Author: kodiac

  • LDN-193189

    Selective bone morphogenetic protein (BMP) type I receptor kinase inhibitor targeting ALK2 and ALK3

    A pyrazolopyrimidine-scaffold small molecule derived from dorsomorphin structure-activity optimization, selectively inhibiting BMP type I receptor kinases ALK2 and ALK3 at low-nanomolar potency with 200-fold selectivity over TGF-beta signaling, and widely adopted as a research tool for BMP pathway dissection, directed stem cell differentiation, and preclinical modeling of fibrodysplasia ossificans progressiva and diffuse intrinsic pontine glioma.

    Abstract

    LDN-193189 (DM-3189; CAS 1062368-24-4) is a cell-permeable, small-molecule inhibitor of bone morphogenetic protein (BMP) type I receptor serine/threonine kinases, developed through structure-activity relationship optimization of dorsomorphin at the Brigham and Women’s Hospital and Harvard Medical School laboratories of Paul B. Yu. The compound inhibits activin receptor-like kinase 2 (ALK2, also designated ACVR1) with an IC50 of approximately 5 nM and activin receptor-like kinase 3 (ALK3, also designated BMPR1A) with an IC50 of approximately 30 nM, while exhibiting approximately 200-fold selectivity for BMP receptors over the transforming growth factor-beta (TGF-beta) type I receptor ALK5 and negligible activity against ALK4 and ALK7 at concentrations below 500 nM. The mechanism of action involves competitive binding at the ATP-binding pocket of BMP type I receptor kinases, preventing receptor autophosphorylation and blocking downstream phosphorylation of the canonical signaling effectors Smad1, Smad5, and Smad8. In addition to canonical Smad pathway inhibition, LDN-193189 suppresses BMP-induced non-canonical signaling through the p38 mitogen-activated protein kinase (MAPK) and Akt (protein kinase B) pathways, providing broader coverage of BMP-dependent intracellular signaling than Smad-selective interventions alone.

    The compound originated from the 2008 Cuny, Yu, and colleagues structure-activity relationship study that optimized the pyrazolo[1,5-a]pyrimidine scaffold of dorsomorphin, a compound itself discovered in 2008 by Yu et al. through a phenotypic zebrafish embryo screen of approximately 7,500 bioactive compounds for agents that could dorsalize the developing embryo and thereby phenocopy loss-of-function mutations in the BMP signaling pathway. Dorsomorphin, while the first small-molecule BMP pathway inhibitor identified, exhibited substantial off-target activity against AMP-activated protein kinase (AMPK), vascular endothelial growth factor receptor 2 (VEGFR2), and platelet-derived growth factor receptor (PDGFR), limiting its utility as a selective BMP pathway probe. LDN-193189 retained the central pyrazolopyrimidine core but incorporated a quinoline moiety and a piperazinylphenyl substituent that conferred markedly improved potency and selectivity for BMP type I receptors over the off-target kinases that compromised dorsomorphin’s pharmacological profile.

    LDN-193189 has become one of the most widely used pharmacological tools for interrogating BMP signaling in developmental biology, stem cell biology, and disease modeling. In stem cell biology, the compound is a core component of the dual SMAD inhibition protocol (in combination with the TGF-beta/Activin/Nodal inhibitor SB431542) developed by Chambers et al. (2009) for the efficient directed differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) toward neuroectodermal and neural progenitor fates, a protocol that has become the standard method for generating central nervous system neurons from human pluripotent stem cells. In disease modeling, the compound has been extensively characterized in preclinical models of fibrodysplasia ossificans progressiva (FOP), a rare genetic disorder caused by gain-of-function mutations in the ACVR1/ALK2 gene that produce constitutive BMP pathway activation and progressive heterotopic ossification of soft tissues. Treatment of mice expressing constitutively active ALK2 with LDN-193189 reduced heterotopic bone formation in the landmark Yu et al. (2008) Nature Medicine study. The compound has also demonstrated preclinical efficacy in orthotopic xenograft models of diffuse intrinsic pontine glioma (DIPG) harboring ACVR1 mutations, extending survival in treated animals. Additional research applications span iron metabolism and hepcidin regulation (through BMP6-dependent Smad signaling in hepatocytes), pulmonary arterial hypertension modeling, chondrogenesis and osteogenesis research, and cancer biology.

    LDN-193189 has not entered human clinical trials and is not a registered medicine in any jurisdiction. The compound is classified as a research tool and is supplied by multiple commercial vendors (Selleck Chemicals, MedChemExpress, Cayman Chemical, Tocris, Sigma-Aldrich, Stemgent/REPROCELL, and others) as the free base or hydrochloride salt at greater than 98 percent purity. In vivo pharmacokinetic characterization in mice has demonstrated oral bioavailability and brain penetration sufficient for central nervous system target engagement, though metabolic liabilities including aldehyde oxidase-dependent metabolism and generation of reactive piperazinyl iminium intermediates have been identified as concerns for clinical translation and have motivated the development of next-generation analogs (LDN-212854, LDN-214117, ML347, DMH1, K02288) with improved selectivity or metabolic profiles. This monograph reviews the chemistry, synthesis, and structural pharmacology of LDN-193189; the molecular mechanism of BMP type I receptor kinase inhibition; the preclinical pharmacology across FOP, DIPG, stem cell, iron metabolism, and cancer applications; the pharmacokinetic and metabolic characterization; sourcing, reconstitution, and handling; stack interactions with other signaling pathway modulators; the adverse-event and safety signal from preclinical studies; and a comparative assessment of five alternative BMP pathway inhibitors against LDN-193189 on five competency standards.

