Phase II Trial of GM-CSF in Advanced Prostate Cancer

Abstract

Objectives. Prostate-specific antigen onlydisease progression following definitivetherapy is significant therapeutic dilemma. The benefit of hormonal therapy remainsunproven and is associated with significanttoxicity, more pronounced with chronic use. Biochemical progression following hormonaltherapy has no standard treatment. Newapproaches to the management of this subsetof patients are needed. A previous studyin advanced prostate cancer demonstratedbiologic activity of granulocytemacrophage-colony stimulating factor. Thepurpose of this study was to evaluate theactivity of granulocyte macrophage-colonystimulating factor in a less heavilypretreated population. Materials and methods. Sixteenpatients with advanced prostate cancer, 7hormonally naïve, and 9 androgenindependent, were treated with granulocytemacrophage-colony stimulating factoradministered subcutaneously at 250 μgthree times a week for up to 6 months. Prostate-specific antigen measurements wereobtained every 2 weeks. Results. No patient achieved anobjective response. Six patientsdemonstrated a 10–15% decline in theirbaseline prostate-specific antigen whichwas maintained during the entire treatmentperiod. Five of these 6 patientsdemonstrated a rise in theirprostate-specific antigen following studycompletion. Therapy was well tolerated,with only 1 grade 3 event which was nottreatment-related. Conclusions. Granulocytemacrophage-colony stimulating factordemonstrates modest biologic evidence ofactivity in prostate cancer as manifestedby prostate-specific antigen response. Further investigation of the mechanism ofactivity and additional clinical evaluationof this agent seems warranted.