A unique three-dimensional model for evaluating the impact of therapy on multiple myeloma

Blood ◽  
2008 ◽  
Vol 112 (7) ◽  
pp. 2935-2945 ◽  
Author(s):  
Julia Kirshner ◽  
Kyle J. Thulien ◽  
Lorri D. Martin ◽  
Carina Debes Marun ◽  
Tony Reiman ◽  
...  
Keyword(s):  
Stem Cells ◽  
Multiple Myeloma ◽  
Plasma Cells ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Preclinical Model ◽  
Drug Resistant ◽  
Three Dimensional Model ◽  
The Impact

AbstractAlthough the in vitro expansion of the multiple myeloma (MM) clone has been unsuccessful, in a novel three-dimensional (3-D) culture model of reconstructed bone marrow (BM, n = 48) and mobilized blood autografts (n = 14) presented here, the entire MM clone proliferates and undergoes up to 17-fold expansion of malignant cells harboring the clonotypic IgH VDJ and characteristic chromosomal rearrangements. In this system, MM clone expands in a reconstructed microenvironment that is ideally suited for testing specificity of anti-MM therapeutics. In the 3-D model, melphalan and bortezomib had distinct targets, with melphalan targeting the hematopoietic, but not stromal com-partment. Bortezomib targeted only CD138+CD56+ MM plasma cells. The localization of nonproliferating cells to the reconstructed endosteum, in contact with N-cadherin–positive stroma, suggested the presence of MM-cancer stem cells. These drug-resistant CD20+ cells were enriched more than 10-fold by melphalan treatment, exhibited self-renewal, and generated clonotypic B and plasma cell progeny in colony forming unit assays. This is the first molecularly verified demonstration of proliferation in vitro by ex vivo MM cells. The 3-D culture provides a novel biologically relevant preclinical model for evaluating therapeutic vulnerabilities of all compartments of the MM clone, including presumptive drug-resistant MM stem cells.

scholarly journals A novel BCMA/CD3 bispecific T-cell engager for the treatment of multiple myeloma induces selective lysis in vitro and in vivo

Leukemia ◽  
2016 ◽  
Vol 31 (8) ◽  
pp. 1743-1751 ◽  
Author(s):  
S Hipp ◽  
Y-T Tai ◽  
D Blanset ◽  
P Deegen ◽  
J Wahl ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
T Cell ◽  
Plasma Cells ◽  
Ex Vivo ◽  
Xenograft Model ◽  
Selective Lysis ◽  
Bispecific T Cell Engager

Abstract B-cell maturation antigen (BCMA) is a highly plasma cell-selective protein that is expressed on malignant plasma cells of multiple myeloma (MM) patients and therefore is an ideal target for T-cell redirecting therapies. We developed a bispecific T-cell engager (BiTE) targeting BCMA and CD3ɛ (BI 836909) and studied its therapeutic impacts on MM. BI 836909 induced selective lysis of BCMA-positive MM cells, activation of T cells, release of cytokines and T-cell proliferation; whereas BCMA-negative cells were not affected. Activity of BI 836909 was not influenced by the presence of bone marrow stromal cells, soluble BCMA or a proliferation-inducing ligand (APRIL). In ex vivo assays, BI 836909 induced potent autologous MM cell lysis in both, newly diagnosed and relapsed/refractory patient samples. In mouse xenograft studies, BI 836909 induced tumor cell depletion in a subcutaneous NCI-H929 xenograft model and prolonged survival in an orthotopic L-363 xenograft model. In a cynomolgus monkey study, administration of BI 836909 led to depletion of BCMA-positive plasma cells in the bone marrow. Taken together, these results show that BI 836909 is a highly potent and efficacious approach to selectively deplete BCMA-positive MM cells and represents a novel immunotherapeutic for the treatment of MM.

scholarly journals Evaluation of in vitro effects of various targeted drugs on plasma cells and putative neoplastic stem cells in patients with multiple myeloma

