Edonerpic maleate (T-817MA)

Edonerpic maleate (T-817MA; 1-{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl}azetidin-3-ol maleate) is a low-molecular-weight neurotrophic agent synthesized at Toyama Chemical Co., Ltd. (a subsidiary of Fujifilm Corporation) and originally identified through phenotypic screening for compounds protective against amyloid-beta(1-40)-induced neurotoxicity in cultured rat cortical neurons. The compound promotes neurite outgrowth at submicromolar concentrations, protects against oxidative and mitochondrial stress in central nervous system neurons, and binds the sigma-1 receptor with a Ki of approximately 16 nanomolar, placing it within the high-affinity stratum of sigma-1 ligands. A landmark 2018 publication in Science (Abe et al.) established that edonerpic maleate binds collapsin response mediator protein 2 (CRMP2) and facilitates experience-driven synaptic delivery of AMPA-type glutamate receptors, accelerating motor function recovery from cortical cryoinjury in mice and internal capsule hemorrhage in nonhuman primates in a training-dependent manner through cortical reorganization. This CRMP2-mediated synaptic plasticity enhancement represents a mechanistically distinct rehabilitation-augmenting pharmacology that has no close clinical precedent.

Clinical development has spanned three indications. In Alzheimer's disease, a Phase 2a trial (373 patients, 224 mg daily, donepezil-stable) and a Phase 2 trial (US202; 484 patients randomized to placebo, 224 mg, or 448 mg daily for 52 weeks at 52 United States centers) were completed; neither trial demonstrated efficacy on primary cognitive endpoints (ADAS-Cog13) or functional secondary measures, and the Alzheimer's disease program was effectively terminated following the negative US202 results published in JAMA Neurology in 2019 [1]. A European Phase 2 trial (T817MAEU201) in mild cognitive impairment and mild Alzheimer's disease was initiated in 2019 with estimated completion in 2023. In post-stroke motor rehabilitation, a Phase 2 trial in Japan evaluated edonerpic maleate in patients with upper limb hemiplegia undergoing rehabilitation. In spinal cord injury, a 2025 study in nonhuman primates demonstrated that edonerpic maleate enhanced grasping recovery with contralesional cortical reorganization, extending the synaptic plasticity mechanism to a third neurological rehabilitation context.

The preclinical pharmacology is extensive: edonerpic maleate attenuates amyloid-beta-induced neurotoxicity and long-term potentiation deficits, preserves hippocampal neurogenesis, rescues motor and cognitive impairments in P301L tau transgenic mice, ameliorates sensorimotor gating deficits in MK-801 and phencyclidine models of schizophrenia, protects dopaminergic neurons in MPTP models, regulates glutamate receptor trafficking through CRMP2- and Arc-dependent mechanisms after traumatic brain injury, attenuates oxidative and endoplasmic reticulum stress through HSP70-HSP90 and Sirt1 signaling in brain ischemia models, and prevents epileptic seizure during recovery from brain damage by balancing excitatory and inhibitory synaptic inputs. The compound was well tolerated in clinical trials; the principal adverse events were gastrointestinal (diarrhea, nausea, vomiting) with dose-dependent incidence. This monograph documents the chemistry, synthesis, multi-target pharmacology, pharmacokinetics, the preclinical and clinical evidence base across all studied indications, sourcing and quality verification considerations, reconstitution and handling, stack-interaction implications, adverse-event signal, and a structured comparative assessment of five neurotrophic and sigma-1 receptor candidates against edonerpic maleate.