Tag: NOVEL

  • ABT-737

    Plain-language summaryIntrigue 50 / 100

    ABT-737 is the structural and pharmacological predecessor to navitoclax: same target profile (BCL-2, BCL-XL, BCL-W), same BH3-mimetic logic, same selective killing of senescent cells in animal models, but missing the modifications that made navitoclax orally bioavailable. So ABT-737 is a research-only compound, given by intraperitoneal injection in mouse studies and never developed for clinical use. It remains widely used in cancer biology and senolytic research as a comparator for newer BCL-2 family inhibitors and as a tool to probe BH3-mimetic biology in cell lines and primary cells. Of historical interest as the original molecule that established the senolytic potential of the BCL-2 family. Not stocked by Kodiac. This monograph is provided for research and educational reference.

    Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

    BH3 mimetic inhibitor of anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-xL, Bcl-w)

    A potent, cell-permeable BH3-mimetic small molecule developed at Abbott Laboratories by fragment-based drug design, capable of high-affinity binding to the hydrophobic groove of Bcl-2, Bcl-xL, and Bcl-w to displace pro-apoptotic BH3-only proteins and trigger Bak/Bax-dependent mitochondrial apoptosis in Bcl-2-dependent tumor cells and senescent cells.

    Abstract

    ABT-737 is a rationally designed BH3 mimetic small molecule that binds with sub-nanomolar affinity (Ki less than 1 nM) to the BH3-binding groove of the anti-apoptotic proteins Bcl-2, Bcl-xL, and Bcl-w, displacing sequestered pro-apoptotic effectors (Bax, Bak) and BH3-only activators (Bid, Bim) to trigger the intrinsic mitochondrial apoptotic pathway [1]. Developed at Abbott Laboratories (now AbbVie) and reported by Oltersdorf et al. in 2005, ABT-737 was the product of a landmark structure-activity relationships by nuclear magnetic resonance (SAR-by-NMR) fragment-based drug discovery campaign in which two small-molecule fragments identified by NMR chemical shift perturbation screening against Bcl-xL were chemically linked and iteratively optimized by parallel synthesis and X-ray crystallography-guided design to yield a compound approximately three orders of magnitude more potent than any prior Bcl-2 family inhibitor [1, 2]. The compound binds weakly (Ki greater than 460 nM) to the structurally related anti-apoptotic proteins Mcl-1 and Bfl-1/A1, a selectivity gap that defines both the therapeutic window and the principal resistance mechanism observed across tumor models.

    In preclinical studies, ABT-737 demonstrated potent single-agent antitumor activity in xenograft models of small-cell lung cancer (SCLC), follicular lymphoma, and chronic lymphocytic leukemia (CLL), producing complete tumor regressions in SCLC models derived from H146 and H187 cell lines and inducing rapid apoptosis in primary CLL cells at an EC50 of approximately 7 nM [1, 3, 4]. Activity extends to acute myeloid leukemia (AML) blasts and leukemia stem cells, multiple myeloma cell lines with Bcl-2 dependence, and several solid tumor models in combination with conventional chemotherapy or targeted agents [5, 6, 7]. The compound preferentially induces apoptosis in malignant cells while showing reduced activity against normal hematopoietic progenitors at equivalent concentrations, a selectivity attributed to the elevated Bcl-2 dependence of transformed cells relative to their normal counterparts.

    A critical limitation of ABT-737 is its lack of oral bioavailability and poor aqueous solubility, properties that confined it to parenteral administration in preclinical models and precluded direct clinical development [1]. These pharmacokinetic constraints motivated the subsequent design of navitoclax (ABT-263), an orally bioavailable analog with equivalent target selectivity, and ultimately venetoclax (ABT-199), a Bcl-2-selective derivative that eliminated the dose-limiting thrombocytopenia caused by Bcl-xL inhibition in platelets [8, 9]. Venetoclax received FDA approval in 2016 for CLL and subsequently for AML, validating the therapeutic hypothesis that ABT-737 established preclinically.

    Beyond oncology, ABT-737 has been characterized as a senolytic agent capable of selectively clearing senescent cells through disruption of the Bcl-2/Bcl-xL-dependent survival program that senescent cells upregulate as part of the senescence-associated anti-apoptotic phenotype (SAAP) [10]. Administration of ABT-737 during the second half of life in progeroid mouse models abrogated senescence markers and increased median survival, extending the compound’s research relevance to aging biology, fibrosis, and tissue regeneration [10, 11].

    This monograph documents the chemistry, synthesis, and fragment-based discovery of ABT-737; the molecular pharmacology of BH3-groove binding and Bak/Bax activation; pharmacokinetic properties and in vivo dosing; the preclinical evidence base across hematologic malignancies, solid tumors, and senescence; sourcing and quality verification considerations; reconstitution and handling; stack interactions and combination strategies; the adverse-event and safety signal (principally Bcl-xL-mediated thrombocytopenia); and a structured comparative assessment of five BH3 mimetic and Bcl-2 family inhibitors (navitoclax, venetoclax, obatoclax, S63845, and AT-101) against ABT-737 on five competency standards.

