Activating KRAS, NRAS, and BRAF Mutants Enhance Proteasome Capacity and Reduce Endoplasmic Reticulum Stress in Multiple Myeloma, Thereby Promoting Plasma Cell Survival and Proteasome Inhibitor Resistance

Abstract Introduction: Multiple myeloma, a malignant proliferation of differentiated plasma cells, is the second most commonly diagnosed hematologic malignancy, and the number of cases may grow by almost 60% between 2010 and 2030. Recent therapeutic advances, including the use of proteasome inhibitors (PIs), have contributed to a doubling of the median overall survival in myeloma patients. This has been paralleled by an increased understanding of the mutational spectrum in this disease, which was first noted almost three decades ago to harbor KRAS and NRAS mutations. KRAS, NRAS, and BRAF mutations which induce p44/42 Mitogen-activated protein kinase (MAPK) signaling are found in about half of myeloma patients, and seem to contribute to proteasome inhibitor (PI) resistance, but the underlying mechanisms still remains elusive. Methods: ANBL-6 and U266 human-derived myeloma cell lines have endogenous wild-type (WT) KRAS, NRAS, and BRAF, and were used in this study. All cell lines were validated through The MD Anderson Cancer Center Characterized Cell Line Core Facility. We established lines stably expressing WT, constitutively active (CA)(G12V/G13D/Q61H), or dominant negative (DN)(S17N) KRAS and NRAS mutants, or V600E or DN BRAF. Cell viability was evaluated using the WST-1 tetrazolium reagent, while the chymotrypsin-, trypsin- and caspase-like activities were determined using fluorogenic substrates. Results: CA KRAS, NRAS, and BRAF mutants reduced the sensitivity of ANBL-6 and U266 cells to bortezomib and carfilzomib, while their DN variants sensitized cells to both PIs. This was associated with an induction by these CA mutants of the proteasome chymotrypsin-, trypsin- and caspase-like activities, while the DN variants reduced proteasome activity. These activity changes occurred in parallel with increased expression at both the mRNA and protein levels of catalytically active Proteasome subunit beta (PSMB)-8, PSMB9, and PSMB10, and of the proteasome assembly chaperone Proteasome maturation protein (POMP). Mechanistic studies showed that MAPK induction by the CA mutants caused activation of the ETS transcription factor (ELK1), which was found to have consensus binding sites in the promoters of PSMB8, PSMB9, PSMB10, and POMP. Notably, ELK1 suppression reduced PSMB8, PSMB9, PSMB10, and POMP expression, directly linking RAS/RAF/MAPK signaling to proteasome biology, and this suppression enhanced PI sensitivity. Inhibition of MAPK signaling with either the MAPK kinase (MEK) inhibitor selumetinib or the pan-RAF inhibitor TAK-632 showed synergistic activity with either bortezomib or carfilzomib that was more consistent in cell lines harboring CA mutants as opposed to the DN or WT constructs. Combination regimens of selumetinib or TAK-632 with either bortezomib or carfilzomib induced greater inhibition of the proteasome chymotrypsin-, trypsin- and caspase-like activities than the PIs as single agents. Finally, CA KRAS, NRAS, and BRAF mutants reduced expression levels of genes and proteins involved in the unfolded protein response (UPR), including Activating transcription factor (ATF)-4, -5, and -6, as well as C/EBP homologous protein transcription factor (CHOP) and the spliced variant of X-box binding protein 1 (XBP1s). In contrast, their dominant negative counterparts enhanced expression of the UPR effectors, consistent with an increase in endoplasmic reticulum (ER) stress. Conclusion: Taken together, the data support the hypothesis that activating MAPK pathway mutations enhance PI resistance by increasing proteasome capacity, and provide a rationale for targeting such patients with PI/RAF or PI/MEK inhibitor combinations. Moreover, they argue that these mutations promote plasma cell survival by reducing cellular stress, thereby distancing myeloma cells from the apoptotic threshold, potentially explaining their high frequency in myeloma. Disclosures Lee: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies Corporation: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Chugai Biopharmaceuticals: Consultancy; Takeda Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees. Dick:Takeda Oncology: Employment, Equity Ownership. Chattopadhyay:Takeda Oncology: Employment. Orlowski:Janssen Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy; BioTheryX, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millenium Pharmaceuticals: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Poseida: Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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The Interaction of Bortezomib with P-Gp, MRP-1 and BCRP Drug Transporters: Implications for Therapeutic Applications of Bortezomib in Advanced Multiple Myeloma and Other Neoplasias.

Blood ◽

10.1182/blood.v114.22.1729.1729 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1729-1729

Author(s):

Melissa G Ooi ◽

Robert O'Connor ◽

Jana Jakubikova ◽

Justine Meiller ◽

Steffen Klippel ◽

...

Keyword(s):

Lung Cancer ◽

Multiple Myeloma ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Significant Activity ◽

