Difficulties with fungal infections in acute myelogenous leukemia patients: immune enhancement strategies.

Invasive fungal infection in severely immunosuppressed patients with acute myelogenous leukemia (AML) remains a serious challenge because (a) of the higher rates of non-drug susceptible fungal sinopulmonary disease; (b) despite advances in diagnostic fungal assays, the correct identification of causative organism(s) is difficult, and antifungal drug susceptibility data are seldom available during clinical decision making; and (c) the increasing frequencies of zygomycosis, scedosporiosis, and highly virulent Candida tropicalis infection have undermined the gains attributed to effective anti-Aspergillus drug therapy. Recombinant cytokines, such as recombinant human (rh)GM-CSF and interferon (IFN)-gamma, have been explored to augment host antifungal immune responses. These cytokines promote activation and recruitment of granulocyte and mononuclear phagocytic effector cells. Prophylaxis with rhGM-CSF was associated with significantly fewer life-threatening and serious (grade > or =3) infections, especially in older patients undergoing treatment for AML. The limited experience with rhGM-CSF for the treatment of invasive fungal infections in combination with antifungal drug(s) was associated with a favorable outcome, and in contrast to Escherichia coli-derived rhGM-CSF, the new preparation (sargramostim) was well tolerated and rarely associated with serious systemic toxicities. Similarly, IFN-gamma has been successfully used in patients with antimicrobial drug-refractory and/or disseminated fungal infection. Most patients tolerate the T-helper type 1 protagonist cytokine without serious adverse events. In difficult-to-treat fungal infections, the addition of cytokines appears to improve outcome and may be considered early in severely immunosuppressed patients with AML.