Randomized comparison of granulocyte colony-stimulating factor versus granulocyte-macrophage colony-stimulating factor plus intensive chemotherapy for peripheral blood stem cell mobilization and autologous transplantation in multiple myeloma

Homing and Engraftment of Hematopoietic Stem Cells Following Transplantation: A Pre-Clinical Perspective

Hematopoietic stem-cell (HSC) transplantation (HSCT) is used to treat various hematologic disorders. Use of genetically modified mouse models of hematopoietic cell transplantation has been critical in our fundamental understanding of HSC biology and in developing approaches for human patients. Pre-clinical studies in animal models provide insight into the journey of transplanted HSCs from infusion to engraftment in bone-marrow (BM) niches. Various signaling molecules and growth factors secreted by HSCs and the niche microenvironment play critical roles in homing and engraftment of the transplanted cells. The sustained equilibrium of these chemical and biologic factors ensures that engrafted HSCs generate healthy and durable hematopoiesis. Transplanted healthy HSCs compete with residual host cells to repopulate stem-cell niches in the marrow. Stem-cell niches, in particular, can be altered by the effects of previous treatments, aging, and the paracrine effects of leukemic cells, which create inhospitable bone-marrow niches that are unfavorable for healthy hematopoiesis. More work to understand how stem-cell niches can be restored to favor normal hematopoiesis may be key to reducing leukemic relapses following transplant.

Prospective Comparative Study of Etoposide plus G-CSF versus G-CSF Alone, Followed by Risk-Adapted Plerixafor for Peripheral Blood Stem Cell Mobilization in Patients with Newly Diagnosed Multiple Myeloma: CAtholic REsearch Network for Multiple Myeloma Study (CAREMM-2001)

To explore the optimal mobilization for multiple myeloma (MM) patients, we conducted a prospective trial comparing single-dose etoposide (375 mg/m2 for one day) plus G-CSF versus G-CSF alone, followed by risk-adapted plerixafor. After randomization, 27 patients in the etoposide group and 29 patients in the G-CSF alone group received mobilizations. Six (22.2%) patients in the etoposide group and 15 (51.7%) patients in the G-CSF alone group received plerixafor based on a peripheral blood CD34+ cell count of < 15/mm3 (p = 0.045). The median count of CD34+ cells collected was significantly higher in the etoposide group (9.5 × 106/kg vs. 7.9 × 106/kg; p = 0.018), but the optimal collection rate (CD34+ cells ≥ 6 × 106/kg) was not significantly different between the two groups (96.3% vs. 82.8%; p = 0.195). The rate of CD34+ cells collected of ≥ 8.0 × 106/kg was significantly higher in the etoposide group (77.8% vs. 44.8%; p = 0.025). Although the rates of grade II-IV thrombocytopenia (63.0% vs. 31.0%; p = 0.031) and grade I-IV nausea (14.8% vs. 0%; p = 0.048) were significantly higher in the etoposide group, the rates of adverse events were low in both groups, with no neutropenic fever or septic shock. Thus, both single-dose etoposide plus G-CSF and G-CSF alone with risk-adapted plerixafor were effective and safe, but the former may be the better option for patients who are expected to receive two or more transplantations.

A comparison of peripheral blood stem cell collection outcomes for multiple myeloma; mobilization matters in the era of IMiD induction

Collection of peripheral blood stem cells (PBSCs) for autologous stem cell transplant (ASCT) requires mobilization from the bone marrow. There is variation in mobilization choice; during the COVID-19 pandemic BSBMT&CT guidelines recommended using granulocyte-colony stimulating factor (G-CSF) alone to minimize the use of chemotherapy. We report on the impact of mobilization regimen on stem cell collection, and whether IMiD-containing induction therapy impacts on mobilization and consequently transplant engraftment times for 83 patients undergoing ASCT at Leeds Teaching Hospitals. Cyclophosphamide plus G-CSF (cyclo-G) mobilization yielded more CD34+ cells (8.94 vs. 4.88 ×106/kg, p = < 0.0001) over fewer days (1.6 vs. 2.4 days, p = 0.007), and required fewer doses of salvage Plerixafor than G-CSF only (13.6% vs. 35%, p = 0.0407). IMiD-containing induction impaired all of these factors. CD34+ doses > 8×106/kg were more frequent with Cyclo-G (62% vs. 11%, p = 0.0001), including for those receiving IMiD 1st line induction (50% vs. 13.3%, p = 0.0381). Note that 92.6% of those receiving IMiD-free inductions were mobilized with Cyclo-G. The novel agents used in modern induction regimens (e.g Daratumumab) have been shown to impair yields, increasing the importance of optimizing mobilization regimens in the first instance. Furthermore, as cellular therapies become established in the management of multiple myeloma emerging data highlights the potential benefits of stem cell top up in the management of the haematological toxicities of these therapies. Our findings support re-adoption of Cyclo-G as the gold standard for mobilization to optimize PBSC harvesting and ensure sufficient cells for subsequent ASCTs.

