The investigational drug elamipretide has therapeutic potential to improve the physical capacity of patients with primary mitochondrial myopathy (PMM), according to the latest results of the Phase 2 MMPOWER-2 study. The positive results support the further clinical development of the drug to tackle this medical condition that lacks therapeutic options.
These and other findings of the clinical trial were presented at the Mitochondrial Medicine Symposium 2017 held by the United Mitochondrial Disease Foundation (UMDF) in Washington DC from June 28 to July 1.
“The lives of patients with primary mitochondrial myopathy, for which there are no FDA-approved treatment options, can be significantly impaired by the debilitating muscle weakness and fatigue they experience daily,” Dr. Amel Karaa, trial investigator, internist, and clinical geneticist at Massachusetts General Hospital said in a press release. “We have seen improvements associated with elamipretide in MMPOWER-2 which merit study in a Phase 3 trial.”
The injectable therapy, also known as Bendavia or MTP-131, was developed by Stealth BioTherapeutics and designed to target dysfunctional mitochondria. Elamipretide restores the ability of mitochondria to serve as the cell’s power source and reduces the levels of damaging oxidative stress produced by its previous dysfunctional activity.
The efficacy, safety, and tolerability of elamipretide are being evaluated in the randomized, placebo-controlled MMPOWER-2 (NCT02805790) clinical trial. All 30 participants with diagnosed mitochondrial disease included in this study had previously completed Stealth BioTherapeutics ‘s first clinical trial MMPOWER (NCT02367014).
In the first trial, the distance patients were able to walk in six minutes (6MWT) improved after five days of treatments with elamipretide. This beneficial effect was found to be dose-dependent. In the ongoing MMPOWER-2, increasing the time of treatment to four weeks was associated with patients improving their 6MWT distance by an average of 20 meters compared to those receiving a placebo, although this endpoint did not reach statistical significance.
However, a detailed analysis additionally showed that the treatment seemed to most benefit those who presented great physical impairment at baseline (able to walk less than 450 meters). These patients were able to walk an average additional 24 meters compared to an additional 8 meters observed in the group of patients with better physical capacity at the beginning of the trial. This observation was consistent with previous results of MMPOWER.
During the trial, elamipretide treatment significantly improved Neuro-Quality of Life Fatigue Short Form score, and the Primary Mitochondrial Myopathy Symptom Assessment Total Fatigue Score — a Stealth BioTherapeutics proprietary patient-reported outcome tool — compared to the placebo group.
No serious treatment-associated adverse events were reported during the trial. The most common side effect reports were mild redness or itching at the injection site.
“We are highly encouraged by the MMPOWER-2 trial’s identification of endpoints to measure changes in both skeletal muscle function and quality of life issues, which are so crucial in this patient population,” said Reenie McCarthy, chief executive officer at Stealth.
“These findings confirm the potential of elamipretide for these patients and help us establish and validate critical details for our planned Phase 3 study. We look forward to working closely with U.S. and European regulatory officials to finalize the design of our Phase 3 trial, which will enroll patients with primary mitochondrial myopathy caused by a variety of genetic mutations,” McCarthy added.