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  • Adamax

    Synthetic melanocortin-derived nootropic peptide with dual N-acetyl and C-terminal adamantane modifications for enhanced blood-brain barrier permeability and neurotrophic factor modulation

    A next-generation ACTH(4-10) analog engineered from Semax with N-terminal acetylation and C-terminal adamantylglycine amidation, designed to extend plasma half-life and central nervous system bioavailability while preserving the parent compound’s neurotrophic, neuroprotective, and monoaminergic pharmacology.

    Abstract

    Adamax (N-Acetyl Semax-Adamantane; Ac-MEHFPGP-AdaGly-NH2) is a synthetic nonapeptide research compound derived from Semax, the Russian-developed ACTH(4-10) analog approved in the Russian Federation for the treatment of ischemic stroke and cognitive impairment. The compound incorporates two structural modifications to the Semax backbone (Met-Glu-His-Phe-Pro-Gly-Pro): an N-terminal acetyl group that shields the peptide from aminopeptidase degradation and a C-terminal adamantylglycine amide that increases lipophilicity, enhances blood-brain barrier penetration, and confers resistance to carboxypeptidase cleavage. These modifications extend the effective half-life from approximately 30 to 60 minutes (Semax) to an estimated 8 to 10 hours and increase central nervous system bioavailability, enabling single daily dosing protocols in research applications.

    The pharmacological rationale for Adamax rests on the established molecular pharmacology of its parent compound Semax and on the broader adamantane medicinal chemistry literature. Semax activates brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) signaling in the hippocampus and basal forebrain, modulates melanocortin-3 and melanocortin-4 receptor (MC3R/MC4R) activity in cortical and hypothalamic circuits, and enhances dopaminergic and serotonergic neurotransmission in the striatum and prefrontal cortex [1, 2, 3]. Adamax preserves this multi-target pharmacology while the adamantane cage, a rigid tricyclo[3.3.1.1(3,7)]decane hydrocarbon scaffold shared with the FDA-approved drugs amantadine and memantine, confers the lipophilicity necessary for passive transcellular blood-brain barrier transit and reduces the susceptibility of the C-terminus to exopeptidase degradation [4, 5].

    Adamax does not have independent, peer-reviewed clinical or preclinical pharmacology publications indexed in PubMed or comparable biomedical databases as of the date of this monograph. All mechanistic characterization is inferred from the extensive published literature on Semax (over 300 publications, predominantly in Russian-language journals with a growing English-language subset), from the P21 (P021) adamantane-modified neurotrophic peptide literature, and from the structure-activity relationships of the ACTH(4-10) melanocortin fragment class. The compound is sold as a research-grade preparation by multiple peptide suppliers and has been identified as a designer peptide in border seizures by the New Zealand Medicines and Medical Devices Safety Authority [6]. It is not approved by any regulatory agency for therapeutic use. Investigators should treat all pharmacological claims as extrapolations from parent-compound data until independent Adamax-specific studies are published. This monograph reviews the chemistry, structural rationale, inferred mechanism of action, pharmacokinetic considerations, the parent-compound evidence base, sourcing and quality verification, reconstitution and handling, stack-interaction considerations, the safety signal profile, and a comparative assessment of five related nootropic peptide compounds (Semax, N-Acetyl Semax Amidate, P21, Selank, Noopept) against Adamax on five competency standards.

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  • J-147

    Phenyl hydrazide neurotrophic compound targeting mitochondrial ATP synthase alpha-F1 subunit with geroprotective and neuroprotective activity

    A synthetic curcumin-derived phenyl hydrazide developed at the Salk Institute through phenotypic screening against multiple age-associated neurotoxicities, identified as a partial modulator of mitochondrial ATP synthase alpha subunit (ATP5A) that activates the CAMKK2/AMPK longevity axis, with robust preclinical neuroprotection and cognitive reversal in aged Alzheimer’s disease mice and advancement to Phase 1 clinical evaluation.

    Abstract

    J-147 (CAS 1146963-51-0; molecular formula C18H17F3N2O2; molecular weight 350.33) is a synthetic phenyl hydrazide small molecule developed at the Salk Institute for Biological Studies in the laboratory of David Schubert through iterative phenotypic optimization beginning from the natural product curcumin. First reported by Chen et al. in 2011, J-147 was selected from a combinatorial chemical library on the basis of nanomolar potency across six cell-based assays modeling age-associated neurotoxicities: trophic factor withdrawal (EC50 25 nM), oxidative stress (EC50 10 to 200 nM), glucose starvation, chemical ischemia, and amyloid-beta 1-42 toxicity. The compound represents approximately 100-fold greater potency than its immediate precursor CNB-001 and vastly greater potency and bioavailability than curcumin itself, which was inactive in the selection assays at achievable concentrations.

