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    • KU-60019: Selective ATM Kinase Inhibitor for Glioma Radio...

    2026-02-03

    KU-60019: Selective ATM Kinase Inhibitor for Glioma Radiosensitization

    Executive Summary: KU-60019 is a potent, selective inhibitor of ataxia telangiectasia mutated (ATM) kinase with an IC50 of 6.3 nM, outperforming earlier analogues like KU-55933 in selectivity and efficacy (APExBIO). It is used to radiosensitize glioma cells by specifically inhibiting ATM-mediated DNA damage responses, resulting in reduced cell survival and migration (Chen et al., 2020). The compound demonstrates 270-fold and 1600-fold selectivity over DNA-PK and ATR, respectively. KU-60019’s mechanism includes suppression of prosurvival signaling (AKT, ERK phosphorylation) and is validated in both p53 wild-type and mutant glioma models. Solubility, storage, and workflow protocols are well-defined for reproducibility in research settings (APExBIO).

    Biological Rationale

    ATM kinase is a central regulator of the DNA damage response (DDR), orchestrating the detection and repair of double-strand DNA breaks. Loss-of-function mutations in ATM cause Ataxia Telangiectasia, a syndrome marked by neurodegeneration and cancer predisposition (Chen et al., 2020). In many tumors, including glioblastoma and high grade serous ovarian cancer, ATM is wild-type and overactive, supporting tumor cell survival and therapy resistance. Therefore, small-molecule ATM kinase inhibitors like KU-60019 offer a rational strategy to sensitize cancer cells to DNA-damaging therapies and disrupt prosurvival signaling. This approach is especially relevant for tumors with functional homologous recombination (HR), which are otherwise resistant to PARP inhibitors and standard chemoradiotherapy (Chen et al., 2020).

    Mechanism of Action of KU-60019

    KU-60019 is a next-generation ATM kinase inhibitor, structurally optimized from KU-55933 for improved potency and selectivity. It competitively inhibits the ATP-binding site of ATM, blocking autophosphorylation and downstream DDR signaling (APExBIO). The compound exhibits an IC50 of 6.3 nM for ATM, 270-fold selectivity over DNA-dependent protein kinase (DNA-PK), and 1600-fold selectivity over ataxia telangiectasia and Rad3-related (ATR) kinase. Inhibition of ATM by KU-60019 impairs DNA double-strand break repair, prevents phosphorylation of AKT and ERK, and suppresses prosurvival and migratory pathways in glioma cells. Radiosensitizing effects are observed in both p53 wild-type (U87) and mutant (U1242) glioma models. Additionally, ATM inhibition by KU-60019 induces metabolic vulnerabilities, suggesting a broader impact on tumor cell homeostasis (KU-55933.com).

    Evidence & Benchmarks

    • KU-60019 inhibits ATM kinase with an IC50 of 6.3 nM, demonstrating 270-fold selectivity versus DNA-PK and 1600-fold versus ATR (APExBIO).
    • Radiosensitization by KU-60019 is observed in both p53 wild-type (U87) and mutant (U1242) human glioma cell lines, leading to impaired repair of irradiation-induced DNA double-strand breaks (Chen et al., 2020).
    • In vitro, KU-60019 suppresses phosphorylation of AKT and ERK, key components of prosurvival signaling, following radiation (nepafenac.com).
    • Cell migration and invasion are inhibited by KU-60019 in a dose-dependent manner in glioma models (chelerythrinechloride.com).
    • In vivo, intratumoral administration of KU-60019 at 10 μM via osmotic pump for 14 days, combined with radiation, significantly suppresses glioma growth (APExBIO).
    • ATM inhibition is synergistic with metabolic drugs (e.g., fenofibrate) in HR-proficient cancer models, inducing cellular senescence and metabolic stress (Chen et al., 2020).

    This article extends prior summaries such as this overview on KU-60019 radiosensitization by detailing selectivity data and metabolic vulnerabilities, and clarifies workflow integration beyond foundational mechanisms. For a focus on metabolic adaptation, see this related article, which this piece updates by integrating new combinatorial strategies.

    Applications, Limits & Misconceptions

    KU-60019 is widely used in preclinical cancer research, particularly for:

    • Radiosensitization of glioma and other solid tumor models with wild-type or mutant p53.
    • Dissecting DNA damage response pathways and prosurvival signaling in vitro.
    • Testing combinatorial therapies, notably with radiation, PARP inhibitors, or metabolic agents.
    • Elucidating mechanisms of cell migration, invasion, and metabolic reprogramming.

    However, ATM inhibition by KU-60019 is generally not effective as monotherapy in most cancer models (Chen et al., 2020). It is not a clinically approved drug and is intended strictly for laboratory research. For further mechanistic and translational perspectives, see this article on metabolic vulnerabilities, which this dossier updates with current selectivity and workflow data.

    Common Pitfalls or Misconceptions

    • KU-60019 is not selective for all PI3K-like kinases; its selectivity is specific to ATM over DNA-PK and ATR.
    • It is ineffective as monotherapy for most advanced tumors; maximal efficacy requires combination with DNA-damaging agents or metabolic modulators (Chen et al., 2020).
    • KU-60019 is not water-soluble; it requires DMSO or ethanol for dissolution.
    • This reagent is not for diagnostic or clinical therapeutic use; strictly for preclinical research (APExBIO).
    • ATM inhibition may not radiosensitize tumor types with defective ATM or HR pathways.

    Workflow Integration & Parameters

    For in vitro studies, KU-60019 is typically used at 3 μM for durations of 1 to 5 days, with solvent systems such as DMSO (≥27.4 mg/mL) or ethanol (≥51.2 mg/mL); it is insoluble in water. In vivo, delivery protocols include intratumoral dosing at 10 μM via osmotic pumps over 14 days. Stock solutions should be stored at or below -20°C and used promptly to prevent degradation. APExBIO (SKU: A8336) provides detailed product handling protocols (KU-60019 product page). For troubleshooting and advanced workflows, see this workflow article, which this dossier complements by specifying up-to-date selectivity and combinatorial data.

    Conclusion & Outlook

    KU-60019 is a rigorously characterized, highly selective ATM kinase inhibitor that serves as a robust research tool for radiosensitizing glioma and uncovering metabolic vulnerabilities in cancer models. Its documented selectivity, reproducible workflow parameters, and validated combinatorial potential make it a preferred choice for DDR pathway studies in preclinical research. The compound is provided by APExBIO for research use only. Ongoing studies are expected to further clarify its utility in combination therapies, particularly in HR-proficient and therapy-resistant tumor contexts (Chen et al., 2020).