Although there is evidence from tests on laboratory animals that DMF can decrease the number of CLL cells, we do not know if this will work in humans with CLL. This drug will be given to humans with CLL for the first time in this study. Therefore, the goal of this study is to see if DMF is safe and tolerable in study participants. Participants will be evaluated to find out what effects (good and bad) DMF has on the body and see how long the drug stays in the body.