Concomitant mobilization of plasma cells and hematopoietic progenitors into peripheral blood of patients with multiple myeloma

Application of mass cytometry to characterize hematopoietic stem cells in apheresis products of patients with hematological malignancies

INTRODUCTION

Hematopoietic stem cell transplantation (HSCT) is a widely used therapy, but its success largely depends on the number and quality of stem cells collected. Current evidence shows the complexity of the hematopoietic system, which implies that, in the quality assurance of the apheresis product, the hematopoietic stem cells are adequately characterized and quantified, in which mass cytometry (MC) can provide its advantages in high-dimensional analysis.

OBJECTIVE

This research aimed to characterize and enumerate CD45dim/CD34+ stem cells using the MC in apheresis product yields from patients with chronic lymphoid malignant diseases undergoing autologous transplantation at the Abu Dhabi Stem Cells Center.

METHODS

An analytical and cross-sectional study was performed on 31 apheresis products from 15 patients diagnosed with multiple myeloma (n = 9) and non-Hodgkin lymphomas (n = 6) eligible for HSCT. The MC was employed using the MaxPar Kit for stem cell immunophenotyping. The analysis was performed manually in the Kaluza and unsupervised by machine learning in Cytobank Premium.

RESULTS

An excellent agreement was found between mass and flow cytometry for the relative and absolute counts of CD45dim/CD34+ cells (Bland-Altman bias: -0.029 and -64, respectively), seven subpopulations were phenotyped and no lineage bias was detected for any of the methods used in the pool of collected cells. A CD34+/CD38+/CD138+ population was seen in the analyses performed on four patients with multiple myeloma.

CONCLUSIONS

The MC helps to characterize subpopulations of stem cells in apheresis products. It also allows cell quantification by double platform. Unsupervised analysis allows results completion and validation of the manual strategy. The proposed methodology can be extended to apheresis products for purposes other than HSCT.

High-dose therapy and autologous peripheral blood stem cell transplantation in patients with multiple myeloma

Since its introduction in 1983, high-dose therapy followed by autologous peripheral blood stem cell transplantation is a pillar of the treatment of patients with multiple myeloma. In the last decades, a multitude of clinical trials helped to improve strategies based on high-dose therapy and autologous stem cell transplantation resulting in a continuously prolongation of overall survival of patients. In this chapter we will review the progress, which has been made in order to enhance the mobilisation of autologous stem cells and increase the effectiveness of this treatment.

Comparison of unmobilized and mobilized graft characteristics and the implications of cell subsets on autologous and allogeneic transplantation outcomes

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) are considered the standard of care for many malignancies, including lymphoma, myeloma, and some leukemias. In many cases, mobilized peripheral blood has become the preferred source of hematopoietic stem cells. The efficacy of different mobilization regimens and transplantation outcomes based on cell doses has been well studied; however, the characteristics of the stem cell graft may be of equal importance with respect to patient outcomes following autologous or allogeneic HSCT. This review summarizes available preclinical and clinical data for bone marrow and mobilized peripheral blood HSCT characteristics, defined as the cell types found in the graft as well as their gene expression profiles. It also explores how graft characteristics can affect bone marrow homing, engraftment, immune reconstitution, and other posttransplantation outcomes in both the allogeneic and autologous HSCT settings.

Ambivalent aspects of interleukin-6 in cerebral ischemia: inflammatory versus neurotrophic aspects

Interleukin-6 (IL-6) is pleiotropic cytokine involved in many central nervous system disorders including stroke, and elevated serum IL-6 has been found in acute stroke patients. IL-6 is implicated in the inflammation, which contributes to both injury and repair process after cerebral ischemia. However, IL-6 is one of the neurotrophic cytokines sharing a common receptor subunit, gp130, with other neurotrophic cytokines, such as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor. The expression of IL-6 is most prominently identified in neurons in the peri-ischemic regions, and LIF expression shows a similar pattern. The direct injection of these cytokines into the brain after ischemia can reduce ischemic brain injury. The cytokine receptors are localized on the neuron surface, suggesting that neurons are the cytokine target. The major IL-6 downstream signaling pathway is JAK-STAT, and Stat3 activation occurs mainly in neurons during postischemic reperfusion. Further investigation is necessary to clarify the exact role of Stat3 signaling in neuroprotection. Taken together, the information suggests that IL-6 plays a double role in cerebral ischemia, as an inflammatory mediator during the acute phase and as a neurotrophic mediator between the subacute and prolonged phases.

