Vertex Reports Positive Inaxaplin Results in Kidney Disease

Boston, Massachusetts, U.S., September 22, 2026

Inaxaplin Shows Reduction in Proteinuria

The Phase 2b AMPLIFIED study evaluated a once-daily 45 mg dose of inaxaplin on top of optimized standard of care. A total of 41 people were enrolled across two cohorts. The first cohort included people with AMKD and modest proteinuria, while the second included people with AMKD, type 2 diabetes, and proteinuria. The primary endpoint was the mean percentage change in UACR at Week 13 compared with baseline, with changes in urine protein-to-creatinine ratio (UPCR) and safety also assessed. In the modest-proteinuria cohort, treatment with inaxaplin resulted in a 42.7% reduction in UACR at Week 13 compared with baseline. UPCR also declined by 44.7%, providing additional evidence of reduced proteinuria in this population.

In the second cohort consisting of people with AMKD and type 2 diabetes, inaxaplin produced a 17.3% reduction in UACR at Week 13, while UPCR decreased by 25.4%. Vertex noted that the treatment effect in this population was smaller than that observed in people with modest proteinuria. The company also reported that the findings in the modest-proteinuria cohort were consistent with results previously observed in a Phase 2a study involving people with AMKD and focal segmental glomerulosclerosis (FSGS). Importantly, most participants in the modest-proteinuria cohort did not have an FSGS diagnosis, broadening the population in which the treatment is being investigated.

Safety Findings Support Continued Development

Vertex reported that inaxaplin was generally safe and well tolerated across both AMPLIFIED cohorts. No serious adverse events related to treatment were reported, and all adverse events were described as mild or moderate. Headache was the most common adverse event, occurring in 7.3% of participants. Five people experienced isolated, asymptomatic elevations in transaminases, which subsequently resolved. These findings add to the safety information being generated as Vertex continues to evaluate inaxaplin across genetically defined kidney disease populations.

The company is developing inaxaplin to target the underlying biology of APOL1-mediated kidney disease, a proteinuric kidney disorder associated with inherited APOL1 variants. The condition can cause kidney-cell injury and damage to the glomeruli, ultimately reducing kidney function and potentially leading to dialysis or kidney transplantation. Vertex estimates that AMKD affects approximately 150,000 people in the United States and Europe, and there are currently no approved therapies specifically for AMKD.

Vertex Completes Enrollment in AMPLITUDE Trial

Alongside the AMPLIFIED findings, Vertex announced completion of enrollment in the global Phase 2/3 AMPLITUDE trial, which is evaluating inaxaplin in people with AMKD and severe proteinuria without other kidney disease-causing comorbidities. The study is designed to assess the effect of once-daily inaxaplin on kidney function and proteinuria compared with placebo when added to standard of care. The final efficacy analysis will evaluate the estimated glomerular filtration rate (eGFR) slope after two years of treatment. Vertex expects to report results from a pre-planned interim analysis in early 2027, after the interim-analysis cohort reaches 48 weeks of treatment. If the results are positive, Vertex said they could potentially support an accelerated approval application in the United States. However, inaxaplin remains an investigational therapy, and the ongoing pivotal study will be important in determining its efficacy and safety in the broader AMKD population. The latest AMPLIFIED results and completion of AMPLITUDE enrollment represent further milestones in Vertex’s effort to develop a targeted treatment for a serious genetically driven kidney disease with significant unmet medical need.

Source: Vertex Pharmaceuticals press release