Prostate-specific antigen kinetics as a measure of the biologic effect of granulocyte-macrophage colony-stimulating factor in patients with serologic progression of prostate cancer

Purpose : To determine the biologic effect of granulocytemacrophage colony-stimulating factor (sangramostim, GMCSF; Immunex Corporation, Seattle, WA) as measured by prostate-specific antigen (PSA) kinetics in patients with serologic progression of prostate cancer after definitive local therapy. Patients and Methods: Patients with prostate cancer who had undergone previous definitive surgical or radiation therapy with nonmetastatic, recurrent disease as manifested by a rising PSA between 0.4 ng/mL and 6.0 ng/mL were enrolled on this phase 11 trial. Patients received 250 mug/m(2)/day of subcutaneous GM-CSF on days 1 through 14 of a 28-day cycle. PSA was measured at day 1 of each cycle. Results: Thirty patients with serologic progression of prostate cancer were treated. The median pretreatment PSA was 2.9 ng/mL. Of the 29 evaluable patients, three patients (110%; 95% confidence interval, 2% to 27%) achieved a 50% reduction in PSA. For the patients (n = 26) in whom the on-treatment PSA doubling time could be calculated, the median PSA doubling time increased from 8.4 months to 15 months (P = .001), and the median slope of the PSA versus time curve decreased with treatment (P = .004). Therapy was well tolerated by all patients, with an average treatment duration of 16.5 cycles (range, 5 to 33). Conclusion: GM-CSF has a biologic effect in patients with serologic progression of prostate cancer after definitive local therapy, as measured by PSA declines and modulation of PSA kinetics. (C) 2003 by American Society of Clinical Oncology.