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  • Elinzanetant

    Dual neurokinin-1 (NK1) and neurokinin-3 (NK3) receptor antagonist for non-hormonal treatment of menopausal vasomotor symptoms

    A non-hormonal, orally bioavailable dual NK1/NK3 receptor antagonist developed through GlaxoSmithKline, NeRRe Therapeutics, KaNDy Therapeutics, and Bayer for the treatment of moderate-to-severe vasomotor symptoms associated with menopause, distinguished from selective NK3 antagonists by concurrent blockade of substance P signaling and consequent additive benefits on sleep, mood, and thermoregulatory dysregulation.

    Abstract

    Elinzanetant (Lynkuet; BAY3427080; formerly NT-814 and GSK1144814) is a potent and selective dual antagonist of the neurokinin-1 (NK1) and neurokinin-3 (NK3) receptors, developed for the non-hormonal treatment of moderate-to-severe vasomotor symptoms (VMS) associated with menopause and with endocrine therapy for hormone receptor-positive breast cancer. The compound received its first regulatory approval in the United Kingdom in July 2025, followed by approvals in Australia, Canada, Switzerland, and the United States, where it was approved by the Food and Drug Administration on October 24, 2025, under the trade name Lynkuet at a recommended dose of 120 mg orally once daily at bedtime. Elinzanetant is the first and only approved dual NK1/NK3 receptor antagonist, mechanistically distinct from fezolinetant (Veozah), which acts solely on the NK3 receptor. The dual mechanism targets kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the hypothalamic arcuate nucleus, where neurokinin B (NKB) acting through NK3 receptors initiates thermoregulatory dysregulation responsible for hot flashes, and substance P (SP) acting through NK1 receptors amplifies KNDy neuronal activity and contributes to sleep disruption, mood disturbance, and peripheral vasodilation. By antagonizing both receptor subtypes, elinzanetant addresses the composite symptom burden of menopause rather than isolated hot flash frequency alone. The compound exhibits high affinity for human NK1 receptors (pKi 8.7 to 10.2) and NK3 receptors (pKi 8.0 to 8.8), with greater than 300-fold selectivity for NK1 and greater than 100-fold selectivity for NK3 over off-target receptors. Pharmacokinetics are characterized by rapid oral absorption (median Tmax approximately 1 hour), absolute oral bioavailability of 52 percent, extensive plasma protein binding (99.7 percent), a large volume of distribution (137 L), and a long elimination half-life of approximately 45 hours that supports once-daily dosing. Metabolism is predominantly CYP3A4-mediated, producing three active metabolites with comparable NK1/NK3 potency at approximately 39 percent of parent plasma exposure. Excretion is predominantly fecal (90 percent as metabolites). The clinical evidence base comprises the OASIS Phase 3 program: OASIS 1 and OASIS 2 (12-week placebo-controlled studies in approximately 400 postmenopausal women each), OASIS 3 (52-week long-term study in 628 women), and OASIS 4 (12-week study in women receiving breast cancer endocrine therapy). All trials met primary endpoints, demonstrating statistically significant and clinically meaningful reductions in VMS frequency and severity at weeks 4 and 12, with onset of effect as early as week 1. Secondary endpoints showed significant improvements in sleep disturbances, menopause-related quality of life, and mood. Long-term efficacy was maintained through 52 weeks in OASIS 3 with no signal of hepatotoxicity, endometrial hyperplasia, or endometrial malignancy. The most common adverse events are headache (7.8 percent) and fatigue (5 percent). Elinzanetant is contraindicated in pregnancy, in severe hepatic impairment, and with concomitant strong CYP3A4 inhibitors. This monograph reviews the chemistry, synthesis, and stereochemistry of elinzanetant; the dual-receptor pharmacology in molecular and neurophysiological detail; the comprehensive human pharmacokinetic record; the clinical evidence base across the OASIS program and the dose-finding SWITCH-1 study; sourcing and quality verification considerations; reconstitution and handling; stack-interaction considerations for research applications; the adverse-event and safety signal profile; and a comparative assessment of five alternative compounds for vasomotor symptom management against elinzanetant on five competency standards.

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  • HU6

    Liver-targeted prodrug of 2,4-dinitrophenol functioning as a controlled metabolic accelerator through mitochondrial uncoupling via adenine nucleotide translocase activation

    A first-in-class controlled metabolic accelerator developed by Rivus Pharmaceuticals as a liver-targeted prodrug of 2,4-dinitrophenol, designed to exploit mitochondrial uncoupling for the treatment of metabolic dysfunction-associated steatohepatitis, obesity-related heart failure with preserved ejection fraction, and related cardiometabolic disorders while mitigating the systemic toxicity historically associated with the parent uncoupler.

    Abstract

    HU6 (dinifedriton; 5-[(2,4-dinitrophenoxy)methyl]-1-methyl-2-nitroimidazole; CAS 2231311-68-3) is a first-in-class controlled metabolic accelerator (CMA) developed by Rivus Pharmaceuticals as an oral prodrug of the mitochondrial uncoupler 2,4-dinitrophenol (DNP). The compound is designed to undergo hepatic bioactivation to release DNP within the liver, thereby increasing proton leak across the inner mitochondrial membrane via activation of the adenine nucleotide translocase (ANT) channel. This controlled mitochondrial uncoupling increases substrate oxidation, preferentially consuming hepatic and systemic fat stores while reducing reactive oxygen species production and preserving lean skeletal muscle mass. The prodrug strategy addresses the principal limitation of DNP itself, which was withdrawn from clinical use in 1938 owing to a narrow therapeutic index characterized by dose-dependent hyperthermia, cataracts, agranulocytosis, and death at supratherapeutic exposures. By restricting DNP release to the hepatic first-pass compartment and minimizing systemic peak concentrations, HU6 achieves a substantially wider therapeutic index than the parent uncoupler while retaining its metabolic efficacy.