Cancer Resistance ◽

Advisory Committees ◽

Bortezomib Treatment

Abstract Abstract 1729 Poster Board I-755 Background Multidrug transporters are energy-dependent transmembrane proteins which can efflux a broad range of anticancer drugs and thereby play a role in resistance to the actions of substrate agents. Classically, three transporters, p-glycoprotein (Pgp; MDR-1; ABCB1), multidrug resistant protein-1 (MRP-1; ABCC1) and breast cancer resistance protein (BCRP; MXR; ABCG2), have been found to have the broadest substrate specificity and a strong correlation with drug resistance in vitro and in vivo in many models and forms of cancer. We have sought to characterize the interaction of bortezomib with these transporters and thereby explore the potential for these agents to play a role in resistance. Bortezomib is a novel proteosome inhibitor with significant activity in multiple myeloma, although subsets of patients remain refractory to the activity of the drug. Hence, better characterization of the interactions of this drug with classical resistance mechanisms may identify improved treatment applications. Methods and Results We investigated the role of these transporters by using isogenic cell line models which are resistant due to overexpression of a particular transporter: DLKP lung cancer cell line that overexpresses MRP-1; DLKP-A which overexpresses Pgp; and DLKP-SQ-Mitox which overexpresses BCRP. DLKP-A cells exhibited a 4.6-fold decrease in responsiveness to bortezomib compared to parental DLKP cells. In DLKP-SQ-Mitox, bortezomib-induced cytotoxicity was comparable to DLKP. When bortezomib was combined with elacridar, a Pgp and BCRP inhibitor, significant synergy was evident in DLKP-A (100% viable cells with single agent treatment versus 11% with the combination), but not DLKP-SQ-Mitox. Sulindac, an MRP-1 inhibitor, combined with bortezomib failed to produce any synergy in MRP-1 positive DLKP cells. Conversely, combination assays of Pgp substrate cytotoxics such as doxorubicin with Bortezomib were largely additive in nature. This indicates that bortezomib has little, if any, direct Pgp inhibitory activity, as combinations of a traditional Pgp inhibitor (such as elacridar) and doxorubicin would show marked synergy rather than just an additive effect in Pgp positive cells. To further characterize the extent of this interaction with Pgp, we conducted cytotoxicity assays in cell lines with varying levels of Pgp overexpression. NCI/Adr-res (ovarian cancer, high Pgp overexpression), RPMI-Dox40 (multiple myeloma, moderate Pgp overexpression) and A549-taxol (lung cancer, low Pgp overexpression). The combination of bortezomib and elacridar that produced the most synergy was in cell lines expressing moderate to high levels of Pgp expression. Cell lines with lower Pgp expression produced an additive cytotoxicity. We next examined whether bortezomib had any direct effect on Pgp expression. In RPMI-Dox40 cells, Pgp expression is reduced in a time-dependent manner with bortezomib treatment. Conclusions Our studies therefore show that bortezomib is a substrate for Pgp but not the other drug efflux pumps. In tumor cells expressing high levels of Pgp, the efficacy of bortezomib is synergistically enhanced by combinations with a Pgp inhibitor, while bortezomib treatment itself can reduce the expression of Pgp. This study suggests that in the subset of patients with advanced multiple myeloma or solid tumors which express high levels of Pgp, inhibition of its function could contribute to enhanced responsiveness to bortezomib. Disclosures Richardson: millenium: Membership on an entity's Board of Directors or advisory committees, Research Funding; celgene: Membership on an entity's Board of Directors or advisory committees, speakers bureau up to 7/1/09; MLNM: speakers bureau up to 7/1/09. Mitsiades:Millennium Pharmaceuticals : Consultancy, Honoraria; Novartis Pharmaceuticals : Consultancy, Honoraria; Bristol-Myers Squibb : Consultancy, Honoraria; Merck &Co: Consultancy, Honoraria; Kosan Pharmaceuticals : Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; PharmaMar: licensing royalties ; Amgen Pharmaceuticals: Research Funding; AVEO Pharma: Research Funding; EMD Serono : Research Funding; Sunesis Pharmaceuticals: Research Funding. Anderson:Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Biotest AG: Consultancy, Research Funding.

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CYC065, a Potent Derivative of Seliciclib Is Active In Multiple Myeloma In Preclinical Studies

Blood ◽

10.1182/blood.v116.21.2999.2999 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2999-2999 ◽

Cited By ~ 1

Author(s):

Samantha Pozzi ◽

Diana Cirstea ◽

Loredana Santo ◽

Doris M Nabikejje ◽

Kishan Patel ◽

...

Keyword(s):

Cell Cycle ◽

Multiple Myeloma ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Preliminary Data ◽

Research Funding ◽

Preclinical Studies ◽

Dependent Manner ◽

Advisory Committees

Abstract Abstract 2999 Multiple myeloma (MM) is a treatable but incurable hematological malignancy and novel targeted therapies are under investigation. MM is characterized by dysregulation of the cell cycle, consequent to the overexpression of cyclins and their related kinases, the cyclins dependent kinases (CDK), a group of Ser/Thr proteine kinases. CDKs represent a promising therapeutic target, and inhibitors have been developed for anticancer treatment. We have previously studied seliciclib in the context of MM. CYC065, a second generation CDK inhibitor is the more potent derivative of seliciclib. It is mainly active on CDK 2, 5 and 9, involved in progression of the cell cycle and protein transcription. It has already shown promising results in preclinical studies in breast cancer and acute leukemia. We tested CYC065 in in vitro experiments in MM. Our preliminary data in 7 MM cell lines showed cytotoxicity of CYC065, both in MM cell lines sensitive as well as resistant to conventional chemotherapy, with an IC50 ranging between 0.06 and 2μ M, at 24 and 48h. Tritiated thymidine uptake assay confirmed the antiproliferative effects of CYC065 in MM, and its ability to overcome the growth advantage conferred by co-culture with bone marrow stromal cells derived from MM patients, and cytokines like interleukin 6 (10ng/ml) and insulin like growth factor-1 (50ng/ml). The anti-proliferative effect was evident both at 24 and 48h, starting at concentrations as low as 0.015μ M. The AnnexinV/PI assay in the MM1.s cell line confirmed CYC065's ability to induce apoptosis in a time dependent manner starting at 9 hours of treatment, at a concentration of 0.125 μ M, inducing 82% of apoptosis after 48h of exposure. Cell cycle analysis in the same MM1.s cell line showed an increase of subG1 phase, starting at 9 hours of treatment, at 0.125 μ M of CYC065. Preliminary results of western blot analysis confirmed the apoptotic effect of CYC065 in the MM1s cell line, highlighted by the cleavage of caspase 3, 8, 9 and PARP. The compound was tested in primary CD138+ cells isolated from three refractory MM patients, confirming its efficacy at 0.125 μ M, both at 24 and 48h. Comparative analysis in PBMCs from normal donors, for the evaluation of the drug toxicity is ongoing and will be presented. In conclusion our preliminary data confirm the efficacy of CYC065 in MM cell lines and primary MM cells, at nanomolar concentrations. Ongoing mechanistic and in vivo studies will delineate its role in the now increasing spectrum of CDK inhibitors in MM and better define its potential for clinical development in MM. Disclosures: Green: Cyclacel: Employment. Anderson:Millennium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Scadden:Fate Therapeutics: Consultancy, Equity Ownership, Patents & Royalties. Raje:Celgene: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Research Funding; Acetylon: Research Funding.

