Astellas Providing Hope for People Living with Primary Mitochondrial Myopathy

Astellas, through its Mitobridge affiliate, has dosed the first patient in its pivotal Phase 2/3 clinical trial for ASP0367*, an oral investigational drug that may improve exercise intolerance and fatigue in Primary Mitochondrial Myopathy (PMM) patients.1

About Primary Mitochondrial Myopathy

PMMs are rare, genetically-defined disorders leading to defects in mitochondrial function that mainly affect skeletal muscle in 1 of 5,000 people in the US. These disorders often hamper the ability of affected cells to produce energy by limiting the breakdown of food and utilization of oxygen and may present serious and life-threatening health conditions such as cardiomyopathy, heart failure, respiratory failure and pneumonia.2

About ASP0367

ASP0367 is a PPAR delta modulator that aims to increase the number and enhance the function of mitochondria in PMM patients’ cells. The PPAR delta pathway regulates mitochondria by turning on different genes in the cell. When the pathway is on, the mitochondria use fatty acids more often and more mitochondria are made. Using more fatty acids for energy results in increased energy production.3

ASP0367 is the lead investigational therapy for Mitobridge in Astellas’ Primary Focus Area of Mitochondrial Biology.

About the MOUNTAINSIDE Clinical Program

The MOUNTAINSIDE program will launch with Phase 2/3 clinical trials that will enroll a total of 139 adult participants (ages 18 to 80) with PMM at 14 sites in the US.4

The Phase 2 trial will assess the safety and tolerability of ASP0367 and determine a dosage level. In phase 3, investigators will use the 6-minute walk test (primary endpoint) and 5 Times Sit to Stand (5XSTS) test (secondary endpoint) to evaluate the functional impact of ASP0367 treatment on exercise tolerance and endurance, as well as the safety and tolerability of ASP0367, relative to placebo. There are also several other secondary and exploratory endpoints to assess how improvements in exercise tolerance and endurance may translate into the participants’ daily life.4

“There are no disease-modifying treatments for PMM patients, and the FDA has recognized this, and thus granted ASP0367 Fast Track Designation,” said Mike Patane, Ph.D., President of Mitobridge. “We’re hopeful that this pivotal trial will deliver on our promise of providing value to PMM patients and their families by treating the debilitating drivers of this disease and thereby helping them improve their quality of life.”

To learn more about the MOUNTAINSIDE trial, please visit and reference NCT04641962.


1 Astellas (2020, October 20). U.S. FDA Grants Fast Track Designation for ASP0367/MA-0211, a Selective PPARδ Modulator Being Developed for the Treatment of Primary Mitochondrial Myopathies [Press release].
2 Mancuso, M. (2019). Primary Mitochondrial Myopathies. National Organization for Rare Disorders.,affecting%20predominantly%20the%20skeletal%20muscle
3 Uz, T. (2021, March 25). ASP0367 Development program and 0367-CL-1201 study update [Conference Presentation]. UMDF Community Webinar, Northbrook, IL United States.
4 NCT04641962. A Study to Evaluate ASP0367 in Participants With Primary Mitochondrial Myopathy (MOUNTAINSIDE).

*ASP0367 is an investigational drug and is not available for use outside of the investigation. The safety and efficacy of the ASP0367 has not been established. There is no guarantee that ASP0367 will receive regulatory approval or become commercially available for uses being investigated. ASP0367 is not authorized for sale in any jurisdiction.

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