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Efficacy of l-Arginine treatment in patients with HTLV-1-associated neurological disease.

  • 2022-12-22
  • Annals of clinical and translational neurology 10(2)
    • Satoshi Nozuma
    • Eiji Matsuura
    • Yuichi Tashiro
    • Ryusei Nagata
    • Masahiro Ando
    • Yu Hiramatsu
    • Yujiro Higuchi
    • Yusuke Sakiyama
    • Akihiro Hashiguchi
    • Kumiko Michizono
    • Keiko Higashi
    • Toshio Matsuzaki
    • Daisuke Kodama
    • Masakazu Tanaka
    • Yoshihisa Yamano
    • Takashi Moritoyo
    • Ryuji Kubota
    • Hiroshi Takashima

Study Design

Type
Clinical Trial
Sample size
n = 20
Population
20 patients (13 [65%] female) with a mean age of 67.8 years diagnosed with HAM/TSP
Methods
open-label, single-arm, Phase 2 study; patients received l-arginine at a dose of 20 g orally for 1 week and were followed-up for 3 weeks
Blinding
Open-label
Duration
1 week
Funding
Unclear

Objective

HTLV-1 infection causes HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), resulting in loss of motor function. In this Phase 2 trial, we assessed the efficacy and safety of l-arginine in patients with HAM/TSP.

Methods

This open-label, single-arm, Phase 2 study enrolled patients diagnosed with HAM/TSP. Patients received l-arginine at a dose of 20 g orally for 1 week and were followed-up for 3 weeks. The primary endpoint was change in walking speed in the 10-m walk test (10MWT). The main secondary endpoints were change in Timed Up and Go Test (TUGT) time, improvement in inflammatory markers in cerebrospinal fluid (CSF), safety, and tolerability.

Results

The study enrolled 20 patients (13 [65%] female) with a mean age of 67.8 years (95% CI 62.3 to 73.3). Although the primary endpoint, the changes in 10MWT time between baseline (Day 0) and Day 7, did not reach statistical significance (mean percent change in time -3.5%, 95% CI -10.8% to 3.7%; P = 0.32), a significant improvement was detected between baseline and Day 14 (-9.4%, 95% CI -16.6% to -2.2%; P = 0.01). Significant improvements were also observed in selected secondary endpoints, including in TUGT time (-9.1%, 95% CI -15.5% to -2.7%; P < 0.01), and in neopterin concentration in CSF (-2.1 pmol/mL, 95% CI -3.8 to -0.5; P = 0.01). Adverse events were infrequent, mild, and resolved rapidly.

Interpretation

l-arginine therapy improved motor function and decreased CSF inflammatory markers. l-arginine thus represents a promising therapeutic option for patients with HAM/TSP.

Trial registration number

UMIN000023854.

Research Insights

  • L-Arginine→Improved Walking Speed

    a significant improvement was detected between baseline and Day 14 (-9.4%, 95% CI -16.6% to -2.2%; P = 0.01)

    Effect
    Beneficial
    Effect size
    Small
    Dose
    20 g/day
  • L-Arginine→Reduced Neopterin Levels

    improvement in inflammatory markers in cerebrospinal fluid (CSF)... and in neopterin concentration in CSF (-2.1 pmol/mL, 95% CI -3.8 to -0.5; P = 0.01)

    Effect
    Beneficial
    Effect size
    Small
    Dose
    20 g/day
  • L-Arginine→Reduced Timed Up and Go Test Time

    Significant improvements were also observed in selected secondary endpoints, including in TUGT time (-9.1%, 95% CI -15.5% to -2.7%; P < 0.01)

    Effect
    Beneficial
    Effect size
    Small
    Dose
    20 g/day

Adverse Events Reported

  • L-Arginine→Overall tolerability

    Adverse events were infrequent, mild, and resolved rapidly.

    Finding
    Reported
    Grade
    mild
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