Stem cell mobilization in multiple myeloma: challenges, strategies, and current developments

Among hematological malignancies, multiple myeloma (MM) represents the leading indication of autologous hematopoietic stem cell transplantation (auto-HCT). Auto-HCT is predominantly performed with peripheral blood stem cells (PBSCs), and the mobilization and collection of PBSCs are essential steps for auto-HCT. Despite the improved success of conventional methods with the incorporation of novel agents for PBSC mobilization in MM, mobilization failure is still a concern. The current review comprehensively summarizes various mobilization strategies for mobilizing PBSCs in MM patients and the evolution of these strategies over time. Moreover, existing evidence substantiates that the mobilization regimen used may be an important determinant of graft content. However, limited data are available on the effects of graft characteristics in patient outcomes other than hematopoietic engraftment. In this review, we discussed the effect of graft characteristics on clinical outcomes, mobilization failure, factors predictive of poor mobilization, and potential mobilization regimens for such patients.

Efficacy of hematopoietic stem cell mobilization regimens in patients with hematological malignancies: a systematic review and network meta-analysis of randomized controlled trials

Background

Efficient mobilization of hematopoietic stem cells (HSCs) from bone marrow niche into circulation is the key to successful collection and transplantation in patients with hematological malignancies. The efficacy of various HSCs mobilization regimens has been widely investigated, but the results are inconsistent.

Methods

We performed comprehensive databases searching for eligible randomized controlled trials (RCTs) that comparing the efficacy of HSCs mobilization regimens in patients with hematological malignancies. Bayesian network meta-analyses were performed with WinBUGS. Standard dose of granulocyte colony-stimulating factor (G-CSF SD) was chosen as the common comparator. Estimates of relative treatment effects for other regimens were reported as mean differences (MD) or odds ratio (OR) with associated 95% credibility interval (95% CrI). The surface under the cumulative ranking curve (SUCRA) were obtained to present rank probabilities of all included regimens.

Results

Databases searching and study selection identified 44 eligible RCTs, of which the mobilization results are summarized. Then we compared the efficacy of mobilization regimens separately for patients with multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) by including 13 eligible trials for network meta-analysis, involving 638 patients with MM and 592 patients with NHL. For patients with MM, data are pooled from 8 trials for 6 regimens, including G-CSF in standard dose (SD) or reduced dose (RD) combined with cyclophosphamide (CY), intermediate-dose cytarabine (ID-AraC) or plerixafor. The results show that compared with G-CSF SD alone, 3 regimens including ID-AraC + G-CSF SD (MD 14.29, 95% CrI 9.99–18.53; SUCRA 1.00), G-CSF SD + Plerixafor SD (MD 4.15, 95% CrI 2.92–5.39; SUCRA 0.80), and CY + G-CSF RD (MD 1.18, 95% CrI 0.29–2.07; SUCRA 0.60) are associated with significantly increased total number of collected CD34⁺ cells (× 10⁶/kg), among which ID-AraC + G-CSF SD ranked first with a probability of being best regimen of 100%. Moreover, ID-AraC + G-CSF SD and G-CSF SD + Plerixafor SD are associated with significantly higher successful rate of achieving optimal target (collecting ≥ 4–6 × 10⁶ CD34⁺ cells/kg). For patients with NHL, data are pooled from 5 trials for 4 regimens, the results show that compared with G-CSF SD alone, G-CSF SD + Plerixafor SD (MD 3.62, 95% CrI 2.86–4.38; SUCRA 0.81) and G-CSF SD plus the new CXC chemokine receptor-4 (CXCR-4) antagonist YF-H-2015005 (MD 3.43, 95% CrI 2.51–4.35; SUCRA 0.69) are associated with significantly higher number of total CD34⁺ cells collected. These 2 regimens are also associated with significantly higher successful rate of achieving optimal target. There are no significant differences in rate of achieving optimal target between G-CSF SD + Plerixafor SD and G-CSF + YF-H-2015005.

Conclusions

In conclusion, ID-AraC plus G-CSF is associated with the highest probability of being best mobilization regimen in patients with MM. For patients with NHL, G-CSF in combination with plerixafor or YF-H-2015005 showed similar improvements in HSCs mobilization efficacy. The relative effects of other chemotherapy-based mobilization regimens still require to be determined with further investigations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02802-6.

Is absence of CD56 a predictive factor for peripheral blood stem cell mobilization failure in patients with multiple myeloma?

BACKGROUND

CD56 is believed to play a major role in MM pathogenesis with a 70% to 80% expression rate in malignant plasma cells at the time of diagnosis. Our objective in this study was to investigate the relationship between the characteristics of CD56 expression in bone marrow aspiration material at the time of diagnosis and the success of stem cell mobilization in patients diagnosed with MM.

METHODS

This monocenter study included 94 patients who were diagnosed with MM and had a stem cell mobilization procedure for autologous hematopoietic stem cell transplantation. The primary endpoint of the study was to compare the mobilization success between the groups with and without CD56 expression. The secondary endpoint was to identify other factors affecting mobilization failure outside CD56.

