Carboplatin is an antitumor agent, with an increased DNA-binding activity in the presence of nucleophiles and human breast cancer MCF-7 cell cytoplasmic extracts. Carboplatin is less cytotoxic to human ovarian cells such as A2780, SKOV3, IGROV1 and HX62 than 17-AAG, with IC50s of 6.177, 12.442, 2.233 and 116.068 μM, respectively. Moreover, Carboplatin does not affect HSP90 or change the activity of 17-AAG to inhibit HSP90. Carboplatin reduces the viability of Brca1 (IC50, 3.4 μM) and Brca2 cells (IC50, 1.9 μM). Carboplatin (25 μM) combined with ABT-888 also shows an apoptotic effect in BRCA1 cells.