Researchers from the M.D. Anderson Cancer Center in Houston, the University of California at San Diego, the Princess Margaret Hospital in Toronto and Georgetown University have reported that the anti-apoptotic molecule, GX15-070, is safe and biologically active for the treatment of refractory chronic lymphoid leukemia (CLL).

GX15-070 is a small molecule inhibitor of Bcl-2 proteins that has been in Phase I testing for a little over one year. The current Phase I/II study enrolled 25 patients with CLL refractory to fludarabine, alkylators and to Rituxan and 40 percent had received Campath (lemtuzumab). The main toxicities of GX15-070 were somnolence, euphoria, ataxia and oxygen desaturation. Mean lymphocyte reduction of 29 percent was seen in 18 patients. There was also an associated correction of anemia and thrombocytopenia. These researchers documented the biologic effects of GX15-070 on apoptosis.