RESULTS

At the time of diagnosis, 49 (52.1%) patients had CD56 expression and 45 (47.9%) did not. Mobilization failed in 11 (11.7%) patients. Age, gender, ISS stage and the number of premobilization treatment regimens were not found predictive of mobilization failure. CD56 negativity was 42.2% in the group that had mobilization success and 90.9% in the group that had mobilization failure (P = .001).

CONCLUSIONS

The fact that CD56 residing on the membrane enables interaction between bone marrow cells and ECM and functions as a signal molecule increases sensitivity to the chemotherapy and G-CSF that are used for mobilization. We found that absence of CD56 can be used as a predictive factor for mobilization failure at the time of diagnosis.

Inferior prognosis in poor mobilizing myeloma patients

INTRODUCTION

Induction treatment followed by autologous stem cell transplantation (ASCT) has been accepted as the standard treatment for multiple myeloma (MM) patients. Granulocyte colony stimulating agent (G-CSF), chemotherapy or agents likes plerixafor are being used for the mobilization of stem cells from bone marrow. In this study, we evaluated the impact of the mobilization methods on the outcome of MM patients after ASCT.

METHOD

The data of 205 MM patients who underwent ASCT at our center between December 2009 and January 2019 were retrospectively analyzed. Patients were divided into 2 groups as good mobilizers (patients who were mobilized with G-CSF alone) and poor mobilizers (patients who were failed to mobilize with G-CSF alone and mobilized with G-CSF + cylophosphomide or G-CSF + plerixafor).

RESULTS

The median progression free survival (PFS) was 18.27 ± 3.22 months in good mobilizers and 14.22 ± 3.7 months in poor mobilizers. In G-CSF + cyclophosphamide method median PFS was 15.4 ± 4.9 months wheras it was only 4 months in G-CSF + plerixafor method. We did not find a statistically significant difference between good and poor mobilizers regarding median PFS (p: 0.342). The median overall survival (OS) was found 34.48 ± 4.2 months in good mobilizers and 15.13 ± 5.78 months in poor mobilizers. In G-CSF + cyclophosphamide method median OS was 17 ± 14.01 months wheras it was 10.66 ± 7.68 months in G-CSF + plerixafor method. We found a statistically significant difference between good and poor mobilizers regarding median OS (p: 0.007*).

CONCLUSION

Our study shows that difficulty in stem cell mobilization is correlated with worse outcome.

Targeting the Spleen as an Alternative Site for Hematopoiesis

Bone marrow is the main site for hematopoiesis in adults. It acts as a niche for hematopoietic stem cells (HSCs) and contains non-hematopoietic cells that contribute to stem cell dormancy, quiescence, self-renewal, and differentiation. HSC also exist in resting spleen of several species, although their contribution to hematopoiesis under steady-state conditions is unknown. The spleen can however undergo extramedullary hematopoiesis (EMH) triggered by physiological stress or disease. With the loss of bone marrow niches in aging and disease, the spleen as an alternative tissue site for hematopoiesis is an important consideration for future therapy, particularly during HSC transplantation. In terms of harnessing the spleen as a site for hematopoiesis, here the remarkable regenerative capacity of the spleen is considered with a view to forming additional or ectopic spleen tissue through cell engraftment. Studies in mice indicate the potential for such grafts to support the influx of hematopoietic cells leading to the development of normal spleen architecture. An important goal will be the formation of functional ectopic spleen tissue as an aid to hematopoietic recovery following clinical treatments that impact bone marrow. For example, expansion or replacement of niches could be considered where myeloablation ahead of HSC transplantation compromises treatment outcomes.

Peripheral blood stem cell mobilization in multiple myeloma: Growth factors or chemotherapy?

High-dose therapy followed by autologous hematopoietic stem cell (HSC) transplant is considered standard of care for eligible patients with multiple myeloma. The optimal collection strategy should be effective in procuring sufficient HSC while maintaining a low toxicity profile. Currently available mobilization strategies include growth factors alone, growth factors in combination with chemotherapy, or growth factors in combination with chemokine receptor antagonists; however, the optimal strategy has yet to be elucidated. Herein, we review the risks and benefits of each approach.

Autologous Stem Cell Mobilization and Collection

Peripheral blood stem cell collection is an effective approach to obtain a hematopoietic graft for stem cell transplantation. Developing hematopoietic stem/progenitor cell (HSPC) mobilization methods and collection algorithms have improved efficiency, clinical outcomes, and cost effectiveness. Differences in mobilization mechanisms may change the HSPC content harvested and result in different engraftment kinetics and complications. Patient-specific factors can affect mobilization. Incorporating these factors in collection algorithms and improving assays for evaluating mobilization further extend the ability to obtain sufficient HSPCs for hematopoietic repopulation. Technological advance and innovations in leukapheresis have improved collection efficiency and reduced adverse effects.

