Ex vivo graft purging and expansion of autologous blood progenitor cell products from patients with multiple myeloma

Purging myeloma cell contaminants and simultaneous expansion of peripheral blood-mobilized stem cells

Human hematopoietic stem cells (HSCs) are widely used as a cellular source for hematopoietic stem cell transplantation (HSCT) in the clinical treatment of hematological malignancies. After transplantation therapy, delays in hematopoietic recovery due to insufficient donor-derived HSCs can lead to increased risks of life-threatening infections and bleeding. Our previous studies developed an efficient ex vivo expansion culture medium (3a medium) for umbilical cord blood-derived HSCs (CBSCs), offering a potential solution to this problem. Nevertheless, the broader applicability of our culture method to alternative cell sources and, of greater significance, its efficacy in eliminating potentially disease-associated contaminated tumor cells, especially in autologous transplantation, raise critical clinical questions. In this study, we modified the 3a medium by incorporating UM729 to replace UM171, adding FMS-like tyrosine kinase 3 (Flt3) ligand, and adjusting the concentrations of butyzamide, 740Y-P, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG, Soluplus) to create the modified-3a medium. This sophistication allowed the efficient expansion of not only CBSCs but also peripheral blood-mobilized HSCs (PBSCs). Additionally, we successfully removed contaminated myeloma cells by adding bortezomib and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) at appropriate concentrations, although we maintained HSCs through the addition of lenalidomide. Our research findings present the potential for widespread clinical application of the modified-3a medium and suggest a safe ex vivo culture technique for expanding human HSCs within peripheral blood-derived donor grafts used for autologous HSCT.

Impact of clonal plasma cells in autografts on outcomes in high-risk multiple myeloma patients

Most patients with multiple myeloma (MM) undergoing autologous hematopoietic stem cell transplantation (autoHCT) eventually relapse, perhaps due to the presence of clonal plasma cells (CPC) in the autograft. We conducted a retrospective analysis to evaluate the impact of CPC in the autograft on the outcomes of high-risk chromosomal abnormalities (HRMM) patients undergoing autoHCT between 2008 and 2018. Patients were divided into CPC+ or CPC- in the autograft by next-generation flow cytometry (NGF). There were 75 CPC + autografts (18%) and 341 CPC- (82%). The CPC + group was less likely to achieve MRD-negative complete remission post-transplant (11% vs. 42%; p < 0.001). Median progression free survival (PFS) and overall survival (OS) were (12.8 vs. 32.1 months) and (36.4 vs. 81.2 months) in the CPC + and CPC- groups, respectively (both p < 0.001). Also in the subset of patients with MRD-negative ≥VGPR prior to autoHCT, those with CPC + autografts had inferior PFS (HR 4.21, p = 0.006) and OS (HR 7.04, p = 0.002) compared to CPC-. In multivariable analysis, the degree of CPC positivity in the autograft was independently predictive of worse PFS (HR 1.50, p = 0.001) and OS (HR 1.37, p = 0.001). In conclusion, both the presence and degree of CPC in the autograft were highly predictive of inferior PFS and OS.

Impact of Mantle Cell Lymphoma Contamination of Autologous Stem Cell Grafts on Outcome after High-Dose Chemotherapy

Simple Summary

High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (Auto-HSCT) is a standard frontline treatment for fit mantle cell lymphoma (MCL) patients. As there is a need for predictive factors to identify patients unlikely to benefit from this therapy, we investigated the prognostic impact of lymphoma cell contamination of autologous stem cell grafts. Analyzing a cohort of 36 MCL patients, we show that lymphoma cell contamination of stem cell grafts is associated with poor outcomes after Auto-HSCT. Its analysis might thus improve risk assessment and enable risk-stratified treatment strategies for MCL patients.

Abstract

Novel predictive factors are needed to identify mantle cell lymphoma (MCL) patients at increased risk for relapse after high-dose chemotherapy and autologous hematopoietic stem cell transplantation (HDCT/Auto-HSCT). Although bone marrow and peripheral blood involvement is commonly observed in MCL and lymphoma cell contamination of autologous stem cell grafts might facilitate relapse after Auto-HSCT, prevalence and prognostic significance of residual MCL cells in autologous grafts are unknown. We therefore performed a multiparameter flow cytometry (MFC)-based measurable residual disease (MRD) assessment in autologous stem cell grafts and analyzed its association with clinical outcome in an unselected retrospective cohort of 36 MCL patients. MRD was detectable in four (11%) autologous grafts, with MRD levels ranging from 0.002% to 0.2%. Positive graft-MRD was associated with a significantly shorter progression-free and overall survival when compared to graft-MRD negative patients (median 9 vs. 56 months and 25 vs. 132 months, respectively) and predicted early relapse after Auto-HSCT (median time to relapse 9 vs. 44 months). As a predictor of outcome after HDCT/Auto-HSCT, MFC-based assessment of graft-MRD might improve risk stratification and support clinical decision making for risk-oriented treatment strategies in MCL.

