NLY01

NLY01 (pegsebrenatide) is a long-acting, brain-penetrant glucagon-like peptide-1 receptor (GLP-1R) agonist constructed by site-specific conjugation of a 50-kilodalton trimeric polyethylene glycol moiety to a cysteine residue engineered at position 40 of the 39-amino-acid exendin-4 peptide. The compound was developed in the laboratory of Seulki Lee at the Johns Hopkins University School of Medicine and advanced to clinical development by Neuraly, Inc., a subsidiary of D&D Pharmatech Co., Ltd. PEGylation extends the plasma elimination half-life from approximately 2 hours (native exendin-4) to 38 hours in mice, 88 hours in non-human primates, and approximately 12.5 days in humans after subcutaneous administration, enabling once-weekly dosing in the clinical setting. The neuroprotective mechanism of NLY01 was characterized in the seminal Yun et al. (2018) report in Nature Medicine, which demonstrated that the compound binds GLP-1R on activated microglia and suppresses secretion of the proinflammatory cytokines interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF-alpha), and the complement protein C1q. These three mediators are necessary and sufficient to drive the conversion of resting astrocytes to the neurotoxic A1 phenotype described by Liddelow et al. (2017). By blocking this microglial-to-astrocyte activation cascade, NLY01 prevents A1 astrocyte formation and preserves neuronal viability. In the alpha-synuclein preformed fibril (PFF) mouse model of sporadic Parkinson's disease, twice-weekly subcutaneous NLY01 at 3 mg/kg prevented dopaminergic neuron loss in the substantia nigra pars compacta, normalized striatal dopamine levels, reduced phosphorylated alpha-synuclein accumulation, and rescued motor function on pole test, rotarod, and amphetamine-induced rotation paradigms. In the human A53T alpha-synuclein transgenic mouse model, NLY01 extended lifespan by over 100 days and reduced neuropathological burden [1]. Subsequent preclinical studies extended the anti-neuroinflammatory mechanism to Alzheimer's disease (Sterling et al. 2021, 5xFAD model: NLY01 blocked beta-amyloid-induced microglial activation, inhibited A1 astrocyte formation, preserved neuronal viability, and improved spatial learning and memory) [2], to glaucoma (Sterling et al. 2020, microbead-induced ocular hypertension model: NLY01 reduced retinal ganglion cell death and suppressed A1 astrocyte conversion through attenuation of C1q, IL-1 alpha, and TNF-alpha in CD11b-positive cells) [3], and to experimental autoimmune encephalomyelitis as a model of multiple sclerosis [4]. The cuprizone demyelination model produced nuanced results; Gharagozloo et al. (2023) found that when cuprizone dosing was controlled by oral gavage (eliminating NLY01-induced weight loss as a confound), the compound did not protect against demyelination or promote remyelination, suggesting that the neuroprotective mechanism may be primarily anti-inflammatory rather than directly pro-myelinating [5]. Clinical development has proceeded through Phase 1 safety and pharmacokinetic characterization in healthy volunteers (NCT03672604) and a Phase 2 randomized, double-blind, placebo-controlled trial in 255 patients with early untreated Parkinson's disease (McGarry et al. 2024, Lancet Neurology). The Phase 2 trial tested subcutaneous NLY01 at 2.5 mg and 5.0 mg versus placebo over 36 weeks; neither dose produced a statistically significant difference on the primary endpoint (change in MDS-UPDRS parts II and III: 2.5 mg difference versus placebo negative 0.39, p = 0.77; 5.0 mg difference 0.36, p = 0.79). Gastrointestinal adverse events were the most frequent treatment-emergent findings, with nausea reported in 39 to 58 percent of active-treatment participants versus 19 percent on placebo. No deaths occurred. An exploratory subgroup analysis suggested possible motor benefit in participants younger than 60 years, a finding that requires prospective validation [6]. FDA clearance for a Phase 2b trial in Alzheimer's disease was received in November 2020, and a Phase 2 investigator-initiated trial for progressive multiple sclerosis (TAG-MS, NCT07497399) began dosing in May 2026 [7]. NLY01 is not approved for any indication by any regulatory authority. This monograph reviews the chemistry, PEGylation, and peptide pharmacology of NLY01; the microglial GLP-1R-mediated anti-neuroinflammatory mechanism; pharmacokinetics across species; the preclinical evidence base across Parkinson's disease, Alzheimer's disease, glaucoma, and multiple sclerosis models; the Phase 2 clinical trial in Parkinson's disease; sourcing and handling considerations; stack-interaction implications with other GLP-1R agonists and anti-Parkinsonian therapies; adverse-event signal; and a structured comparative assessment of five GLP-1R agonist candidates (exenatide, liraglutide, semaglutide, lixisenatide, PT320) against NLY01 on five competency standards.