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Lin28B/Let-7 Axis Regulates Multiple Myeloma Proliferation By Enhancing c-Myc and Ras Survival Pathways

Blood ◽

10.1182/blood.v122.21.273.273 ◽

2013 ◽

Vol 122 (21) ◽

pp. 273-273

Author(s):

Salomon Manier ◽

John T Powers ◽

Antonio Sacco ◽

Michaela R Reagan ◽

Michele Moschetta ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Proliferation ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Advisory Board ◽

Loss Of Function ◽

Advisory Committees ◽

Expression Levels ◽

Gain And Loss

Abstract Background MicroRNAs (miRNAs) play a pivotal role in tumorigenesis, due to their ability to target mRNAs involved in the regulation of cell proliferation, survival and differentiation. Lin28B is an RNA binding protein that regulates Let-7 miRNA maturation. Lin28B and Let-7 have been described to act as oncogenes or tumor suppressor genes, respectively, as demonstrated both in solid cancer and hematologic malignancies. However, the role of the Lin28B/Let-7 axis in Multiple Myeloma (MM) has not been studied. Method Lin28B level expression in MM patients was studied using previously published gene expression profiling (GEP) datasets. Let-7 expression levels were assessed in CD138+ primary MM cells and bone marrow stromal cells (BMSCs) by using PCR, as well as in circulating exosomes using miRNA array (Nanostring® Technology). Exosomes were collected from both normal and MM peripheral blood, using ultracentrifugation; and further studied by using electron microscopy and immunogold labeling for the detection of CD63 and CD81. The knockdown of Lin28B was performed on MM cell lines (U266, MM.1S, MOLP-8) by using a lentiviral Lin28B shRNA. Gain- and loss-of function studies for Let-7 were performed using Let-7 mimic and anti-Let-7 transfection in MM cell lines (MM1S, U266) and primary BMSCs. Cell proliferation has been evaluated by using thymidine assays. Effects of Let-7 and Lin28B on signaling cascades have been evaluated by western blot. Results Two independent GEP datasets (GSE16558; GSE2658) were analyzed for Lin28B expression, showing a significantly higher level in MM patients compared to healthy controls. In addition, high Lin28B levels correlated with a shorter overall survival (p = 0.0226). We next found that the Let-7 family members are significantly down-regulated in MM primary cells, particularly Let-7a and b (5 fold change, p < 0.05), as demonstrated by using qRT-PCR. Similarly, miRNA arrays showed a lower expression of Let-7-related miRNAs in circulating exosomes obtained from MM patients compared to healthy individuals. We further dissected the functional relevance of Lin28B in MM cells, by performing Lin28 knockdown (KD) in MM cell lines (U266, MOLP-8). This led to a significant decrease in MM cell proliferation associated with G1 phase cell cycle arrest. This was supported by up-regulation of Let-7 and down-regulation of c-Myc, Ras and Cyclin D1 in Lin28 KD MM cells. To further prove that Lin28B-dependent effects on MM cells are mediated by Let7, we next showed that let-7 gain- and loss-of-function studies regulate MM cell proliferation and Myc expression. Lin28B regulation in MM cells is dependent on Let-7, as demonstrated by an increase of both cell proliferation and c-Myc expression after anti-Let-7 transfection in the Lin28B KD cells. We therefore studied the regulation of Let-7 in MM cells through the interaction with BMSCs. Let-7 expression levels were significantly lower in BMSCs obtained from MM patients compared to healthy donors. Interestingly, the Let-7 expression level in MM cells was increased after co-culture with Let-7 over-expressing BMSCs, associated with a decrease of both cell proliferation and c-Myc expression. This suggests a potential transfer of Let-7 from BMSCs to MM cells. Conclusion This work describes a new signaling pathway involving Lin28B, Let-7, Myc and Ras in MM. Let-7 expression in MM cells is also regulated through the interaction of MM cells with BMSCs, leading to cell proliferation and Myc regulation in MM. Interference with this pathway might offer therapeutic perspectives. Disclosures: Leleu: CELGENE: Honoraria; JANSSEN: Honoraria. Daley:Johnson and Johnson: Consultancy, Membership on an entity’s Board of Directors or advisory committees; MPM Capital: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Verastem: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Epizyme: Consultancy, Membership on an entity’s Board of Directors or advisory committees; iPierian: Consultancy, Membership on an entity’s Board of Directors or advisory committees; Solasia, KK: Consultancy, Membership on an entity’s Board of Directors or advisory committees. Ghobrial:Onyx: Advisoryboard Other; BMS: Advisory board, Advisory board Other, Research Funding; Noxxon: Research Funding; Sanofi: Research Funding.

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Expression Of Truncated Protein Tyrosine Phosphatase, Receptor Type, O (PTPROt) Influences Multiple Myeloma Sensitivity To Bortezomib Through Akt Signaling, and Is a Favorable Clinical Prognostic Factor

Blood ◽

10.1182/blood.v122.21.2520.2520 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2520-2520

Author(s):

Hua Wang ◽

Veerabhadran Baladandayuthapani ◽

Zhiqiang Wang ◽

Jiexin Zhang ◽

Heather Yan Lin ◽

...

Keyword(s):

Multiple Myeloma ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Myeloma Cell ◽

