Vertex Pharmaceuticals has confirmed the progression of inaxaplin (VX-147) into the Phase III portion of the international Phase II/III pivotal study for APOL1-mediated kidney disease (AMKD).  

The trial will compare a 45mg once-daily oral dose of inaxaplin to a placebo, in addition to standard of care. 

AMKD is a chronic kidney disease caused by variants in the APOL1 gene. Nearly 100,000 individuals in Europe and the US have two APOL1 genetic variants, as well as proteinuric kidney disease.  

The clinical trial aims to evaluate the impact of inaxaplin on kidney function and proteinuria in patients with proteinuric kidney disease mediated by two APOL1 gene variants.  

The study has now been expanded and will include adolescents aged ten to 17 years with AMKD.  

Inaxaplin is being investigated as a small molecule inhibitor of APOL1, targeting AMKD’s underlying cause.  

The primary efficacy endpoint for patients receiving inaxaplin compared to placebo is the estimated glomerular filtration rate (eGFR) slope, with the secondary efficacy endpoint being time to composite clinical outcome, defined as a sustained decline of ≥30% from baseline in the eGFR, onset of end-stage kidney disease, or mortality.  

This will lead to the final analysis which will take place once the subjects have a minimum of two years of eGFR data and after around 187 composite clinical outcomes have been recorded. 

A pre-planned interim analysis has also been planned at week 48 to evaluate eGFR slope and proteinuria changes, which could lead to accelerated approval of inaxaplin for AMKD patients living in the US, if positive. 

Enrolment for this study is currently underway, and more than 200 sites are now operational in the US and globally. 

Data from the previously conducted Phase IIa trial showed that inaxaplin significantly reduced urine protein to creatinine ratio (UPCR) by 47.6% at 13 weeks of the treatment, indicating the potential of an oral APOL1 inhibitor to decrease proteinuria in AMKD patients. 

Vertex chief medical officer and global medicines development and medical affairs executive vice-president Carmen Bozic said: “Advancing this trial into Phase III and broadening the trial to include younger patients is a critical step forward in bringing this potential therapy to patients who are waiting.”