Oncotarget ◽  
2016 ◽  
Vol 7 (40) ◽  
pp. 65627-65642 ◽  
Author(s):  
Katharina Blatt ◽  
Harald Herrmann ◽  
Gabriele Stefanzl ◽  
Wolfgang R. Sperr ◽  
Peter Valent
Keyword(s):  
Stem Cells ◽  
Multiple Myeloma ◽  
Plasma Cells ◽  
Targeted Drugs ◽  
Neoplastic Stem Cells ◽  
In Vitro Effects

A Unique Pre-Clinical Model Providing Access to a Drug Resistant Population within the Multiple Myeloma Stem Cell Niche in a Novel 3-D Culture System for Bone Marrow.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 547-547
Author(s):  
Julia Kirshner ◽  
Kyle J. Thulien ◽  
Lorri D. Martin ◽  
Carina Debes Marun ◽  
Tony Reiman ◽  
...  
Keyword(s):  
Stem Cells ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Stem Cell ◽  
Culture System ◽  
Hematopoietic Cells ◽  
Drug Resistant ◽  
Culture Model

Abstract Bone marrow (BM), a site of hematopoiesis, is a multicellular tissue with a complex architecture. Multiple myeloma (MM) is an incurable plasma cell malignancy where even patients in remission succumb to an inevitable relapse. While considerable progress has been made towards understanding and treating MM, to date, there is no culture system which can recapitulate the complex interactions within the BM microenvironment. Current failure to grow the MM clone within the context of human microenvironment hampers progress into the understanding of the biology of MM and design of biologically relevant therapies. Here we present an in vitro three-dimensional (3-D) tissue culture model which recapitulates the human BM microenvironment allowing for the growth and expansion of the MM clone. Cells from the BM aspirates are grown in a fibronectin, laminin and collagen rich ECM designed to reconstruct in vitro endosteum and central marrow, mimicking the in vivo microenvironment of the BM. Proliferation and redistribution of cells within reconstructed ECM results in stratification of the culture, mimicking the in vivo condition where cells occupy individual niches. Cellular composition of the culture is maintained in accordance with the proliferation properties of the BM where osteoblasts, osteoclasts, adipocytes and stromal cells differentiate along with the full complement of the hematopoietic cells. BM cultures from normal donors are well-organized with osteoclasts and hematopoietic cells occupying distinct positions in the ECM. In contrast, reconstructed BM from MM patients is disorganized in 3-D where osteoclasts intermingle with the hematopoietic compartment. The MM malignant clone is expanded in 3-D cultures as measured by real-time quantitative PCR (rqPCR) for genomic clonotypic VDJ sequences. Malignant B and plasma cells proliferate in these cultures and FISH analysis reveals that their progeny harbor chromosomal abnormalities identical to those that mark the malignant clone prior to culture. Preclinical testing of emerging therapeutics targeted for multiple myeloma is hindered by the failure of the current models to sustain growth of the myeloma clone. In the 3-D culture, myeloma clone expands within its native environment providing an ideal preclinical model where conventional (Melphalan) and novel (Velcade) therapeutics efficiently and selectively kill their target cells. In the 3-D BM culture model, non-proliferating, label retaining cells (LRC) concentrate at a putative endosteum-marrow junction, where hematopoietic stem cells have been shown to localize in vivo, suggesting that the drug-resistant myeloma stem cells localize to the endosteal niche. In a colony-forming assay, drug-resistant LRC purified from the 3-D cultures form clonal colonies composed of malignant cells with patient specific clonotypic VDJ sequences. Recapitulation of the BM architecture in vitro is a first step towards the identification and therapeutic targeting of the elusive myeloma stem cell.