Quality assessment of autografting by probability evaluation: model estimation by clinical end-points in newly diagnosed multiple myeloma patients

BACKGROUND

Pre-transplant clinical evaluation of autografting is an important step in predicting post-transplant support, complications and safety. Today, unfavorable outcomes such as early death or graft failure are rare, making them unsuitable for quality assessment of supportive autografting. However, end-points constructed from frequently occurring clinical events may estimate clinically relevant prognostic models.

METHODS

The present retrospective analysis was based on two consecutive clinical trials in the Nordic area including up to 640 newly diagnosed multiple myeloma patients.

RESULTS

In the model, the efficacy (time on antibiotics and use of transfusions) was influenced by pre-transplant variables, including sex, nationality, serum creatinine, hemoglobin, disease stage at diagnosis, response following induction therapy, length of priming and average graft CD34+ cell number per day of harvest. The toxicity end-point (time to blood cell recovery) was influenced by nationality, marrow plasma cell percentage, serum creatinine, M-component isotype, response to induction therapy, length of priming and graft CD34+ cell number. The safety (early disease recurrence or death) was influenced by serum creatinine, hemoglobin, treatment response and CD34+ cell number.

DISCUSSION

In conclusion, the model illustrates that intervention strategies in quality assessment of autografting may benefit from probability estimates of graded clinical end-points.

Molecular monitoring of minimal residual disease in patients with multiple myeloma

Improvement of transplantation strategies and a multitude of emerging novel therapies result in a better treatment outcome in patients with multiple myeloma (MM). This gives rise to the need for sensitive methods to detect minimal residual disease (MRD) in MM. Qualitative molecular monitoring using allele-specific oligonucleotide PCR for the immunoglobulin heavy chain (IgH) is well established to detect clonotypic cells after therapy or in stem cell harvests. Recently, real-time IgH PCR or limiting dilution based PCR assays offer the possibility to quantify the amount of residual tumour cells. In this review, different qualitative and quantitative IgH PCR techniques will be discussed as well as the current clinical role of molecular monitoring of MRD in patients with MM.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of multiple myeloma: an evidence-based review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of multiple myeloma (MM) is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published medical literature and for grading the quality of the evidence, the strength of the evidence, and the strength of the treatment recommendations. Treatment recommendations based on the evidence presented in the review were made unanimously by a panel of MM experts. Recommendations for SCT as an effective therapy for MM include the following: SCT is preferred to standard chemotherapy as de novo therapy; SCT is preferred as de novo rather than salvage therapy; autologous peripheral blood stem cell transplantation (PBSCT) is preferred to bone marrow transplantation (BMT); and melphalan is preferred to melphalan plus total body irradiation as the conditioning regimen for autologous SCT. Recommendations that SCT is not effective include the following: current purging techniques of bone marrow. Recommendations of equivalence include the following: PBSCT using CD34+ selected or unselected stem cells. No recommendation is made for indications or transplantation techniques that have not been adequately studied, including the following: SCT versus standard chemotherapy as salvage therapy, tandem autologous SCT, autologous or allogeneic SCT as a high-dose sequential regimen, allogeneic BMT versus PBSCT, a preferred allogeneic myeloablative or non-myeloablative conditioning regimen, and maintenance therapy post-autologous SCT with interferon alpha post-SCT. The priority area of needed future research is maintenance therapy posttransplantation with nothing versus interferon alpha versus other agents such as corticosteroids or thalidomide or its derivatives.

Efficacy and safety of CD34-selected and CD19-depleted autografting in multiple myeloma patients: a pilot study

OBJECTIVE

If multiple myeloma patients are to be cured after high-dose treatment supported by autologous stem cell transplantation, grafts must be purged of circulating myeloma cells. Myeloma cells are present in all grafts and have been identified as CD38(++)CD45(-) plasma cells, plasma blasts, and CD19(+) B cells.

MATERIALS AND METHODS

In an attempt to improve the purging strategy, we studied a two-step procedure consisting of CD34(+) enrichment followed by CD19 depletion. This article describes the evaluation of this sequential magnetic microbead selection after 18 procedures in 14 patients.

RESULTS

The processed autografts contained a median CD34 purity of 81% (range 21-99%) and a recovery of 47% (range 15-82%). Flow cytometric analysis documented the expected reduction of CD34(-) B cells and plasma cells, in most cases to a level below the sensitivity of flow cytometry. Real-time reverse transcriptase polymerase chain reaction documented a CD19 mRNA relative reduction to 0.042 (range 0.01-0.21). Allele-specific oligonucleotide IgH primers were designed for five patients. All products were positive for clonal myeloma cells before processing, but only 1 of 5 was negative after the procedure. The clinical outcome after reinfusion of the processed autografts was evaluated by blood cell recovery and found to be within the range expected from engraftment of unmanipulated autografts. One patient who had delayed platelet recovery associated with cytomegalovirus infection recovered after anti-cytomegalovirus treatment.

