A New Class of Selective ATM Inhibitors as Combination Partners of DNA Double-Strand Break Inducing Cancer Therapies

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Radiotherapy and DNA-damaging agents are key cancer treatments.
• Double-strand breaks (DSB) are lethal if unrepaired.
• Ataxia telangiectasia-mutated (ATM) kinase is crucial for DSB repair and cell-cycle checkpoints.

Purpose of the Study:

• To describe the pharmacological activities of novel ATM inhibitors M3541 and M4076.
• To evaluate their potential to enhance cancer therapy.
• To explore their combination potential with other therapeutics.

Main Methods:

• Biochemical assays to determine ATM kinase inhibition potency and selectivity.
• In vitro studies in cancer cells to assess DSB repair and cell growth inhibition.
• In vivo studies using human tumor xenografts in mice treated with inhibitors and radiotherapy.
• Combination studies with PARP and topoisomerase I inhibitors.

Main Results:

• M3541 and M4076 demonstrated sub-nanomolar ATM kinase inhibition with high selectivity.
• In cancer cells, inhibitors suppressed DSB repair and clonogenic growth, potentiating radiation effects.
• Oral administration in mice significantly enhanced antitumor activity, leading to complete tumor regressions.
• Efficacy correlated with ATM inhibition and downstream target modulation.
• Strong combination potential was observed with PARP and topoisomerase I inhibitors.

Conclusions:

• M3541 and M4076 are potent and selective ATM inhibitors with significant therapeutic potential.
• These inhibitors enhance radiotherapy by impairing DSB repair and checkpoint control.
• M4076 is currently in clinical investigation, highlighting its promising clinical translation.