Towards CD38-Targeted Immunochemotherapy of Multiple Myeloma: Significant Improvement of Anti-Myeloma Effects of Lenalidomide, Bortezomib and Dexamethason by CD38-Specific Antibody Daratumumab, Even in Chemotherapy Resistant/Intolerant Patients

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4988-4988
Author(s):  
Inger S. Nijhof ◽  
Jeroen Lammerts van Bueren ◽  
Berris van Kessel ◽  
Michel de Weers ◽  
Joost M Bakker ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Research Funding ◽  
Plasma Cells ◽  
Ex Vivo ◽  
Human Antibody ◽  
Synergistic Activity ◽  
Effector Cells ◽  
Complement Dependent Cytotoxicity

Abstract Abstract 4988 To date, multiple myeloma (MM) remains an incurable malignancy of antibody-producing clonal plasma cells. The introduction of a new generation of immunomodulatory agents, such as lenalidomide (LEN), and the potent proteasome inhibitor bortezomib (BORT), used alone or in combination with steroids (dexamethasone; DEX or prednisone; PRED) has significantly improved the overall survival of MM patients. Nonetheless, all chemotherapy strategies are eventually hampered by the development of drug-resistance. Towards a novel and effective targeted immunotherapy for MM, we have developed daratumumab (DARA), a CD38 human antibody with broad-spectrum killing activity. In vitro, DARA induces substantial anti-MM effects mainly via ADCC (antibody dependent cellular cytotoxicity) and CDC (complement dependent cytotoxicity). In ex vivo assays, which allowed us to address killing of MM cells in bone marrow aspirates isolated from MM patients, enhanced or even synergistic MM cell killing was observed when DARA was combined with LEN, or with cocktails of LEN/BORT/DEX and melphalan/BORT/DEX. We now extended these ex vivo analyses to evaluate whether DARA in combination with LEN, BORT and DEX could improve the lysis of MM cells in bone marrow aspirates derived from 22 patients of whom 9 became refractory for LEN and 6 for LEN and BORT. DARA significantly enhanced the lysis of MM cells when combined with LEN or BORT in virtually all patients, including the LEN- and LEN/BORT-refractory patients. The combination of DARA+BORT and DARA+DEX induced additive killing, suggestive of lysis by independent mechanisms. When combined with LEN, DARA improved the lysis of MM cells in a synergistic manner in both non-refractory and LEN-refractory patients. This is suggestive of killing by at least partly complementary mechanisms. Synergistic activity of LEN and DARA was attributable to LEN-induced activation of effector cells that were involved in DARA-mediated ADCC. In addition, enhanced/synergistic direct killing of MM cells was observed. Experiments are under way to further investigate the mechanism underlying synergistic activity of DARA and LEN. In conclusion, our results provide a rationale for clinical evaluation of DARA in combination with LEN, BORT and DEX including in patients refractory to these drugs. Disclosures: van Bueren: genmab: Employment. de Weers:genmab: Employment. Bakker:genmab: Employment. Parren:genmab: Employment. Lokhorst:genmab: Consultancy, Research Funding. Mutis:genmab: Research Funding.

Melphalan and XPO1 Inhibitor Combination Therapy for the Treatment of Multiple Myeloma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2084-2084 ◽  
Author(s):  
Joel G Turner ◽  
Jana L Dawson ◽  
Steven Grant ◽  
Kenneth H. Shain ◽  
Yun Dai ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
De Novo ◽  
Ex Vivo ◽  
Myeloma Cell ◽  
Drug Resistant ◽  
Cell Viability Assay ◽  
Myeloma Cells ◽  
Multiple Myeloma Cell