CONCLUSIONS

This pilot study documented engraftment after reinfusion of CD34-selected and CD19-depleted autografts. However, one patient suffered from unexpected prolonged thrombocytopenia. The efficacy of the procedure was evaluated and reduction of myeloma cells was indicated, with only one autograft free of clonal cells.

Gene scanning of VDJH-amplified segments is a clinically relevant technique to detect contaminating tumor cells in the apheresis products of multiple myeloma patients undergoing autologous peripheral blood stem cell transplantation

Contaminating tumour cells in apheresis products have proved to influence the outcome of patients with multiple myeloma (MM) undergoing autologous stem cell transplantation (APBSCT). The gene scanning of clonally rearranged VDJ segments of the heavy chain immunoglobulin gene (VDJH) is a reproducible and easy to perform technique that can be optimised for clinical laboratories. We used it to analyse the aphereses of 27 MM patients undergoing APBSCT with clonally detectable VDJH segments, and 14 of them yielded monoclonal peaks in at least one apheresis product. The presence of positive results was not related to any pre-transplant characteristics, except the age at diagnosis (lower in patients with negative products, P = 0.04). Moreover, a better pre-transplant response trended to associate with a negative result (P = 0.069). Patients with clonally free products were more likely to obtain a better response to transplant (complete remission, 54% vs 28%; >90% reduction in the M-component, 93% vs 43% P = 0.028). In addition, patients transplanted with polyclonal products had longer progression-free survival, (39 vs 19 months, P = 0.037) and overall survival (81% vs 28% at 5 years, P = 0.045) than those transplanted with monoclonal apheresis. In summary, the gene scanning of apheresis products is a useful and clinically relevant technique in MM transplanted patients.

Peripheral blood monoclonal B-cells predict the event free survival in multiple myeloma

Reinfusion of myeloma progenitor cells may contribute to relapse of multiple myeloma after autologous stem cell transplantation. The aim of our study was to investigate whether monoclonal B-cells are present in the apheresis product and to evaluate the clinical relevance of these cells. Leukapheresis products of 55 patients were purged with anti-B-cell-Monoclonal antibodies (MoAbs) and immunobeads. Monoclonal B-cells were found in 85% of patients within the B-cell population. In one third of all myeloma patients, the majority of B-cells was represented by monoclonal myeloma progenitor B-cells, whereas in two thirds of patients monoclonal cells only represented a small part of the entire B-cell population. As shown by sequence analysis, monoclonal precursor B-cells and malignant plasma cells had the identical genetic CDR III sequence. The purging efficacy, using a negative selection system, was a median of 3 logs (range 1,5-3,5). No statistical difference in the purging efficacy was found when 3, 4 or 5 MoAbs against B-cells antigens were used. However, a tumor specific signal could be detected in the purged harvest of all patients, when the highly sensitive ASO-PCR approach was used. Furthermore, we found a direct correlation between the amount of remaining monoclonal cells after negative selection and the event free survival of myeloma patients. 10/15 patients with a median of 20 x 10(3) monoclonal cells in the purged product relapsed at a median of 1,4 years, whereas only 6/24 patients with an oligoclonal pattern including a low number of remaining monoclonal cells relapsed at a median of 2,2 years. The event free survival (EFS) was statistically different between the two groups (p = 0,014).

Tumour kinetics in multiple myeloma before, during, and after treatment

Tumour progression was monitored in seven multiple myeloma (MM) patients undergoing a novel oral chemotherapy regimen (cyclophosphamide, idarubicin and dexamethasone; CID) followed by early autologous stem cell transplantation (ASCT). Allele-specific oligonucleotide PCR (ASO-PCR) was used to semi-quantitate the number of tumour cells within the peripheral blood (PB) and PB progenitor cell (PBPC) harvests and compared with paraprotein levels and morphological bone marrow (BM) assessments. Tumour cells were detected in the PB of all patients at diagnosis, but decreased in response to CID therapy. All but two of the 22 PBPC collections contained MM cells, the levels of which were statistically correlated with overall clinical response to therapy, but not with individual BM or PB tumour loads prior to mobilisation. We also found no correlation between the day of leucapheresis collection and the number of contaminating MM cells, CD34+ cells or MM cells per CD34+ cell. Regardless of tumour contamination levels in the PBPC collections, the majority of patients demonstrated post-ASCT clearing of circulating MM cells. This study suggests that levels of circulating MM cells may be the best indication of patient response to treatment and argues against the theory of differential mobilisation of tumour cells and CD34+ cells in response to cytokine treatment.

