The present invention relates to a method of treating cancer selected from the group of cancers consisting of prostate cancer, renal cancer, breast cancer, ovarian cancer, CNS cancer, melanoma, lung cancer, and bladder cancer. This method involves administering to a patient in need of such treatment a therapeutically effective amount of a betulinol derivative compound of Formula (I). Also disclosed are conjugated and immunoconjugated derivatives of the compound of Formula (I) as well as methods of making and using them.