Study participants will undergo tumor imaging with the radioactive drug Tc-99m Sestamibi. This drug accumulates in tumor cells and is eliminated from them in much the same way that some cancer drugs are eliminated from cells. The drug is injected into a vein and a series of pictures are taken with a gamma camera. After this baseline scan, patients will receive a dose of XR9576 and undergo a second scan 24 hours later. The scan will show whether XR9576 affects the accumulation and elimination of Sestamibi in tumor cells. This procedure may provide a way to monitor cancers for evidence of chemotherapy resistance and show if XR9576 can improve the effectiveness of therapy.