Infectious and immunosuppressive complications of purine analog therapy.

PURPOSE: The purine analogs fludarabine, cladribine, and pentostatin are active agents in the treatment of indolent lymphoid malignancies. This report reviews the pattern, severity, and consequences of the immunosuppression and myelotoxicity associated with these agents. METHODS: The literature was searched using MedLine and Cancerline, as well as the bibliographies of published reports through the winter of 1994 and 1995. RESULTS: Each of these drugs induces profound lymphocytopenia. A marked decrease in CD4 cells may persist for several years, while other mononuclear-cell populations recover more rapidly. The spectrum of infections encountered in these patients appears to be altered to include a wide range of opportunistic organisms. Factors that increase the risk of these infections include concurrent corticosteroids, extensive prior therapy, particularly with another purine analog, and poor response to purine analog treatment. CONCLUSION: Because of the frequency of life-threatening infections with unusual pathogens that may occur in patients treated with purine analogs, aggressive and early diagnostic evaluation and appropriate use of myeloid growth factors may be necessary to ensure appropriate antimicrobial therapy.