Multiple myeloma (MM) is a hematologic disease characterized by the accumulation of malignant plasma cells in the bone marrow. Triplet induction regimens incorporating novel agents have shown to improve response and prolong progression free survival (PFS) and even overall survival (OS) [1, 2]. Autologous hematopoietic stem cell transplantation (aHSCT), performed in first remission or at relapse, is standard of care for younger fit patients [3, 4, 5]. Successful mobilization and collection of peripheral blood stem cells (PBSC) are required before aHSCT. A target dose of 2 × 106 PBSC per kg body weight is considered a minimum for timely hematopoietic reconstitution, although a higher dose, 3 to 5 × 106 PBSC per kg body weight, is thought to be optimal for earlier engraftment [6, 7, 8]. A second aHSCT can be performed within 6 months (tandem transplant) or following progression. Therefore, an attempt to collect PBSC for at least two aHSCT should be considered. Mobilization with chemotherapy (e.g., intermediate doses of cyclophosphamide) and granulocyte-colony stimulating factor (G-CSF) is standard in most transplant centers and provides higher stem cell yields in fewer apheresis procedures at the cost of increased toxicity and less predictable onset date of apheresis in comparison with G-CSF mobilization only [9, 10]. On the other hand, G-CSF only mobilization fails to achieve the target doses of PBSC in 5–30% of patients [8, 11, 12, 13].
Known factors affecting stem cell mobilization are age, advanced disease status, extensive treatment, thrombocytopenia, prior exposure to irradiation, and alkylating agents . Novel induction regimens using proteasome inhibitors (PI) and especially immunomodulatory drugs (IMIDs) might impact the ability to mobilize and harvest stem cells [14, 15]. In case of lenalidomide, a second generation IMID, there are data supporting its adverse impact on mobilization after prolonged treatment. However, there is no clear evidence of bortezomib impact on stem cell harvest [8, 10]. In the IFM 2005/01 trial comparing bortezomib and dexamethasone (VD) with vincristin, adriamycin, and dexamethasone (VAD), a trend to lower stem cells yields was observed in patients receiving bortezomib [12, 16]. G-CSF alone mobilization was used in this trial. On the contrary, in the HOVON-65/GMMG-HD4 trial comparing bortezomib, adriamycin, dexamethasone (PAD) with VAD, all patients successfully collected stem cells for aHSCT and no impact of bortezomib on collection was observed [17, 18]. Of note, chemomobilization with cyclophosphamide and adriamycin was used as the mobilization procedure. There are limited and contradictory data on the impact of thalidomide on PBSC mobilization and collection, but the impact appears to be small [15, 19, 20]. In addition, the use of G-CSF mobilization alone is a predisposing factor for mobilization failure [11, 14, 15].
Triplet induction regimens incorporating bortezomib, thalidomide, and dexamethasone (VTD) or bortezomib, cyclophosphamide and dexamethasone (VCD) are current standards of care. The available data show a benefit of VTD compared with VCD but at the expense of a higher prevalence of polyneuropathy [4, 5, 21]. There are limited data available for the two regimens on stem cell mobilization efficacy, especially considering the potential negative impact of thalidomide. Owing to feasibility and safety reasons, we use G-CSF only mobilization in MM patients at our institution, with chemomobilization and plerixafor reserved for mobilization failures. We undertook a retrospective analysis of our registry data regarding the impact of VTD and VCD induction on stem cell mobilization with G-CSF alone.