Abstract Introduction High-dose melphalan chemotherapy with autologous stem cell transplant remains the standard of care for the treatment of multiple myeloma. However, patients eventually develop drug resistance and die from progressive disease despite the introduction of therapies using proteosome inhibitors (PIs) and immunomodulatory drugs (IMIDs). The incurable nature of multiple myeloma clearly demonstrates the need for novel agents and treatments. Here, our aim was to investigate whether the use of XPO1 (exportin 1, CRM1) inhibitors (XPO1i) could sensitize de novo and acquired drug-resistant multiple myeloma cells both in vitro and ex vivo to the alkylating agent melphalan. Materials and Methods Human multiple myeloma cell lines NCI-H929, RPMI-8226, U266 and PBMC controls were treated in vitro with the XPO1i KOS-2464 and the orally available Selective Inhibitor of Nuclear Export (SINE) selinexor (KPT-330) or) +/- melphalan. Multiple myeloma cells were grown at high-density conditions (>3-5x106 cells/mL). High-density multiple myeloma cells have been shown to possess de novo drug resistance. Sensitivity of the XPO1i/melphalan-treated NCI-H929 cells was measured by cell viability assay (CellTiter-Blue). Apoptosis in XPO1i/melphalan-treated NCI-H929, RPMI-8226, and U266 cells was assayed using flow cytometry (activated caspase 3). Proximity ligation assays were performed to assess XPO1-p53 binding in the presence of an XPO1i. Western blots of XPO1i-treated myeloma cells were performed for nuclear and total p53. Drug-resistant U266 (PSR) and 8226 (8226/B25) myeloma cell lines were developed by incremental exposure to bortezomib. PSR cells are able to grow in 15 nM bortezomib and the 8226/B25 in 25 nM. These resistant myeloma cells were treated in vitro with XPO1i +/- melphalan. Sensitivity to therapy was measured by apoptosis and cell viability assay. Multiple myeloma cells isolated from patients with newly diagnosed, relapsed, or refractory disease were treated with XPO1i +/- melphalan and CD138+/light chain+ myeloma cells and assayed for apoptosis. Results Multiple myeloma cell (NCI-H929) viability was decreased synergistically by XPO1i when used in combination with melphalan, as shown by the calculated combinatorial index (CI) values. We examined sequencing of the drugs and found that concurrent treatment with melphalan (10 µM) and selinexor (300 nM) for 48 hours produced the best results (CI value 0.370, n=6). Sequential treatment (selinexor for 24 hours followed by melphalan for an additional 24 hours) or the reverse sequence had slightly less synergy, with CI values of 0.491 (n=9) and 0.565 (n=3), respectively. Normal PBMC control cells were unaffected by XPO1i/melphalan treatment as shown by viability and apoptotic assays. Proximity ligation assay demonstrated that XPO1i blocks XPO1/p53 binding. Western blot showed that the XPO1i treatment of myeloma cells increased nuclear and total p53. Drug-resistant 8226/B25 myeloma cells but not PSR cells were found to be resistant to melphalan when compared to parental cell lines. Both resistant myeloma cell lines were sensitized by XPO1i to melphalan as shown by apoptosis assay (3- to 10-fold). CD138+/light chain+ myeloma cells derived from newly diagnosed, relapsed, and refractory myeloma patients were also sensitized by XPO1 inhibitors to melphalan as demonstrated by apoptotic assays (e.g. activated caspase 3). Conclusions XPO1i synergistically improved the response of de novo and acquired drug-resistant myeloma cells to melphalan in vitro and ex vivo. It is possible that this synergy may be due to an increase of nuclear p53 by XPO1i and the reported activation of p53 by melphalan. Future studies include in vitro experiments using drug-resistant human U266 myeloma cells in NOD-SCID-gamma mice and clinical trials using melphalan in combination with the SINE selinexor. Combination therapies using selinexor and melphalan may significantly improve the treatment of myeloma. Disclosures Kauffman: Karyopharm Therapeutics: Employment. Shacham:Karyopharm Therapeutics: Employment.

Magnetically actuated microrobots as a platform for stem cell transplantation

2019 ◽  
Vol 4 (30) ◽  
pp. eaav4317 ◽  
Author(s):  
Sungwoong Jeon ◽  
Sangwon Kim ◽  
Shinwon Ha ◽  
Seungmin Lee ◽  
Eunhee Kim ◽  
...  
Keyword(s):  
Stem Cells ◽  
Brain Slice ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Magnetically Actuated ◽  
Magnetic Microrobots ◽  
Hippocampal Neural Stem Cells ◽  
Human Nose

