Bridging the clinical-research gap: Harnessing an electronic data capture, integration, and visualization platform to systematically assess prospective patient-reported outcomes in mitochondrial medicine.

PURPOSE: Optimizing individualized clinical care in heterogeneous rare disorders, such as primary mitochondrial disease (PMD), will require gaining more comprehensive and objective understanding of the patient experience by longitudinally tracking quantifiable patient-specific outcomes and integrating subjective data with clinical data to monitor disease progression and targeted therapeutic effects. METHODS: Electronic surveys of patient (and caregiver) reported outcome (PRO) measures were administered in REDCap within clinical domains commonly impaired in patients with PMD in the context of their ongoing routine care, including quality of life, fatigue, and functional performance. Descriptive statistics, group comparisons, and inter-measure correlations were used to evaluate system feasibility, utility of PRO results, and consistency across outcome measure domains. Real-time tracking and visualization of longitudinal individual-level and cohort-level data were facilitated by a customized data integration and visualization system, MMFP-Tableau. RESULTS: An efficient PRO electronic capture and analysis system was successfully implemented within a clinically and genetically heterogeneous rare disease clinical population spanning all ages. Preliminary data analyses demonstrated the flexibility of this approach for a range of PROs, as well as the value of selected PRO scales to objectively capture qualitative functional impairment in four key clinical domains. High inter-measure reliability and correlation were observed. Between-group analyses revealed that adults with PMD reported significantly worse quality of life and greater fatigue than did affected children, while PMD patients with nuclear gene disorders reported lower functioning relative to those with an mtDNA gene disorder in several clinical domains. CONCLUSION: Incorporation of routine electronic data collection, integration, visualization, and analysis of relevant PROs for rare disease patients seen in the clinical setting was demonstrated to be feasible, providing prospective and quantitative data on key clinical domains relevant to the patient experience. Further work is needed to validate specific PROs in diverse PMD patients and cohorts, and to formally evaluate the clinical impact and utility of harnessing integrated data systems to objectively track and integrate quantifiable PROs in the context of rare disease patient clinical care.

Clinical, radiological, biochemical and molecular characterization of a new case with multiple mitochondrial dysfunction syndrome due to IBA57: Lysine and tryptophan metabolites as potential biomarkers.

Iron­sulfur clusters (FeS) are one of the most primitive and ubiquitous cofactors used by various enzymes in multiple pathways. Biosynthesis of FeS is a complex multi-step process that is tightly regulated and requires multiple machineries. IBA57, along with ISCA1 and ISCA2, play a role in maturation of [4Fe-4S] clusters which are required for multiple mitochondrial enzymes including mitochondrial Complex I, Complex II, lipoic acid synthase, and aconitase. Pathogenic variants in IBA57 have been associated with multiple mitochondrial dysfunctions syndrome 3 (MMDS3) characterized by infantile to early childhood-onset psychomotor regression, optic atrophy and nonspecific dysmorphism. Here we report a female proband who had prenatal involvement including IUGR and microcephaly and developed subacute psychomotor regression at the age of 5 weeks in the setting of preceding viral infection. Brain imaging revealed cortical malformation with polymicrogyria and abnormal signal alteration in brainstem and spinal cord. Biochemical analysis revealed increased plasma glycine and hyperexcretion of multiple organic acids in urine, raising the concern for lipoic acid biosynthesis defects and mitochondrial FeS assembly defects. Molecular analysis subsequently detected compound heterozygous variants in IBA57, confirming the diagnosis of MMDS3. Although the number of MMDS3 patients are limited, certain degree of genotype-phenotype correlation has been observed. Unusual brain imaging in the proband highlights the need to include mitochondrial disorders as differential diagnoses of structural brain abnormalities. Lastly, in addition to previously known biomarkers including high blood lactate and plasma glycine levels, the increase of 2-hydroxyadipic and 2-ketoadipic acids in urine organic acid analysis, in the appropriate clinical context, should prompt an evaluation for the lipoic acid biosynthesis defects and mitochondrial FeS assembly defects.