Patients and methods
We retrospectively analyzed data from our national registry from the January 1, 2014 to December 31, 2017. All patients gave written consent for registry data collection. A total of 72 consecutive patients with newly diagnosed MM who received first-line induction treatment with VTD or VCD and underwent stem cell mobilization with G-CSF were included. Patients receiving additional treatment or patients with relapsed/refractory disease were not included. VTD treatment consisted of 3 week cycles of bortezomib 1.3 mg/m2 subcutaneous on days 1, 4, 8, and 11, thalidomide 100 mg daily and dexamethasone 40 mg on days 1–4 of the first cycle and once per week thereafter. VCD treatment incorporated bortezomib and dexamethasone in the same schedule as for VTD plus cyclophosphamide 500 mg/m2 on day 1, 8, and 15. Following 3–4 cycles of induction treatment, stem cells were mobilized using subcutaneous filgrastim 10 mcg/kg rounded to the nearest available dose for 5 consecutive days. Circulating CD34+ cells were determined in peripheral blood on day 5, and apheresis was initiated at a CD34+ cell count > 20/μL. Patients with a circulating CD34+ cell count < 20/μL received additional filgrastim on day 6. Cobe spectra apheresis system was used for stem cell collection.
Mobilization failure was defined as circulating CD34+ cell count < 20/μL up to 6 days after mobilization with G-CSF or patients with a yield < 2.0 × 106 CD34+ cells/kg in three apheresis procedures . The average number of CD34+ cells was the arithmetic mean of CD34+ cell counts on all collection days. The number of procedures was the number of collection procedures per patient that were not mobilization failures. The number of collected cells was the total number of collected CD34+ cells per kg body weight of the patient. The dose for a single transplant of 2 × 106 CD34+ cells/kg and 3 × 106 CD34+ cells/kg was considered the minimum and optimal dose, respectively. For two hematopoietic stem cell transplantations (HSCTs), the double dose of cells was required.
The association between the treatment and the defined variables was analyzed using the chi-square test or Student’s t-test for independent samples as required. All two-sided p values < 0.05 were considered statistically significant. Statistical analysis was carried out using SPSS v23.
Twenty-eight and 44 patients received induction treatment with VCD and VTD, respectively. Both cohorts were balanced in terms of age, gender, and other disease characteristics (Tab. I). After data on the higher efficacy were available in 2016, VTD was the preferred regimen, which explains the greater number of patients in this group. No difference was observed in the number of induction cycles before mobilization between the two groups. Three patients received local radiation therapy to the spine and one received local radiation to the pelvis. One of the patients in the VTD group, who received radiation to the spine, failed mobilization with G-CSF alone. The mobilization failure rates were 7% and 9% for VCD and VTD, respectively. All patients failing mobilization with G-CSF later successfully collected PBSC with chemomobilization or plerixafor. The average number of CD34+ cells in peripheral blood on the day of collection was 60.7 × 106/L and 41.1 × 106/L, and the number of apheresis procedures was 3 and 2 for VCD and VTD, respectively. The total number of collected stem cells for the VCD and VTD cohort was 7.0 × 106/kg and 6.7 × 106/kg recipient body weight. In total, 86% of patients receiving VCD induction and 75% of patients receiving VTD induction, collected enough stem cell for at least 2 aHSCTs. The median time to neutrophil engraftment was 13 days in both cohorts. No statistical difference was observed in the number of apheresis procedures, collected cells, the ability to collect a minimum and optimal dose for two aHSCTs, and the time to neutrophil engraftment between the two groups (Tab. II).