    The scientific foundation for HU6 derives from the seminal work of Perry et al. (2015), published in Science, demonstrating that a controlled-release mitochondrial protonophore (CRMP) formulation of DNP reversed diabetes, hypertriglyceridemia, hepatic steatosis, and liver fibrosis in rat models of metabolic syndrome and nonalcoholic steatohepatitis (NASH) without systemic toxicity [1]. This proof of concept was extended to dysmetabolic nonhuman primates by Goedeke et al. (2019), who reported that CRMP produced 20 to 30 percent reductions in fasting plasma triglycerides and low-density lipoprotein cholesterol with concurrent resolution of hepatic steatosis [2]. Rivus Pharmaceuticals was founded in 2019 to advance these findings into clinical development, selecting HU6 as the lead clinical candidate from a portfolio of controlled metabolic accelerator assets.

    Three Phase 2 clinical trials have been completed or are in progress. The first Phase 2a trial in 80 patients with nonalcoholic fatty liver disease (NAFLD) and body mass index (BMI) of 28 to 45 kg/m2 demonstrated dose-dependent reductions in liver fat content of 26.8 to 35.6 percent from baseline over 61 days at doses of 150, 300, and 450 mg once daily, compared with a 5.4 percent increase in the placebo group, with concurrent body weight reductions of 0.52 to 2.75 kg; results were published in The Lancet Gastroenterology and Hepatology [3]. The Phase 2a HuMAIN trial in 66 patients with obesity-related heart failure with preserved ejection fraction (HFpEF) met its primary endpoint of body weight reduction (2.86 kg versus placebo over 19 weeks), with fat-selective weight loss preserving skeletal muscle mass and producing significant improvements in left ventricular ejection fraction (3.76 percent) and end-systolic volume; results were published in JAMA Cardiology [4, 5]. The Phase 2 M-ACCEL trial in 228 patients with biopsy-confirmed metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis stages F2 to F3 demonstrated statistically significant liver fat reductions of 27.0 to 31.2 percent versus 6.7 percent with placebo over 26 weeks, with approximately 50 to 58 percent of treated patients achieving the clinically meaningful threshold of 30 percent or greater liver fat reduction associated with MASH resolution and fibrosis improvement [6].

    Across all three trials, HU6 demonstrated a favorable safety profile with no treatment-related serious adverse events in a cumulative safety database exceeding 500 patients. The most commonly reported treatment-emergent adverse events were flushing (32 percent in early trials, reduced in later formulations), diarrhea (25 percent), and palpitations (12 percent), with discontinuation rates due to adverse events below 5 percent. Gastrointestinal adverse event rates in the M-ACCEL trial were comparable to placebo (14 versus 16 percent). The compound is currently advancing through the AMPLIFY Phase 2 trial for MASH with plans for late-stage clinical development. This monograph reviews the chemistry, mechanism of action, pharmacokinetics, preclinical and clinical evidence, safety profile, and comparative positioning of HU6 against five alternative therapeutic approaches to MASH and metabolic liver disease.

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  • Aficamten

    Selective small-molecule allosteric inhibitor of cardiac beta-myosin heavy chain (MYH7) ATPase activity

    A next-generation cardiac myosin inhibitor developed by Cytokinetics as CK-3773274, engineered for optimized pharmacokinetic properties relative to mavacamten, approved by the United States Food and Drug Administration in December 2025 for the treatment of symptomatic obstructive hypertrophic cardiomyopathy under the trade name MYQORZO.

    Abstract

    Aficamten (CK-3773274, trade name MYQORZO) is a selective, allosteric, reversible small-molecule inhibitor of cardiac myosin motor activity developed by Cytokinetics, Inc. for the treatment of hypertrophic cardiomyopathy (HCM). The compound reduces myocardial contractility by stabilizing a weak actin-binding, pre-power-stroke state of the beta-cardiac myosin head, thereby decreasing the number of functional myosin cross-bridges available during each cardiac cycle and attenuating the left ventricular outflow tract (LVOT) obstruction that drives symptoms in obstructive HCM. Aficamten binds to an allosteric site between the upper 50 kDa and lower 50 kDa subdomains of the myosin catalytic domain, overlapping with the blebbistatin binding pocket but distinct from the mavacamten binding site, and dramatically slows phosphate release from the myosin ATPase cycle to a rate slower than the conventional super-relaxed state.

    The compound was engineered to address pharmacokinetic limitations of mavacamten, the first-in-class cardiac myosin inhibitor. Aficamten achieves a plasma elimination half-life of approximately 75 to 100 hours (compared to 7 to 9 days for mavacamten), reaches steady-state plasma concentrations within approximately 2 weeks of daily dosing (compared to approximately 6 weeks for mavacamten), demonstrates reversibility of pharmacodynamic effects within 24 to 48 hours, exhibits a shallow exposure-response relationship that widens the therapeutic window, and is metabolized by multiple cytochrome P450 enzymes (CYP2C9, CYP3A4, CYP2D6, CYP2C19) rather than predominantly by the polymorphic CYP2C19, thereby reducing the drug-drug interaction burden and eliminating the requirement for CYP metabolizer genotyping.