    The molecular target of J-147 was identified in 2018 by Goldberg et al. as the alpha-F1 subunit of mitochondrial ATP synthase (ATP5A), using drug affinity responsive target stability (DARTS) and biotinylated affinity precipitation approaches. J-147 partially inhibits ATP synthase activity with an EC50 of approximately 20 nM and saturates at approximately 23.6 percent inhibition, producing a dose-dependent increase in cytosolic calcium that activates calcium/calmodulin-dependent protein kinase kinase beta (CAMKK2), which phosphorylates AMP-activated protein kinase (AMPK) at threonine 172. The resulting AMPK activation modulates mammalian target of rapamycin complex 1 (mTORC1) signaling, acetyl-CoA carboxylase 1 (ACC1) activity, and downstream metabolic pathways linked to both aging and neurodegeneration. ATP5A knockdown phenocopies J-147 across multiple neuroprotection assays, and J-147 provides no additional protection in ATP5A-knockdown cells, confirming target engagement specificity.

    In preclinical models, J-147 administered orally at 200 ppm in food (approximately 10 mg/kg/day) prevents cognitive decline in young APP/swePS1-deltaE9 transgenic mice over 7 months, preserves synaptic proteins (drebrin, synapsin-1, synaptophysin), reduces soluble amyloid-beta 1-40 and 1-42, increases brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), facilitates long-term potentiation at concentrations of 0.01 to 1 micromolar, and reduces oxidative stress and neuroinflammation markers. In aged (20-month) APP/PS1 mice, 3 months of J-147 treatment reverses established cognitive deficits in water maze, fear conditioning, and elevated plus maze paradigms. In the SAMP8 senescence-accelerated mouse model, J-147 attenuates age-associated hippocampal transcriptional drift by approximately 6 percent (P less than 10 to the negative 10). In Drosophila melanogaster, J-147 extends median lifespan by 9.5 to 12.5 percent.

    Pharmacokinetically, J-147 demonstrates 28 percent oral bioavailability in mice, a plasma half-life of 1.5 hours, a brain half-life of 2.5 hours, brain concentrations of approximately 600 nM at 2 hours after a 20 mg/kg oral dose (5- to 10-fold above its neuroprotective EC50), and a brain-to-plasma ratio of approximately 0.5. The compound is classified as having high blood-brain barrier penetration by the MDCK-MDRI cell culture model. Safety evaluation demonstrates no genotoxicity (Ames test negative to 0.36 mM), no acute toxicity in rats at 2 g/kg, no hERG channel inhibition, a CeeTox predicted toxicity value of 90 micromolar (yielding a therapeutic safety window of 782 to 3600-fold over efficacy concentrations), and no significant off-target activity across more than 60 CNS receptors, 352 protein kinases, and extensive enzyme panels. The sole notable off-target interactions are modest dopamine transporter (EC50 0.649 micromolar) and monoamine oxidase B (EC50 1.88 micromolar) activities at concentrations 6.5- to 19-fold above the neuroprotective range. A Phase 1 randomized double-blind placebo-controlled clinical trial (NCT03838185) was initiated in February 2019 by Abrexa Pharmaceuticals and completed in February 2020; results have not been published. The compound is not approved by any regulatory authority and is supplied exclusively as a research compound.

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  • Navitoclax (ABT-263)

    Orally bioavailable BH3-mimetic inhibitor of anti-apoptotic BCL-2 family proteins (BCL-2, BCL-XL, BCL-W) with senolytic and anti-fibrotic activity

    A first-in-class orally bioavailable BH3-domain mimetic developed at Abbott Laboratories that binds BCL-2, BCL-XL, and BCL-W with sub-nanomolar affinity, inducing mitochondrial apoptosis in malignant and senescent cells, and now advancing in combination with ruxolitinib in myelofibrosis.

    Abstract

    Navitoclax (ABT-263) is an orally bioavailable, small-molecule BH3-domain mimetic that binds with sub-nanomolar affinity to three anti-apoptotic members of the B-cell lymphoma 2 (BCL-2) protein family: BCL-2 (Ki less than or equal to 1 nM), BCL-XL (Ki less than or equal to 0.5 nM), and BCL-W (Ki less than or equal to 1 nM). The compound was developed at Abbott Laboratories (now AbbVie) as an orally bioavailable successor to the intravenous-only BH3 mimetic ABT-737, retaining the high-affinity, multi-target BCL-2 family binding of the parent molecule while achieving moderate oral bioavailability suitable for chronic dosing. Navitoclax occupies the hydrophobic BH3-binding groove on anti-apoptotic BCL-2 family members, displacing sequestered pro-apoptotic effectors BAX and BAK and thereby triggering mitochondrial outer membrane permeabilization, cytochrome c release, caspase activation, and intrinsic apoptosis in cells dependent on BCL-2 or BCL-XL for survival.

    The compound entered oncology clinical development in 2007. Phase 1 studies in chronic lymphocytic leukemia (CLL) demonstrated substantial single-agent activity, with an objective response rate of 31 percent and durable responses (median progression-free survival 25 months) in relapsed or refractory disease [1]. Phase 1 and Phase 2 studies in small-cell lung cancer (SCLC) and other solid tumors demonstrated limited single-agent activity, with an objective response rate of 2.6 percent in relapsed SCLC [2]. Clinical development as a single-agent oncologic therapy was constrained by mechanism-based, dose-limiting thrombocytopenia arising from BCL-XL inhibition in circulating platelets, which depend on BCL-XL for survival [3]. This on-target platelet toxicity motivated the development of the BCL-2-selective derivative venetoclax (ABT-199), which retains potent BCL-2 inhibition while sparing BCL-XL and thereby avoiding thrombocytopenia; venetoclax received FDA approval for CLL in 2016 and has become the foundational BCL-2-targeted agent in hematologic oncology.