Magnetic microrobots were developed for three-dimensional culture and the precise delivery of stem cells in vitro, ex vivo, and in vivo. Hippocampal neural stem cells attached to the microrobots proliferated and differentiated into astrocytes, oligodendrocytes, and neurons. Moreover, microrobots were used to transport colorectal carcinoma cancer cells to tumor microtissue in a body-on-a-chip, which comprised an in vitro liver-tumor microorgan network. The microrobots were also controlled in a mouse brain slice and rat brain blood vessel. Last, microrobots carrying mesenchymal stem cells derived from human nose were manipulated inside the intraperitoneal cavity of a nude mouse. The results indicate the potential of microrobots for the culture and delivery of stem cells.

scholarly journals In vivo quantitative assessment of therapeutic response to bortezomib therapy in disseminated animal models of multiple myeloma with [18F]FDG and [64Cu]Cu-LLP2A PET

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anchal Ghai ◽  
Nikki Fettig ◽  
Francesca Fontana ◽  
John DiPersio ◽  
Mike Rettig ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Therapeutic Response ◽  
Plasma Cells ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Molar Activity ◽  
Quantitative Pet

Abstract Background Multiple myeloma (MM) is a disease of cancerous plasma cells in the bone marrow. Imaging-based timely determination of therapeutic response is critical for improving outcomes in MM patients. Very late antigen-4 (VLA4, CD49d/CD29) is overexpressed in MM cells. Here, we evaluated [18F]FDG and VLA4 targeted [64Cu]Cu-LLP2A for quantitative PET imaging in disseminated MM models of variable VLA4 expression, following bortezomib therapy. Methods In vitro and ex vivo VLA4 expression was evaluated by flow cytometry. Human MM cells, MM.1S-CG and U266-CG (C: luciferase and G: green fluorescent protein), were injected intravenously in NOD-SCID gamma mice. Tumor progression was monitored by bioluminescence imaging (BLI). Treatment group received bortezomib (1 mg/kg, twice/week) intraperitoneally. All cohorts (treated, untreated and no tumor) were longitudinally imaged with [18F]FDG (7.4–8.0 MBq) and [64Cu]Cu-LLP2A (2–3 MBq; Molar Activity: 44.14 ± 1.40 MBq/nmol) PET, respectively. Results Flow cytometry confirmed high expression of CD49d in U266 cells (> 99%) and moderate expression in MM.1S cells (~ 52%). BLI showed decrease in total body flux in treated mice. In MM.1S-CG untreated versus treated mice, [64Cu]Cu-LLP2A localized with a significantly higher SUVmean in spine (0.58 versus 0.31, p < 0.01) and femur (0.72 versus 0.39, p < 0.05) at week 4 post-tumor inoculation. There was a four-fold higher uptake of [64Cu]Cu-LLP2A (SUVmean) in untreated U266-CG mice compared to treated mice at 3 weeks post-treatment. Compared to [64Cu]Cu-LLP2A, [18F]FDG PET detected treatment-related changes at later time points. Conclusion [64Cu]Cu-LLP2A is a promising tracer for timely in vivo assessment of therapeutic response in disseminated models of MM.

scholarly journals In silico Prediction Followed By in Vitro validation Identifies the Survivin Inhibitor YM155 As a Potent Secondary Drug Against Pi-Resistant Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5543-5543
Author(s):  
Harish Kumar ◽  
Ujjal Kumar Mukherjee ◽  
Li Chen ◽  
Amit Kumar Mitra
Keyword(s):  
Stem Cells ◽  
Multiple Myeloma ◽  
Cell Lines ◽  
In Silico ◽  
Proteasome Inhibitors ◽  
Standard Of Care ◽  
Myeloma Cell ◽  
Drug Resistant ◽  
Multiple Myeloma Cell