Optimized Nutrition in Mitochondrial Disease Correlates to Improved Muscle Fatigue, Strength, and Quality of Life.

We sought to prospectively characterize the nutritional status of adults ≥ 19 years (n = 22, 27% males) and children (n = 38, 61% male) with genetically-confirmed primary mitochondrial disease (PMD) to guide development of precision nutritional support strategies to be tested in future clinical trials. We excluded subjects who were exclusively tube-fed. Daily caloric requirements were estimated using World Health Organization (WHO) equations to predict resting energy expenditure (REE) multiplied by an activity factor (AF) based on individual activity levels. We developed a Mitochondrial Disease Activity Factors (MOTIVATOR) score to encompass the impact of muscle fatigue typical of PMD on physical activity levels. PMD cohort daily diet intake was estimated to be 1,143 ± 104.1 kcal in adults (mean ± SEM, 76.2% of WHO-MOTIVATOR predicted requirement), and 1,114 ± 62.3 kcal in children (86.4% predicted). A total of 11/22 (50%) adults and 18/38 (47.4%) children with PMD consumed ≤ 75% predicted daily Kcal needs. Malnutrition was identified in 16/60 (26.7%) PMD subjects. Increased protein and fat intake correlated with improved muscle strength in those with insufficient daily Kcal intake (≤ 75% predicted); higher protein and fat intake correlated with decreased muscle fatigue; and higher protein, fat, and carbohydrate intake correlated with improved quality of life (QoL). These data demonstrate the frequent occurrence of malnutrition in PMD and emphasize the critical need to devise nutritional interventions to optimize clinical outcomes.

HEAL Preventing Opioid Use Disorder: a Vision for Research to Increase Access to Prevention Services.

Launched in 2018, the National Institutes of Health (NIH) Helping to End Addiction Long-term Initiative®, or NIH HEAL Initiative, is an aggressive effort to speed scientific solutions to stem this national public health crisis. Investments in new strategies to prevent opioid misuse are a key component of this comprehensive response to the opioid epidemic. In 2019, funded through the NIH HEAL Initiative® and administered by the National Institute on Drug Abuse (NIDA), HEAL Preventing Opioid Use Disorder (HEAL Preventing OUD) research program began, filling the gap of needed upstream prevention interventions. The vision for HEAL Preventing OUD is that: Healthcare organizations and public systems will be able to make evidence-based preventive intervention services accessible to all persons who experience risk for opioid and other substance misuse or use disorder. Realizing this vision will require research investments in four strategic areas: (1) risk identification; (2) intervention development; (3) social determinants, health equity, and policy; and (4) dissemination, implementation, scale up, and sustainment. There exists tremendous potential for prevention to be a viable solution for the ongoing opioid crisis, particularly through investments in upstream, equitable, and sustainable prevention services.

Red cell transfusions in children with thalassemia: Outcomes of a10 mL/kg/h infusion rate.

Children with transfusion-dependent thalassemia have an impaired ability to synthesize alpha or beta globin, which results in anemia. Packed red blood cell (PRBC) transfusions are required to increase hemoglobin, which supports appropriate growth and development. PRBC transfusions must be completed within 4 h; however, infusion rates vary across institutions. Our institution infuses PRBCs up to 10 mL/kg/h. A descriptive study of 21 children who received a total of 276 transfusions during 2021 demonstrated that this rate is safe and well tolerated. Shorter transfusion times support patients' and families' time, resources, and quality of life and aptly utilize institutional resources.

Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: Primary mitochondrial myopathies (PMMs) encompass a group of genetic disorders that impair mitochondrial oxidative phosphorylation, adversely affecting physical function, exercise capacity, and quality of life (QoL). Current PMM standards of care address symptoms, with limited clinical impact, constituting a significant therapeutic unmet need. We present data from MMPOWER-3, a pivotal, phase-3, randomized, double-blind, placebo-controlled clinical trial that evaluated the efficacy and safety of elamipretide in participants with genetically confirmed PMM. METHODS: After screening, eligible participants were randomized 1:1 to receive either 24 weeks of elamipretide at a dose of 40 mg/d or placebo subcutaneously. Primary efficacy endpoints included change from baseline to week 24 on the distance walked on the 6-minute walk test (6MWT) and total fatigue on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA). Secondary endpoints included most bothersome symptom score on the PMMSA, NeuroQoL Fatigue Short-Form scores, and the patient global impression and clinician global impression of PMM symptoms. RESULTS: Participants (N = 218) were randomized (n = 109 elamipretide; n = 109 placebo). The m0ean age was 45.6 years (64% women; 94% White). Most of the participants (n = 162 [74%]) had mitochondrial DNA (mtDNA) alteration, with the remainder having nuclear DNA (nDNA) defects. At screening, the most frequent bothersome PMM symptom on the PMMSA was tiredness during activities (28.9%). At baseline, the mean distance walked on the 6MWT was 336.7 ± 81.2 meters, the mean score for total fatigue on the PMMSA was 10.6 ± 2.5, and the mean T score for the Neuro-QoL Fatigue Short-Form was 54.7 ± 7.5. The study did not meet its primary endpoints assessing changes in the 6MWT and PMMSA total fatigue score (TFS). Between the participants receiving elamipretide and those receiving placebo, the difference in the least squares mean (SE) from baseline to week 24 on distance walked on the 6MWT was -3.2 (95% CI -18.7 to 12.3; p = 0.69) meters, and on the PMMSA, the total fatigue score was -0.07 (95% CI -0.10 to 0.26; p = 0.37). Elamipretide treatment was well-tolerated with most adverse events being mild to moderate in severity. DISCUSSION: Subcutaneous elamipretide treatment did not improve outcomes in the 6MWT and PMMSA TFS in patients with PMM. However, this phase-3 study demonstrated that subcutaneous elamipretide is well-tolerated. TRIAL REGISTRATION INFORMATION: Trial registered with clinicaltrials.gov, Clinical Trials Identifier: NCT03323749; submitted on October 12, 2017; first patient enrolled October 9, 2017. CLINICALTRIALS: gov/ct2/show/NCT03323749?term = elamipretide&draw = 2&rank = 9. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that elamipretide does not improve the 6MWT or fatigue at 24 weeks compared with placebo in patients with primary mitochondrial myopathy.

Use of Elamipretide in patients assigned treatment in the compassionate use program: Case series in pediatric patients with rare orphan diseases.

Several mitochondrial diseases are caused by pathogenic variants that impair membrane phospholipid remodeling, with no FDA-approved therapies. Elamipretide targets the inner mitochondrial membrane where it binds to cardiolipin, resulting in improved membrane stability, cellular respiration, and ATP production. In clinical trials, elamipretide produced clinical and functional improvements in adults and adolescents with mitochondrial disorders, such as primary mitochondrial myopathy and Barth syndrome; however, experience in younger patients is limited and to our knowledge, these are the first case reports on the safety and efficacy of elamipretide treatment in children under 12 years of age. We describe the use of elamipretide in patients with mitochondrial disorders to provide dosing parameters in patients aged <12 years.

iPSC-Derived Neurons from Patients with POLG Mutations Exhibit Decreased Mitochondrial Content and Dendrite Simplification.

Mutations in POLG, the gene encoding the catalytic subunit of DNA polymerase gamma, result in clinical syndromes characterized by mitochondrial DNA (mtDNA) depletion in affected tissues with variable organ involvement. The brain is one of the most affected organs, and symptoms include intractable seizures, developmental delay, dementia, and ataxia. Patient-derived induced pluripotent stem cells (iPSCs) provide opportunities to explore mechanisms in affected cell types and potential therapeutic strategies. Fibroblasts from two patients were reprogrammed to create new iPSC models of POLG-related mitochondrial diseases. Compared with iPSC-derived control neurons, mtDNA depletion was observed upon differentiation of the POLG-mutated lines to cortical neurons. POLG-mutated neurons exhibited neurite simplification with decreased mitochondrial content, abnormal mitochondrial structure and function, and increased cell death. Expression of the mitochondrial kinase PTEN-induced kinase 1 (PINK1) mRNA was decreased in patient neurons. Overexpression of PINK1 increased mitochondrial content and ATP:ADP ratios in neurites, decreasing cell death and rescuing neuritic complexity. These data indicate an intersection of polymerase gamma and PINK1 pathways that may offer a novel therapeutic option for patients affected by this spectrum of disorders.

