Study Evaluating Impact of IL-7 on CD4 Lymphopenia, Risks of Severe Haematological Toxicity and Tumor Progression in Metastatic Breast Cancer Patients

Placebo before the 1st (D0, D7, D14)and during the 3rd CT cycle (D57, D64, D71)

patients will receive an induction cycle of CYT107 (10µg/kg/week subcutaneously for 3 weeks) before the 1st CT cycle (D0, D7, D14) and the placebo during the 3rd CT cycle (D57, D64, D71)

patients will receive the placebo before the 1st CT cycle (D0, D7, D14) and a delayed treatment with CYT107 (10µg/kg/week subcutaneously for 3 weeks) during the 3rd CT cycle (D57, D64, D71)

patients will receive an induction cycle of CYT107 (10µg/kg/week subcutaneously for 3 weeks) before the 1st CT cycle (D0, D7, D14) and a maintenance cycle of IL-7 (10µg/kg/week subcutaneously for 3 weeks) during the 3rd CT cycle (D57, D64, D71)