Advisory Committees ◽

Over Expression ◽

Resistant Disease ◽

Drug Naïve ◽

Rpmi 8226

Abstract Background Proteasome inhibitors such as bortezomib and carfilzomib are an important part of our current chemotherapeutic armamentarium against multiple myeloma, and have improved outcomes in the up-front, relapsed, and relapsed/refractory settings. Their efficacy has been demonstrated both as single agents, and as part of rationally designed combination regimens, but they are at this time used empirically, since biomarkers to identify patients who would most or least benefit from their application have not been clinically validated. Moreover, the vast majority of patients eventually develop drug-resistant disease which precludes further proteasome inhibitor use through mechanisms that have not been fully elucidated. Methods We compared gene expression profiles (GEPs) of a panel of bortezomib-resistant myeloma cell lines and their vehicle-treated, drug-naïve counterparts to identify significant changes associated with drug resistance. The list of genes whose expression was changed by at least 2-fold was compared with independent RNA interference studies whose goal was to identify genes whose suppression conferred drug resistance. Further validation of genes of interest was pursued in a panel of myeloma cell lines, and in clinically annotated GEP databases. Results Suppression of PTPROt expression was noted in bortezomib-resistant RPMI 8226 and ANBL-6 myeloma cells compared to isogenic, drug-naïve controls, and this was confirmed by quantitative PCR. Overexpression of PTRPOt in RPMI 8226, ANBL-6 and other myeloma cell lines was by itself sufficient to increase the level of apoptotic, sub-G0/G1 cells compared to vector controls, or cells expressing a phosphatase-dead PTPROt mutant. Moreover, PTPROt enhanced the ability of bortezomib to reduce myeloma cell viability, in association with increased activation of caspases 8 and 9. Exogenous over-expression of PTPROt was found to reduce the activation status of Akt, a known anti-apoptotic pathway that reduces bortezomib activity, based on Western blotting with antibodies to phospho-Akt (Ser473), and Akt kinase activity assays. Notably, we also found that exogenous over-expression of PTPROt resulted in increased expression levels of p27Kip1. Interestingly, array CGH data from studies of myeloma cell lines and primary cells showed that the PTPROt gene was located in a genomic region with a high propensity for loss. Analysis of the Total Therapy databases of GEP and patient outcomes available on the Multiple Myeloma Genomics Portal showed that higher than median expression of PTPROt was associated with better long-term survival (P=0.0175). Finally, analysis of the Millennium Pharmaceuticals database of studies of bortezomib in the relapsed and relapsed/refractory setting showed high PTRPOt expression was more frequently seen in patients who achieved complete remission (P<0.01), and was associated with a better median overall survival (P=0.0003). Conclusions Taken together, the data support the possibility that high expression of PTPROt is a good prognostic factor for response to bortezomib-containing therapies, and that this may occur through modulation by PTPROt of the Akt pathway. Moreover, they suggest that strategies to enhance the expression of PTPROt should be investigated to restore bortezomib sensitivity in patients with proteasome inhibitor-resistant disease. Disclosures: Orlowski: Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.

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Hypersialylation Protects Multiple Myeloma Cells from NK Cell-Mediated Immunosurveillance and This Can be Overcome By Targeted Desialylation Using a Sialyltransferase Inhibitor

Blood ◽

10.1182/blood-2019-126613 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 138-138

Author(s):

John Daly ◽

Subhashis Sarkar ◽

Alessandro Natoni ◽

Robert Henderson ◽

Dawn Swan ◽

...

Keyword(s):

Multiple Myeloma ◽

Sialic Acid ◽

Nk Cells ◽

Board Of Directors ◽

Cell Lines ◽

Immune Evasion ◽

Research Funding ◽

Nk Cell ◽

Advisory Committees

Introduction: Evading Natural Killer (NK) cell-mediated immunosurveillance is key to the development of Multiple Myeloma (MM). Recent attention has focused on the role of hypersialylation in facilitating immune-evasion of NK cells. Abnormal cell surface sialylation is considered a hallmark of cancer and we have implicated hypersialylation in MM disease progression. Certain sialylated glycans can act as ligands for the sialic acid-binding immunoglobulin-like lectin (Siglec) receptors expressed by NK cells (Siglec-7 and Siglec-9). These ITIM motif-containing inhibitory receptors transmit an inhibitory signal upon sialic acid engagement. We hypothesized that desialylation of MM cells or targeted interruption of Siglec expression could lead to enhanced NK cell mediated cytotoxicity of MM cells. Methodology: MM cells were treated with the sialidase neuraminidase prior to co-culture with primary NK (PNK) cells. MM cells were treated with 300µM 3Fax-Neu5Ac (sialyltransferase inhibitor) for 3 days prior to co-cultures with PNK cells. PNK cells were expanded, IL-2 activated (500U/ml) overnight, or naïve (resting). Primary MM samples/MM cell lines were screened with Siglec-7/9 chimeras (10µg/ml). PNK (IL-2 activated) cells were stained with anti-Siglec-7 and anti-Siglec-9 antibodies. Siglec-7 was targeted for knockout (KO) using the CRISPR/Cas9 system, a pre-designed guideRNA and the MaxCyteGT transfection system. MM cells were treated with 10µg/ml of Daratumumab prior to co-culture with expanded PNK cells. Results: Using recombinant Siglec-7/9 chimeras a panel of MM cell lines (MM1S, RPMI-8226, H929, JJN3 and U266) were shown to express ligands for Siglec-7 and Siglec-9 (>85%, n=3). Primary MM cells isolated from BM of newly diagnosed (n=3) and relapsed patients (n=2) were also shown to express Siglec-7 ligands (72.5±17.5%, 36.5% respectively). PNK cells express Siglec-7 and Siglec-9 (94.3±3.3% and 61±8.8% respectively, n=6). Desialylation of the MM cell lines JJN3 and H929 using neuraminidase significantly enhanced killing of MM cells by healthy donor (HD) derived PNK cells (expanded, IL-2 activated and naïve, n=7) at multiple effector:target (E:T) cell ratios. Furthermore, de-sialylation of JJN3 and H929 using neuraminidase resulted in increased NK cell degranulation (CD107α expression), compared to a glycobuffer control (n=7). De-sialylation, using 300µM 3Fax-Neu5Ac, resulted in strongly enhanced killing of MM1S by expanded HD-derived PNK cells at multiple E:T ratios (n=5, p<0.01 at 0.5:1, p<0.001 at 1:1, p<0.01 at 2.5:1). Furthermore, CD38 expression on H929 MM cells significantly increased after treatment with 300µM 3Fax-Neu5Ac for 3 days (p<0.01, n=3). In a cytotoxicity assay, expanded PNK cell-mediated antibody dependent cellular cytotoxicity (ADCC) of H929 MM cells pre-treated with Daratumumab (anti-CD38 moAb) and 3Fax-Neu5Ac was significantly higher than H929 cells pre-treated with Dara (p<0.05 at 0.5:1, p<0.01 at 1:1) or 3Fax-Neu5Ac (p<0.01 at 0.5:1, p<0.01 at 1:1) alone (n=5). Using CRISPR/Cas9, over 50% complete KO of Siglec-7 was observed on expanded PNK cells, yet did not result in enhanced NK cell-mediated cytotoxicity against either H929 or JJN3 (n=7). Siglec-9 KO using CRISPR/Cas9 is ongoing. Discussion: Hypersialylation of MM cells facilitates immune evasion and targeted removal of sialic acid strongly enhances the cytotoxicity of NK cells against MM. However, to date the role of Siglecs remains inconclusive. Nevertheless, our data suggest that targeted desialylation is a novel therapeutic strategy worth exploring in MM. In particular, upregulation of CD38 provides a strong rationale for combinatory strategies employing targeted desialylation with CD38 moAbs such as Daratumumab, with the goal of maximizing ADCC. Disclosures Sarkar: Onkimmune: Research Funding. O'Dwyer:Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; GlycoMimetics Inc: Research Funding; AbbVie: Consultancy.