    Clinical development of aficamten has proceeded through a comprehensive program. The Phase 1 dose-escalation study in 102 healthy participants demonstrated dose-proportional pharmacokinetics, dose-dependent reductions in left ventricular ejection fraction (LVEF), and favorable tolerability with no serious adverse events. The Phase 2 REDWOOD-HCM trial in patients with symptomatic obstructive HCM demonstrated statistically significant reductions in resting and post-Valsalva LVOT gradients, with 78.6 to 92.9 percent of patients achieving target gradient reduction at 10 weeks. The pivotal Phase 3 SEQUOIA-HCM trial randomized 282 patients with symptomatic obstructive HCM to aficamten or placebo for 24 weeks and met its primary endpoint of improved peak oxygen uptake (pVO2), with a least-squares mean difference of 1.74 mL/kg/min (p = 0.000002), along with statistically significant improvements in all 10 prespecified secondary endpoints including NYHA functional class, Kansas City Cardiomyopathy Questionnaire scores, and LVOT gradient reduction. The Phase 3 MAPLE-HCM trial demonstrated superiority of aficamten monotherapy over metoprolol monotherapy, with a pVO2 least-squares mean difference of 2.3 mL/kg/min (p < 0.0001). The Phase 3 ACACIA-HCM trial in 516 patients with non-obstructive HCM met both dual primary endpoints for symptom burden and exercise capacity improvement.

    The United States Food and Drug Administration approved aficamten on December 19, 2025, for the treatment of adults with symptomatic obstructive HCM to improve functional capacity and symptoms, marketed as MYQORZO. The approval includes a boxed warning regarding the risk of heart failure due to systolic dysfunction and a Risk Evaluation and Mitigation Strategy (REMS) requiring echocardiographic monitoring. The principal adverse reaction observed at greater than 5 percent incidence above placebo was hypertension (8 percent versus 2 percent). LVEF reduction below 50 percent occurred in 3.5 percent of aficamten-treated patients in SEQUOIA-HCM compared to 0.7 percent on placebo; all instances were mild, reversible, and not associated with clinical heart failure events. This monograph reviews the chemistry, mechanism, pharmacokinetics, preclinical and clinical evidence, safety profile, handling considerations, and comparative assessment of aficamten against five alternative agents for the management of hypertrophic cardiomyopathy.

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  • GT20029

    Topical proteolysis-targeting chimera (PROTAC) androgen receptor degrader

    A first-in-class topical PROTAC androgen receptor degrader developed by Kintor Pharmaceutical for androgenetic alopecia and acne vulgaris, distinguished from conventional antiandrogen therapies by catalytic, substoichiometric receptor protein elimination through the ubiquitin-proteasome system with negligible systemic exposure.

    Abstract

    GT20029 is a small-molecule proteolysis-targeting chimera (PROTAC) designed for topical application to skin and scalp, representing the first PROTAC compound to enter and complete clinical trials via the topical route of administration. Developed by Suzhou Kintor Pharmaceutical Ltd. on a proprietary PROTAC platform employing a novel cereblon (CRBN) E3 ubiquitin ligase recruiting element (the TD-106 scaffold), GT20029 functions as a bifunctional molecular bridge: one pharmacophore engages the androgen receptor (AR) ligand-binding domain, a chemical linker spans the two recruiting elements, and a second pharmacophore recruits the CRBN-containing Cullin-RING E3 ubiquitin ligase complex, resulting in polyubiquitination and proteasomal degradation of the AR protein [1, 2]. The catalytic mechanism permits each GT20029 molecule to cycle through multiple rounds of AR degradation, enabling pharmacologically effective AR elimination at low topical concentrations. In preclinical dihydrotestosterone (DHT)-induced mouse models, GT20029 significantly promoted hair regrowth and reversed follicular miniaturization; in testosterone propionate-induced hamster flank organ models, it significantly inhibited sebaceous gland enlargement, supporting the dual indication development for androgenetic alopecia (AGA) and acne vulgaris [3].

    Phase I clinical trials were completed in both China (92 subjects) and the United States (123 subjects) as randomized, double-blind, placebo-controlled studies with single ascending dose (SAD) and multiple ascending dose (MAD) cohorts. GT20029 demonstrated excellent safety and tolerability across all dose levels, with no systemic exposure above the lower limit of quantitation (0.003 ng/mL) in the SAD cohort and maximal plasma concentrations not exceeding 0.015 ng/mL after 14 days of continuous topical application in the MAD cohort, confirming that the compound acts locally with negligible systemic absorption [3]. The Phase II trial for AGA enrolled 180 male patients with Hamilton-Norwood grade IIIv to V pattern hair loss across 12 centers in China in a multicenter, randomized, double-blind, placebo-controlled design. Patients received GT20029 solution at 0.5% or 1.0% concentration, applied once daily (QD) or twice weekly (BIW), for 12 weeks. The primary endpoint was the change from baseline in non-vellus target area hair count (TAHC). The 0.5% QD group demonstrated an increase of 16.80 hairs per square centimeter, 6.69 hairs per square centimeter greater than placebo (P less than 0.05); the 1.0% BIW group demonstrated an increase of 11.94 hairs per square centimeter, 7.36 hairs per square centimeter greater than placebo (P less than 0.05) [4, 5]. Target area hair width also improved significantly in the 1.0% BIW group versus placebo. No adverse sexual events were observed in any treatment group, distinguishing GT20029 from systemic 5-alpha-reductase inhibitors. The Phase II trial for acne vulgaris, conducted across 10 centers in China, also met its primary endpoint for total lesion count reduction (excluding nodules) at the 0.5% QD dose (P = 0.01 versus placebo), with both 0.5% and 1.0% QD groups achieving highly significant reductions in inflammatory lesion counts (P less than 0.01) [6].

    On the basis of these results, Kintor has advanced GT20029 into Phase III clinical trials for male AGA in China and has initiated Phase II trials in the United States. The compound is not yet registered in any jurisdiction. The chemical structure of GT20029 has not been publicly disclosed; the molecular formula, molecular weight, and Chemical Abstracts Service registry number are not available in the public domain. This monograph reviews the available pharmacology, mechanism of action, preclinical and clinical evidence, pharmacokinetics, safety profile, handling considerations, and a comparative assessment of GT20029 against five alternative approaches to androgen-mediated dermatological conditions.

