Granulocyte‐macrophage colony‐stimulating factor: Preliminary observations on the influences of dose, schedule, and route of administration in patients receiving cyclophosphamide and carboplatin

Background. In an attempt to learn how best to administer granulocyte‐macrophage colony‐stimulating factor (GMCSF), the authors performed a Phase I study of this agent. They were interested in the influences of dose, schedule, and route of administration on the effects of GMCSF in patients receiving standardized 1‐day regimens of cyclophosphamide (CYCLO) and carboplatin (CBDCA). Methods. Between June 1988 and March 1991,57 patients with advanced cancer received GMCSF in association with CYCLO 1 g/m² plus CBDCA 225‐700 mg/mz. After the first dose escalation to 300 mg/m² of CBDCA, patients who had previously received chemotherapy or radiation therapy were excluded. GMCSF was administered in three different doses, five different schedules, and by two different routes. Altogether, 17 different treatment groups were observed. In addition, 24‐hour GMCSF serum concentration curves were charted in four patients. Results. Using four sequential groups of three patients each who had received myelosuppressive treatment, treatment with CYCLO 1 g/m² and CBDCA 225 mg/m², the apparent superiority of daily subcutaneous injection over 30‐minute daily IV infusion of GMCSF was demonstrated graphically. Subsequently, the authors observed apparent enhancement of GMCSF effects beyond those produced by the initially selected 20‐day basic 10 μg/kg daily SC regimen beginning 2 days after chemotherapy. When administered SC every 12 hours for 14 days beginning the day after chemotherapy, GMCSF appeared to ameliorate the severity of both leukopenia and thrombocytopenia. These effects permitted escalation of the CBDCA dose to 700 mg/m² (with 1 g/m² of CYCLO) before cytotoxic tolerance limits were reached. Graphic small group comparisons suggest that GMCSF given SC in doses of 5 pg/kg twice daily may produce comparable leukocyte and platelet support after chemotherapy with lower toxicity than occurs from higher doses. Prechemotherapy priming with GMCSF twice daily for an additional 4 days (days −6 to −3) seems to ameliorate post‐chemotherapy cytopenias further but at the cose of some increased risk of GMCSF toxicity. Although most of the toxic effects of moderate‐dose GMCSF are controlled by antihistamines and ibuprofen, oral glucocorticoids (e.g., prednisone, 10 mg twice daily during the second week of GMCSF administration) may be required in patients with serositis, pulmonary infiltrates, or severe skin eruptions. Conclusions. Our observations suggest that GMCSF should be administered SC in doses of approximately 5 μg/kg every 12 hours for 10‐14 days beginning the day after chemotherapy. Prechemotherapy priming with these same doses for four additional days (days −6 to −3) may additionally ameliorate postchemotherapy leukopenia and thrombocytopenia, but with increased risk of toxicity.