Drug resistance is a major cause of concern in cancer chemotherapy that not only reduces efficacy but also causes toxicity through overdosing. Multiple myeloma (MM) is the second-most common haematological malignancy in the USA that remains a challenging disease to cure due to the presence of significant complexity and heterogeneity at molecular level with high treatment cost. Proteasome inhibitor, the standard of care drug, has proven to remarkably improve myeloma patient outcomes but is associated with dose limiting toxicities and drug resistance. Therefore, new combination treatment regimens are urgently needed for the treatment of PI-resistant MM that can lower the required dose of standard-of-care drug without compromising on treatment efficacy. We have created an optimization-regularization based computational prediction method called secDrug that uses large-scale pharmacogenomics databases to identify novel secondary drugs against PI-resistance when used as single agent or in combination. We applied secDrug to PIs-resistant cell lines (>100) in the Genomics of Drug Sensitivity in Cancer (GDSC) database and predicted the top drugs that can be best combined with PIs to overcome PI-resistance in MM. These include: Survivin inhibitor (YM155), Nicotinamide phospho ribosyl transferase or Nampt inhibitor (FK866), PIKfyve inhibitor (YM201636), Raf inhibitor (PLX-4720), Bcl2 inhibitor (Navitoclax),HSP90 inhibitor (17-AAG), AKT inhibitor (KIN00102), HDAC inhibitors (Panobinostat, SAHA), S6K1-specific inhibitor (PF-4708671), and the neddylation inhibitor (MLN4924). To validate our prediction results, we treated human multiple myeloma cell lines (HMCLs) highly resistant to the proteasome inhibitors Bortezomib, Carfilzomob, Oprozomib and Ixazomib and >10 clonally derived acquired resistant cells with the top predicted best secondary drugs. Next, we treated three pairs of parental PI-sensitive (P) and clonally-derived PI-resistant (R) cell lines from PI-sensitive (P) HMCLs representing acquired PI-response with the top predicted drug combinations. Our preliminary in vitro data confirmed our in silico predictions of secondary drugs based on secDrug analysis. Among these, YM155 and YM155 + Ixazomib showed strikingly very high in vitro cytotoxicity against PI- resistant MM cell lines (Figure 1). The results, based on Chou-Talalay's combination index (CI) theorem, show that this combination works highly synergistically where the IC50 of ixazomib in MM cells was significantly reduced in presence of YM155. Similar results were obtained for the other top predicted combination regimens. Our findings provide a strong case for combining YM155 with ixazomib to enhance sensitivity or overcome resistance to ixazomib and thereby improve patient outcome. Further, this study provides additional support towards using secDrug for predicting secondary drugs in cancers resistant to the standard-of-care therapy. Currently, we are exploring the molecular mechanisms behind the synergism between proteasome inhibitors and the top drugs identified by our algorithm as candidates for secondary combination therapies using next-gen transcriptomics and single-cell analysis approaches. Earlier studies have shown that YM155 potentially induces selective cell death in human pluripotent stem cells. Further, the presence of cancer stem cells sub population/ MM-CSCs in drug-resistant tumors have been shown to significantly contribute to the development of PI-resistance in MM. Hence, we propose that YM155 reverses PI-resistance by reducing the stem cell load in multiple myeloma cell line model system. Therefore, our future plan is to assess the effects of YM155 on MM-cancer stem cells like subclones/ sub population/ MM-CSCs including CD19- CD138- quiescent stem cells, ALDH+ and side populations/SP) in drug-resistant tumors. Overall, our in vitro validation results corroborated with our in silico prediction of secondary drugs. Disclosures No relevant conflicts of interest to declare.

scholarly journals Oncolytic immunotherapy and bortezomib synergy improves survival of refractory multiple myeloma in a preclinical model

2019 ◽  
Vol 3 (5) ◽  
pp. 797-812 ◽  
Author(s):  
Chandini M. Thirukkumaran ◽  
Zhong Qiao Shi ◽  
Gerard J. Nuovo ◽  
Joanne Luider ◽  
Karen A. Kopciuk ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Therapeutic Strategy ◽  
Plasma Cells ◽  
Therapeutic Potential ◽  
Standard Of Care ◽  
Tumor Burden ◽  
Preclinical Model ◽  
Cytokine Release ◽  
Systemic Nature