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  • Pegozafermin

    GlycoPEGylated fibroblast growth factor 21 (FGF21) analog with extended half-life for metabolic and hepatic disease

    A long-acting glycoPEGylated analog of fibroblast growth factor 21 engineered to recapitulate the endocrine metabolic activity of native FGF21, developed by 89bio for the treatment of metabolic dysfunction-associated steatohepatitis and severe hypertriglyceridemia.

    Abstract

    Pegozafermin (BIO89-100) is a glycoPEGylated recombinant analog of human fibroblast growth factor 21 (FGF21), a hepatokine central to the regulation of lipid metabolism, glucose homeostasis, and energy expenditure. The compound was engineered using site-specific glycosylation and PEGylation to extend the circulating half-life from approximately 0.5 to 2 hours (native FGF21) to 55 to 100 hours, enabling once-weekly or once-every-two-week subcutaneous administration while preserving the receptor binding profile of the native hormone. Pegozafermin signals through the FGF receptor 1c (FGFR1c) and FGF receptor 3c in complex with the obligate coreceptor beta-klotho (KLB), activating the extracellular signal-regulated kinase 1/2 (ERK1/2) cascade and downstream transcription factors that govern hepatic de novo lipogenesis, adipose tissue adiponectin secretion, fatty acid oxidation, and insulin sensitivity. The compound was originally developed by Teva Pharmaceutical Industries and subsequently licensed to 89bio, Inc. in 2019 for global development (excluding Israel).

    In the Phase 2b ENLIVEN trial (Loomba et al., 2023, New England Journal of Medicine), 222 patients with biopsy-confirmed nonalcoholic steatohepatitis (NASH) and stage F2 or F3 fibrosis were randomized to pegozafermin 15 mg weekly, 30 mg weekly, 44 mg every two weeks, or placebo for 24 weeks. The co-primary histological endpoints were met at both the 30 mg weekly and 44 mg every-two-week doses: fibrosis improvement of at least one stage without worsening of steatohepatitis was achieved in 26 percent and 27 percent of treated patients, respectively, compared with 7 percent on placebo. NASH resolution without fibrosis worsening was achieved in 23 percent and 26 percent, respectively, compared with 2 percent on placebo. Hepatic fat fraction measured by magnetic resonance imaging proton density fat fraction (MRI-PDFF) decreased by 48.2 percent (30 mg weekly) and 41.9 percent (44 mg every two weeks) versus 5.0 percent on placebo. Alanine aminotransferase levels normalized in 59 to 65 percent of treated patients versus 24 percent on placebo, and the fibrosis biomarker PRO-C3 decreased by 17 to 18 percent versus a 6.4 percent increase on placebo.

    In the Phase 2 ENTRIGUE trial in severe hypertriglyceridemia (Bhatt et al., 2023, Nature Medicine), pegozafermin at doses of 9 to 27 mg weekly or 36 mg every two weeks produced a pooled median triglyceride reduction of 57.3 percent versus 11.9 percent on placebo, with 79.7 percent of treated patients achieving triglycerides below 500 mg/dL compared with 29.4 percent on placebo. Secondary lipid endpoints included reductions in non-HDL cholesterol (18.3 percent), apolipoprotein B (10.5 percent), apolipoprotein C3 (41.9 percent), and increases in HDL cholesterol of up to 44.5 percent at the 27 mg weekly dose.

    Safety across both trials was characterized by mild-to-moderate gastrointestinal adverse events (nausea, diarrhea) and injection site reactions. No hepatotoxicity, drug-induced liver injury, or clinically significant bone density changes were observed. One treatment-related serious adverse event (acute pancreatitis in a patient with gallbladder sludge) was reported in the ENLIVEN trial.

    Pegozafermin received Breakthrough Therapy designation from the United States Food and Drug Administration and Priority Medicines (PRIME) designation from the European Medicines Agency for the treatment of MASH with fibrosis in September 2023. The compound is currently in Phase 3 development in the ENLIGHTEN program (MASH with fibrosis and compensated cirrhosis) and the ENTRUST program (severe hypertriglyceridemia). This monograph reviews the compound identification, discovery and development history, molecular pharmacology of the FGF21 signaling axis, pharmacokinetics, preclinical pharmacology, clinical evidence base, sourcing and quality verification, reconstitution and handling, stack interactions and combinations, adverse events and safety signal, and a comparative assessment of five alternative metabolic liver disease candidates against pegozafermin on five competency standards.

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  • Methallylescaline

    Substituted phenethylamine psychedelic of the scaline series; 5-HT2A receptor agonist and structural analog of mescaline

    A synthetic 4-methallyloxy-3,5-dimethoxyphenethylamine first characterized by Alexander Shulgin, distinguished from mescaline by approximately six-fold greater potency, prolonged duration of action, and a steep dose-response relationship attributable to enhanced lipophilicity and optimized 5-HT2A receptor engagement.

    Abstract

    Methallylescaline (MAL; 2-[3,5-dimethoxy-4-(2-methylprop-2-enoxy)phenyl]ethanamine) is a synthetic psychedelic phenethylamine of the scaline structural class, first synthesized and self-administered by Alexander Shulgin in the early 1980s and formally documented in entry number 99 of his 1991 reference work PiHKAL (Phenethylamines I Have Known and Loved). The compound is the 4-methallyloxy homolog of mescaline (3,4,5-trimethoxyphenethylamine), differing from the parent alkaloid by replacement of the 4-methoxy group with a 2-methylprop-2-enyloxy (methallyloxy) substituent. This structural modification increases lipophilicity, enhances blood-brain barrier permeability, and produces a compound with approximately six-fold greater potency than mescaline, an oral dose range of 40 to 65 milligrams (compared to 200 to 400 milligrams for mescaline), and a duration of action of 12 to 16 hours.

