LPX-TI641, a Tim3/4 Agonist, Induces Long-Term Immune Tolerance in Multiple Sclerosis Models

Background: Current disease-modifying therapies (DMTs) for multiple sclerosis (MS) attenuate pathogenic immune responses but are limited by safety and tolerability concerns. Antigen-specific tolerance approaches provide targeted immunomodulation yet remain constrained by their dependence on known autoantigens. LPX-TI641, an orally bioavailable, clinical-stage small-molecule agonist of Tim-3/4, represents an antigen-independent strategy to restore immune tolerance by expanding regulatory T cells (Tregs). Methods: LPX-TI641 was evaluated in vitro for its ability to induce Treg populations in murine splenocytes. Therapeutic efficacy was assessed in vivo using MOG_35-55- and PLP_139-151-induced experimental autoimmune encephalomyelitis (EAE) mouse models. Ex vivo, peripheral blood mononuclear cells (PBMCs) from people with MS (PwMS) were analyzed for Treg phenotype and function in response to LPX-TI641. Results: LPX-TI641 induced dose-dependent expansion of CD4⁺Foxp3⁺ and CD4⁺Foxp3⁺Tim-3⁺ Tregs in vitro. In EAE models, treatment significantly reduced disease severity, prevented relapses, and maintained clinical benefit after discontinuation. In PBMCs from patients with MS, LPX-TI641 restored diminished Tim-3⁺ Treg populations and reversed Treg dysfunction in recall assays. Efficacy in animal models was comparable to or exceeded that of high-efficacy DMTs, including natalizumab. Conclusions: LPX-TI641 promotes antigen-independent immune tolerance through Tim receptor agonism and Treg expansion. These findings support its potential as a novel therapeutic candidate for MS, addressing the limitations of current DMTs.