ZNF365/ZFP365 biomarker predictive of anti-cancer response

A method of inhibiting the proliferation of breast cancer cells having less than a diploid copy number of ZNF365 in a human subject, the method comprising administering an inhibitor of PARP-1 and/or PARP-2 to a human subject determined to have less than a diploid copy number of ZNF365 n breast cancer cells, wherein the determination is achieved by:

• a) measuring the copy number of ZNF365 in a test sample comprising breast cancer cells;
• and
• b) determining that a less than diploid copy number of ZNF365 is present in the breast cancer cells in the test sample.