Stealth BioTherapeutics’ elamipretide has flopped again. The latest setback saw the mitochondria-targeted peptide fail to beat placebo in a phase 2 clinical trial in geographic atrophy (GA), an advanced form of dry age-related macular degeneration (AMD).
ReCLAIM-2 randomized 176 patients with GA to receive 40 mg of elamipretide or placebo once a day. The drug candidate failed to beat placebo against primary endpoints that looked at changes in vision as measured by low-luminance best-corrected visual acuity and GA area. Elamipretide previously flunked a phase 3 trial in primary mitochondrial myopathy.
Stealth looked past the primary endpoint fail to see positives, noting that “administration of elamipretide resulted in a 2 or more line gain in LLVA for greater than 15% of patients completing the 48-week trial” and that a significant reduction in ellipsoid zone loss was seen. Justis Ehlers, advanced optical coherence tomography (OCT) analysis director for ReCLAIM-2, talked up the ellipsoid zone finding.
"We are excited by this finding that elamipretide resulted in reduction of progressive ellipsoid zone attenuation and may be a leading indicator for progression to more advanced disease," Ehlers said in a statement. “We believe that mitochondrial dysfunction plays an important role in AMD progression and ellipsoid zone loss on OCT is a potential important biomarker and endpoint for both intermediate AMD and evaluating long-term GA progression risk.”
The perceived positives were enough for Stealth CEO Reenie McCarthy to start talking about pivotal trial design, noting that evidence elamipretide improves mitochondrial function in the retina may provide the study team with “important enrichment strategies.”
Whether Stealth can secure the money to execute its plan is another question. The biotech ended last year with $47.1 million, leading it to warn investors of “a substantial doubt” about its ability to continue as a going concern. Stealth raised $8.5 million last month.
The money needs to support multiple activities, with Stealth running a phase 3 clinical trial in primary mitochondrial myopathy and planning studies in Duchenne muscular dystrophy and Barth syndrome, an indication in which the FDA knocked back an approval filing last year. Shares in Stealth fell more than 30% in premarket trading following news of the GA failure, dragging the stock down to $0.25.