Patient demographics and baseline characteristics
|Age, years N (Range)||58 (29–69)||58 (34–70)|
|Male N (%)||18 (64)||30 (68)|
|MM stage, ISS N (%)|
|1||7 (25)||13 (30)|
|2||8 (29)||17 (39)|
|3||12 (43)||10 (23)|
|Diag. N (%)|
|Light Chain only||6 (21)||7 (16)|
|IgA||10 (36)||8 (18)|
|IgG||12 (43)||26 (59)|
|Induction cycles N (Median, Range)||3 (3–4)||3 (2–4)|
|RT before mobilization N (%)||1 (4)||3 (7)|
|Elev. Creat. at mobilization N (%)||2 (7)||1 (2)|
|Response after induction|
|≥ VGPR||14 (50 %)||28 (64 %)|
|PR||14 (50 %)||16 (36 %)|
Stem cell mobilization and harvest results
|Mobilization failure N (%)||2 (7)||4 (9)||p = 0.771|
|Average CD34+ cells in blood on day of collection (Mean x 106/L, Range)||60.7 (8.4 – 431)||41.1 (6.45–132.3)||p = 0.139|
|Number of procedures (Median, Range)||3 (0–4)||2 (0–4)||p = 0.434|
|Collected cells (Mean x 106/kg, Range)||7.0 (0 – 12.5)||6.7 (0–13.9)||p = 0.710|
|Minimum for two aHSCTs N (%)||24 (86)||33 (75)||p = 0.275|
|Optimal for two aHSCTs N (%)||18 (64)||27 (61)||p = 0.803|
|Time to Neu. engraftment (Median, Range)||13 (10–15)||13 (11–15)|
Triplet induction therapy incorporating novel drugs is standard of treatment for patients with MM [1, 2]. Two commonly used combinations are VTD and VCD [4, 5, 21]. In our center, we use G-CSF only mobilization for patients with MM at first attempt. In patients failing to collect a sufficient number of PBSC, we switch to chemomobilization or the use of plerixafor. There are no published data on the difference between VTD and VCD regarding the effectiveness of G-CSF only mobilization. Owing to unresolved concerns that thalidomide in combination with other agents might impact the efficacy of G-CSF only mobilization, we decided to retrospectively analyze our patient registry and present the data.
The mobilization failure rates for VTD and VCD in our patient group were similar to some reports in the literature [13, 23]. Since G-CSF only mobilization and age > 60 are important predictors for mobilization failure, the low failure rates in our cohort of patients with a median age of 58 years and using G-CSF only mobilization are unexpectedly low . This is likely due to reducing the number of induction cycles to a median of 4 before proceeding to mobilization and not using melphalan as part of the induction regimen, thereby reducing the toxicity to the bone marrow. Approximately 30% of MM patients receive radiation therapy during induction for palliation of bone pain or spinal cord compression . Radiation therapy negatively influences PBSC mobilization and harvest and can even negatively impact overall and PFS [25, 26]. Restraint in radiotherapy in patients eligible for aHSCT treated with novel agents, and novel approaches in radiotherapy have probably decreased the number of mobilization failures in our patient cohort. In our patient cohort, only one patient received radiation therapy prior to successful G-CSF only mobilization (data not shown). All patients failing first mobilization later successfully collected a sufficient number of PBSC with chemomobilization or plerixafor.
The average number of CD34+ cells in peripheral blood on collection day was higher in the VCD cohort than in the VTD cohort; however, the difference was not statistically significant. The lower number of CD34+ stem cells can be attributed to the toxic effects of thalidomide on hematopoietic stem cells . Studies about mice have shown that intermittent dosing of cyclophosphamide has a stem cell sparing effect . Therefore, cyclophosphamide during induction has probably no impact on stem cell mobilization and harvesting. The lack of statistical difference in the number of CD34+ cells in peripheral blood between VTD and VCD can be attributed to the relatively small number of subjects in the study. However, the number of collection procedures and collected stem cell was the same between the cohorts.
Most patients in both groups collected sufficient numbers of PBSC for two aHSCTs. Still, the number of patients achieving an optimal dose for two transplants was only around 60%. Because a higher dose of PBSC is preferred for earlier engraftment with possible lower morbidity, higher numbers of PBSC should be collected [6, 7, 8]. The relatively low number of patients collecting the optimal dose of stem cells for two aHSCTs (6 × 106 CD34+ cells/kg) is a weakness of G-CSF only mobilization, and our results are in line with other published results [12, 16, 29]. The addition of plerixafor to G-CSF improves G-CSF mobilization and can increase the number of patients archiving the optimal dose of PBSC for two aHSCTs .