How to manage poor mobilizers for high dose chemotherapy and autologous stem cell transplantation?

Today, peripheral blood stem cells are the preferred source of stem cells over bone marrow. Therefore, mobilization plays a crutial role in successful autologous stem cell transplantation. Poor mobilization is generally defined as failure to achieve the target level of at least 2×10⁶ CD34⁺ cells/kg body weight. There are several strategies to overcome poor mobilization: 1) Larger volume Leukapheresis (LVL) 2) Re-mobilization 3) Plerixafor 4) CM+Plerixafor (P)+G-CSF and 5) Bone Marrow Harvest. In this review, the definitions of successful and poor mobilization are discussed. Management strategies for poor mobilization are defined. The recent research on new agents are included.

Bendamustine, etoposide and dexamethasone to mobilize peripheral blood hematopoietic stem cells for autologous transplantation in patients with multiple myeloma

Chemotherapeutic agents without cross-resistance to prior therapies may enhance PBSC collection and improve patient outcomes by exacting a more potent direct antitumor effect before autologous stem cell transplant. Bendamustine has broad clinical activity in transplantable lymphoid malignancies, but concern remains over the potential adverse impact of this combined alkylator-nucleoside analog on stem cell mobilization. We performed a prospective, nonrandomized phase II study including 34 patients with multiple myeloma (MM) (n=34; International Staging System (ISS) stages I (35%), II (29%) and III (24%); not scored (13%)) to evaluate bendamustine's efficacy and safety as a stem cell mobilizing agent. Patients received bendamustine (120 mg/m2 IV days 1, 2), etoposide (200 mg/m2 IV days 1-3) and dexamethasone (40 mg PO days 1- 4) (bendamustine, etoposide and dexamethasone (BED)) followed by filgrastim (10 μg/kg/day SC; through collection). All patients (100%) successfully yielded stem cells (median of 21.60 × 106/kg of body weight; range 9.24-55.5 × 106/kg), and 88% required a single apheresis. Six nonhematologic serious adverse events were observed in 6 patients including: neutropenic fever (1, grade 3), bone pain (1, grade 3) and renal insufficiency (1, grade 1). In conclusion, BED safely and effectively mobilizes hematopoietic stem cells.

Hematopoietic progenitor cell mobilization for autologous transplantation - a literature review

The use of high-dose chemotherapy with autologous support of hematopoietic progenitor cells is an effective strategy to treat various hematologic neoplasms, such as non-Hodgkin lymphomas and multiple myeloma. Mobilized peripheral blood progenitor cells are the main source of support for autologous transplants, and collection of an adequate number of hematopoietic progenitor cells is a critical step in the autologous transplant procedure. Traditional strategies, based on the use of growth factors with or without chemotherapy, have limitations even when remobilizations are performed. Granulocyte colony-stimulating factor is the most widely used agent for progenitor cell mobilization. The association of plerixafor, a C-X-C Chemokine receptor type 4 (CXCR4) inhibitor, to granulocyte colony stimulating factor generates rapid mobilization of hematopoietic progenitor cells. A literature review was performed of randomized studies comparing different mobilization schemes in the treatment of multiple myeloma and lymphomas to analyze their limitations and effectiveness in hematopoietic progenitor cell mobilization for autologous transplant. This analysis showed that the addition of plerixafor to granulocyte colony stimulating factor is well tolerated and results in a greater proportion of patients with non-Hodgkin lymphomas or multiple myeloma reaching optimal CD34⁺ cell collections with a smaller number of apheresis compared the use of granulocyte colony stimulating factor alone.

Efficacy of biosimilar granulocyte colony-stimulating factor versus originator granulocyte colony-stimulating factor in peripheral blood stem cell mobilization in de novo multiple myeloma patients

BACKGROUND AIMS

Filgrastim and lenograstim are the standard granulocyte colony-stimulating factor (G-CSF) agents for peripheral blood stem cell mobilization (PBSC) in patients who undergo autologous stem cell transplantation.

METHODS

To assess whether biosimilars are effective, we conducted a single-center, prospective study that included 40 consecutive de novo multiple myeloma patients who received cyclophosphamide 4 g/m(2) per day plus biosimilar filgrastim G-CSF to mobilize PBSC. These patients were compared with a group of 37 patients matched for age, diagnosis, previous chemotherapy and mobilization who had been treated with originator G-CSF. The mean number of CD34+ cells/μL in the peripheral blood was 199.6 ± 207.4 in the biosimilar and 192.8 ± 154.7 in the originator group (P = 0.87). The median number of CD34+ cells/kg recipient collected was 11.5 ± 5.8 and 12.3 ± 5.3 in the biosimilar and originator groups, respectively (P = 0.51). The mobilization failure rate was 2.5% and 2.7% in the biosimilar filgrastim and originator filgrastim cohorts (P = NS), respectively.

RESULTS

Twenty-nine patients in the biosimilar group and 28 patients in the originator group underwent autologous transplantation. There were no statistically significant differences between the biosimilar and originator G-CSF cohorts in terms of hematopoietic recovery parameters and transplant-related toxicities.