    Navitoclax has continued in clinical development in combination regimens. The Phase 3 TRANSFORM-1 trial of navitoclax combined with the JAK1/JAK2 inhibitor ruxolitinib in treatment-naive myelofibrosis met its primary endpoint, demonstrating a spleen volume reduction of 35 percent or greater (SVR35) at week 24 in 63.2 percent of patients on the combination compared with 31.5 percent on ruxolitinib plus placebo [4]. The Phase 3 TRANSFORM-2 trial in relapsed or refractory myelofibrosis is ongoing with anticipated completion in late 2026. These results position navitoclax as a potential first-in-class BCL-2 family inhibitor approved for myelofibrosis.

    A second major research application emerged in 2016 with the identification of navitoclax as a potent senolytic agent. Senescent cells, which accumulate with aging and after genotoxic stress, upregulate BCL-XL and other anti-apoptotic BCL-2 family members as part of the senescence-associated apoptosis-resistance program. Zhu et al. (2016) and Chang et al. (2016) demonstrated that navitoclax selectively eliminates senescent cells in vitro and in vivo, rejuvenating aged hematopoietic stem cells, clearing senescent muscle stem cells, and improving vascular function in aged mice [5, 6]. The compound has since been characterized as anti-fibrotic in preclinical models of idiopathic pulmonary fibrosis, where it induces apoptosis in fibroblasts overexpressing BCL-2 family members and reverses established fibrosis [7]. These findings have positioned navitoclax as the prototype research senolytic and a pharmacological tool for investigating the contribution of cellular senescence to aging, fibrosis, and degenerative disease.

    Pharmacokinetics in humans are characterized by slow oral absorption (time to peak concentration approximately 7 to 9 hours), a terminal elimination half-life of approximately 15 to 17 hours, high plasma protein binding (greater than 99 percent), and low volume of distribution (0.5 to 0.7 L/kg). The compound is metabolized by CYP3A4 and is a moderate inhibitor of CYP2C8 and a strong inhibitor of CYP2C9. Approximately 90 percent of the administered dose is excreted in feces, with approximately half as metabolites. A high-fat meal increases oral exposure by approximately 70 percent. The compound is not approved by any regulatory authority for any indication. It is available as a research-grade preparation from multiple chemical suppliers. Investigators should obtain analytical confirmation of identity and purity on every lot.

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  • Omecamtiv Mecarbil

    First-in-class selective small-molecule cardiac myosin activator

    A selective allosteric activator of the cardiac myosin heavy chain discovered at Cytokinetics through high-throughput sarcomere screening, distinguished from all prior inotropes by direct augmentation of actin-myosin cross-bridge formation independent of intracellular calcium signaling, with a positive Phase 3 cardiovascular outcomes signal in heart failure with reduced ejection fraction concentrated among patients with the most severely depressed systolic function.

    Abstract

    Omecamtiv mecarbil (CK-1827452, AMG 423) is a first-in-class selective small-molecule activator of cardiac myosin, the beta-myosin heavy chain (MYH7) motor protein of the ventricular sarcomere. Discovered at Cytokinetics, Inc. through high-throughput screening of a reconstituted calcium-responsive sarcomere assay and advanced through extensive structure-activity optimization from a poorly soluble nitro-aromatic hit compound, omecamtiv mecarbil binds an allosteric pocket on the cardiac myosin catalytic domain (S1 subfragment) that stabilizes the lever arm in a primed, pre-powerstroke conformation. The compound accelerates the rate-limiting phosphate release step of the cross-bridge cycle, increasing the number of myosin heads engaged with the actin filament during systole and prolonging the duration of force generation, without increasing intracellular calcium concentration or myocardial oxygen consumption. X-ray crystallographic studies have resolved the binding site at 2.45 Angstrom resolution, revealing interactions with the converter domain, relay helix, and N-terminal subdomain that induce a 15-degree rotation and approximately 4 Angstrom translation of the converter. Selectivity for cardiac over skeletal and smooth muscle myosin is structurally rationalized by divergent converter domain residues across isoforms. The clinical development program, spanning nine Phase 1 studies, four Phase 2 trials, and two Phase 3 trials over more than a decade, has established the pharmacodynamic signature of omecamtiv mecarbil: concentration-dependent prolongation of systolic ejection time, increased stroke volume and ejection fraction, decreased ventricular volumes, and reduced NT-proBNP, achieved without the tachycardia, hypotension, or proarrhythmic signals characteristic of catecholamine-based inotropes. The pivotal GALACTIC-HF trial (n = 8,256; NCT02929329) demonstrated a statistically significant reduction in the primary composite endpoint of cardiovascular death or first heart failure event (hazard ratio 0.92; 95% CI 0.86 to 0.99; p = 0.03), with the treatment benefit concentrated among patients with the lowest baseline ejection fractions (LVEF 22% or below: HR 0.83; 95% CI 0.73 to 0.95) and highest NT-proBNP levels. Cardiovascular death alone was not significantly reduced (HR 1.01). The METEORIC-HF trial (n = 276; NCT03759392) found no significant improvement in peak exercise capacity over 20 weeks, indicating that the cardiovascular outcomes benefit may operate through reduction of heart failure decompensation events rather than augmented peak aerobic performance. Pharmacokinetics are characterized by high oral bioavailability (approximately 93%), a terminal half-life of approximately 18 to 21 hours supporting twice-daily dosing, metabolism primarily through a decarbamylation pathway with modest CYP3A4 and CYP2D6 contributions, and balanced renal and fecal elimination. Omecamtiv mecarbil does not prolong the QTc interval at therapeutic concentrations. The compound received a Complete Response Letter from the United States Food and Drug Administration in February 2023; a confirmatory Phase 3 trial (COMET-HF) in patients with severely reduced ejection fraction is ongoing with expected completion in 2028. This monograph reviews the chemistry, structural pharmacology, comprehensive pharmacokinetic characterization, the complete clinical evidence base including positive and negative trials with subgroup analyses, the sourcing and handling considerations for research applications, and a comparative assessment of five heart failure agents against omecamtiv mecarbil on five competency standards. The compound is investigational and is not approved by any regulatory authority.

