Vimentin intermediate filament is involved in multiple steps of viral infection such as viral entry, trafficking and egress, as well as in various mechanisms of hyperinflammation such as the restraint of Treg cell functions and the activation of NLRP3 inflammasome. We evaluated a vimentin-binding small molecule compound ALD-R491 for its effects on cellular processes related to viral infection and for its efficacy in treating SARS-CoV2 infection in vitro and in vivo. In cultured cells, the compound could reduce endocytosis by 10%, endosomal trafficking by 40% and exosomal release by over 30%. In an infection system consisting of a lentiviral pseudotype bearing the SARS-CoV-2 spike protein and HEK293 cells over-expressing the human ACE2 receptor with multiplicity of infection (MOI) of 1, 10 and 100, the compound inhibited the infection up to a maximum of over 90%, with IC50 < 50 nM, CC50 > 10 μM, and SI > 200. After oral administration of ALD-R491 in rats, the plasma concentration of the compound reached the peak (Tmax) at around 5 h with a half-life (T1/2) of about 5 h. The compound was widely distributed and enriched in tissues in vivo in rats with a volume of distribution (Vd) of over 2,000 ml/kg. The lung and the lymph nodes were among the tissues with high drug exposures. In rats receiving oral gavage of the compound at 30 mg/kg, the drug exposure in the lung and the lymph nodes maintained at levels over 1 μM from 1 h to 6 h after the oral dosing. In the syngeneic mouse tumor CT26 model, ALD-R491 was found to activate regulatory T cells (Tregs) in vivo and enhance de novo generation of Tregs in lymph nodes of the mice. In the Mouse-Adapted SARS-CoV2 model, aged mice (11-12 months) were used to provide a harder test of recovery from infection that reflects the severeness of COVID-19 in old patients. For therapeutic treatment, the mice were orally administered with the compound 24 h after the SARS-CoV2 infection once per day on Day 1, Day 2 and Day 4. At 10 mg/kg, ALD-R491 significantly reduced the body weight loss of the mice (p<0.01 on Day 5 post-infection). At both 3 mg/kg and 10 mg/kg, the compound significantly reduced the hemorrhagic score for the lungs (p<0.01 and p<0.05, respectively, on Day 5). These results indicate that vimentin intermediate filament is an effective host-directed antiviral target. Importantly, the vimentin-binding small molecule ALD-R491 impacts multiple aspects of SARS-CoV2 infection, has a favorable oral pharmacokinetics and a wide therapeutic window, and therefore may be a promising therapeutic candidate for treating COVID-19. Statement: Aluda Pharmaceuticals, Inc. has utilized the non-clinical and pre-clinical services program offered by the National Institute of Allergy and Infectious Diseases.

Citation Format: Zhizhen Li, Jianping Wu, Baoshi Yuan, Kenneth Dinnon, III, Lian Mo, Fei Zhou, Yingying Dong, Kendra Gully, Ralph Baric, Rachel Graham, Ying Xu, Ruihuan Chen. Targeting vimentin impacts multiple cellular processes, blocks the spike protein-ACE2-mediated pseudoviral infection in vitro and reduces the symptom and lung injury in aged mice with mouse-adapted SARS-CoV-2 infection in vivo [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P35.