The Potential of Mesenchymal Stromal Cells in Neuroblastoma Therapy for Delivery of Anti-Cancer Agents and Hematopoietic Recovery

Neuroblastoma is one of the most common pediatric cancers and a major cause of cancer-related death in infancy. Conventional therapies including high-dose chemotherapy, stem cell transplantation, and immunotherapy approach a limit in the treatment of high-risk neuroblastoma and prevention of relapse. In the last two decades, research unraveled a potential use of mesenchymal stromal cells in tumor therapy, as tumor-selective delivery vehicles for therapeutic compounds and oncolytic viruses and by means of supporting hematopoietic stem cell transplantation. Based on pre-clinical and clinical advances in neuroblastoma and other malignancies, we assess both the strong potential and the associated risks of using mesenchymal stromal cells in the therapy for neuroblastoma. Furthermore, we examine feasibility and safety aspects and discuss future directions for harnessing the advantageous properties of mesenchymal stromal cells for the advancement of therapy success.

Selective purging of human multiple myeloma cells from peripheral blood mononuclear cells: a preliminary study

Background

High-dose chemotherapy followed by autologous peripheral blood stem-cell transplantation are standards of therapy for patients diagnosed with multiple myeloma. The purging process to remove contaminating residual myeloma cells could improve patient outcomes. In this study, a purging method of human multiple myeloma cells from peripheral blood mononuclear cells was evaluated.

Materials and methods

The human myeloma cell line RPMI-8226 (Seoul, Korea) was treated with bortezomib (Selleck Chemicals, Houston, TX, USA) or lenalidomide (Sigma Aldrich, St. Louis, MO, USA). The mixture of the human peripheral blood mononuclear cell line PCS-800-011 (ATCC, USA) and RPMI-8226 was treated with bortezomib or lenalidomide for 24 hours. The efficacy of purging myeloma cells was evaluated by 8-color flow cytometric analysis.

Results

The cytotoxicity of bortezomib (10-160 nmol/L) and lenalidomide (200-3,200 nmol/L) was investigated on RPMI-8226 myeloma cell line. A 24-hour incubation with bortezomib at 10, 20, 40, 80, 160 nmol/L induced 5.45%±0.07%, 47.15%±1.20%, 57.15%±0.21%, 72.35%±0.07%, and 84.75%±0.49% growth inhibition in RPMI-8226 cells, respectively. A 24-hour incubation with lenalidomide at 200, 400, 800, 1,600, and 3,200 nmol/L induced 5.45%±0.07%, 7.55%±0.07%, 9.75%±0.35%, 18.25%±0.21%, and 39.75%±0.78% growth inhibition in RPMI-8226 cells, respectively. Bortezomib (40 nmol/L, 24 hours) and lenalidomide (3,200 nmol/L, 24 hours) effectively removed CD38⁺CD138⁺ cells from peripheral mononuclear cells. RPMI-8226 cells showed abberant phenotype CD56⁺/CD45^-.

Conclusion

The results of the present study demonstrated that the bortezomib and lenalidomide treatment in RPMI-8226 multiple myeloma cells effectively removed the contaminated plasma cells.

A Phase I Study of the Safety and Feasibility of Bortezomib in Combination With G-CSF for Stem Cell Mobilization in Patients With Multiple Myeloma

BACKGROUND

We previously reported that administration of bortezomib (BTZ) after 4 days of granulocyte colony-stimulating factor (G-CSF) significantly augments mobilization in mice. We hypothesized that administration of BTZ at peak G-CSF mobilization in patients with multiple myeloma (MM) would be safe, augment mobilization, and have an in vivo purging effect on circulating myeloma cells.

PATIENTS AND METHODS

This was a phase I study using 3 dose levels of BTZ. G-CSF was administered for 5 days. On the evening of the fourth day, a single dose of BTZ was administered. Peripheral blood was drawn 1 to 2 hours before and 15 to 18 hours after BTZ administration (before day 5 G-CSF administration) to analyze the mobilization effect of BTZ. Standard apheresis was then performed starting on day 5. After mobilization, patients underwent autologous stem cell transplantation (ASCT) per institutional guidelines.