Autologous stem cell transplantation as post-remission therapy in adult acute myelogenous leukemia: does platelet contamination of peripheral blood mobilized stem cell grafts influence the risk of leukemia relapse?

Conventional chemotherapy of acute myelogenous leukemia (AML) results in an overall long-term disease-free survival of less than 50%, but for selected subsets of younger patients the prognosis can be improved by allogeneic stem cell transplantation. The use of autologous stem cell transplantation is now investigated as an alternative to allotransplantation due to its lower risk of serious complications. However, autotransplantation is associated with a relatively high risk of post-transplant AML relapse that can be derived from contaminating leukemia cells in the autograft. Peripheral blood mobilized stem cell (PBSC) grafts usually contain a higher number of platelets. The degree of platelet contamination is determined by the peripheral blood platelet count at the time of harvesting, and the platelets become activated and release soluble mediators during the ex vivo handling of PBSC grafts. Many of these platelet-derived mediators can bind to specific receptors expressed by AML blasts, and the platelet contamination may then alter AML blast survival and thereby influence the risk of post-transplant leukemia relapse. Therefore, we conclude that the platelet contamination of autologous stem cell grafts is possibly of clinical importance, but the effect of this nonstandardized parameter is difficult to predict in individual patients because the number of graft-contaminating platelets, the degree of platelet activation, and the effects of platelet-derived mediators on AML blasts differ between patients.

The detection of contaminating clonal cells in apheresis products is related to response and outcome in multiple myeloma undergoing autologous peripheral blood stem cell transplantation

In the present paper, we report on the use of the heteroduplex PCR technique to detect the presence of clonally rearranged VDJ segments of the heavy chain immunoglobulin gene (VDJH) in the apheresis products of patients with multiple myeloma (MM) undergoing autologous peripheral blood stem cell (APBSC) transplantation. Twenty-three out of 31 MM patients undergoing APBSC transplantation with VDJH segments clonally rearranged detected at diagnosis were included in the study. Samples of the apheresis products were PCR amplified using JH and VH (FRIII and FRII) consensus primers and subsequently analyzed with the heteroduplex technique, and compared with those obtained at diagnosis. 52% of cases yielded positive results (presence of clonally rearranged VDJH segments in at least one apheresis). The presence of positive results in the apheresis products was not related to any pretransplant characteristics with the exception of response status at transplant. Thus, while no one patient with positive apheresis products was in complete remission (CR), negative immunofixation, before the transplant, five cases (46%) with negative apheresis were already in CR at transplant (P = 0.01). The remaining six cases with heteroduplex PCR negative apheresis were in partial remission before transplant. Patients with clonally free products were more likely to obtain CR following transplant (64% vs 17%, P= 0.02) and a longer progression-free survival, (40 months in patients transplanted with polyclonal products vs 20 with monoclonal ones, P = 0.03). These results were consistent when the overall survival was considered, since it was better in those patients with negative apheresis than it was in those with positive (83% vs 36% at 5 years from diagnosis, P= 0.01). These findings indicate that the presence of clonality rearranged VDJH segments is related to the response and outcome in MM transplanted patients.

Delayed stem cell transplantation for the management of relapsed or refractory multiple myeloma

The optimal timing of stem cell transplantation for multiple myeloma is controversial. Late stem cell collection is undesirable because of the inability to mobilize stem cells. We report on 64 recipients of stem cells collected within 1 year after diagnosis, none of whom had transplantation in plateau phase of their disease. Patients seen within 12 months after diagnosis received four cycles of standard vincristine, doxorubicin, and dexamethasone (VAD) chemotherapy and then had stem cells mobilized. Patients were then placed on maintenance vincristine, BCNU, melphalan, cyclophosphamide, and prednisone or melphalan and prednisone chemotherapy for 12 cycles. At the sign of first progression, transplantation occurred. Fourteen patients were refractory to VAD chemotherapy, 20 relapsed on maintenance chemotherapy, and 30 relapsed off chemotherapy. The time to platelet engraftment was not affected by the duration of stem cell cryopreservation or extent of chemotherapy exposure after mobilization. The complete response rate was 34%. The actuarial median survival from initial diagnosis, from transplant day 0, and post-transplant progression-free survival was 51, 20 and 11.4 months, respectively. The patient status at transplantation and percentage of plasma cells circulating in the blood at apheresis influenced post-transplant survival; circulating plasma cells, status at transplantation and plasma cell labeling index influenced progression-free survival. Response duration was shorter in patients relapsing on chemotherapy.