Chronic lymphocytic leukemic patients, resistant to chemotherapy

In four reported studies, intensive chemotherapy of various types was administered to large groups of patients with chronic lymphocytic leukemia (CLL) in advanced stages. About half of the patients were non-responders to the therapy. Resistance to therapy was also found in 12% of patients with early CLL and in 19 CLL patients who had in vitro radioresistant lymphocytes before therapy. The findings support the hypothesis of the heterogeneity of CLL patients and suggest the need for new methods for therapy of non-responders and for in vitro or in vivo tests to diagnose non-responders.