The trials also showed that ISF35 stimulates the immune system to act against CLL cells and sensitize leukemic cells to subsequent treatment. Repeat infusions of ISF35 administered as a single agent to subjects with CLL resulted in durable reductions in circulating and lymph-node bound leukemic cells. Furthermore, CLL patients with 17p deletion responded to standard courses of FCR after receiving ISF35 and achieved durable remissions.