RESULTS

Ten patients were enrolled. There were no dose-limiting toxicities. Median peripheral blood CD34⁺ cells at day 4 before BTZ administration was 16 per microliter and 15 hours later was 32 per microliter suggesting that administration of BTZ at peak G-CSF mobilization augments the mobilization effect of G-CSF. The effect of BTZ on circulating MM cells was unclear. All patients had successful engraftment after ASCT.

CONCLUSION

Administration of 1 dose of BTZ at peak G-CSF mobilization was safe and well tolerated, enhanced stem cell mobilization, and did not affect graft viability. The mobilization effect of BTZ at peak G-CSF mobilization shown in this phase I study needs to be confirmed in a larger randomized trial.

Mouse Flk-1+Sca-1- mesenchymal stem cells: functional plasticity in vitro and immunoregulation in vivo

OBJECTIVES

Mesenchymal stem cells (MSCs) represent a powerful tool in regenerative medicine because of their differentiation and migration capacities. Moreover, the immunomodulatory ability of MSCs may be used to develop therapies for the treatment of autoimmune diseases.

METHODS

In this study, we isolated Flk-1Sca-1 MSCs from bone marrow (bMSCs). Next, we studied their biological characteristics and immunologic functions. We also investigated their effects on graft-versus-host disease (GVHD) associated with allogeneic bone marrow transplantation in mice.

RESULTS

Flk-1Sca-1 bMSCs were able to differentiate into fat and cartilage cells, indicating that the isolated cells had stem cell properties. They could also suppress alloantigen-induced T cell proliferation in vitro in a dose-dependent manner. Infusion of bMSCs into allogeneic bone marrow-transplanted mice alleviated the lethal GVHD that occurred in control recipient mice. There was significantly lower mortality among the recipients of the Flk-1Sca-1 bMSCs that also ameliorated the clinical symptoms and GVHD histopathology. Beneficial effects on GVHD by Flk-1Sca-1 bMSCs were also observed when MSCs were engineered to express anti-inflammatory cytokines IL-4 and IL-10 and decrease expression of proinflammatory cytokines IFN-γ, TNF-α, and IL-2.

CONCLUSION

Flk-1Sca-1 bMSCs have stem cell properties and can efficiently ameliorate the GVHD associated with allogeneic bone marrow transplantation in mice.

Concise review: next-generation cell therapies to prevent infections in neutropenic patients

High-dose chemotherapy is accompanied by an obligate period of neutropenia. Resulting bacterial and fungal infections are the leading cause of morbidity and mortality in neutropenic patients despite prophylactic antimicrobials and hematopoietic growth factor supplements. Replacing neutrophils in the patient through transfusion of donor cells is a logical solution to prevent fulminant infections. In the past, this strategy has been hampered by poor yield, inability to store collected cells, and possible donor morbidity caused by granulocyte colony-stimulating factor injections and apheresis. Today, neutrophil-like cells can be manufactured in the laboratory at the clinical scale from hematopoietic stem and progenitor cells enriched from umbilical cord blood. This article reviews the rationale for focusing research efforts toward ex vivo neutrophil production and explores clinical settings for future trials.

Applications of human hematopoietic stem cells isolated and expanded from different tissues in regenerative medicine

Bone marrow transplantation is a well-established stem cell-based therapy for the management of malignant and nonmalignant hematological disorders. In addition to the bone marrow, therapeutic hematopoietic stem cells (HSCs) can also be obtained from umbilical cord blood and mobilized peripheral blood. Transplantation of HSCs isolated from these tissues can be carried out with or without prior enrichment of specific cell types. New methodologies have been developed for lineage-specific HSC expansion and their transplantation as a supplementary treatment to whole bone marrow transplantation. In this review we have described the current methodologies for isolating and processing HSCs from various tissues, and discussed strategies to generate sufficient and functional HSCs for clinical and preclinical applications by expansion ex vivo. The various disease conditions in which these cells could be used, and the methods for delivering the cells into patients, are also discussed.

