Pyrimethamine for the Treatment of Relapsed Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

In this research study we will start by looking for the highest dose of pyrimethamine that can be given safely to CLL patients without severe or unmanageable side effects. This dose will then be used for a larger Phase II study to assess the efficacy of pyrimethamine for the treatment of CLL/SLL. Pyrimethamine is an antibiotic that is used for the treatment of certain infections. Previous research studies have shown that pyrimethamine may target a protein in tumor cells, called STAT3, which may be important for the growth of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) cells. Pyrimethamine can kill CLL/SLL cells in the laboratory, and we are therefore undertaking this study to assess whether pyrimethamine will result in clinical benefit or tumor responses in CLL in patients.