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  • Petrelintide

    Long-acting lipidated human amylin analog and dual amylin/calcitonin receptor agonist (DACRA) for once-weekly subcutaneous administration

    A 36-amino-acid acylated peptide engineered from human amylin with a lactam bridge, N-methylations, and C20 diacid lipidation enabling neutral-pH stability, albumin-mediated half-life extension to approximately 10 days, and once-weekly dosing for obesity and weight management.

    Abstract

    Petrelintide (ZP-8396) is a long-acting, subcutaneously administered analog of human amylin developed by Zealand Pharma A/S (Soborg, Denmark) as a potential foundational therapy for chronic weight management in adults with overweight and obesity. The compound is a 36-amino-acid acylated peptide bearing a lactam bridge replacement of the native Cys2-Cys7 disulfide bond, N-methylations at Gly24 and Ile26 to prevent amyloid fibrillation, strategic asparagine deletions and substitutions to eliminate deamidation-prone residues, a C-terminal hydroxyproline substitution for enhanced receptor potency, and an N-terminal C20 diacid lipidation via a gamma-glutamic acid linker that confers reversible albumin binding and a human terminal half-life of approximately 10 days, supporting convenient once-weekly dosing. Petrelintide exhibits potent balanced agonism at the amylin-3 receptor (AMY3R, EC50 0.33 nM) and the calcitonin receptor (CTR, EC50 0.32 nM) in cAMP accumulation assays, classifying it as a dual amylin and calcitonin receptor agonist (DACRA). In diet-induced obese rat models, repeated dosing produces dose-dependent reductions in food intake and body weight with preferential fat mass loss and relative preservation of lean mass. Clinical development has progressed rapidly. A first-in-human Phase 1 single ascending dose trial (NCT05096598) established safety and tolerability at subcutaneous doses of 0.04 to 2.4 mg, with a human half-life supporting weekly administration. A Phase 1b multiple ascending dose trial in 48 participants with overweight or obesity demonstrated mean body weight reductions of 4.8% (2.4 mg), 8.6% (4.8 mg), and 8.3% (9.0 mg) versus 1.7% with placebo after 16 weekly doses, with no serious or severe adverse events and gastrointestinal tolerability substantially superior to the adverse-event profiles reported for GLP-1 receptor agonist monotherapy at comparable weight-loss magnitudes. The Phase 2 ZUPREME-1 trial (NCT06662539) in 493 adults with obesity met its primary endpoint across all five dose arms, achieving up to 10.7% mean body weight reduction at 42 weeks with placebo-like tolerability, zero vomiting at the maximally effective dose, and discontinuation rates due to adverse events comparable to placebo (4.8% versus 4.9%). In March 2025, Roche entered an exclusive global collaboration and licensing agreement with Zealand Pharma valued at up to 5.3 billion US dollars to co-develop and co-commercialize petrelintide as monotherapy and in fixed-dose combination with CT-388, a dual GLP-1/GIP receptor agonist. Phase 3 initiation for chronic weight management is planned for the second half of 2026. Petrelintide is an investigational compound; its safety and efficacy have not been established by any regulatory authority. This monograph reviews the peptide chemistry, receptor pharmacology, preclinical and clinical evidence base, pharmacokinetic profile, and comparative positioning of petrelintide within the amylin receptor agonist landscape, grounded in the primary literature through May 2026. Investigators should treat all data as preliminary pending registration-quality Phase 3 results and regulatory evaluation.

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  • Reldesemtiv

    Second-generation fast skeletal muscle troponin activator (FSTA) selective for fast skeletal muscle fibers

    A next-generation fast skeletal muscle troponin activator developed by Cytokinetics to amplify skeletal muscle force output through calcium sensitization of the sarcomere, evaluated in Phase 2 and Phase 3 clinical trials in amyotrophic lateral sclerosis and spinal muscular atrophy.