CONCLUSIONS

The efficacy of biosimilar G-CSF appears to be equivalent to the reference G-CSF.

Optimizing mobilization strategies in difficult-to-mobilize patients: The role of plerixafor

Peripheral blood stem cell collection is currently the most widely used source for hematopoietic autologous transplantation. Several factors such as advanced age, previous chemotherapy, disease and marrow infiltration at the time of mobilization influence the efficacy of CD34(+) progenitor cell mobilization. Despite the safety and efficiency of the standard mobilization protocols (G-CSF ± chemotherapy), there is still a significant amount of mobilization failure rate (10-40%), which necessitate novel agents for effective mobilization. Plerixafor, is a novel agent, has been recently approved for mobilization of hematopoietic stem cells (HSCs). The combination of Plerixafor with G-CSF provides the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail with standard mobilization regimens. The development and optimization of practical algorithms for the use Plerixafor is crucial to make hematopoietic stem cell mobilization more efficient in a cost-effective way. This review is aimed at summarizing how to identify poor mobilizers, and define rational use of Plerixafor for planning mobilization in hard-to-mobilize patients.

Cyclophosphamide-based hematopoietic stem cell mobilization before autologous stem cell transplantation in newly diagnosed multiple myeloma

High-dose cyclophosphamide (Cy) is frequently employed for peripheral blood mobilization of hematopoietic stem cells before high-dose chemotherapy with autologous stem cell transplantation (ASCT) in multiple myeloma (MM). The benefit of mobilization with Cy over filgrastim (granulocyte colony-stimulating factor; G-CSF) alone is unclear. Between 2000 and 2008, 167 patients with newly diagnosed MM underwent single ASCT after melphalan conditioning at our institution. Seventy-three patients were mobilized with G-CSF alone, and 94 patients with Cy plus G-CSF (Cy+G-CSF). We retrospectively analyzed Cy's impact on both toxicity and efficacy. Mobilization efficiency was augmented by Cy; a mean total of 12 versus 5.8 × 10(6) CD34+ cells/kg were collected from patients mobilized with Cy+G-CSF versus G-CSF, respectively, (P < 0.01), over a mean of 1.6 versus 2.2 days of peripheral blood apheresis (p = 0.001). Mobilization-related toxicity was also, however, augmented by Cy; 14% of Cy+G-CSF patients were hospitalized because of complications versus none receiving G-CSF (P < 0.0001). Toxicity, including death, related to ASCT was similar between cohorts. Regarding long-term outcomes, multivariate analysis revealed no difference for Cy+G-CSF versus G-CSF (hazard ratio 0.8 for event-free survival [95% confidence interval {CI} 0.57-1.25] and 0.96 for overall survival [95% CI 0.61-1.54]). In summary, we show that mobilization with Cy increases toxicity without positively impacting long-term outcomes in MM. Our findings place into question Cy's benefit as a routine component of stem cell mobilization regimens in MM. Randomized trials are needed to elucidate the risks and benefits of Cy more definitively.

Optimizing autologous stem cell mobilization strategies to improve patient outcomes: consensus guidelines and recommendations

Autologous hematopoietic stem cell transplantation (aHSCT) is a well-established treatment for malignancies such as multiple myeloma (MM) and lymphomas. Various changes in the field over the past decade, including the frequent use of tandem aHSCT in MM, the advent of novel therapies for the treatment of MM and lymphoma, and the addition of new stem cell mobilization techniques, have led to the need to reassess current stem cell mobilization strategies. Mobilization failures with traditional strategies are common and result in delays in treatment and increased cost and resource utilization. Recently, plerixafor-containing strategies have been shown to significantly reduce mobilization failure rates, but the ideal method to maximize stem cell yields and minimize costs associated with collection has not yet been determined. A panel of experts convened to discuss the currently available data on autologous hematopoietic stem cell mobilization and transplantation and to devise guidelines to optimize mobilization strategies. Herein is a summary of their discussion and consensus.

Advances in stem cell mobilization

The use of mobilized peripheral blood stem cells (PBSCs) has largely replaced the use of bone marrow as a source of stem cells for both allogeneic and autologous stem cell transplantation. G-CSF with or without chemotherapy is the most commonly used regimen for stem cell mobilization. Some donors or patients, especially the heavily pretreated patients, fail to mobilize the targeted number of stem cells with this regimen. A better understanding of the mechanisms involved in hematopoietic stem cell (HSC) trafficking could lead to the development of newer mobilizing agents and therapeutic approaches. This review will cover the current methods for stem cell mobilization and recent developments in the understanding of the biology of stem cells and the bone marrow microenvironment.

Mobilisation strategies for normal and malignant cells

This review evaluates the latest information on the mobilisation of haemopoietic stem cells for transplantation, with the focus on what is the current best practice and how new understanding of the bone marrow stem cell niche provides new insights into optimising mobilisation regimens. The review then looks at the mobilisation of mesenchymal stromal cells, immune cells as well as malignant cells and what clinical implications there are.

