Effect of Chemotherapy with Alkylating Agents on the Yield of CD34+ Cells in Patients with Multiple Myeloma. Results of the Spanish Myeloma Group (GEM) Study

Background And Objectives: Although alkylating agents are clearly beneficial in multiple myeloma (MM), their deleterious effect on bone marrow hematopoietic progenitor cells usually precludes their use as front-line therapy in patients scheduled to undergo autologous stem cell transplantation (ASCT). We analyzed the impact of first-line chemotherapy with alkylating agents on stem cell collection in MM patients.

Design And Methods: Seven hundred and eighty-nine patients included in the Spanish multicenter protocol GEM-2000 underwent mobilization therapy after four courses of alternating VBMCP/VBAD chemotherapy.

Results: The mobilization regimens consisted of standard or high-dose granulocyte colony-stimulating factor (G-CSF) in 551 (70%) patients, and chemotherapy and G-CSF in 206 (26%) patients. The CD34+ cell yield was lower than 4x10(6)/kg in 388 patients (49%), and equal or greater than 4x10(6)/kg in 401 patients (51%). Multivariate analysis indicated that advanced age (p<0.0001) and longer interval between diagnosis and mobilization (p=0.012) were the two variables associated with a lower CD34+ cell yield. Significant differences in CD34+ cell yield were not observed between the mobilization regimens. Of the 789 patients included in the protocol, 726 (92%) underwent the planned ASCT, whereas 25 (3%) patients did not because of the low number of CD34+ cells collected. Following ASCT, 0.5x10(9) neutrophils/L could be recovered after 11 days (median time; range, 5-71 days) and 20x10(9) platelets/L could be recovered after 12 days (median time; range, 6-69 days).

Interpretation And Conclusions: A short-course of therapy with alkylating agents according to the GEM-2000 protocol was associated with an appropriate CD34+ cell collection, and allowed the planned ASCT to be performed in the majority of MM patients.