Bcl-2 is one of several proteins that positively and negatively regulate cell death. Bcl-2 inhibits programmed cell death and is consistently over-expressed in B-CLL patients. This over-expression of bcl-2 that occurs in many forms of leukemia contributes to the relentless accumulation of lymphocytes that fail to die and to their resistance to chemotherapy.

In the laboratory, Antisense drugs such as Genasense™ have demonstrated an ability to inhibit bcl-2 expression in CLL, thereby reducing resistance to programmed cell death and to chemotherapy. Antisense treatment is currently being tested in clinical trials, followed by state-of-the art anticancer therapy in an effort to improve patient outcome.