Stealth BioTherapeutics’ planned Phase III trial of elamipretide in genetically-confirmed mitochondrial myopathy has drawn physician debate over whether Stealth’s proposed 4-week protocol is long enough to capture relevant efficacy and safety data.
Physicians added the Six-Minute Walk Test (6MWT), the primary endpoint in the Phase II study, must be included as either a Phase III primary or secondary endpoint for FDA approval, but true clinical benefit will be better captured by additional functional cardiac and muscular measures. A crossover trial with approximately 30 patients would solve recruitment and powering concerns, physicians added. They were divided over elamipretide’s long-term safety risks and consequently the necessary dosing timeframe.
This news service reported on 31 January physicians expect Stealth’s Phase II extension study of elamipretide in mitochondrial myopathy (NCT02805790; MMPOWER-2) to show similar efficacy in the 6MWT as the original study (NCT02367014; MMPOWER). However, the study's clinical significance was debated.