This is a retrospective observational cohort database analysis. The study will review retrospectively the records of patients undergoing a first peripheral blood stem cell mobilization for multiple myeloma in the databases from approximately 15 hospitals which are part of the IFM collaborative group. Patient records will be divided into two groups of 50 patients minimum, maximum 100 patients or up to the number of patient records that could be extracted. The first group of patients will have received plerixafor plus G-CSF without the administration of chemotherapy as a mobilization strategy and a second group of patients will have received cyclophosphamide plus G-CSF as a mobilization strategy.

All consecutive patients with complete set of data (and who underwent apheresis) treated between 2009 and 2013 with G-CSF and plerixafor and all consecutive patients with complete data (and who underwent apheresis) treated between 2009 and 2013 with G-CSF and cyclophosphamide will be included.

All data that will be analyzed will be extracted from the selected IFM institutions which are located in France.

Inclusion Criteria:

• Hematology patients diagnosed with Multiple Myeloma who are candidates for autologous hematopoietic stem cell transplantation (ASCT) upfront.
• Age > 18 years
• Undergone prior successful peripheral blood stem cell mobilization with Cyclophosphamid or Plerixafor

Exclusion Criteria:

• Age < 18 years;
• Primary diagnosis other than Multiple Myeloma

The first group of patients will have received plerixafor plus G-CSF without the administration of chemotherapy as a mobilization strategy and a second group of patients will have received cyclophosphamide plus G-CSF as a mobilization strategy.

All consecutive patients with complete set of data (and who underwent apheresis) treated between 2009 and 2013 with G-CSF and plerixafor and all consecutive patients with complete data (and who underwent apheresis) treated between 2009 and 2013 with G-CSF and cyclophosphamide will be included.