LM11A-31

LM11A-31, also designated C-31 and LM11A-31-BHS in its clinical salt form, is a non-peptide, orally bioavailable, brain-penetrant small molecule modulator of the p75 neurotrophin receptor (p75NTR), identified through virtual screening of a pharmacophoric model derived from the beta-hairpin loop 1 domain of nerve growth factor and first reported by Massa, Bhatt, and Bhatt at the Longo laboratory in 2006 [1]. The compound selectively engages the p75NTR extracellular domain to shift receptor signaling from degenerative to trophic outputs: it downregulates proapoptotic and pro-inflammatory cascades mediated by c-Jun N-terminal kinase (JNK), caspase-3, and RhoA, while concurrently promoting neuronal survival through activation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) pathways [1, 2]. LM11A-31 additionally functions as a potent antagonist of proneurotrophic growth factor (proNGF) binding to p75NTR, blocking proNGF-induced neuronal death in hippocampal cultures at nanomolar concentrations [1]. The compound does not interact with the TrkA receptor and therefore preserves canonical NGF-TrkA trophic signaling, a selectivity property central to its neuroprotective rationale.

Preclinical pharmacology studies spanning more than a decade have demonstrated that oral administration of LM11A-31 prevents and in some cases reverses multiple hallmarks of Alzheimer's disease pathology in transgenic mouse models, including excess tau phosphorylation at proline-directed and non-proline-directed sites, tau misfolding, tau cleavage, tau oligomerization, tau seeding activity, accumulation of paired helical filaments, microglia and astrocyte activation, cholinergic neurite dystrophy, dendritic spine loss, and hippocampus-dependent cognitive deficits [2, 3, 4, 5, 6, 7]. Notably, LM11A-31 exerts these broad neuroprotective effects without measurably altering amyloid-beta plaque burden or soluble amyloid-beta concentrations, indicating that its mechanism operates downstream or in parallel to amyloid pathology [3, 4]. The compound has additionally demonstrated efficacy in preclinical models of Huntington's disease, acute ischemic stroke, traumatic brain injury, diabetic retinopathy, Parkinson's disease, and age-related basal forebrain cholinergic neuron degeneration [8, 9, 10, 11, 12, 13].

A Phase 2a randomized, double-blind, placebo-controlled trial conducted across 21 centers in five European countries enrolled 242 participants with mild to moderate Alzheimer's disease, randomized 1:1:1 to placebo, 200 mg in the published literature, or 400 mg in the published literature of LM11A-31-BHS for 26 weeks [14]. The trial met its primary endpoint of safety and tolerability. Secondary and exploratory biomarker analyses demonstrated that LM11A-31 significantly slowed the annual rate of increase in cerebrospinal fluid amyloid-beta 42, amyloid-beta 40, the presynaptic marker SNAP25, the postsynaptic marker neurogranin, and the astrocyte activation marker YKL-40 compared to placebo. Structural MRI and FDG-PET voxel-wise analyses showed hypothesis-consistent treatment effects favoring drug over placebo in cortical and hippocampal regions, though these did not reach conventional statistical significance. Cognitive endpoints (ADAS-Cog-13, MMSE, neuropsychological test battery) did not show statistically significant treatment effects at 26 weeks, consistent with the exploratory design and limited duration of the trial. The compound is currently in Phase 2 clinical development for Alzheimer's disease under PharmatrophiX Inc. and has entered a platform trial for progressive supranuclear palsy (PSP).

LM11A-31 is a research compound with no approved therapeutic indication in any jurisdiction. Investigators should obtain analytical confirmation of identity and purity on every lot.