Abstract The oncolytic reovirus (RV) has demonstrated clinical efficacy and minimal toxicity in a variety of cancers, including multiple myeloma (MM). MM is a malignancy of plasma cells that is considered treatable but incurable because of the 90% relapse rate that is primarily from drug resistance. The systemic nature of MM and the antitumor immunosuppression by its tumor microenvironment presents an ongoing therapeutic challenge. In the present study, we demonstrate that RV synergizes with the standard-of-care MM drug bortezomib (BTZ) and, importantly, enhances its therapeutic potential in therapy-resistant human MM cell lines in vitro. Using the syngeneic Vk*MYC BTZ-resistant immunocompetent transplantable MM murine model, we also demonstrate that mice harboring BTZ-insensitive MM tumors respond to the RV/BTZ combination treatment in terms of decreased tumor burden and improved overall survival (P &lt; .00001). We demonstrate that BTZ augments RV replication in tumor-associated endothelial cells and myeloma cells, leading to enhanced viral delivery and thereby stimulating cytokine release, immune activity, apoptosis, and reduction of the MM-associated immune suppression. We conclude that combined RV/BTZ is an attractive therapeutic strategy with no safety signals for the treatment of MM.

Cancer Stem Cell Targeting in Multiple Myeloma by GRN163L, a Novel and Potent Telomerase Inhibitor.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2540-2540 ◽  
Author(s):  
William Matsui ◽  
Qiuju Wang ◽  
Milada Vala ◽  
James P. Barber ◽  
Alan Meeker ◽  
...  
Keyword(s):  
Stem Cells ◽  
Multiple Myeloma ◽  
Cell Lines ◽  
Plasma Cells ◽  
Cell Populations ◽  
Telomerase Inhibition ◽  
Telomerase Inhibitor ◽  
Clonogenic Growth

Abstract Telomerase activity (TA) is required within normal cells capable of long-term replication, including stem cells and is upregulated in many cancers. In the absence of TA or presence of TA inhibitors, the progressive shortening of telomeres ultimately results in cellular senescence and/or apoptosis. These observations support that TA inhibitors represent a novel class of anti-tumor agents. Much evidence suggests that human cancers display a hierarchical cellular organization that mirrors normal tissues. Cancer stem cells (CSC) are derived from the malignant transformation of normal stem cells and progenitors and retain the capacity to self-renew. Moreover, CSC give rise to differentiated tumor cells that form the bulk of the tumor mass, but have little or no capacity for long-term proliferation. We recently demonstrated that the malignant CD138+ plasma cells in multiple myeloma (MM) have limited replicative potential; instead they arise from the differentiation of clonogenic CSC that resemble normal memory B cells (CD138negCD19+CD27+). In addition, several groups have demonstrated that telomerase inhibitors are active against human MM cell lines in vitro and in vivo. We examined TA in CD138+ plasma cells and CD138neg precursors, and studied the effects of telomerase inhibition against both cell populations. We isolated CD138+ and CD138neg cells by FACS from three human MM cell lines (RPMI 8225, NCI-H929, and U266) and measured TA using a PCR-based assay of activity. For each cell line, TA was detectable within both the CD138neg and CD138+ cell populations. GRN163L is a lipid conjugated 13 nucleotide thio-phosphoramidate oligonucleotide that acts as a potent and specific active site inhibitor of telomerase. We found that treatment with GRN163L (0.1–5μM) markedly reduced TA within 48 hours. To examine the effects of telomerase inhibition on clonogenic growth, we continuously cultured CD138+ and CD138neg RPMI 8226 cells with GRN163L (1μM). Cells were collected weekly, washed to remove GRN163L, and then plated in methylcellulose to assess colony formation. We found that GRN163L was active against both CD138+ and CD138neg cells and eliminated the colony forming potential of both by 5 weeks. Similarly, we found that GRN163L inhibited the in vitro clonogenic growth of CD138neg MM CSC isolated from the bone marrow aspirates of patients with MM. These data demonstrate that TA is detectable within both immature MM CSC and mature MM plasma cells, and that CSC from both cell lines and primary clinical samples are targeted by the telomerase inhibitor GRN163L. Therefore, this agent may offer a novel therapeutic approach to myeloma as well as other diseases in which CSC have been identified.

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