    Abstract

    Reldesemtiv (CK-2127107) is a small-molecule fast skeletal muscle troponin activator (FSTA) that selectively binds the regulatory troponin complex in fast skeletal muscle fibers, slows the rate of calcium release from troponin C, and thereby sensitizes the sarcomere to calcium at submaximal stimulation frequencies. The compound was discovered at Cytokinetics, Inc. through property-based optimization of a high-throughput screening hit, yielding improved free exposure, in vivo muscle activation potency, and tolerability relative to the first-generation FSTA tirasemtiv, which had failed the Phase 3 VITALITY-ALS trial primarily because of dose-limiting tolerability (dizziness, nausea, weight loss, insomnia) and a 34.2 percent treatment discontinuation rate. Reldesemtiv does not activate slow skeletal or cardiac troponin complexes, providing a selectivity basis for its intended use in conditions characterized by fast skeletal muscle weakness secondary to attenuated neuronal input, including amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), and chronic obstructive pulmonary disease. In a Phase 1 pharmacodynamic study in 16 healthy volunteers, reldesemtiv amplified the tibialis anterior force-frequency response by approximately 60 percent at 10 Hz nerve stimulation at the highest plasma concentrations tested, confirming the mechanism of action in human skeletal muscle. Pharmacokinetics across five Phase 1 studies demonstrated dose-proportional exposure with a terminal half-life of approximately 5 to 14 hours depending on dose, a time to peak concentration of 2 to 3 hours, and similar pharmacokinetic profiles in young and elderly subjects. The Phase 2 FORTITUDE-ALS trial (n=458; 12 weeks; placebo, 150, 300, or 450 mg twice daily) did not reach statistical significance on its primary endpoint of slow vital capacity change (p=0.11), though trends favoring reldesemtiv were observed across all three endpoints and a post hoc analysis of the ALSFRS-R functional scale reached nominal significance (p=0.01). The Phase 2 SMA study (n=70; 8 weeks; 150 or 450 mg twice daily) reported statistically significant improvement in six-minute walk distance at week 4 (35.6 m, p=0.0037) and maximum expiratory pressure at week 8 (13.2 cmH2O, p=0.03) in the 450 mg group, with concentration-response relationships in the highest plasma concentration quartile reaching significance on both endpoints. The Phase 3 COURAGE-ALS trial (n=486; 24 weeks; 300 mg twice daily versus placebo; 83 centers in 16 countries) was terminated for futility at the second planned interim analysis when conditional power for the primary endpoint (ALSFRS-R score change at 24 weeks) was 8.4 percent. The primary analysis showed a mean difference of negative 1.1 points (95 percent CI, negative 2.17 to negative 0.08; p=0.04), numerically favoring placebo. No preplanned subgroup favored reldesemtiv. The compound is not approved by any regulatory authority for any indication. This monograph reviews the chemistry, discovery, molecular pharmacology, pharmacokinetics, preclinical and clinical evidence, sourcing, handling, adverse events, and a comparative assessment of reldesemtiv against tirasemtiv, tofersen, riluzole, edaravone, and risdiplam on five competency standards.

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  • Roluperidone

    Sigma-2 receptor antagonist and serotonin 5-HT2A receptor antagonist with alpha-1A adrenergic receptor antagonism

    A cyclic amide derivative with equipotent nanomolar antagonism at sigma-2 and 5-HT2A receptors, developed by Minerva Neurosciences as monotherapy for the negative symptoms of schizophrenia and distinguished from conventional antipsychotics by the absence of dopaminergic receptor binding.