Pathogenic mtDNA variants, in particular single large-scale mtDNA deletions, are strongly associated with post-lingual onset sensorineural hearing loss in primary mitochondrial disease.

In this retrospective cohort study of 193 consecutive subjects with primary mitochondrial disease (PMD) seen at the Children's Hospital of Philadelphia Mitochondrial Medicine Frontier Program, we assessed prevalence, severity, and time of onset of sensorineural hearing loss (SNHL) for PMD cases with different genetic etiologies. Subjects were grouped by genetic diagnosis: mitochondrial DNA (mtDNA) pathogenic variants, single large-scale mtDNA deletions (SLSMD), or nuclear DNA (nDNA) pathogenic variants. SNHL was audiometrically confirmed in 27% of PMD subjects (20% in mtDNA pathogenic variants, 58% in SLSMD and 25% in nDNA pathogenic variants). SLSMD had the highest odds ratio for SNHL. SNHL onset was post-lingual in 79% of PMD cases, interestingly including all cases with mtDNA pathogenic variants and SLSMD, which was significantly different from PMD cases caused by nDNA pathogenic variants. SNHL onset during school age was predominant in this patient population. Regular audiologic assessment is important for PMD patients, and PMD of mtDNA etiology should be considered as a differential diagnosis in pediatric patients and young adults with post-lingual SNHL onset, particularly in the setting of multi-system clinical involvement. Pathogenic mtDNA variants and SLSMD are less likely etiologies in subjects with congenital, pre-lingual onset SNHL.

A Tale of Progressive Painless Vision Loss in a 64-Year-Old Man Due to Leber Hereditary Optic Neuropathy.

ABSTRACT: A 64-year-old man presented with painless sequential bilateral vision loss, consistent with optic neuropathy, over the span of months. The significant decline in his visual function was out of proportion to the appearance of the optic nerves (which were not pale) or changes in his retinal nerve fiber layer thickness on optical coherence tomography. Neuroimaging revealed only mild T2 signal abnormality and faint enhancement in the left optic nerve. Extensive workup for potential infectious, metabolic, inflammatory, and ischemic etiologies was unremarkable. Empiric treatment with intravenous steroids did not slow or ameliorate the vision loss. Ultimately, genetic analysis revealed a missense m.11778G>A mutation in mitochondrial MT-ND4 gene, consistent with Leber hereditary optic neuropathy. Initiation of multivitamin supplements and idebenone unfortunately did not result in recovery of vision.

A homozygous splice variant in ATP5PO, disrupts mitochondrial complex V function and causes Leigh syndrome in two unrelated families.

Mitochondrial complex V plays an important role in oxidative phosphorylation by catalyzing the generation of ATP. Most complex V subunits are nuclear encoded and not yet associated with recognized Mendelian disorders. Using exome sequencing, we identified a rare homozygous splice variant (c.87+3A>G) in ATP5PO, the complex V subunit which encodes the oligomycin sensitivity conferring protein, in three individuals from two unrelated families, with clinical suspicion of a mitochondrial disorder. These individuals had a similar, severe infantile and often lethal multi-systemic disorder that included hypotonia, developmental delay, hypertrophic cardiomyopathy, progressive epileptic encephalopathy, progressive cerebral atrophy, and white matter abnormalities on brain MRI consistent with Leigh syndrome. cDNA studies showed a predominant shortened transcript with skipping of exon 2 and low levels of the normal full-length transcript. Fibroblasts from the affected individuals demonstrated decreased ATP5PO protein, defective assembly of complex V with markedly reduced amounts of peripheral stalk proteins, and complex V hydrolytic activity. Further, expression of human ATP5PO cDNA without exon 2 (hATP5PO-∆ex2) in yeast cells deleted for yATP5 (ATP5PO homolog) was unable to rescue growth on media which requires oxidative phosphorylation when compared to the wild type construct (hATP5PO-WT), indicating that exon 2 deletion leads to a non-functional protein. Collectively, our findings support the pathogenicity of the ATP5PO c.87+3A>G variant, which significantly reduces but does not eliminate complex V activity. These data along with the recent report of an affected individual with ATP5PO variants, add to the evidence that rare biallelic variants in ATP5PO result in defective complex V assembly, function and are associated with Leigh syndrome.