[Hematopoietic stem cells mobilization: state of the art in 2011 and perspectives]

High-dose chemotherapy with stem cells support has largely improved in terms of hematopoietic stem and progenitor cells harvest procedures as well as in those, which target or manipulate the cellular composition of autologous graft. Optimal preparative regimens and supportive care had lead to better use of autologous transplantation procedure. For other patients assigned to hematopoietic transplantation, availability of allogeneic donors appears to be an interesting alternative source of hematopoietic stem cells. Since three decades, hematopoietic growth factors development has allowed mobilization optimization and collection of peripheral hematopoietic stem cells leading to reduced days of hospitalization and less blood products requirements, being more cost-effective for patients in autologous transplantation settings and for stem cell collection facilities in allogeneic ones. New perspectives include, besides ex vivo manipulation of graft, development of mobilizing drugs in order to perform transplantation even in poor mobilizers patients. An important goal is achieved with the description of genetic polymorphisms related to optimal mobilization of stem cells. New approach using more promising and selective agents called chemokines, such as plerixafor the main leader among these agents are now available and appear complementary for alternative approach using cytokines alone (G-CSF, GM-CSF, SCF). The aim of this review is to assess the evolution of theses biotechnologies and their role in different steps of autologous transplantation and allogeneic stem cells collection.

Proposed definition of 'poor mobilizer' in lymphoma and multiple myeloma: an analytic hierarchy process by ad hoc working group Gruppo ItalianoTrapianto di Midollo Osseo

Many lymphoma and myeloma patients fail to undergo ASCT owing to poor mobilization. Identification of poor mobilizers (PMs) would provide a tool for early intervention with new mobilization agents. The Gruppo italianoTrapianto di Midollo Osseo working group proposed a definition of PMs applicable to clinical trials and clinical practice. The analytic hierarchy process, a method for group decision making, was used in setting prioritized criteria. Lymphoma or myeloma patients were defined as ‘proven PM' when: (1) after adequate mobilization (G-CSF 10 μg/kg if used alone or ⩾5 μg/kg after chemotherapy) circulating CD34⁺ cell peak is <20/μL up to 6 days after mobilization with G-CSF or up to 20 days after chemotherapy and G-CSF or (2) they yielded <2.0 × 10⁶ CD34⁺ cells per kg in ⩽3 apheresis. Patients were defined as predicted PMs if: (1) they failed a previous collection attempt (not otherwise specified); (2) they previously received extensive radiotherapy or full courses of therapy affecting SC mobilization; and (3) they met two of the following criteria: advanced disease (⩾2 lines of chemotherapy), refractory disease, extensive BM involvement or cellularity <30% at the time of mobilization; age ⩾65 years. This definition of proven and predicted PMs should be validated in clinical trials and common clinical practice.

Mobilization of hematopoietic stem cells into the peripheral blood

Hematopoietic stem cells can be mobilized out of the bone marrow into the blood for the reconstitution of hematopoiesis following high-dose therapy. Methods to improve mobilization efficiency and yields are rapidly emerging. Traditional methods include chemotherapy with or without myeloid growth factors. Plerixafor, a novel agent that disrupts the CXCR4-CXCL12 bond, the primary hematopoietic stem cell anchor in the bone marrow, has recently been US FDA-approved for mobilizing hematopoietic stem cells in patients with non-Hodgkin lymphoma and multiple myeloma. Plerixafor and myeloid growth factors as single agents appear safe to use in family or volunteer hematopoietic stem cells donors. Plerixafor mobilizes leukemic stem cells and is not approved for use in patients with acute leukemia. Patients failing to mobilize adequate hematopoietic stem cells with myeloid growth factors can often be successfully mobilized with chemotherapy plus myeloid growth factors or with plerixafor and granulocyte colony-stimulating factor.

Chemomobilization with Etoposide is Highly Effective in Patients with Multiple Myeloma and Overcomes the Effects of Age and Prior Therapy

The optimal mobilization strategy prior to autologous stem cell transplantation for patients with multiple myeloma remains unclear. Mobilization with cytokines alone appears to yield suboptimal results in older patients as well as patients who have received prior lenalidomide. To avoid the marked cytopenias and risks of hemorrhagic cystitis associated with the administration of cyclophosphamide, we investigated the efficacy and safety of chemomobilization with an intermediate dose etoposide (VP-16; 375 mg/m(2) on days +1 and +2) and granulocyte-colony stimulating factor (G-CSF) (5 μg/kg twice daily from day +3 through the final day of collection). We reviewed our institutional experience with 152 myeloma patients mobilized with this regimen. The addition of VP-16 to G-CSF resulted in successful mobilization in 100% of patients, including 143 (94%) who collected successfully in a single day. A total of 99% of patients, including those with prior XRT and/or prior lenalidomide or thalidomide therapy, collected at least 5 × 10(6) cells/kg in 1 or 2 days of apheresis, and the median total number of CD34(+) cells collected in the entire population was 12 × 10(6) cells/kg. Collection was predictable, with 61% of patients collecting on day +11, and the rest between days +7 and +13. There were no variables, including age, prior imid exposure, radiation therapy, or total amount of prior therapy that were associated with suboptimal mobilization. Adverse effects of the regimen included supportive transfusions required in 31 (20%) patients, and fevers requiring hospitalization or intravenous antibiotics in 26 (17%) patients. VP-16 and G-CSF appears to be a safe and effective mobilization regimen for patients with multiple myeloma undergoing autologous stem cell transplantation, producing excellent stem cell yield with the majority of patients requiring 1 day of apheresis.

