Safety of outpatient stem cell mobilization with low- or intermediate-dose cyclophosphamide in newly diagnosed multiple myeloma patients

OBJECTIVES Autologous stem cell transplantation is the gold standard for eligible newly diagnosed multiple myeloma patients. Patients are usually hospitalized for administration of mobilization chemotherapy. We aimed to assess safety and efficacy of mobilization therapy with low-dose (2 g/m2 ) and intermediate-dose (3-4 g/m2 ) cyclophosphamide administered as outpatient. METHODS A total of 176 consecutive newly diagnosed transplant-eligible myeloma patients receiving outpatient mobilization were retrospectively evaluated. Induction therapy was mainly performed with new drugs (91%). RESULTS Chemotherapy was very well tolerated with 16.6% of patients having all-grade adverse events (AEs) and only 1.2% having severe AEs. The most frequently reported AEs were nausea and vomiting grade 1-2 (6.8%). Only 5.7% of patients required hospitalization for AEs. Stem cell collection was successful in 93.1% of patients, with a median CD34+ harvest of 8.7 × 106 /kg. Target for 2 autologous stem cell transplantation (at least 6 CD34+  × 106 /kg) was reached by 76.3% of patients. Administration of plerixafor on demand was necessary in 12.1% of patients. CONCLUSIONS Outpatient mobilization with low- and intermediate-dose cyclophosphamide appears an efficient and safe procedure, with minimal and manageable AEs and low rate of hospitalization.