Tumor lysis syndrome after treatment of chronic lymphocytic leukemia with cladribine

To the Editor: In the November 18 issue of the Journal, Dann et al.¹ reported a case of tumor lysis syndrome after treatment with 2-chlorodeoxyadenosine (cladribine) in a patient with refractory chronic lymphocytic leukemia. We would like to report another case of tumor lysis syndrome resulting from treatment with 2-chlorodeoxyadenosine. A 59-year-old man presented to the Mayo Clinic for a second opinion concerning therapy for his chronic myelogenous leukemia in chronic phase, which had been diagnosed approximately 18 months earlier. The patient could not tolerate hydroxyurea, had dose-limiting thrombocytopenia when treated with busulfan, and did not want to try interferon.