Vasodilator and Exercise Study for DMD (VASO-REx)

Phase 2RecruitingNCT06290713

University of Florida50 enrolled

Overview

Examining two strategies as potential adjuvant therapies for Duchenne muscular dystrophy (DMD); aerobic exercise training (to induce adaptations in skeletal muscle and improve cardiovascular health) and tadalafil, an FDA-approved vasodilator (to optimize blood flow and muscle perfusion which is impaired and often overlooked in DMD). Target: improved muscle function, vascular health, and DMD treatment.

Duchenne muscular dystrophy (DMD) is characterized by rapid muscle deterioration, mitochondrial and vascular impairments, resulting in premature loss of ambulation and mortality. Disease-modifying therapeutics are emerging and although they are expected to improve muscle function and daily activity in boys with DMD, most are not designed to correct the vascular impairment. This impairment is due to the lack of restoration of neuronal nitric oxide synthase signaling, which is crucial for vasodilation during and after exercise. The investigators believe limitations in study design were responsible for the lack of efficacy. Therefore, this study combines tadalafil with aerobic exercise to necessitate increased blood flow and activate the drug. This Exploratory Clinical Trial will assess two potential adjuvant therapies for ambulatory boys with DMD (6 years and older): 1) aerobic exercise training and 2) tadalafil, an FDA-approved vasodilator drug. Preclinical and clinical data, including recent findings from the principal investigator's lab, support the use of these strategies and their potential to benefit muscle perfusion, fatigue, and quality of life. The study will first test for drug responsiveness (increase in muscle oxygenation) after a single dose. Drug-responsive boys with DMD will be randomized to a 6-month intervention of daily tadalafil or placebo, combined with structured cycle exercise training. Participants will receive exercise-related equipment for use at home and be monitored by the research team via video. The study will quantify the intervention's impact on vascular impairment, muscle pathophysiology (inflammation, fat accumulation, mitochondrial dysfunction), exertional fatigue, and cycling performance. Our findings are expected to yield: 1. Criteria to identify DMD patients most likely to benefit from tadalafil as adjuvant therapy. 2. Evidence of a powerful synergy between drug impact and exercise training in DMD.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Interventions

TadalafilDRUG

Patients will be given either the intervention medication or a placebo (double-blinded, randomized trial) and will be asked to take the medication every day for 6 months in conjunction with weekly exercise sessions.

PlaceboDRUG

Exercise TrainingOTHER

The home-based cycling exercise training program is designed to improve muscle strength and endurance. Participants will engage in individualized exercise sessions up to four times per week, lasting up to 40 minutes each. Live video and heart rate monitoring will ensure proper exercise performance and allow for adjustments to the program throughout the study. The participants will receive the exercise equipment for use at home.

Eligibility

Sex: MALEMin age: 6 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Diagnosis of DMD confirmed by genetic report * Minimum entry age of 6.0 years old * Ambulatory * On stable glucocorticoid regimen (for \> 3 months) Exclusion Criteria: * Contraindication to a Magnetic resonance Imaging examination (e.g. severe claustrophobia, magnetic implants, unable/unwilling to perform test) * Presence of unstable medical problems, including severe cardiomyopathy, left ventricular ejection fraction \<45%, cardiac conduction abnormalities as evidenced on ECG, uncontrolled seizure disorder, uncontrolled hypo or hypertension * Presence of a secondary condition that impacts muscle function or muscle metabolism (e.g., myasthenia gravis, endocrine disorder, mitochondrial disease) * Presence of a secondary condition leading to developmental delay or impaired motor control (e.g., cerebral palsy) or previous history of unprovoked rhabdomyolysis * Contraindications to phosphodiesterase 5 inhibitors (use of nitrates, alpha-adrenergic blockers, other phosphodiesterase 5 inhibitors) or other medications known to modulate blood flow or muscle metabolism * Participation in currently approved FDA trials or other investigational clinical trials during the period of the study

Outcomes

Primary Outcomes

Vascular responsiveness after muscle contraction to a single dose of tadalafil.

Responsiveness will be determined by an increase in post-contractile muscle oxygenation using MRI-Blood Oxygen Level Dependent (BOLD) responses after dosing compared to before. Study participants demonstrating an increase (\>50%) in post-contractile BOLD after tadalafil will be enrolled into Aim 2 of this study.

Time frame: up to 4 weeks after the completion of Visits 1 and 2 of Aim 1.

Cycling time to fatigue

The study will assess the impact of tadalafil on exercise performance and fatigue resistance compared to placebo. Participants will undergo a maximal effort cycling test before and after the intervention period. The time it takes for participants to reach exhaustion (TTE) will be recorded as the primary outcome measure. Measurement: Time to exhaustion (TTE) during a maximal effort cycling test on a recumbent, stationary ergometer. This test will quantify fatigue resistance by measuring the duration participants can sustain maximal effort cycling.

Time frame: Baseline and 6 month follow-up visits of Aim 2.

Secondary Outcomes

Quadriceps muscle Fat Fraction

This outcome serves as a measure of disease severity. This measure is a sensitive and reproducible biomarker of DMD muscle pathology.

Time frame: Aim 1 and Aim 2 (baseline and 6 month follow-up)

Metabolic recovery

The rate of phosphocreatine resynthesis after leg exercise will be quantified and serves as index of skeletal muscle mitochondrial oxidative capacity. (Part of Aim 2 of the study).