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Methyljasmonate, An Inhibitor of Glycolytic Energy Production, Displays Pre-Clinical Activity against Multiple Myeloma Cells.

Blood ◽

10.1182/blood.v114.22.1741.1741 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1741-1741

Author(s):

Steffen Klippel ◽

Jana Jakubikova ◽

Jake Delmore ◽

Melissa G. Ooi ◽

Douglas McMillin ◽

...

Keyword(s):

Cell Cycle ◽

Multiple Myeloma ◽

Cell Death ◽

Cancer Cells ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Energy Production ◽

Advisory Committees ◽

Normal Cells

Abstract Abstract 1741 Poster Board I-767 Background In contrast to most normal cells, cancer cells typically produce energy predominantly by glycolysis as demonstrated by O. Warburg more than 50 years ago. Methyljasmonate (MJ), a hormone produced by plants in response to biotic & abiotic stresses such as herbivory and wounding, has been shown to prevent the interaction of hexokinase (Hxk) and voltage dependent anion channels (VDACs), thereby significantly impacting the onset of glycolytic energy production. This may explain promising preclinical results observed with MJ against a variety of cancer cells, including myeloid leukemia and B-cell lymphoma cell lines. Methods and Results We tested the potential of MJ against Multiple Myeloma (MM) cells. We first evaluated the response of 16 different MM cell lines to 24 h of exposure to MJ concentrations of 0.5 – 3.5 mM using MTT assays. 15/16 of the MM cell lines tested displayed an IC50 of < 1.5 mM. In contrast, HS-5 stroma cells and peripheral blood mononuclear cells (PBMCs) did not respond to that MJ concentration, and even at a concentration of 2.5 mM MJ showed a maximal reduction of cell viability of 40%. Similarly to MM cell lines, purified CD138+ primary tumor cells of 3 MM patients displayed an IC50 of < 1.5 mM, suggesting that the differential sensitivity of MM vs. normal cells to MJ is not restricted to cell lines, but is also observed with primary tumor cells. Importantly, neither co-culture with HS-5 stroma nor IL-6 protected MM cells against MJ. Cell death commitment assays revealed that 1h exposure of 1.5 mM MJ induced cell death. Annexin V/PI FACS analysis of MJ-exposed MM cells showed that the cell death is mainly driven by apoptosis, evidenced by cleavage of caspases 3, 8 and 9 as well as of PARP. However, pre-incubation of MM cells with specific caspase inhibitors such as 10 mM of AC-DEVD-CHO, Z-IETD-fmk, Z-LEHD-fmk or 50 mM of Z-VAD only minimally protects the cancer cells from MJ exposure. Therefore, the impact of the MJ is not solely due to caspase triggered proteolytic cascades. Measurements of cellular ATP content by cell titer glow (CTG; Promega, Madison, WI) assay showed rapid depletion of ATP triggered by MJ action in sensitive MM cell lines. Additionally, we observed that 1 h exposure to 2 mM MJ modulated signaling pathways including IRS1/PI3K/AKT, MEK1/2, as well as Stat3 and JNK. FACS-based cell cycle analysis after propidium iodide staining did not show cell cycle arrest, but rather a rapid transition of cells to G0/G1 No correlation of sensitivity of MM cell lines and the number of mitochondria per cancer cell, as determined by Mitotracker Green (Invitrogen, Carlsbad, CA) -based flow analysis, was observed. We next examined if MJ exhibits either significant antagonism or synergy with established or novel anti-MM agents, including Bortezomib, Lenalidomide, Doxorubicin, Rapamycin or Dexamethasone, but discovered neither. However, MJ displayed synergy when combined with 2-Deoxyglucose. Finally, MJ was tested in vivo in scid/nod mice irradiated with 150 rads, injected with 1× 106 MM1S cells, and then, treated at 500 mg/kg by IP administration on a 5 days on / 2 days off schedule starting two weeks after tumor cell injection, There was an overall survival advantage of MJ-treated animals over the respective controls, with all treated mice (n=10) still alive but 6/10 control mice dead after 27 d. Conclusions Based on its rapidity of anti-MM action, favorable safety profile in preclinical models, distinct pattern of molecular sequelae, and compatibility with established anti-MM agents, MJ represents a promising investigational anti-MM agent. Disclosures Laubach: Novartis: Consultancy, Honoraria. Richardson:Millennium: (Speakers Bureau up to 7/1/09), Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: (Speakers Bureau up to 7/1/09), Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Anderson:Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Mitsiades:Novartis Pharmaceuticals: Consultancy, Honoraria; Milllennium: Consultancy, Honoraria; Bristol-Myers Squibb : Consultancy, Honoraria; Merck &Co.: Consultancy, Honoraria; Kosan Pharmaceuticals : Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; PharmaMar: Patents & Royalties; Amgen: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis Pharmaceuticals: Research Funding.

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Carfilzomib (CFZ), a Novel Proteasome Inhibitor for Relapsed or Refractory Multiple Myeloma, Is Associated with Minimal Peripheral Neuropathic Effects.

Blood ◽

10.1182/blood.v114.22.430.430 ◽

2009 ◽

Vol 114 (22) ◽

pp. 430-430 ◽

Cited By ~ 10

Author(s):

Ravi Vij ◽

Luhua Wang ◽

Robert Z Orlowski ◽

A. Keith Stewart ◽

Sundar Jagannath ◽

...

