| abstract |
The present invention provides compounds having formula (II): n nwherein X, n, R 1 –R 12 are defined herein, or a pharmaceutically acceptable salt thereof. The invention also provides a pharmaceutical composition comprising a therapeutically effective amount of a compound represented by formula (II) and a pharmaceutically acceptable carrier or excipient. The invention further provides a method for treating cancer comprising administering to a patient in need of such treatment a therapeutically effective amount of a compound represented by formula (II). |