Platform

Inhibitors of the well-supported target NEU3: We identified potent NEU3 inhibitors which mimic the sialic acid transition state in NEU3. Many are < 200 Da, and some have < 2 nM IC50’s in human NEU3 activity assays (see the Target Overview page) including ability to cause human LAP to release active TGF-beta1, ability to desialyate SAP, and ability to cause human PBMC to upregulate extracellular IL-6. Some compounds are new composition of matter.

Strong efficacy and no discernible toxicity: We tried 3 of our new NEU3 inhibitors in the mouse bleomycin model of pulmonary fibrosis. Daily dosing starting at 10 days, at 1 mg/ kg for two compounds, and 0.1 mg/kg for a third, inhibited fibrosis (two showing no significant difference from no-bleomycin control). No toxicity was observed in the mice, or below 2 mM in cell-based assays. (for more information on this and the 2 figures below, see Karhadkar, T.R., Meek, T.D., and Gomer, R.H.  Inhibiting sialidase-induced TGF-β1 activation attenuates pulmonary fibrosis in mice.  Journal of Pharmacology and Experimental Therapeutics, 376, 106-117 (2021)). Eurofins “HitProfilingScreen + CYP450 (Total # of Assays: 38)” with lead compounds at 10 µM (the standard concentration of a test compound in these assays) showed “No significant results noted.”The lead compounds show no discernible toxicity in an Ames test, micronucleus tests, and chromosome aberration tests.

Histology indicates efficacy of inhibitors: Mice were treated with bleomycin to induce pulmonary fibrosis, or saline as a control. Starting at day 10, mice were treated daily with buffer (control), or NEU3 inhibitors. At day 21 mice were euthanized and and lung sections were stained with H&E. In the saline treated mice, the lungs show no discernible toxicity of the inhibitors. In the bleomycin-treated mouse subsequently treated with buffer, a large purple-stained fibrotic mass is visible. In the bleomycin-treated mice subsequently treated with inhibitors, there is little evidence of fibrosis.

A hydroxyproline assay indicates efficacy of inhibitors: Mouse lungs from the above experiment were assayed for hydroxyproline content, a standard marker of the collagen present in fibrotic lesions. S indicates saline, B, bleomycin.

Easy surrogate marker: IPF patients and bleomycin-treated mice show elevated desialylation of serum glycoproteins, and our NEU3 inhibitors block this desialylation in the mouse bleomycin model.