Mobilization in myeloma revisited: IMWG consensus perspectives on stem cell collection following initial therapy with thalidomide-, lenalidomide-, or bortezomib-containing regimens

The past decade has witnessed a paradigm shift in the initial treatment of multiple myeloma with the introduction of novel agents such as thalidomide, lenalidomide, and bortezomib, leading to improved outcomes. High-dose therapy and autologous stem cell transplantation remains an important therapeutic option for patients with multiple myeloma eligible for the procedure. Before the advent of the novel agents, patients underwent stem cell collection prior to significant alkylating agent exposure, given its potential deleterious effect on stem cell collection. With increasing use of the novel agents in the upfront setting, several reports have emerged raising concerns about their impact on the ability to collect stem cells. An expert panel of the International Myeloma Working Group (IMWG) was convened to examine the implications of these therapies on stem collection in patients with myeloma and to develop recommendations for addressing these issues. Here we summarize the currently available data and present our perspective on the problem and potential options to overcome this problem. Specifically, we recommend early mobilization of stem cells, preferably within the first 4 cycles of initial therapy, in patients treated with novel agents and encourage participation in clinical trials evaluating novel approaches to stem cell mobilization.

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)

Multiple myeloma is the most common indication for high-dose chemotherapy with autologous stem cell support (ASCT) in North America today. Stem cell procurement for ASCT has most commonly been performed with stem cell mobilization using colony-stimulating factors with or without prior chemotherapy. The target CD34+ cell dose to be collected as well as the number of apheresis performed varies throughout the country, but a minimum of 2 million CD34+ cells/kg has been traditionally used for the support of one cycle of high-dose therapy. With the advent of plerixafor (AMD3100) (a novel stem cell mobilization agent), it is pertinent to review the current status of stem cell mobilization for myeloma as well as the role of autologous stem cell transplantation in this disease. On June 1, 2008, a panel of experts was convened by the International Myeloma Foundation to address issues regarding stem cell mobilization and autologous transplantation in myeloma in the context of new therapies. The panel was asked to discuss a variety of issues regarding stem cell collection and transplantation in myeloma especially with the arrival of plerixafor. Herein, is a summary of their deliberations and conclusions.

Successful mobilization of peripheral blood stem cells with bortezomib + high-dose cyclophosphamide + G-CSF in a light chain myeloma patient after failure with Total Therapy 2

Autologous stem cell transplantation is considered the best post-induction therapy for multiple myeloma (MM). Therefore, therapy for myeloma should be chosen not only on the basis of efficacy, but also taking into account their impact on the hematopoietic stem cell compartment. We describe the case of a MM patient in which a successful mobilization of peripheral stem cells was obtained with bortezomib, cyclophosphamide and G-CSF, after two failed attempts in the framework of Total Therapy 2. The patient underwent an autologous transplantation, showing a rapid and complete post-transplant hematological recovery. Our experience suggests that bortezomib is an effective anti-myeloma agent without negative impact on stem cell mobilization, even in patients with a previous history of failed harvest.

Autologous stem cell transplantation in the elderly including pre- and post-treatment options

Multiple myeloma (MM) is a disease of the elderly with a median age at diagnosis of 67 years in a referral population. High-dose chemotherapy (HDT) and autologous stem cell transplantation has been shown to improve survival in patients with MM in randomized trials and remains the preferred option for eligible patients. However, the randomized clinical trials demonstrating an advantage for HDT included only patients younger than 65 years and evidence supporting its role for the elderly patients has been based on retrospective reviews. The introduction of thalidomide, lenalidomide and bortezomib has changed the paradigm for treatment of myeloma and improved the outcome for these patients. Several ongoing clinical trials are evaluating the role of these novel agents in this population, specifically comparing these to HDT-based approaches. Other trials are examining the role of maintenance therapy post-HDT with these novel drugs with or without steroids. The role of HDT will be further redefined in the coming years with improvements in other therapies.

