31 P-MRS of healthy human brain: Measurement of guanosine diphosphate mannose at 7 T

Evidence of brain target engagement in Parkinson's disease and multiple sclerosis by the investigational nanomedicine, CNM-Au8, in the REPAIR phase 2 clinical trials

BACKGROUND

Impaired brain energy metabolism has been observed in many neurodegenerative diseases, including Parkinson's disease (PD) and multiple sclerosis (MS). In both diseases, mitochondrial dysfunction and energetic impairment can lead to neuronal dysfunction and death. CNM-Au8® is a suspension of faceted, clean-surfaced gold nanocrystals that catalytically improves energetic metabolism in CNS cells, supporting neuroprotection and remyelination as demonstrated in multiple independent preclinical models. The objective of the Phase 2 REPAIR-MS and REPAIR-PD clinical trials was to investigate the effects of CNM-Au8, administered orally once daily for twelve or more weeks, on brain phosphorous-containing energy metabolite levels in participants with diagnoses of relapsing MS or idiopathic PD, respectively.

RESULTS

Brain metabolites were measured using 7-Tesla 31P-MRS in two disease cohorts, 11 participants with stable relapsing MS and 13 participants with PD (n = 24 evaluable post-baseline scans). Compared to pre-treatment baseline, the mean NAD+/NADH ratio in the brain, a measure of energetic capacity, was significantly increased by 10.4% after 12 + weeks of treatment with CNM-Au8 (0.584 units, SD: 1.3; p = 0.037, paired t-test) in prespecified analyses of the combined treatment cohorts. Each disease cohort concordantly demonstrated increases in the NAD+/NADH ratio but did not reach significance individually (p = 0.11 and p = 0.14, PD and MS cohorts, respectively). Significant treatment effects were also observed for secondary and exploratory imaging outcomes, including β-ATP and phosphorylation potential across both cohorts.

CONCLUSIONS

Our results demonstrate brain target engagement of CNM-Au8 as a direct modulator of brain energy metabolism, and support the further investigation of CNM-Au8 as a potential disease modifying drug for PD and MS.

ATP line splitting in association with reduced intracellular magnesium and pH: a brain 31 P MR spectroscopic imaging (MRSI) study of pediatric patients with myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGADs)

Over the past four decades, ATP, the obligatory energy molecule for keeping all cells alive and functioning, has been thought to contribute only one set of signals in brain ³¹ P MR spectra. Here we report for the first time the observation of two separate β-ATP peaks in brain spectra acquired from patients with myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGADs) using 3D MRSI at 7 T. In voxel spectra with β-ATP line splitting, these two peaks are separated by 0.46 ± 0.18 ppm (n = 6). Spectral lineshape analysis indicates that the upper field β-ATP peak is smaller in relative intensity (24 ± 11% versus 76 ± 11%), and narrower in linewidth (56.8 ± 10.3 versus 41.2 ± 10.3 Hz) than the downfield one. Data analysis also reveals a similar line splitting for the intracellular inorganic phosphate (P_i ) signal, which is characterized by two components with a smaller separation (0.16 ± 0.09 ppm) and an intensity ratio (26 ± 7%:74 ± 7%) comparable to that of β-ATP. While the major components of P_i and β-ATP correspond to a neutral intracellular pH (6.99 ± 0.01) and a free Mg²⁺ level (0.18 ± 0.02 mM, by Iotti's conversion formula) as found in healthy subjects, their minor counterparts relate to a slightly acidic pH (6.86 ± 0.07) and a 50% lower [Mg²⁺ ] (0.09 ± 0.02 mM), respectively. Data correlation between β-ATP and P_i signals appears to suggest an association between an increased [H⁺ ] and a reduced [Mg²⁺ ] in MOGAD patients.