    The principal molecular target of methallylescaline is the serotonin 5-hydroxytryptamine type 2A (5-HT2A) receptor, at which the compound acts as an agonist to produce the characteristic psychedelic phenomenology of the phenethylamine class: visual distortion, perceptual intensification, synesthesia, and altered cognition. The compound also binds the 5-HT2C receptor and, at higher concentrations, the 5-HT1A receptor (Ki in the low micromolar range). The receptor interaction profile was formally characterized in the Kolaczynska, Luethi, Trachsel, Hoener, and Liechti (2022) systematic study of 4-alkoxy-3,5-dimethoxyphenethylamines (mescaline derivatives) and related amphetamines, which established that scalines as a class bind 5-HT2A and 5-HT2C receptors with affinities up to 63-fold and 34-fold greater than mescaline, respectively. The study further demonstrated that extending and branching the 4-alkoxy substituent increased binding affinity and activation potency at the 5-HT2A receptor while producing variable effects at the 5-HT2B receptor, a finding with implications for both potency and cardiovascular safety assessment.

    Pharmacokinetic data specific to methallylescaline in humans are absent from the peer-reviewed literature. Inferences drawn from mescaline pharmacokinetics (oral absorption with Tmax of approximately 2 hours, plasma half-life of approximately 3.5 hours, predominant elimination by oxidative deamination and renal excretion of unchanged drug) and from the structural properties of the methallyloxy substituent (increased lipophilicity, probable hepatic O-dealkylation to yield a demethylated phenolic metabolite) suggest that methallylescaline is rapidly absorbed, extensively distributed to central nervous system tissue, and eliminated over a time course consistent with its prolonged 12 to 16 hour subjective duration. The steep dose-response relationship reported by Shulgin, in which small increments in dose produce disproportionately large increases in effect intensity, is characteristic of agonists operating near the inflection point of a sigmoidal concentration-effect curve and may reflect cooperative receptor binding or threshold-dependent downstream signaling amplification.

    Preclinical pharmacology data for methallylescaline are limited. The Halberstadt, Chatha, Chapman, and Brandt (2019) study of the mouse head-twitch response (a 5-HT2A receptor-mediated behavioral proxy for psychedelic potency) characterized several mescaline analogs in the scaline series and established the general principle that extension of the 4-alkoxy chain increases in vivo potency relative to mescaline. No clinical trials, controlled human pharmacology studies, or formal toxicology assessments of methallylescaline have been conducted. The compound has no approved medical indication in any jurisdiction.

    This monograph documents the chemistry, synthesis, structural class, and nomenclature of methallylescaline; the receptor pharmacology as characterized in the Kolaczynska et al. (2022) systematic study; inferred pharmacokinetics based on the mescaline pharmacokinetic record and structural analogy; preclinical pharmacology from the scaline head-twitch response literature; the absence of clinical evidence; sourcing and quality verification considerations; reconstitution and handling; stack interaction considerations; adverse events and safety signal; and a comparative assessment of five structurally or mechanistically related phenethylamine psychedelics (mescaline, escaline, allylescaline, proscaline, and 3C-E) against methallylescaline on five competency standards.

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  • Efimosfermin

    Long-acting Fc-fusion fibroblast growth factor 21 (FGF21) analog with direct antifibrotic, anti-steatotic, and metabolic regulatory activity

    An engineered, once-monthly IgG1-Fc-fused FGF21 analog developed by Novartis and advanced through Boston Pharmaceuticals and GSK for the treatment of metabolic dysfunction-associated steatohepatitis, distinguished from other FGF21 analogs by a 21-day pharmacokinetic half-life that permits monthly subcutaneous dosing and by Phase 2 evidence of fibrosis reversal and MASH resolution in patients with moderate-to-advanced hepatic fibrosis.

    Abstract

    Efimosfermin alfa (formerly LLF580 under Novartis origination, subsequently designated BOS-580 under Boston Pharmaceuticals development, and now GSK-6519754 following acquisition by GSK plc) is a genetically engineered, long-acting analog of human fibroblast growth factor 21 (FGF21), a hepatokine and adipokine that regulates hepatic lipid oxidation, adipose tissue glucose uptake, triglyceride metabolism, and inflammatory signaling through formation of a ternary complex with the transmembrane tyrosine kinase FGF receptor 1c (FGFR1c) and the obligate co-receptor beta-klotho (KLB). The molecule is a homodimeric fusion protein in which two copies of a stabilized FGF21 variant are fused at their N-termini to the crystallizable fragment (Fc) of human immunoglobulin G1 (IgG1). The FGF21 domain is further stabilized by the introduction of a non-native disulfide bond and point mutations that increase proteolytic resistance, together producing a pharmacokinetic half-life of approximately 21 days in humans and enabling subcutaneous administration once every four weeks. This dosing interval distinguishes efimosfermin from the weekly-dosed FGF21 analogs efruxifermin (Akero Therapeutics) and pegozafermin (89bio), which require subcutaneous injection every one to two weeks.

