Currently, there are no real treatments for patients with primary mitochondrial myopathy (PMM). Most therapies, such as physical, occupational, or speech therapy, are designed to simply lessen or mitigate symptoms. However, this may be changing. In case you missed it, a news release from late March 2021 shares that REN001, a potential PMM treatment, received Fast Track designation from the FDA.
REN001
Developed by pharmaceutical company Reneo Pharmaceuticals, Inc. (“Reneo”), REN001 is a selective peroxisome proliferator-activated receptor delta (PPARδ) agonist. The orally administered treatment is currently being evaluated as a potential therapy for patients with PPM. Additionally, researchers are evaluating REN001 for patients with long-chain fatty acid oxidation disorders and glycogen storage disorder type V. Since patients with mitochondrial diseases are unable to produce adenosine triphosphate (ATP), REN001 works to modulate gene activity and increase ATP production.
In March, the FDA granted Fast Track designation to REN001. This process, which must be requested by the drug developer, works to help with development and review of investigational therapies. In particular, Fast Track status is granted to treatments which could fill an unmet need in patients with rare, serious, or life-threatening conditions. According to the FDA:
Filling an unmet medical need is defined as providing a therapy where none exists or providing a therapy which may be potentially better than available therapy. If there are available therapies, a fast track drug must show some advantage over available therapy, such as: showing superior effectiveness, effect on serious outcomes or improved effect on serious outcomes; avoiding serious side effects of an available therapy; improving the diagnosis of a serious condition where early diagnosis results in an improved outcome; [and] decreasing a clinical significant toxicity of an available therapy that is common and causes discontinuation of treatment.
Primary Mitochondrial Myopathy (PMM)
Primary mitochondrial myopathies (PMM) are mitochondrial diseases associated with mitochondrial defects. Normally, mitochondria generate energy within cells. However, when genetic mutations or alterations occur within mitochondrial DNA, it prevents the mitochondria from functioning properly. As a result, muscular issues may occur. Mutations can be inherited from parents or can occur spontaneously. An estimated 1-2 in every 10,000 people has PMM. Although the condition can occur at any age, PMM is often more severe in younger patients and milder when it occurs in adulthood.
Signs and symptoms of PMM vary, even in patients with the same genetic mutations. However, some common or characteristic PMM symptoms include:
- Muscle weakness
- Note: Some patients may also experience muscle cramping or wasting.
- Nausea
- Progressive eye muscle paralysis
- Note: Additional vision-related symptoms associated with PMM include vision impairment, double vision, and upper eyelid drooping.
- Stunted growth
- Developmental delays
- Diabetes
- Headache
- Difficulty swallowing or speaking
- Short stature
- Exhaustion after physical exertion or activity
- Slurred speech
- Abnormal heartbeats
- Seizures
- Heart failure