BTK inhibition limits B-cell-T-cell interaction through modulation of B-cell metabolism: implications for multiple sclerosis therapy.

Inhibition of Bruton's Tyrosine Kinase (BTKi) is now viewed as a promising next-generation B-cell-targeting therapy for autoimmune diseases including multiple sclerosis (MS). Surprisingly little is known; however, about how BTKi influences MS disease-implicated functions of B cells. Here, we demonstrate that in addition to its expected impact on B-cell activation, BTKi attenuates B-cell:T-cell interactions via a novel mechanism involving modulation of B-cell metabolic pathways which, in turn, mediates an anti-inflammatory modulation of the B cells. In vitro, BTKi, as well as direct inhibition of B-cell mitochondrial respiration (but not glycolysis), limit the B-cell capacity to serve as APC to T cells. The role of metabolism in the regulation of human B-cell responses is confirmed when examining B cells of rare patients with mitochondrial respiratory chain mutations. We further demonstrate that both BTKi and metabolic modulation ex vivo can abrogate the aberrant activation and costimulatory molecule expression of B cells of untreated MS patients. Finally, as proof-of-principle in a Phase 1 study of healthy volunteers, we confirm that in vivo BTKi treatment reduces circulating B-cell mitochondrial respiration, diminishes their activation-induced expression of costimulatory molecules, and mediates an anti-inflammatory shift in the B-cell responses which is associated with an attenuation of T-cell pro-inflammatory responses. These data collectively elucidate a novel non-depleting mechanism by which BTKi mediates its effects on disease-implicated B-cell responses and reveals that modulating B-cell metabolism may be a viable therapeutic approach to target pro-inflammatory B cells.

Early developmental delay in Leigh syndrome spectrum disorders is associated with poor clinical prognosis.

BACKGROUND: Leigh spectrum syndrome (LSS) is a primary mitochondrial disorder characterized by neurodevelopmental regression and metabolic stroke typically in early life. Developmental delay (DD) is known to follow episodes of neurologic regression in LSS, although primary developmental delay (pDD) has been rarely reported. We hypothesized that pDD precedes regression in a broader subset of LSS individuals and may associate with worse long-term educational outcomes. METHODS: From a retrospective cohort, subjects with pathogenic variant(s) in a nuclear or mitochondrial gene associated with LSS and consistent clinical manifestations and neuroradiological findings. Detailed developmental histories and neurologic outcomes were extracted. RESULTS: Of 69 LSS subjects, 47 (68.1%) had a history of pDD and 53 (76.8%) had neurodevelopmental regression. We identified 3 distinct developmental phenotypes: [1] pDD followed by regression (N = 31/69, 44.9%), [2] pDD without subsequent regression (16/69, 23.2%), [3] regression without pDD (N = 22/69, 31.9%). A history of pDD was associated with earlier disease onset (p = 0.0003) and worse educational outcomes (OR 22.14). CONCLUSION: LSS is associated with multiple developmental phenotypes and pDD is associated with negative educational outcomes. pDD occurring prior to neurologic regression suggests that mitochondrial energetics impact developmental trajectories prior to acute metabolic failure and regression, providing an opportunity for earlier diagnosis and/or therapeutic intervention.

Advanced approach for comprehensive mtDNA genome testing in mitochondrial disease.