Reovirus as a successful ex vivo purging modality for multiple myeloma

Autologous stem cell rescue (ASCT) following high-dose myeloablative chemotherapy is considered to be a therapeutic option for many multiple myeloma (MM) patients; however relapse post ASCT presents a major challenge. The oncolytic potential of reovirus has been previously demonstrated and is currently undergoing phase I monotherapy clinical trials for MM and phase II/III clinical trials for solid tumors. Here we tested the hypothesis that reovirus can successfully purge MM in a murine model that partially recapitulates human MM. RPMI 8226, MM1S, H929 and U266 human myeloma cell lines were exposed to reovirus and oncolysis was assessed. Apheresis product admixed with MM cells was purged with live reovirus (LV) or dead virus (DV) and purging efficacy was monitored via flow cytometry, reverse transcribed-PCR (RT-PCR) and disease relapse in non obese diabetic/severe combined immune deficient (NOD/SCID) mice. Significant LV purging was seen with MM1S, H929 and U266 and the complete ex vivo purging achieved with RPMI 8226 was confirmed by flow cytometry, RT-PCR and absence of disease relapse in vivo. Mice that received LV-purged autografts exhibited 100% survival in comparison to mice that received DV-purged controls. Reovirus's unique ability to kill MM while sparing hematopoietic stem cells places it as an attractive purging agent for MM during ASCT.

Transcriptional repression of Bim by a novel YY1-RelA complex is essential for the survival and growth of Multiple Myeloma

Multiple Myeloma (MM) is an incurable plasma cell cancer that is caused by several chromosomal translocations and gene deletions. Although deregulation of several signaling pathways including the Nuclear Factor-Kappa B (NF-κB) pathway has been reported in MM, the molecular requirement and the crosstalk between NF-κB and its target genes in MM cell survival has been largely unclear. Here, we report that Yin Yang1 (YY1), a target gene for NF-κB, is hyperexpressed in most MM tumor cells obtained from human patients, exhibits constitutive nuclear localization, and is essential for survival of MM cells. Mechanistically, we report a novel YY1-RelA complex formation, which is essential to transcriptionally repress a proapoptotic gene Bim. In line with this, depletion of YY1 or RelA resulted in elevated levels of Bim and apoptosis. Moreover, both YY1 and RelA are recruited to the Bim promoter and are required to repress the Bim promoter. Importantly, depletion of YY1 or RelA almost completely impaired the colony forming ability of MM progenitor cells suggesting that both RelA and YY1 are essential for the survival and growth of MM progenitor cells. Moreover, depletion of either YY1 or RelA completely inhibited MM tumor growth in xenograft models for human myeloma. Thus, a novel RelA-YY1 transcriptional repression complex is an attractive drug target in MM.

Cell-specific multifunctional processing of heterogeneous cell systems in a single laser pulse treatment

Current methods of cell processing for gene and cell therapies use several separate procedures for gene transfer and cell separation or elimination, because no current technology can offer simultaneous multifunctional processing of specific cell subsets in highly heterogeneous cell systems. Using the cell-specific generation of plasmonic nanobubbles of different sizes around cell-targeted gold nanoshells and nanospheres, we achieved simultaneous multifunctional cell-specific processing in a rapid single 70 ps laser pulse bulk treatment of heterogeneous cell suspension. This method supported the detection of cells, delivery of external molecular cargo to one type of cells and the concomitant destruction of another type of cells without damaging other cells in suspension, and real-time guidance of the above two cellular effects.

Selective purging of human multiple myeloma cells from autologous stem cell transplantation grafts using oncolytic myxoma virus

Autologous stem cell transplantation and novel therapies have improved overall survival of patients with multiple myeloma; however, most patients relapse and eventually succumb to their disease. Evidence indicates that residual cancer cells contaminate autologous grafts and may contribute to early relapses after autologous stem cell transplantation. Here, we demonstrate that ex vivo treatment with an oncolytic poxvirus called myxoma virus results in specific elimination of human myeloma cells by inducing rapid cellular apoptosis while fully sparing normal hematopoietic stem and progenitor cells. The specificity of this elimination is based on strong binding of the virus to myeloma cells coupled with an inability of the virus to bind or infect CD34(+) hematopoietic stem and progenitor cells. These 2 features allow myxoma to readily identify and distinguish even low levels of myeloma cells in complex mixtures. This ex vivo rabbit-specific oncolytic poxvirus called myxoma virus treatment also effectively inhibits systemic in vivo engraftment of human myeloma cells into immunodeficient mice and results in efficient elimination of primary CD138(+) myeloma cells contaminating patient hematopoietic cell products. We conclude that ex vivo myxoma treatment represents a safe and effective method to selectively eliminate myeloma cells from hematopoietic autografts before reinfusion.