Selective Inhibition of BRCA2-Deficient Mammary Tumor Cell Growth by AZD2281 and Cisplatin

TLDR

The study evaluates the efficacy of the PARP‑1 inhibitor AZD2281 on BRCA2‑deficient mouse mammary tumor cells and its potential synergy with cisplatin. Researchers generated and characterized clonal BRCA2‑deficient and BRCA2‑proficient mouse mammary tumor cell lines, tested their sensitivity to standard cytotoxic agents and AZD2281, and performed in‑vitro combination assays with cisplatin. The BRCA2‑deficient cell lines were highly sensitive to AZD2281, showing the strongest differential growth inhibition and synergistic cytotoxicity with cisplatin, whereas BRCA2‑proficient controls were resistant, underscoring AZD2281’s potential as a targeted therapy for BRCA‑mutated breast cancer.

Abstract

Abstract Purpose: To assess efficacy of the novel, selective poly(ADP-ribose) polymerase-1 (PARP-1) inhibitor AZD2281 against newly established BRCA2-deficient mouse mammary tumor cell lines and to determine potential synergy between AZD2281 and cisplatin. Experimental Design: We established and thoroughly characterized a panel of clonal cell lines from independent BRCA2-deficient mouse mammary tumors and BRCA2-proficient control tumors. Subsequently, we assessed sensitivity of these lines to conventional cytotoxic drugs and the novel PARP inhibitor AZD2281. Finally, in vitro combination studies were done to investigate interaction between AZD2281 and cisplatin. Results: Genetic, transcriptional, and functional analyses confirmed the successful isolation of BRCA2-deficient and BRCA2-proficient mouse mammary tumor cell lines. Treatment of these cell lines with 11 different anticancer drugs or with γ-irradiation showed that AZD2281, a novel and specific PARP inhibitor, caused the strongest differential growth inhibition of BRCA2-deficient versus BRCA2-proficient mammary tumor cells. Finally, drug combination studies showed synergistic cytotoxicity of AZD2281 and cisplatin against BRCA2-deficient cells but not against BRCA2-proficient control cells. Conclusion: We have successfully established the first set of BRCA2-deficient mammary tumor cell lines, which form an important addition to the existing preclinical models for BRCA-mutated breast cancer. The exquisite sensitivity of these cells to the PARP inhibitor AZD2281, alone or in combination with cisplatin, provides strong support for AZD2281 as a novel targeted therapeutic against BRCA-deficient cancers.