Role of autologous stem cell transplantation in multiple myeloma

High-dose chemotherapy with autologous stem cell transplantation (ASCT) has been shown to improve survival in patients with multiple myeloma in randomized trials and is the standard of care for eligible patients. Recent randomized trials suggest a survival benefit with tandem ASCT, notably for patients failing to achieve a very good response to initial transplantation. Other randomized trials, as well as smaller phase II trials and retrospective studies, have allowed us to improve the process of ASCT in terms of the stem cell collection, conditioning regimens, and extension of the therapy to a wider patient population. The introduction of thalidomide, lenalidomide, and bortezomib have changed the paradigm for treatment of myeloma and significantly improved the outcome for these patients. The role of ASCT will clearly be redefined in the coming years with improvements in other therapies.

A randomized study comparing filgrastim versus lenograstim versus molgramostim plus chemotherapy for peripheral blood progenitor cell mobilization

We conducted a prospective randomized clinical trial to assess the mobilizing efficacy of filgrastim, lenograstim and molgramostim following a disease-specific chemotherapy regimen. Mobilization consisted of high-dose cyclophosphamide in 45 cases (44%), and cisplatin/ifosfamide/etoposide or vinblastine in 22 (21%), followed by randomization to either filgrastim or lenograstim or molgramostim at 5 microg/kg/day. One hundred and three patients were randomized, and 82 (79%) performed apheresis. Forty-four (43%) patients were chemonaive, whereas 59 (57%) were pretreated. A median number of one apheresis per patient (range, 1-3) was performed. The median number of CD34+ cells obtained after mobilization was 8.4 x 10(6)/kg in the filgrastim arm versus 5.8 x 10(6)/kg in the lenograstim arm versus 4.0 x 10(6)/kg in the molgramostim arm (P=0.1). A statistically significant difference was observed for the median number of days of growth factor administration in favor of lenograstim (12 days) versus filgrastim (13 days) and molgramostim (14 days) (P<0.0001) and for the subgroup of chemonaive patients (12 days) versus pretreated patients (14 days) (P<0.001). In conclusion, all three growth factors were efficacious in mobilizing peripheral blood progenitor cells with no statistically significant difference between CD34+ cell yield and the different regimens, and the time to apheresis is likely confounded by the different mobilization regimens.

Biological response modifiers as adjuncts to stem cell transplantation

Cytokines produced by immune and non-immune cells serve as potent mediators with the properties of signal cells that coordinate the immune response. They are delivered by cells either to the systemic circulation or to the local environment. They are being used at present in the field of stem cell transplantation (SCT) in order to improve transplant outcome. This paper reviews the existing data on pre-, peri- and post-SCT treatment with cytokines.

High-dose chemotherapy with autologous hematopoietic stem cell transplantation in patients with multiple myeloma

Multiple myeloma, for all practical purposes, remains an incurable malignancy; however, 5-year survival has improved substantially during the past 30 years. A major contribution to improved outcome is the use of high-dose chemotherapy and stem cell transplantation. This multifaceted approach to therapy requires an understanding of appropriate induction therapy, techniques for stem cell mobilization, appropriate conditioning and supportive care. Also of importance are prognosis, features that predict outcome, the suitability of transplant candidates, and post-transplantation maintenance therapy.

Results of autologous and allogeneic hematopoietic cell transplant therapy for multiple myeloma

We compared the results of autologous and allogeneic peripheral blood hematopoietic cell transplant (HCT) in 87 patients with multiple myeloma using myeloablative preparative regimen. Autologous transplant (n=70) led to a lower 100-day transplant-related mortality (TRM) of 4% [0-9%] compared to 18% [0-36%] in allogeneic recipients (P=0.02). More frequent complete responses were seen in allogeneic recipients (64% [37-91%] vs 34% [23-45%] in autologous recipients, P=0.09). In autologous recipients, survival at 1 year was 86% [80-95%] and, it fell to 50% [47-75%] at 4 years, whereas in allogeneic recipients, survival at 1 and 4 years remained at 64% [40-87%]. In patients surviving more than one year, 4-year survival was superior in allogeneic (100%) vs autologous recipients (58% [41-75%], P=0.02). A trend toward higher relapse was seen in autologous transplant patients (73% [55-90%] vs 37% [11-63%] in allogeneic transplant patients, P=0.1). We observed good tolerance of myeloablative conditioning regimen followed by either autologous or allogeneic transplant. Although autologous HCT is associated with lower TRM, allogeneic HCT has acceptable TRM, and is more likely to provide a sustained response. Allogeneic HCT may be suitable in younger patients, soon after diagnosis, and in those with chemosensitive disease.

Colony-stimulating factors in the management of neutropenia and its complications

Granulocyte colony-stimulating factor (CSF) and granulocyte-macrophage CSF are potent drugs used to increase neutrophil counts after myelosuppressive chemotherapy. However, in various indications, the use of CSFs has no clinical benefit with regard to morbidity or mortality from infectious complications, frequency of antibiotic use, or rate of hospitalization. Thus, the application of CSFs should be limited to indications with proven clinical benefits or evidence of cost-effectiveness. This review will provide an overview of the state-of-the-art use of CSFs in chemotherapy-associated neutropenia, transplantation, and bone marrow failure syndromes. In addition, recently developed drugs for accelerated hematopoietic recovery will be presented.