A new experimental drug called PCI-32765 selectively kills the cancer cells that cause chronic lymphocytic leukemia (CLL), according to a new study. The study shows that the agent selectively kills the malignant B lymphocytes that cause CLL. This is important, the researchers say, because current CLL therapies kill T lymphocytes along with the cancerous B lymphocytes. A drug that kills malignant B lymphocytes and spares T lymphocytes could dramatically improve outcomes for CLL patients.