To conclude, this study provides further data on VTD safety with respect to stem cell mobilization in comparison with VCD. The addition of thalidomide to bortezomib and dexamethasone showed no negative impact on stem cell mobilization and harvest in patients undergoing G-CSF only mobilization in our patient group.
Conflict of interest
MSkerget has received speaker honoraria from Amgen, Celgene and Teva Pharmaceutical. BS has received speaker honoraria from Amgen. MSever has received speaker honoraria from Amgen, Celgene and Teva Pharmaceutical.
The work described in this article has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans; EU Directive 2010/63/EU for animal experiments; Uniform requirements for manuscripts submitted to biomedical journals.
Rosiñol L, Oriol A, Teruel AI, et al. Superiority of bortezomib, thalidomide, and dexamethasone (VTD) as induction pretransplantation therapy in multiple myeloma: a randomized phase 3 PETHEMA/GEM study. Blood 2012;120:1589–96.
Durie BGM, Hoering A, Abidi MH, et al. Bortezomib with lenalidomide and dexamethasone versus lenalidomide and dexamethasone alone in patients with newly diagnosed myeloma without intent for immediate autologous stem-cell transplant (SWOG S0777): a randomised, open-label, phase 3 trial. Lancet 2017;389:519–27.
Roussel M, Avet-Loiseau H, Moreau P, et al. Frontline therapy with bortezomib, lenalidomide, and dexamethasone (VRD) induction followed by autologous stem cell transplantation, VRD consolidation and lenalidomide maintenance in newly diagnosed multiple myeloma patients: primary results of the IFM 2008 phase II study. Blood 2010;116:624.
Moreau P, Hulin C, Macro M, et al. VTD is superior to VCD prior to intensive therapy in multiple myeloma: results of the prospective IFM2013-04 trial. Blood 2016;127:2569–74.
Leiba M, Kedmi M, Duek A, et al. Bortezomib-cyclophosphamide-dexamethasone (VCD) versus bortezomib-thalidomide-dexamethasone (VTD) - based regimens as induction therapies in newly diagnosed transplant eligible patients with multiple myeloma: a meta-analysis. Br J Haematol 2014;166:702–10.
Bensinger W, Appelbaum F, Rowley S, et al. Factors that influence collection and engraftment of autologous peripheral-blood stem cells. J Clin Oncol 1995;13:2547–55.
Giralt S, Stadtmauer EA, Harousseau JL, et al. International myeloma working group (IMWG) consensus statement and guidelines regarding the current status of stem cell collection and high-dose therapy for multiple myeloma and the role of plerixafor (AMD 3100). Leukemia 2009;23:1904–12.
Sevindik OG, Korkmaz S, Altuntas F. Current status of art mobilization in Myeloma. Transfus Apher Sci 2017;56:850–3.
Gertz MA, Kumar SK, Lacy MQ, et al. Comparison of high-dose CY and growth factor with growth factor alone for mobilization of stem cells for transplantation in patients with multiple myeloma. Bone Marrow Transplant 2009;43:619–25.
Wallis WD, Qazilbash MH. Peripheral blood stem cell mobilization in multiple myeloma: Growth factors or chemotherapy? World J Transplant 2017;7:250–9.
Popat U, Saliba R, Thandi R, et al. Impairment of filgrastim-induced stem cell mobilization after prior lenalidomide in patients with multiple myeloma. Biol Blood Marrow Transplant 2009;15:718–23
Harousseau JL, Mathiot C, Attal M, et al. Bortezomib/dexamethasone versus VAD as induction prior to autologous stem cell transplantion (ASCT) in previously untreated multiple myeloma (MM): Updated data from IFM 2005/01 trial. J Clin Oncol 2008;26:8505.
Pusic I, Jiang SY, Landua S, et al. Impact of mobilization and remobilization strategies on achieving sufficient stem cell yields for autologous transplantation. Biol Blood Marrow Transplant 2008;14:1045–56.