Keyword(s):

Multiple Myeloma ◽

Peripheral Neuropathy ◽

Board Of Directors ◽

Proteasome Inhibitor ◽

Research Funding ◽

Class Effect ◽

Advisory Committees ◽

Ortho Biotech ◽

Grade 3

Abstract Abstract 430 Background: Peripheral neuropathy (PN) is a feature of multiple myeloma (MM) itself as well as a debilitating side effect and major dose-limiting toxicity of thalidomide (THAL) and bortezomib (BTZ) (Chaudry et al, J Peripher Nerv Syst. 2008). Although the mechanism of BTZ-induced PN (BIPN) is unknown, PN may not be a proteasome inhibitor class effect. Carfilzomib (CFZ) is a highly selective proteasome inhibitor with activity in relapsed or refractory MM. CFZ overcomes BTZ-resistance in vitro (Kuhn et al, Blood 2007), lacks the off-target activities of BTZ (Kapur et al, Blood 2008), and does not cause neurotoxicity in long-term chronic (e.g. up to 9 months) animal toxicology studies (Kirk et al, Blood 2008). In Phase I and 1b/2 trials (total n=138), CFZ was not associated with dose-limiting PN. Here we report on the experience of CFZ treatment from two ongoing Phase 2 trials in relapsed or refractory MM. Methods: Patients with relapsed or refractory MM received CFZ, 20 mg/m2 IV, Days 1, 2, 8, 9, 15, and 16 in a 28-day cycle for up to 12 cycles on studies PX-171-003 and PX-171-004. Neuropathy history, neurological physical exam and PN-related quality of life data (FACT-GOG/NTx v 4.0 scores) were collected at screening. Prospective neurological exams and subjective reporting of PN using the FACT-GOG/Ntx subscale v.4 questionnaire occurred every 2 cycles until study discontinuation to proactively assess for PN. Adverse Event (AE) data were also collected. AEs reported as ‘neuropathy peripheral', ‘neuropathic pain', ‘neuropathy', and ‘peripheral sensory neuropathy' were included as PN. AE reports of ‘paraesthesias' and ‘dysesthesias' were counted separately. Results: To date, baseline data are availabel for 136 patients. At screening, 73 (54%) patients had active PN, including 64 (47%) with Grade (G) 1 and 9 (7%) with G2. 111 (82%) patients had a history of PN which was attributed to prior chemotherapy, 86 cases of which were attributed to either THAL or BTZ. THAL was implicated in 57 cases, BTZ in 45 cases, and both THAL and BTZ in 17 cases. For 27 of these patients, PN was the primary reason for THAL or BTZ discontinuation. The mean number of CFZ doses was 27 (4.5 four-week cycles) and 27 (20%) patients completed at least 8 cycles. Peripheral neuropathy AEs (all grades) were reported in 21 (15%) patients; 12 (9%) cases were considered possibly related to CFZ. Grade ≥ 3 PN was reported in only 3 (2%) patients. In one patient, the Grade 3 neuropathy lasted from treatment days 2 to 3 (i.e., < 36 hours) and resolved; the patient continued on CFZ at full dose for 30 days before discontinuing study due to progressive MM. In a second patient, Grade 3 neuropathy occurred on study day 91. The dose was reduced from 20 mg/m2 to 15 mg/m2, at the same twice-weekly frequency; the PN resolved to G1 and the patient continued on therapy until day 133. The third patient had G3 PN that occurred from days 260-281 and resolved to G1 while still on full dose CFZ. This patient completed the full 12-cycle protocol (∼1 year CFZ treatment). Paraesthesias and dysesthesia were reported in 10 (7%) patients; all were G1 or 2. There were no missed doses or CFZ treatment discontinuations due to PN, paraesthesias or dysesthesias. Comparative FACT-GOG/Ntx subscale scores were availabel for 95 patients. There was no statistically significant change in FACT-GOG/NTx scores from baseline to the end of the study. Neurological exams did not identify any additional peripheral neuropathy beyond those reported as AEs. Conclusions: In MM patients receiving CFZ therapy, reports of PN, paraesthesias and dysesthesia are generally mild and do not result in missed doses or CFZ discontinuation, allowing long-term treatment and prolonged disease control. These data, along with the experience from other clinical trials, indicate that PN is not a class effect of proteasome inhibitors. Disclosures: Vij: Proteolix: Consultancy, Research Funding. Wang:Proteolix, Inc.: Research Funding. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Trudel:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Belch:Ortho Biotech: Honoraria, Research Funding. Bahlis:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria, Speakers Bureau. Le:Proteolix, Inc.: Employment. Cruickshank:Proteolix, Inc.: Employment. Bennett:Proteolix: Employment. Molineaux:Proteolix, Inc.: Employment, Equity Ownership. Siegel:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

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MLN4924, a Novel Investigational NEDD8 Activating Enzyme Inhibitor, Exhibits Preclinical Activity In Multiple Myeloma and Waldenström's Macroglobulinemia through Mechanism Distinct From Existing Proteasome Inhibitors

Blood ◽

10.1182/blood.v116.21.2988.2988 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2988-2988

Author(s):

Douglas W. McMillin ◽

Zachary Hunter ◽

Jake Delmore ◽

Val Monrose ◽

Peter G Smith ◽

...

Keyword(s):

Gene Expression ◽

Multiple Myeloma ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Normal Donor ◽

