Evaluate the preclinical efficacy of the small molecule positive modulator of hepatocyte growth factor (HGF)/MET, ATH-1105, in a mouse model of amyotrophic lateral sclerosis (ALS).

Activation of the MET receptor by HGF promotes neuroprotective, neurotrophic, and anti-inflammatory mechanisms. Small molecule positive modulators of HGF/MET, including ATH-1105, have been developed to explore the therapeutic potential of this target. ALS is characterized by progressive motor neuron degeneration and demyelination, accompanied by systemic inflammation and pathological aggregation of TAR DNA-binding protein 43 (TDP-43) in 97% of patients. We hypothesized that treatment with ATH-1105 would be beneficial in a TDP-43 mouse model of ALS.

ATH-1105 at 10 or 20 mg/kg was orally administered daily to male Prp-TDP43^A315T mice (n=10/group) for two months. At baseline and after one and two months of treatment, we conducted a battery of motor behavior tests, and assessed sciatic nerve health by compound muscle action potential (CMAP) and nerve conduction velocity (NCV) measurements. Plasma biomarkers of inflammation (IL-6, TNF-α) and neurodegeneration (neurofilament light chain [NfL]) were interrogated after one and two months of treatment. Sciatic nerves were stained for quantification of axonal and myelin parameters as well as phospho-TDP-43 aggregation at study termination.

The deterioration of motor function in TDP-43 animals was significantly mitigated in a dose-dependent manner after treatment with ATH-1105, and significant functional improvement of sciatic nerve conduction was observed. Additionally, plasma levels of all biomarkers assessed were significantly decreased, indicating reduced systemic inflammation and neurodegeneration in treated TDP-43 mice. Sciatic nerve histology revealed a protection of motor axon numbers and myelination, as well as a reduction in axonal phospho-TDP-43 aggregation by ATH-1105.

ATH-1105 was found to be protective across a multitude of functional and structural measures of ALS disease progression. These findings support the continued development of this small molecule positive modulator of HGF/MET for ALS.