    Abstract

    Roluperidone (MIN-101, formerly MT-210 and CYR-101) is a cyclic amide (isoindolinone) derivative that combines high-affinity antagonism at the sigma-2 receptor (TMEM97; Ki 8.19 nM) and the serotonin 5-HT2A receptor (Ki 7.53 nM) with lower-affinity antagonism at alpha-1A adrenergic receptors (Ki 4.17 nM), while exhibiting essentially no binding at dopamine D1 through D5 receptors, muscarinic, cholinergic, or histaminergic receptors. This receptor binding profile distinguishes roluperidone from all marketed antipsychotics and underwrites a pharmacological rationale for addressing the negative symptoms of schizophrenia through nondopaminergic mechanisms. The sigma-2 receptor, identified in 2017 as the transmembrane protein TMEM97, is expressed at high density in cortical and hippocampal neurons and is implicated in calcium signaling, cholesterol homeostasis, autophagy, and the modulation of dopaminergic and glutamatergic neurotransmission. The 5-HT2A antagonist component promotes slow-wave sleep normalization, a deficit that is consistently documented in schizophrenia and that correlates with negative symptom severity. Roluperidone was originally synthesized by Mitsubishi Tanabe Pharma Corporation (designated MT-210), licensed through Cyrenaic Pharmaceuticals (CYR-101), and advanced through clinical development by Minerva Neurosciences (MIN-101). In a Phase 2b randomized, double-blind, placebo-controlled trial of 244 patients with stable schizophrenia and moderate-to-severe negative symptoms (MIN-101C03), roluperidone monotherapy at 32 mg/day and 64 mg/day produced statistically significant improvement on the PANSS negative symptom factor score at 12 weeks (effect sizes 0.45 and 0.58, respectively; both p < 0.025). In the subsequent Phase 3 trial (EMERGENT-3, NCT03397134, 513 patients), the 64 mg/day dose reached nominal statistical significance on the primary negative symptom endpoint in the modified intent-to-treat analysis (p = 0.044, effect size 0.26), with statistically significant improvements in social functioning on the Personal and Social Performance scale (p = 0.021, effect size 0.27) and a negative symptom responder rate of 39% versus 23% on placebo (p = 0.006). Network intervention analysis of both trials identified avolition as the directly targeted symptom, with improvements cascading across the broader negative symptom constellation. Pharmacokinetics are characterized by oral bioavailability of 73% to 81%, peak plasma concentration at approximately 3.5 hours, and a plasma elimination half-life of approximately 7 hours after a 64 mg dose, supporting once-daily administration. CYP2D6 is involved in metabolism, and poor or intermediate CYP2D6 metabolizers were excluded from the Phase 3 trial. Tolerability across both trials was notable for the absence of clinically meaningful weight gain, metabolic changes, extrapyramidal symptoms, or prolactin elevation; the principal safety signal was QTc interval prolongation leading to discontinuation of three patients at the 64 mg dose in the Phase 3 trial. Minerva Neurosciences filed a New Drug Application with the U.S. Food and Drug Administration in April 2023. The FDA issued a Complete Response Letter in February 2024, citing insufficient evidence of effectiveness from a single adequate trial, absence of data on concomitant antipsychotic administration, and the need for additional evidence of clinical meaningfulness. The compound remains in development as of the monograph date. This monograph documents the chemistry, dual-receptor pharmacology, pharmacokinetics, preclinical and clinical evidence base, safety profile, and a comparative assessment of five compounds in the negative symptom treatment space against roluperidone on five competency standards. The compound is investigational and is not approved by any regulatory authority for any indication.

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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.

  • Dalzanemdor

    First-in-class oxysterol-derived positive allosteric modulator of the N-methyl-D-aspartate receptor

    A first-in-class synthetic analog of the endogenous cholesterol metabolite 24(S)-hydroxycholesterol, developed by Sage Therapeutics as an oral NMDA receptor positive allosteric modulator for cognitive impairment in Huntington’s disease, Alzheimer’s disease, and Parkinson’s disease, with development discontinued in late 2024 following negative Phase 2 efficacy readouts across all three indications.

    Abstract

    Dalzanemdor (development code SAGE-718) is a first-in-class, orally bioavailable, small-molecule positive allosteric modulator (PAM) of the N-methyl-D-aspartate receptor (NMDAR), structurally derived from the endogenous cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-HC). The compound was designed by Sage Therapeutics to address cognitive impairment in neurodegenerative disorders associated with NMDAR hypofunction, including Huntington’s disease, Alzheimer’s disease, and Parkinson’s disease. Dalzanemdor potentiates NMDAR-mediated currents at all four GluN2 subunit-containing receptor assemblies (GluN1/GluN2A through GluN1/GluN2D) with equipotency, exhibiting EC50 values in the low-nanomolar range (approximately 79 to 86 nM) and high intrinsic activity. The modulation increases NMDAR channel open probability without directly gating the receptor in the absence of endogenous glutamate, a feature that preserves physiological patterns of synaptic transmission and mitigates the excitotoxicity risk associated with direct NMDAR agonism.

    The compound emerged from a research program initiated by the foundational discovery of Paul et al. (2013) demonstrating that 24(S)-HC, the major brain-specific cholesterol metabolite synthesized by CYP46A1, is a potent and selective endogenous NMDAR PAM at submicromolar concentrations. Medicinal chemistry optimization at Sage Therapeutics yielded dalzanemdor (compound 5 in the Hill et al. 2022 disclosure), a trifluoromethylated oxysterol with an optimized pharmacokinetic profile for oral dosing. In preclinical models, dalzanemdor enhanced NMDAR-mediated long-term potentiation in hippocampal slices, increased excitatory postsynaptic potential amplitude in striatal medium spiny neurons, and reversed cognitive and behavioral deficits induced by NMDAR channel blockers and cholesterol depletion, without producing epileptiform activity or neurodegeneration on chronic dosing.

    Phase 1 dose-finding studies (single-ascending dose, 0.35 to 3.0 mg; multiple-ascending dose, 0.5 to 1.0 mg for 14 days) in healthy participants and Huntington’s disease participants established a pharmacokinetic profile characterized by oral absorption with median Tmax of 4 to 7 hours, terminal half-life of approximately 28 to 40 hours after single doses extending to 99 to 125 hours after multiple doses, and dose-proportional exposures suitable for once-daily dosing. Exploratory cognitive assessments in Huntington’s disease participants during the Phase 1 multiple-ascending dose study showed statistically significant improvement on the Two-Back Learning Task (executive function). Open-label Phase 2 studies in Parkinson’s disease mild cognitive impairment (PARADIGM, n=18) and Alzheimer’s disease (LUMINARY, n=26) generated signals of improvement on measures of executive function and learning. However, three subsequent randomized, double-blind, placebo-controlled Phase 2 studies (PRECEDENT in Parkinson’s disease, LIGHTWAVE in Alzheimer’s disease, DIMENSION in Huntington’s disease) each failed to meet their primary cognitive endpoints. Sage Therapeutics discontinued all clinical development of dalzanemdor in November 2024.

