Using Gamma-H2ax And H2ax Quantitative Elisa For Monitoring Dna Damage Induced By Chemotherapeutic Agents And Irradiation Exposure.

2559 Background: Gamma-H2AX (γH2AX) is a biomarker for DNA double-strand breaks and programmed cell death, but variable relative amounts of H2AX in different samples causes ambiguity in the meaning of the γH2AX level unless it is related to total H2AX levels. We developed a 96-well plate-based ELISA for quantifying γH2AX and H2AX levels in crude extracts of tumor cells, CTCs and biopsy tissues and are validating it for applications in irradiation exposure monitoring and in pharmacodynamic evaluation of anti-cancer agents. Methods: The ELISA was used to analyze extracts of several NCI60 tumor cell lines that had been exposed to a variety of agents, including ionizing radiation, inhibitors of Top-1 (CPT, SN-38, Topotecan), PARP (ABT-888, AZD-2281, MK-4827) and ATR (VE-821, VE-822, AZD-6738, Compound 45, NU-6027), and their combinations. Combination regimens of CPT-11 with PARP inhibitors (ABT-888, AZD-2281, MK-4827) were further evaluated in vivo in the A375 xenograft mouse model. Patient samples obtained f...