Advisory Committees ◽

Safety Studies ◽

Ubiquitin Proteasome ◽

Efficacy Studies

Abstract Abstract 2988 Background: Multiple myeloma (MM) and Waldenström Macroglobulinemia (WM) have both shown clinical responses to Bortezomib therapy which blocks the elimination of ubiquitin tagged regulatory proteins by the proteasome. The NEDD8 activating enzyme (NAE)-inhibitor MLN4924 is a novel agent which demonstrates selective inhibition of the proteins for degradation in the ubiquitin pathway and may offer benefits to MM and WM patients through the more targeted approach. Methods: A panel of human MM and WM cell lines were tested for their in vitro response to MLN4924 using MTT colorimetric survival assays. MM and WM cell lines tested exhibited dose and time dependent decrease of their viability upon exposure to MLN4924 (IC50=25-150 nM). In addition, miRNA and gene expression studies in response to MLN4924 were compared to treatment of the same cells with bortezomib. In vivo safety studies were performed in mice and animal efficacy studies are ongoing in both MM and WM engrafted mice. Results: A panel of MM and WM cells were treated with MLN4924 for 72hrs and compared to the colon carcinoma line HCT116 and normal cell lines HS-5 (stroma) and THLE-3 (hepatocytes). In addition, a longitudinal assessment of viability of MM1S (MM) and BCWM1 (WM) cells during a 72hr incubation with MLN4924 (500nM) showed commitment to death <48hrs. This result, coupled with the observation that normal donor peripheral blood mononuclear cells (PBMCs) and HS-5 stromal cells were less sensitive (IC50 >1000 nM) than the MM or WM cell lines tested, suggest that this compound exhibits a rapid, tumor-selective effect at clinically relevant conditions. We also evaluated primary MM (CD138+) and WM (CD19+) patient bone marrow cells and observed sub-μ M activity by MLN4924. In addition, we tested a series of combinations of MLN4924 with dexamethasone, doxorubicin and bortezomib in both MM1S and BCWM1 cells lines and observed additive activity or greater with MLN4924. Gene expression profiling revealed distinct signatures, in MM1S and BCWM1 lines, as well as distinct patterns of gene expression changes which were induced by MLN4924 vs. bortezomib. For instance, while bortezomib potently induces a compensatory upregulation of transcripts for ubiquitin/proteasome and heat shock protein genes which, in MM1S or BCWM1 cells, were not observed in response to MLN4924 treatment. Additional studies with the proteasome inhibitor MLN9708 revealed similar patterns of expression as bortezomib. These results indicate that MLN4924 does not induce pronounced proteotoxic stress in MM or WM cells, highlighting the distinct effect of MLN4924 on the ubiquitin/proteasome pathway compared to inhibitors which target the 20S proteasome subunit. Longitudinal miRNA profiling revealed a distinct pattern of miRNA expression in MLN4924-treated vs. bortezomib-treated MM and WM cells. Lastly, animal safety studies showed that MLN4924 was tolerated at doses up to 60mg/kg 2x daily for 1 week. Efficacy studies in MM and WM are ongoing. Conclusions: MLN4924 induces cell killing at sub-μ M concentrations for both MM and WM cells with higher sensitivity of tumor cells compared to normal tissues, exhibits selective gene expression and miRNA regulation and can be safely administered to mice. These studies provide the framework for the clinical investigation of MLN4924 in MM and WM. Disclosures: McMillin: Axios Biosciences: Equity Ownership. Smith:Millennium: Employment. Birner:Millennium: Employment. Richardson:Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees. Anderson:Millennium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Treon:Millennium Pharmaceuticals, Genentech BiOncology, Biogen IDEC, Celgene, Novartis, Cephalon: Consultancy, Honoraria, Research Funding; Celgene Corporation: Research Funding; Novartis Corporation: Research Funding; Genentech: Consultancy, Research Funding. Mitsiades:Millennium: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Merck &Co.: Consultancy, Honoraria; Kosan Pharmaceuticals: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Centrocor: Consultancy, Honoraria; PharmaMar: Patents & Royalties; OSI Pharmaceuticals: Research Funding; Amgen Pharmaceuticals: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis: Research Funding; Gloucester Pharmaceuticals: Research Funding.

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Thalidomide, Lenalidomide and Pomalidomide Disrupt Epstein-Barr Virus (EBV) Latency: Clinical Implications

Blood ◽

10.1182/blood.v122.21.3499.3499 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3499-3499 ◽

Cited By ~ 1

Author(s):

Richard Julian Jones ◽

Shannon C. Kenney ◽

Christopher Dawson ◽

Robert Z. Orlowski

Keyword(s):

Multiple Myeloma ◽

B Cells ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Lytic Cycle ◽

Early Gene ◽

Advisory Committees ◽

Ebv Reactivation ◽

Latently Infected

Abstract Introduction Thalidomide (THAL), and the IMiDs® immunomodulatory agents lenalidomide (LEN), and pomalidomide (POM) are all approved for use in multiple myeloma (MM) either as single agents, or in combination with dexamethasone (DEX). Despite the enhanced efficacy of these novel agents, concern has arisen as to the increased incidence of secondary primary malignancies (SPM). For example, the IFM 2005-002 trial reported cases of lymphoblastic leukemia and Hodgkin’s disease (HD) following LEN use (Attal, Lauwers-Cances et al. 2012) in MM patients on maintenance therapy. Also, a recent case report described a MM patient who developed HD who had been treated with salvage therapy containing THAL(Chim, Choi et al. 2013), and two publications reported EBV reactivation in MM patients treated with LEN (Kneppers, van der Holt et al. 2011; Kroger, Zabelina et al. 2013). As HD is causally linked to EBV, this raises the question as to whether the IMiDs reactivate latent EBV infection in normal memory B-cells, and thereby increase the risk of EBV-related malignancies. To this end, we have investigated the ability of the IMiD’s to induce reactivation of latently infected B-cell lines. Methods A panel of latently infected EBV-positive B-cell lines including Burkitt’s lymphoma (BL) cells and lymphoblastoid cell lines (LCL) were treated with either LEN, THAL or POM, and the status of the EBV lytic cycle was evaluated using in vitro and in vivo models. Results Treatment of BL and LCL cell lines with physiological concentrations of IMiDs (1-5 μM) induced the immediate early gene BZLF1 and the early gene BMRF1. Interestingly, the ability to induce EBV reactivation was in their potency order (i.e. POM>LEN>THAL). The IMiD’s also induced lytic cell death, as an LCL carrying a BZLF1-deleted EBV, which is incapable of undergoing a lytic cycle, showed no change in cell viability, compared to wild-type cells which had increased cell death. The addition of the nucleoside analogue ganciclovir (GCV) enhanced the cytotoxic effect of LEN and POM alone in BL cells lines. An in vivo xenograft model of BL demonstrated that the combination of LEN and GCV was highly efficacious at suppressing tumor cell growth, thus confirming the ability of LEN to stimulate the EBV-lytic life cycle. The ability to induce EBV reactivation was directly related to the stimulation of phosphatidylinositol-3 kinase (PI3K) signaling, which was completely blockaded by the PI3K-δ inhibitor, CAL101. The combination of LEN with either, DEX or rituximab, induced increased BMRF1 compared to the LEN alone. Conclusions The IMiD class of drugs has a potent ability to reactivate the lytic cycle in B-cells latently infected with EBV. We hypothesize that the IMiD’s reactivate latently infected resting memory B cells through enhancing PI3K signaling. This reactivation may be further potentiated when the IMiDs are used in combination with rituximab or DEX, which may simultaneously enhance the EBV lytic cycle and suppress the host immune response. These findings suggest the possibility that immunocompromised patients who receive IMiDs should be monitored for evidence of EBV reactivation. Also, this may suggest a mechanism by which patients may develop EBV-associated SPM, an effect which is similar to the methotrexate induced EBV-positive lymphomas seen in rheumatoid arthritis patients (Feng, Cohen et al. 2004). References Attal, M., V. Lauwers-Cances, et al. (2012). “Lenalidomide maintenance after stem-cell transplantation for multiple myeloma.” The New England journal of medicine 366(19): 1782-1791. Chim, C. S., P. T. Choi, et al. (2013). “Hodgkin's lymphoma as a second cancer in multiple myeloma never exposed to lenalidomide.” Annals of hematology 92(6): 855-857. Feng, W. H., J. I. Cohen, et al. (2004). “Reactivation of latent Epstein-Barr virus by methotrexate: a potential contributor to methotrexate-associated lymphomas.” Journal of the National Cancer Institute 96(22): 1691-1702. Kneppers, E., B. van der Holt, et al. (2011). “Lenalidomide maintenance after nonmyeloablative allogeneic stem cell transplantation in multiple myeloma is not feasible: results of the HOVON 76 Trial.” Blood 118(9): 2413-2419. Kroger, N., T. Zabelina, et al. (2013). “Toxicity-reduced, myeloablative allograft followed by lenalidomide maintenance as salvage therapy for refractory/relapsed myeloma patients.” Bone marrow transplantation 48(3): 403-407. Disclosures: Orlowski: Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.