    This monograph documents the chemistry, structural pharmacology, oxysterol-site mechanism, human pharmacokinetics, the complete clinical trial inventory including both positive open-label signals and negative controlled results, sourcing and handling considerations for research-grade material, adverse-event profile, and a comparative assessment of five NMDAR-targeting compounds against dalzanemdor on five competency standards. The compound is not approved by any regulatory authority. Research-grade dalzanemdor is available from chemical suppliers for in vitro and in vivo investigation of NMDAR positive allosteric modulation; investigators should obtain analytical confirmation of identity and purity on every lot.

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  • Acoramidis

    Selective transthyretin tetramer kinetic stabilizer designed to mimic the naturally occurring T119M protective variant

    A fluorinated benzoic acid derivative engineered to replicate the enthalpy-driven transthyretin stabilization of the protective T119M genetic variant, approved for transthyretin amyloid cardiomyopathy following a positive Phase 3 trial demonstrating reductions in all-cause mortality and cardiovascular hospitalization.

    Abstract

    Acoramidis (AG10) is a potent, selective, orally bioavailable small-molecule kinetic stabilizer of the transthyretin (TTR) tetramer, approved in the United States, European Union, United Kingdom, and Japan for the treatment of cardiomyopathy caused by wild-type or hereditary transthyretin-mediated amyloidosis (ATTR-CM). The compound was rationally designed to replicate the molecular mechanism of the naturally occurring T119M variant of TTR, a protective mutation that stabilizes the tetramer against the rate-limiting dissociation step that initiates amyloid fibril formation. Structurally, acoramidis is a 3,5-dimethylpyrazole linked through a propyloxy tether to a 4-fluorobenzoic acid; the pyrazole ring forms two hydrogen bonds with serine 117 and serine 117 prime residues at the floor of the thyroxine binding pocket, replicating the inter-dimer contact created by the threonine-to-methionine substitution in T119M carriers. This enthalpy-driven binding mechanism (binding enthalpy of negative 13.6 kilocalories per mole, compared to negative 5.0 kilocalories per mole for tafamidis) underpins the high selectivity of acoramidis for TTR over albumin and its capacity to achieve greater than 90 percent tetramer stabilization across the entire dosing interval at steady state. The clinical development program for acoramidis established pharmacokinetic parameters favorable for twice-daily oral dosing: rapid absorption (time to peak concentration less than one hour), terminal elimination half-life of approximately 25 hours, metabolism principally by UGT-mediated glucuronidation rather than cytochrome P450 enzymes, and renal elimination of conjugated metabolites. The pivotal Phase 3 ATTRibute-CM trial randomized 632 patients with wild-type or hereditary ATTR-CM to acoramidis 800 milligrams (as the hydrochloride salt) twice daily or placebo for 30 months. On the primary hierarchical endpoint (a four-component analysis of all-cause mortality, cardiovascular-related hospitalization, NT-proBNP change, and six-minute walk distance), acoramidis demonstrated a win ratio of 1.8 (95 percent confidence interval 1.4 to 2.2; P less than 0.001). The time-to-event composite of all-cause mortality or first cardiovascular hospitalization favored acoramidis with a hazard ratio of 0.64 (95 percent confidence interval 0.50 to 0.83; P equals 0.0008), with Kaplan-Meier curves separating at three months and benefit sustained through 42 months of follow-up in the open-label extension. A cardiac magnetic resonance substudy demonstrated stabilization of left ventricular mass and improvement of ejection fraction in the acoramidis arm relative to progressive deterioration in placebo recipients. The adverse event profile was similar to placebo; diarrhea (11.6 versus 7.6 percent) and gout (10.9 versus 8.1 percent) were the most frequent treatment-emergent events occurring at higher rates with acoramidis. This monograph reviews the chemistry, synthesis, and rational design of acoramidis; the enthalpy-driven TTR stabilization mechanism characterized through isothermal titration calorimetry and X-ray crystallography; the complete human pharmacokinetic profile; preclinical pharmacology in rodent and canine models; the clinical evidence base from Phase 1 through Phase 3 and the open-label extension; sourcing and quality considerations for research applications; reconstitution and handling; metabolic and pharmacodynamic interactions; the adverse event and safety profile; and a comparative assessment of five transthyretin-directed therapies (tafamidis, diflunisal, patisiran, vutrisiran, and eplontersen) against acoramidis on five competency standards. Acoramidis is a prescription medicine in its approved jurisdictions and is available as a research-grade preparation for investigational applications outside the approved indication. Investigators should obtain analytical confirmation of identity and purity on every research-grade lot.

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