    The compound entered clinical development as LLF580 in a Novartis-sponsored Phase 1/2 trial (CLLF580X2102) in obese adults with modest hypertriglyceridemia, where 300 mg subcutaneously every four weeks for 12 weeks produced a 54 percent reduction in serum triglycerides, a 36 percent increase in HDL cholesterol, a 52 percent reduction in hepatic fat fraction by magnetic resonance imaging-estimated proton density fat fraction (MRI-PDFF), a 24 percent reduction in pro-peptide type III collagen (Pro-C3, a circulating fibrosis biomarker), and improvements in insulin sensitivity (38 percent reduction in fasting insulin, 29 percent reduction in C-peptide, and a 103 percent increase in adiponectin), all without significant body weight change. The compound was subsequently licensed to Boston Pharmaceuticals, renamed BOS-580, and advanced into a Phase 2a multicenter randomized double-blind placebo-controlled trial in participants with phenotypic metabolic dysfunction-associated steatohepatitis (MASH), followed by a Phase 2b trial (NCT04880031) in 84 patients with biopsy-confirmed MASH and F2 or F3 fibrosis, where 300 mg once monthly for 24 weeks produced fibrosis improvement of at least one stage without MASH worsening in 45.2 percent of treated patients versus 20.6 percent on placebo (p = 0.038), MASH resolution without fibrosis worsening in 67.7 percent versus 29.4 percent on placebo (p < 0.01), and clinically meaningful improvements in glycemic control markers including glycated hemoglobin.

    In May 2025, GSK plc completed acquisition of efimosfermin from Boston Pharmaceuticals for 1.2 billion United States dollars upfront and up to 800 million dollars in milestone payments, with tiered royalties owed to Novartis Pharma AG. The compound has received United States Food and Drug Administration Breakthrough Therapy Designation and European Medicines Agency Priority Medicines (PRIME) Designation for the treatment of MASH. Phase 3 development (the ZENITH program) commenced in December 2025, with a potential first launch projected for 2029. GSK has indicated development plans in both MASH (including compensated cirrhosis) and alcohol-related liver disease (ALD), with potential for combination therapy with GSK’990, a complementary hepatology pipeline candidate. This monograph reviews the chemistry, molecular design, and receptor pharmacology of efimosfermin; the FGF21 signaling pathway; the comprehensive preclinical and clinical pharmacokinetic record; the clinical evidence base across Phase 1/2 and Phase 2 trials; the sourcing and quality considerations for this biologic investigational agent; reconstitution and handling; stack interactions and combinations; adverse events and safety signals; and a comparative assessment of five FGF21-pathway therapeutic candidates against efimosfermin on five competency standards.

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    FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

  • T3D-959

    Dual peroxisome proliferator-activated receptor delta/gamma (PPARd/g) agonist with primary PPARd selectivity and brain-penetrant insulin-sensitizing activity

    A non-thiazolidinedione dual nuclear receptor agonist originally developed for metabolic disease and repositioned as a first-in-class brain insulin-sensitizing therapy for Alzheimer’s disease, distinguished by concurrent PPARd and PPARg activation, high central nervous system penetrance, and Phase 2 evidence of disease-modifying effects on cognition and amyloid biomarkers.

    Abstract

    T3D-959 (DB-959, DB-959Na as the sodium salt) is an orally bioavailable, brain-penetrant, non-thiazolidinedione dual agonist of peroxisome proliferator-activated receptor delta (PPARd; human ED50 19 nM) and peroxisome proliferator-activated receptor gamma (PPARg; human ED50 297 nM), conferring approximately 15-fold selectivity for the delta isoform. The compound was originally synthesized by Bayer and advanced through Phase 1 clinical trials for dyslipidemia and type 2 diabetes by DARA BioSciences before being acquired in 2013 by T3D Therapeutics and repositioned as a disease-modifying candidate for Alzheimer’s disease (AD) on the basis of the “type 3 diabetes” hypothesis, which posits that sporadic AD is driven by progressive brain insulin resistance, deficient insulin and insulin-like growth factor signaling, and consequent neurometabolic dysfunction. T3D-959 is the first PPARd-activating compound to enter clinical development for AD and represents a mechanistically distinct approach from the anti-amyloid antibody and cholinesterase inhibitor classes that dominate the current AD therapeutic landscape. Preclinical characterization in the intracerebral streptozotocin (i.c. STZ) rat model of sporadic AD, conducted principally by the de la Monte laboratory at Brown University, demonstrated that oral T3D-959 at doses of 0.3 to 3.0 mg/kg/day preserved spatial learning and memory in the Morris water maze, prevented brain weight loss, normalized phosphorylated tau and amyloid precursor protein-amyloid beta 42 (AbPP-Ab42) levels, reduced markers of oxidative stress, and partially restored cholinergic enzyme expression and white matter integrity. Therapeutic effects were observed even when treatment was delayed seven days after the STZ insult, suggesting relevance to mild and moderate disease stages. A separate preclinical study demonstrated that T3D-959 at 1.0 mg/kg/day improved motor function and prevented cerebellar white matter atrophy in the same model. An exploratory Phase 2a clinical trial in 36 subjects with mild to moderate AD (Chamberlain et al. 2020) demonstrated safety and tolerability at oral doses of 3, 10, 30, and 90 mg daily for 14 days, with no serious adverse events. Pharmacokinetic analysis confirmed dose-dependent systemic exposure exceeding the PPARd ED50 at all doses tested. Plasma metabolomics showed dose-dependent reductions in branched-chain amino acids and ceramides and increases in acylcarnitines, consistent with improved insulin sensitivity and enhanced fatty acid beta-oxidation. FDG-PET neuroimaging demonstrated dose-dependent increases in regional cerebral glucose metabolism, with the strongest effects in the putamen, anterior cingulate, insula, and orbital frontal cortex. Cognitive assessments showed improvements on the ADAS-Cog11 at 30 mg and on the Digit Symbol Substitution Test at all doses, with a delayed improvement pattern consistent with a transcriptional regulatory mechanism of action and an apparent ApoE4 genotype interaction. The Phase 2 PIONEER trial, a 24-week multicenter randomized double-blind placebo-controlled study in 250 patients with mild to moderate AD, reported positive top-line results in November 2023 at the 16th Clinical Trials on Alzheimer’s Disease (CTAD) conference. In the modified intent-to-treat population (n=141), the 30 mg group showed improvement on ADAS-Cog11 (0.73 versus 2.70 on placebo; p=0.073), and the 15 mg group showed improvement on ADCS-CGIC (0.39 versus 0.86 on placebo; p=0.060). Plasma amyloid beta 42/40 ratio improved significantly in the 30 mg (p=0.011) and 45 mg (p=0.033) groups, and the neurodegeneration marker neurogranin improved significantly in the 30 mg group (p=0.035). The compound was well tolerated, with adverse event rates similar between active and placebo arms (37.3% versus 43.1%) and no treatment-related serious adverse events. A Phase 2b/3 trial (NCT06964230) at 30 mg daily for 78 weeks in approximately 376 patients with biomarker-validated mild to moderate AD is planned to initiate in 2026. T3D-959 is not approved for any indication in any jurisdiction. This monograph reviews the chemistry, dual-receptor pharmacology, preclinical evidence base, clinical development program, pharmacokinetics, sourcing, reconstitution, stack interactions, adverse-event signal, and a comparative assessment of five alternative PPAR-targeting and insulin-sensitizing candidates against T3D-959 on five competency standards.