Mitochondrial disease diagnosis requires interrogation of both nuclear and mitochondrial (mtDNA) genomes for single-nucleotide variants (SNVs) and copy number alterations, both in the proband and often maternal relatives, together with careful phenotype correlation. We developed a comprehensive mtDNA sequencing test ('MitoGenome') using long-range PCR (LR-PCR) to amplify the full length of the mtDNA genome followed by next generation sequencing (NGS) to accurately detect SNVs and large-scale mtDNA deletions (LSMD), combined with droplet digital PCR (ddPCR) for LSMD heteroplasmy quantification. Overall, MitoGenome tests were performed on 428 samples from 394 patients with suspected or confirmed mitochondrial disease. The positive yield was 11% (43/394), including 34 patients with pathogenic or likely pathogenic SNVs (the most common being m.3243A > G in 8/34 (24%) patients), 8 patients with single LSMD, and 3 patients with multiple LSMD exceeding 10% heteroplasmy levels. Two patients with both LSMD and pathogenic SNV were detected. Overall, this LR-PCR/NGS assay provides a highly accurate and comprehensive diagnostic method for simultaneous mtDNA SNV detection at heteroplasmy levels as low as 1% and LSMD detection at heteroplasmy levels below 10%. Inclusion of maternal samples for variant classification and ddPCR to quantify LSMD heteroplasmy levels further enables accurate pathogenicity assessment and clinical correlation interpretation of mtDNA genome sequence variants and copy number alterations.

Nutrition rehabilitation-related complications in primary mitochondrial disorders.

Primary mitochondrial disorders (PMDs) comprise a group of hundreds of individual genetic diseases affecting mitochondrial function, including oxidative phosphorylation and energy production. The estimated prevalence of these disorders ranges from 2.9 to 20 cases per 100,000. PMDs are commonly associated with malnutrition and growth failure. There is a paucity of literature regarding nutrition assessment and long-term data in the PMD population. We present three patients with various PMDs who presented complications related to malnutrition: (1) a 16-year-old male with Kearns-Sayre syndrome developed type 2 insulin-requiring diabetes mellitus after the initiation of high-calorie nutrition rehabilitation via gastrostomy tube (G-tube); (2) an 11-year-old female with myoclonic epilepsy associated with ragged red fibers developed diarrhea with metabolic decompensation and profound neurological and respiratory deterioration during nutrition rehabilitation after surgical G-tube placement; and (3) a 19-year-old male with a WARS2-associated PMD manifesting with developmental delay and severe parkinsonism presented complications related to poor wound healing after gastrojejunostomy tube placement. The last patient required prolonged hospitalization in the intensive care unit. Clinicians should be vigilant in monitoring these possible complications, as no standards of care exist for the initiation of enteral nutrition for this unique population.

Genetic and Clinical Predictors of Ataxia in Pediatric Primary Mitochondrial Disorders.

Evaluation of ataxia in children is challenging in clinical practice. This is particularly true for highly heterogeneous conditions such as primary mitochondrial disorders (PMD). This study aims to explore cerebellar and brain abnormalities identified on MRI as potential predictors of ataxia in patients with PMD and, likewise, to determine the effect of the patient's genetic profile on these predictors as well as determination of the temporal relationship of clinical ataxia with MRI findings. We evaluated clinical, radiological, and genetic characteristics of 111 PMD patients younger than 21 years of age at The Children's Hospital of Philadelphia. Data was extracted from charts. Blinded radiological evaluations were carried out by experienced neuroradiologists. Multivariate logistic regression and generalized equation estimates were used for analysis. Ataxia was identified in 41% of patients. Cerebellar atrophy or putaminal involvement with mitochondrial DNA (mtDNA) mutations (OR 1.18, 95% CI 1.1-1.3, p < 0.001) and nuclear DNA mutation with no atrophy of the cerebellum (OR 1.14, 95% CI 1.0-1.3, p = 0.007) predicted an increased likelihood of having ataxia per year of age. Central tegmental tract predicted the presence of ataxia independent of age and pathogenic variant origin (OR 9.8, 95% CI 2-74, p = 0.009). Ataxia tended to precede the imaging finding of cerebellar atrophy. Cerebellar atrophy and putaminal involvement on MRI of pediatric-onset PMD may predict the presence of ataxia with age in patients with mtDNA mutations. This study provides predicted probabilities of having ataxia per year of age that may help in family counseling and future research of the population.