Double blind trial of a deuterated form of linoleic acid (RT001) in Friedreich ataxia

OBJECTIVES

Friedreich ataxia is (FRDA) an autosomal recessive neurodegenerative disorder associated with intrinsic oxidative damage, suggesting that decreasing lipid peroxidation (LPO) might ameliorate disease progression. The present study tested the ability of RT001, a deuterated form of linoleic acid (D2-LA), to alter disease severity in patients with FRDA in a double-blind placebo-controlled trial.

METHODS

Sixty-five subjects were recruited across six sites and received either placebo or active drug for an 11-month study. Subjects were evaluated at 0, 4, 9, and 11 months, with the primary outcome measure being maximum oxygen consumption (MVO2) during cardiopulmonary exercise testing (CPET). A key secondary outcome measure was a composite statistical test using results from the timed 1-min walk (T1MW), peak workload, and MVO2.

RESULTS

Forty-five subjects completed the protocol. RT001 was well tolerated, with no serious adverse events related to drug. Plasma and red blood cell (RBC) membrane levels of D2-LA and its primary metabolite deuterated arachidonic acid (D2-AA) achieved steady-state concentrations by 4 months. No significant changes in MVO2 were observed for RT001 compared to placebo. Similarly, no differences between the groups were found in secondary or exploratory outcome measures. Post hoc evaluations also suggested minimal effects of RT001 at the dosages used in this study.

INTERPRETATIONS

The results of this study provide no evidence for a significant benefit of RT001 at the dosages tested in this Friedreich ataxia patient population.

The infantile neuroaxonal dystrophy rating scale (INAD-RS)

Background

INAD is an autosomal recessive neurogenetic disorder caused by biallelic pathogenic variants in PLA2G6. The downstream enzyme, iPLA₂, plays a critical role in cell membrane homeostasis by helping to regulate levels of phospholipids. The clinical presentation occurs between 6 months and 3 years with global developmental regression, hypotonia, and progressive spastic tetraparesis. Progression is often rapid, resulting in severe spasticity, visual impairment, and cognitive decline, with many children not surviving past the first decade of life. To date, no accepted tool for assessing the severity of INAD exists; other commonly used scales (e.g. CHOP-INTEND, Modified Ashworth, Hammersmith Functional Motor Scale) do not accurately gauge the current severity of INAD, nor are they sensitive/specific enough to monitor disease progression. Finally, these other scales are not appropriate, because they do not address the combination of CNS, peripheral nerve, and visual pathology that occurs in children with INAD.

Methods

We have developed and validated a structured neurological examination for INAD (scored out of 80). The examination includes six main categories of pediatric developmental evaluation: 1) gross motor-and-truncal-stability skills, 2) fine motor skills, 3) bulbar function, 4) ocular function, 5) temporo-frontal function, and, 6) Functional evaluation of the autonomic nervous system. A cohort of patients diagnosed with INAD were followed prospectively to validate the score against disease severity and disease progression.

Results

We show significant correlation between the total neurological assessment score and months since symptom onset with a statistically significant (p = 6.7 × 10^− 07) correlation between assessment score and disease onset. As hypothesized, the coefficient of months-since-symptom-onset is strongly negative, indicating a negative correlation between total score and months since symptom onset.

Conclusion

We have developed and validated a novel neurological assessment score in INAD that demonstrates strong correlation with disease severity and disease progression.

Treatment of infantile neuroaxonal dystrophy with RT001: A di-deuterated ethyl ester of linoleic acid: Report of two cases

BACKGROUND

Infantile neuroaxonal dystrophy (INAD) is a rare, autosomal recessive disease due to defects in PLA2G6 and is associated with lipid peroxidation. RT001 is a di-deuterated form of linoleic acid that protects lipids from oxidative damage.

METHODS

We evaluated the pharmacokinetics (PK), safety, and effectiveness of RT001 in two subjects with INAD (subject 1: 34 months; subject 2: 10 months). After screening and baseline evaluations, subjects received 1.8 g of RT001 BD. PK analysis and clinical evaluations were made periodically.

MAIN FINDINGS

Plasma levels of deuterated linoleic acid (D2-LA), deuterated arachidonic acid (D2-AA), D2-LA to total LA, and D2-AA to total AA ratios were measured. The targeted plasma D2-LA ratio (>20%) was achieved by month 1 and maintained throughout the study. RBC AA-ratios were 0.11 and 0.18 at 6 months for subjects 1 and 2; respectively. No treatment-related adverse events occurred. Limited slowing of disease progression and some return of lost developmental milestones were seen.

CONCLUSIONS

Oral RT001 was administered safely in two subjects with INAD. Early findings suggest that the compound was well tolerated, metabolized and incorporated in the RBC membrane. A clinical trial is underway to assess efficacy.

Randomized, clinical trial of RT001: Early signals of efficacy in Friedreich's ataxia

BACKGROUND

RT001 is a deuterated ethyl linoleate that inhibits lipid peroxidation and is hypothesized to reduce cellular damage and recover mitochondrial function in degenerative diseases such as Friedreich's ataxia.

OBJECTIVE

To evaluate the safety, pharmacokinetics, and preliminary efficacy of RT001 in Friedreich's ataxia patients.

DESIGN/METHODS

We conducted a phase I/II double-blind, comparator-controlled trial with 2 doses of RT001 in Friedreich's ataxia patients (9 subjects each cohort). Subjects were randomized 2:1 to receive either RT001 (1.8 or 9.0 g/day), or a matching dose of nondeuterated ethyl linoleate as comparator for 28 days. The primary endpoints were safety, tolerability, and pharmacokinetic analysis. Secondary endpoints included cardiopulmonary exercise testing and timed 25-foot walk.

RESULTS

Nineteen patients enrolled in the trial, and 18 completed all safety and efficacy measurements. RT001 was found to be safe and tolerable, with plasma levels approaching saturation by 28 days. One subject with a low body mass index experienced steatorrhea taking a high dose and discontinued the study. Deuterated arachidonic acid (a brain-penetrant metabolite of RT001) was found to be present in plasma on day 28. There was an improvement in peak workload in the drug group compared to placebo (0.16 watts/kg; P = 0.008), as well as an improvement trend in peak oxygen consumption (change of 0.16 L/min; P = 0.116), and in stride speed (P = 0.15).

CONCLUSIONS

RT001 was found to be safe and tolerable over 28 days, and improved peak workload. Further research into the effect of RT001 in Friedreich's ataxia is warranted. © 2018 International Parkinson and Movement Disorder Society.