Granulocyte-macrophage colony-stimulating factor mitigates the neutropenia of combined interferon alfa and zidovudine treatment of acquired immune deficiency syndrome-associated Kaposi's sarcoma.

The combined use of zidovudine (ZDV) and interferon (IFN) alfa-2a has been shown to have antiretroviral and antitumor potential benefit in the treatment of acquired immune deficiency syndrome (AIDS)-associated Kaposi's sarcoma (KS). However, the clinical use of this combination is frequently complicated by the overlapping myelotoxicity of these agents. We report here the results of a phase I/II study in which granulocyte-macrophage colony-stimulating factor (GM-CSF) was used for those KS patients who became neutropenic while receiving ZDV (1,200 mg/d) and IFN (9 x 10(6) U/d). Nineteen of 29 patients (66%) developed an absolute neutrophil count (ANC) of less than 1,000 cells per cubic millimeter and were begun on GM-CSF. All experienced a prompt increase in the ANC. Those patients receiving GM-CSF/ZDV/IFN alfa-2a had an improved end of study ANC when compared with the ZDV/IFN alfa-2a group, but did not have an increased rate of tumor response, end of study CD4 cell count, or improvement in any other hematologic variable. The use of GM-CSF was not associated with increased toxicity and, in particular, was not associated with a change in serum human immunodeficiency virus (HIV) p24 antigen. Tumor response was noted in 50% of the assessable patients (33% overall) despite "high-risk" characteristics in 80%. Of the responding patients, seven were on GM-CSF and might have otherwise required an alteration in ZDV/IFN alfa-2a dose level. Further study of GM-CSF as an alternate to dose modification of this (ZDV/IFN alfa-2a) and other combination therapies for AIDS patients is warranted.