Kumar S, Dispenzieri A, Lacy MQ, et al. Impact of lenalidomide therapy on stem cell mobilization and engraftment post-peripheral blood stem cell transplantation in patients with newly diagnosed myeloma. Leukemia 2007;21:2035–42.
Pozotrigo M, Adel N, Landau H, et al. Factors impacting stem cell mobilization failure rate and efficiency in multiple myeloma in the era of novel therapies: experience at Memorial Sloan Kettering Cancer Center. Bone Marrow Transplant 2013;48:1033–9.
Moreau P, Hulin C, Marit G, et al. Stem cell collection in patients with de novo multiple myeloma treated with the combination of bortezomib and dexamethasone before autologous stem cell transplantation according to IFM 2005–01 trial. Leukemia 2010;24:1233–5.
Sonneveld P, Schmidt-Wolf I, van der Holt B, et al. HOVON-65/GMMG-HD4 randomized phase III trial comparing bortezomib, doxorubicin, dexamethasone (PAD) vs VAD followed by high-dose melphalan (HDM) and maintenance with bortezomib or thalidomide in patients with newly diagnosed multiple myeloma (MM). Blood 2010;116:40.
Sonneveld P, Salwender H-J, Van Der Holt B, et al. Bortezomib induction and maintenance in patients with newly diagnosed multiple myeloma: long-term follow-up of the HOVON-65/GMMG-HD4 trial. Blood 2015;126:27.
Auner HW, Mazzarella L, Cook L, et al. High rate of stem cell mobilization failure after thalidomide and oral cyclophosphamide induction therapy for multiple myeloma. Bone Marrow Transplant 2011;46:364–7.
Breitkreutz I, Lokhorst HM, Raab MS, et al. Thalidomide in newly diagnosed multiple myeloma: influence of thalidomide treatment on peripheral blood stem cell collection yield. Leukemia 2007;21:1294–9.
Cavo M, Pantani L, Pezzi A, et al. Bortezomib-thalidomidedexamethasone (VTD) is superior to bortezomib-cyclophosphamidedexamethasone (VCD) as induction therapy prior to autologous stem cell transplantation in multiple myeloma. Leukemia 2015;29:2429–31.
Olivieri A, Marchetti M, Lemoli R et all. Proposed definition of ‘poor mobilizer’ in lymphoma and multiple myeloma: an analytic hierarchy process by ad hoc working group Gruppo Italiano Trapianto di Midollo Osseo. Bone Marrow Transplant 2012;47:342–51.
Kröger N, Zeller W, Hassan HT, et al. Successful mobilization of peripheral blood stem cells in heavily pretreated myeloma patients with G-CSF alone. Ann Hematol 1998;76:257–62.
Hosing C, Saliba RM, Ahlawat S, et al. Poor hematopoietic stem cell mobilizers: a single institution study of incidence and risk factors in patients with recurrent or relapsed lymphoma. Am J Hematol 2009;84:335–7.
Talamo G, Dimaio C, Abbi KKS, et al. Current role of radiation therapy for multiple myeloma. Front Oncol 2015;5:40.
Sauer S, Fischer AM, Fraenzle A, et al. Impact of radiation therapy on stem cell harvest in multiple myeloma. Blood 2014;124:5822.
Tachikawa S, Nishimura T, Nakauchi H, Ohnuma K. Thalidomide induces apoptosis in undifferentiated human induced pluripotent stem cells. Vitr Cell Dev Biol Anim 2017;53:841–51.
Gardner R V, McKinnon E, Astle CM. Analysis of the stem cell sparing properties of cyclophosphamide. Eur J Haematol 2001;67:14–22.
DiPersio JF, Stadtmauer EA, Nademanee A, et al. Plerixafor and G-CSF versus placebo and G-CSF to mobilize hematopoietic stem cells for autologous stem cell transplantation in patients with multiple myeloma. Blood 2009;113:5720–6.