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  • Hopantenic acid

    Pantoyl-GABA conjugate nootropic with GABAergic, cholinergic, and pantothenic acid-related central nervous system activity

    A synthetic homolog of pantothenic acid in which beta-alanine is replaced by gamma-aminobutyric acid, developed in the Soviet Union and Japan as a nootropic and neuroprotective agent with registered indications across pediatric and adult neurology in the Russian Federation.

    Abstract

    Hopantenic acid (homopantothenic acid, D-homopantothenic acid, N-pantoyl-GABA) is a synthetic structural analog of pantothenic acid (vitamin B5) in which the beta-alanine moiety is replaced by gamma-aminobutyric acid (GABA), producing a hybrid molecule that combines GABAergic pharmacology with pantothenate-related metabolic activity and the capacity to cross the blood-brain barrier, a property that free GABA lacks. The compound was first synthesized in the 1950s in Japan, entered clinical use as the calcium salt (calcium hopantenate) in Japan in 1978 and in the Soviet Union in 1977, and is registered in the Russian Federation under the brand names Pantogam and Pantocalcin for a broad range of neurological, psychiatric, and developmental indications in children and adults, including cognitive impairment of cerebrovascular origin, attention deficit hyperactivity disorder, perinatal encephalopathy, cerebral palsy with hyperkinetic features, epilepsy adjunctive therapy, neurogenic bladder disorders, stuttering, and tic disorders. A racemic formulation (D,L-hopantenic acid, marketed as Pantogam Active) was introduced in Russia in 2008 and exhibits enhanced anxiolytic and anticonvulsant properties attributed to the L-isomer’s interaction with GABA-A receptors and dopamine D2 receptors. The compound is not approved by the United States Food and Drug Administration, by the European Medicines Agency, or by any Western regulatory authority. The molecular pharmacology of hopantenic acid is multifaceted. At the neurotransmitter level, the compound acts as a weak agonist at the GABA-B receptor complex, with a cross-reactive potency of approximately 0.2 percent relative to GABA in radioreceptor assays, and interacts with GABA-A receptors and dopamine D2 receptors at higher concentrations. In parallel, hopantenic acid enhances high-affinity choline transport into cortical and hippocampal synaptosomes and stimulates choline acetyltransferase activity, producing a secondary cholinergic facilitation that is the principal basis for the nootropic and antidementia pharmacology characterized in preclinical studies by Nakahiro et al. (1988) and others [1, 2]. At the metabolic level, the compound is a competitive antagonist of pantothenic acid at the pantothenate kinase step of coenzyme A (CoA) biosynthesis; phosphorylation by pantothenate kinase produces phospho-hopantenic acid, which potently inhibits phosphopantothenoylcysteine synthetase and reduces cellular CoA levels [3]. This pantothenic acid antagonism is the molecular basis for the most serious reported adverse effect of the compound: a Reye-like syndrome of acute encephalopathy with hepatic steatosis, hyperammonemia, and hypoglycemia reported in multiple case series in Japan during the 1980s, principally in elderly and pediatric patients on chronic high-dose therapy, and reproduced in dogs by Noda et al. (1991) [4, 5, 6]. The encephalopathy was preventable by concurrent pantothenic acid supplementation, confirming the antagonistic mechanism. Pharmacokinetics following oral administration of the calcium salt are characterized by rapid absorption (time to peak plasma concentration approximately 1.5 hours), moderate oral bioavailability (approximately 64 percent in preclinical models), an elimination half-life of approximately 6.7 hours, and predominantly renal excretion without significant hepatic metabolism [7]. The clinical evidence base for hopantenic acid is dominated by Russian-language publications of variable methodological rigor, with the most robust trial being a multicenter, double-blind, placebo-controlled study of Pantogam in 100 children with attention deficit hyperactivity disorder, which reported statistically significant improvement on the ADHD-DSM-IV rating scale and sustained attention measures over four months at 30 mg/kg/day [8]. Additional clinical evidence supports the use of the racemic formulation (Pantogam Active) for cognitive and anxiety disorders in patients with arterial hypertension and chronic cerebral ischemia [9, 10]. This monograph reviews the chemistry, synthesis, and stereochemistry of hopantenic acid; the multifaceted mechanism of action spanning GABAergic, cholinergic, and CoA-related pathways; the pharmacokinetic profile; the clinical evidence across registered and investigational indications; the Reye-like encephalopathy safety signal and its mechanistic basis; sourcing and quality verification; reconstitution and handling; stack interactions; and a structured comparative assessment of five alternative nootropic and GABAergic compounds against hopantenic acid on five competency standards.

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