Randomized, Controlled, Dose-Range Study of Ro 25-8315 Given Before and After a High-Dose Combination Chemotherapy Regimen in Patients With Metastatic or Recurrent Breast Cancer Patients

PURPOSE: To evaluate the safety, pharmacokinetics, and efficacy of three different dose levels of pegylated granulocyte colony-stimulating factor (Ro 25-8315) on progenitor cell mobilization and hematologic recovery in cancer patients. PATIENTS AND METHODS: Breast cancer patients (n = 36) were randomly assigned to receive before (part I) and after (part II) chemotherapy either a single-dose injection of Ro 25-8315 (20 μg/kg, n = 9; 60 μg/kg, n = 9; 100 μg/kg, n = 10) or a standard daily dose of filgrastim (part I, 10 μg/kg/d; part II, 5 μg/kg/d) (control group, n = 8). RESULTS: Overall, Ro 25-8315 was well tolerated. In part I, more progenitor cell mobilization was observed with Ro 25-8315 100 μg/kg. The peak of circulating CD34 + cells was obtained at day +5 in the four groups, and the absolute neutrophil count (ANC) returned to less than 20 × 10 9 /L by day +15. In part II, high levels of circulating CD34 + cells (> 20 cells/μL) were obtained in all four groups. The chemotherapy-induced neutropenia (< 1 × 10 9 /L) was similar in the four groups. Ro 25-8315 100 μg/kg was more effective than filgrastim in reducing the number of patients with an ANC less than 0.5 × 10 9 /L on day +12 after chemotherapy. CONCLUSION: A single injection of Ro 25-8315 100 μg/kg might be the optimal dose for steady-state peripheral-blood progenitor cell mobilization. A single injection of 20, 60, or 100 μg/kg could be as efficient as daily administration of filgrastim to correct chemotherapy-induced cytopenia. The optimal dose of Ro 25-8315 should be determined according to the planned chemotherapy regimen.