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Proteasome Inhibitor Treatment in Multiple Myeloma Can Mobilize Hematopoietic Stem Cells in the Absence of G-CSF

Blood ◽

10.1182/blood.v124.21.2452.2452 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2452-2452

Author(s):

John N. Allan ◽

David Jayabalan ◽

Ruben Niesvizky ◽

Tomer M Mark ◽

Roger Pearse ◽

...

Keyword(s):

Multiple Myeloma ◽

Flow Cytometry ◽

Stem Cell ◽

Board Of Directors ◽

Proteasome Inhibitor ◽

Research Funding ◽

Fold Change ◽

Multiparameter Flow Cytometry ◽

Advisory Committees ◽

Hematopoietic Stem

Abstract Introduction Proteasome inhibitor (PI) use in patients (pts) with multiple myeloma (MM) has been associated with increased hematopoietic stem/progenitor cell (HSPC) collection yields in both induction and autologous stem cell collection settings (Niesvizky et al., 2013). Animal models have confirmed this observation (Ghobadi et al., 2012). The mechanism remains unclear, but there is suggestion PI treatment affects pathways associated with HSPC anchoring and migration (Niesvizky et al., 2013). The effect of PIs on HSPC migration in the absence of filgastrim (G-CSF) stimulation remains unknown. We sought to characterize the molecular mechanisms of HSPC mobilization in a cohort of pts undergoing active PI treatment. Methods MM pts undergoing treatment with PIs were consented to obtain peripheral blood (PB) under IRB approval. Pts were eligible if they had symptomatic MM and were undergoing treatment with a PI. Pts receiving alkylating chemotherapy (such as cyclophosphamide) in combination with a PI were excluded. Pts were enrolled on the first day of a new cycle containing a PI. PB was drawn prior to administration of the PI (T0) and just prior to the next dose of PI, 24 or 72 hours later (T1), depending on whether the pt was receiving carfilzomib or bortezomib, respectively. PB mononuclear cells were collected and purified with Ficoll-Paque, viably frozen in CS-10 freezing medium and stored in liquid nitrogen. Serum samples were collected after a 1:2 dilution with PBS and stored at -80oF. Cells were later thawed to perform multiparameter flow cytometry and colony forming unit (CFU) assays. Multiparameter flow cytometry was performed using a BD LSR-II and analyzed using FloJo V9.0 software. Cells were gated on CD45dim SSC-lo characteristics. HSPCs were defined as CD34+/CD133+. Pts were stratified into 3 groups (>2, 1-2, <1) based on fold change in peripheral HSPCs from baseline T0. Expression of surface markers including CD38, CD184, CD202b, CD25, CD90 and CD31 within the HSPC population, were analyzed. Serum protein concentrations were analyzed using ELISAs. Results Twenty-three pts consented and collected at the 2 prespecified time points. Six pts (26%) increased the percentage of peripheral HSPCs>2 fold. Nine (39%) and 8 (35%) pts increased the percentage of HSPCs 1-2 fold and <1 fold over T0 percentage, respectively. There were no statistical differences within the 3 groups, in baseline characteristics, prior chemotherapy, use of IMIDs, or radiation exposure history. There was a significant positive correlation between peripheral HSPC fold change and CFU formation p=0.003 indicating the mobilized HSPC population’s capacity to form progeny. Furthermore, there was a significant negative correlation between fold change of HSPCs and CD90 expression on CD34+ CD133+ CD38- stem cell populations at T1 p=0.032. To determine changes in serum proteins as a result of PI treatment that could contribute to HSPC mobilization we evaluated TGF-ß levels in 13 pt plasma samples. Two pts from the>2fold group were available and revealed TGF-ß levels increase 67.24 pg/mL compared to a decrease of 17.67 pg/mL in 5 pts in the <1fold group trending towards significance p=0.094. Baseline levels of TGF-ß in the two groups,>2fold and <1fold were 18.1 pg/mL and 30.1 pg/mL respectively, which was not significant. Discussion Observations have noted increased HSPC yields in animal models and MM pts after treatment with PIs in both induction and mobilizing regimens (Ghobadi et al., 2012; Niesvizky et al., 2013). Here we demonstrate that treatment with PIs is associated with increases in peripheral HSPC percentages in approximately 2/3 of MM pts despite the lack of concurrent G-CSF. Decreased CD90 has previously been observed in peripherally mobilized HSPC products and, similar to TGF-ß, plays a role in regulation of Rhokinase GTPase pathways known to affect migration and adherence of many different cell types (Tsuchiya et al., 1997; Kim et al., 2006; Wen et al., 2013; Kim et al., 2014). Our study shows a correlation between decreased CD90 expression and fold increase of peripheral HSPCs. We also found an increase in TGF-ß serum levels after treatment in the>2fold group compared to the <1fold group, which may approach statistical significance with more sampling. These findings may help understand the failure to collect adequate HSPCs in a subset of MM pts and could highlight new pathways to disrupt and improve HSPC mobilization regimens. Disclosures Niesvizky: Onyx Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Research Funding, Speakers Bureau; Millennium: The Takeda Oncology Company: Consultancy, Research Funding, Speakers Bureau. Mark:Onyx: Research Funding, Speakers Bureau; Millennium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Rossi:Celgene: Speakers Bureau.

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