[Effect of bortezomib on the efficiency of hematopoietic stem cell mobilization in patients with multiple myeloma].

Aim: To study the results of mobilizing and collecting autologous hematopoietic stem cells (HSC) in patients with multiple myeloma (MM) receiving bortezomib as part of induction therapy regimens.

Materials And Methods: In June 2001 to April 2010, the Department of Bone Marrow Transplantation, Hematology Research Center, Ministry of Health and Social Development of Russia, mobilized autologous HSC in 93 patients with MM, by using cyclophosphan (CF) and granulocyte colony-stimulating factor. The analysis covered 73 patients who received VAD and/or bortezomib-containing courses as induction therapy. Group 1 comprised 30 patients whose induction therapy was performed as 3-4 courses of VAD. Group 2 included 19 patients who had 2-4 courses of PAD or 4-8 courses of bortezomib + dexamethasone in addition to 1-3 courses of VAD. Group 3 combined 24 patients who used 6-8 courses of bortezomib + dexamethasone or 3-4 courses of PAD + 4-6 courses of bortezomib + dexamethasone.

Results: In Group 1 patients whose induction therapy was performed as 3-4 courses of VAD, baseline peripheral blood CD34+ cell counts were 3,575 +/- 631 in 1 ml, which was statistically significantly higher than those in Group 2 patients who had bortezomib-containing courses in addition to VAD courses. In Group 2 patients, premobilization CD34+ cell counts were 2,164 +/- 516 in 1 ml. The lowest blood CD34+ cell levels (1,586 -/+ 405 in 1 ml) were observed in Group 3 patients in whom bortezomib was used as first-line therapy. In Group 1 patients, the maximum peripheral blood counts of CD34+ cells were 322,287 +/- 73,994 in 1 ml, which was significantly higher than their maximum level in Groups 2 (231,624 +/- 39,708 in 1 ml) and 3 (161,007 +/- 44,266 in 1 ml) patients. The efficiency of mobilization proved to be high; more than 4.0.10(6)/kg of CD34+ cells were collected in all the patients with bortezomib-containing induction therapy, which allowed two autologous HSC transplantations to be carried out.

Conclusion: Adding bortezomib at the stage of induction has no significant impact on the results of HSC mobilization and collection. By taking into account the possibility of achieving a complete or very good partial response in 40-60% of the patients using the bortezomib-containing regimens as first-line therapy, bortezomib should be considered as an essential drug as part of induction therapy.