primary endpoint, the urine albumin-to-creatinine ratio (UACR), decreased by an average of 42.7% at week 13 in the mild-proteinuria group. It decreased by an average of 17.3% in the group with concurrent type 2 diabetes.

The secondary endpoint, the urine protein-to-creatinine ratio (UPCR), also decreased by 44.7% in the mild-proteinuria group and by 25.4% in the group with concurrent diabetes.

Carmen Bozic, Vertex’s chief medical officer (CMO), described the effect observed in patients with mild proteinuria as “striking.” She added that although the effect size was smaller in the group with concurrent diabetes, the results were encouraging.

Vertex plans to discuss these results with regulators alongside data from the AMPLITUDE trial. AMPLITUDE has completed enrollment and is scheduled to report results from a prespecified interim analysis early next year. If the results are positive, they could support an application for accelerated approval from the U.S. Food and Drug Administration (FDA).

Suzy Lisa, Vertex’s senior vice president of investor relations, said AMPLITUDE could address a patient population of approximately 150,000 people in the United States and Europe. If the FDA-approved label includes the two AMPLIFIED populations, the eligible patient population would increase by approximately 100,000.

Guggenheim Securities gave primary AMKD a 65% probability of success in an investor note dated Aug. 3. It assigned a lower probability of 45% to the indication involving concurrent type 2 diabetes.

Inaxaplin is a small-molecule compound that inhibits APOL1 channel function and is expected to compete with Maze Therapeutics’ MZE829. Maze has released phase 2 data in a mixed kidney disease population that included patients with diabetes, and analysts rated MZE829’s potential to be best in class highly, but the company’s stock price declined.