AZD2461: Novel PARP Inhibitor for Breast Cancer Research

Executive Summary: AZD2461 is a selective PARP inhibitor with an IC50 of 5 nM for PARP-1, demonstrating cytotoxicity in MCF-7 and SKBR-3 breast cancer cells through G2 phase cell cycle arrest (Schwartz 2022). In vivo, AZD2461 reduces PAR levels in KB1P tumor-bearing mice, with activity lasting several hours post-administration. The compound displays reduced affinity for P-glycoprotein, mitigating drug resistance seen with other PARP inhibitors (APExBIO). AZD2461 is well tolerated in long-term studies and significantly prolongs relapse-free survival in preclinical tumor models. The product is supplied as a solid, with high solubility in DMSO and ethanol, and recommended storage at -20°C.

Biological Rationale

Poly (ADP-ribose) polymerases (PARPs) are nuclear enzymes that detect and signal DNA single-strand breaks, facilitating base excision repair. PARP-1 is the principal isoform involved in DNA repair and programmed cell death. Inhibition of PARP activity leads to accumulation of DNA damage, synthetic lethality in cells deficient in homologous recombination (e.g., BRCA1/2 mutations), and selective cytotoxicity in cancer cells reliant on PARP-mediated repair pathways (Schwartz 2022). Targeting PARP-1 is a validated approach in breast and ovarian cancer research, particularly for overcoming resistance to traditional chemotherapeutics.

Mechanism of Action of AZD2461

AZD2461 inhibits PARP-1 enzymatic activity with a reported IC50 of 5 nM (cell-free assay, 25°C, Tris-HCl buffer, pH 8.0) (APExBIO). In cell-based studies, AZD2461 induces G2 phase cell cycle arrest and reduces the S phase population in MCF-7 and SKBR-3 breast cancer lines. This results in a concentration- and time-dependent reduction in viable cell numbers over 48–72 hours at 5–50 μM. The compound’s structure (C22H22FN3O3) confers lower affinity for P-glycoprotein (Pgp), decreasing efflux and enhancing activity in drug-resistant cancer cells. In vivo, AZD2461 maintains PARP inhibition for several hours, with PAR levels returning to baseline within 24 hours post-dose in KB1P tumor mouse models.

Evidence & Benchmarks

• AZD2461 demonstrates an IC50 of 5 nM for PARP-1 in biochemical assays (cell-free, 25°C, Tris-HCl, pH 8.0) (APExBIO).
• Reduces MCF-7 and SKBR-3 breast cancer cell viability in a dose- and time-dependent manner (5–50 μM, 48–72 h, RPMI-1640, 10% FBS) (Schwartz 2022).
• Induces G2 phase cell cycle arrest and decreases S phase fraction, as measured by flow cytometry in treated breast cancer cells (Schwartz 2022).
• In KB1P tumor-bearing mice, a single AZD2461 dose inhibits PARP activity for several hours, with recovery to baseline by 24 h (in vivo pharmacodynamics) (APExBIO).
• AZD2461 shows reduced affinity for Pgp transporters compared to olaparib, supporting efficacy in Pgp-overexpressing cancer cell contexts (Schwartz 2022).
• Long-term administration is well tolerated in mice and significantly extends relapse-free survival (median duration, preclinical BRCA1-mutated tumor models) (Schwartz 2022).

For advanced mechanistic insights and translational strategies, see this article, which details cell cycle and DNA repair pathway modulation. The present dossier extends these findings by providing quantitative benchmarks and practical workflow parameters.

Applications, Limits & Misconceptions

AZD2461 is optimized for breast cancer research, particularly in BRCA1/2-mutated and PARP-dependent models. Its lower Pgp affinity makes it suitable for studies on drug resistance mechanisms. The product is not intended for clinical use. Performance is context-dependent; efficacy in non-breast cancer models or in cells with proficient homologous recombination may be limited. For a broader exploration of DNA repair modulation and resistance, see this article, which AZD2461’s dossier extends by focusing on robust, quantitative in vitro and in vivo data.

Common Pitfalls or Misconceptions

• AZD2461 is not water-soluble; improper solvent selection may impair activity. Use DMSO (≥16.35 mg/mL) or ethanol (≥45.2 mg/mL with sonication) for stock solutions (APExBIO).
• Not all cancer cell lines respond equally; activity is highest in PARP-dependent or BRCA-deficient backgrounds.
• Pgp-mediated resistance is reduced but not eliminated; extremely high Pgp expression may still impact efficacy.
• The compound is for research use only; not for use in humans or clinical trials.
• Cell culture and dosing parameters must be optimized; standard ranges are 5–50 μM for 48–72 h.

For troubleshooting and advanced experimental workflows, see this guide, which our dossier updates with recent benchmarking data.

Workflow Integration & Parameters

AZD2461 (A4164) is supplied as a solid by APExBIO (product page). Dissolve in DMSO or ethanol (with ultrasonic assistance for higher concentrations). Store at -20°C. Prepare fresh solutions for each use; avoid long-term storage in solution. Recommended concentrations are 5–50 μM, with 48–72 h incubation for cell-based assays. For in vivo models, dosing and schedule should be adapted based on tumor type, mouse strain, and pharmacokinetic parameters. Ensure parallel controls for solvent and vehicle effects. PARP activity can be measured by PAR ELISA or immunoblotting for PARylated proteins. Cell proliferation and viability can be assessed using standard assays (e.g., MTT, CellTiter-Glo).

Conclusion & Outlook

AZD2461 is a validated tool for studying PARP-1 inhibition, DNA repair pathway modulation, and drug resistance in breast cancer research. Its favorable solubility, reduced Pgp affinity, and robust preclinical efficacy make it suitable for advanced translational workflows. APExBIO provides comprehensive product support and quality assurance for AZD2461. Future research may expand its applications in other PARP-dependent malignancies and refine dosing strategies for combination therapies. For strategic insights on next-generation PARP inhibition, see this article; the current dossier supplies detailed parameters and benchmarking to guide experimental design.