Aberrant CDK7 Activity Drives the Cell Cycle and Transcriptional Dysregulation to Support Multiple Myeloma Growth: An Attractive Molecular Vulnerability

Abstract Multiple myeloma (MM) cells are characterized by cell cycle dysregulation, epigenetic heterogeneity, and perturbation of the transcriptional landscape. We have previously shown that chemical and genetic perturbation of transcriptional regulator CDK7 significantly and selectively impacted MM cell growth and viability, supporting it as a pharmacologically relevant target for MM. Indeed, selective CDK7 inhibitor YKL-5-124 was active against a large panel of MM cell lines and primary MM cells, with a significantly lower IC50 compared to PHA-activated normal donor peripheral blood mononuclear cells (PBMCs). The efficacy of YKL-5-124 was confirmed in vivo in several murine models of MM, including disseminated models. Gene expression analysis after CDK7 inhibition in several MM cell lines revealed that transcripts for only a subset of genes were substantially affected by treatment with low dose of YKL-5-124, showing a strong leading-edge enrichment for downregulation of E2F expression program, cell cycle, DNA damage, and MYC targets. We have indeed confirmed a potent reduction in phosphorylation of RB protein, with consequent decrease of E2F activity in MM cells, supporting CDK7 as a central hub in the oncogenic CDK-pRb-E2F pathway in MM cells, with its expression and activity positively correlated with E2F transcriptional output in patient MM cells. Importantly, dual inhibition with low doses of YKL-5-124 and BRD4 inhibitor JQ1, displayed superior activity against a panel of MM cell lines and primary MM cells compared to single perturbation alone by both converging on a subset of key SE-associated dependencies as well as impacting distinct oncogenic expression programs. To identify synthetically lethal targets and mechanisms of resistance to CDK7 inhibition, we performed a genome-wide CRISPR-Cas9 knockout screen in the MM1S cells treated with YKL-5-124 or DMSO. We found that BCL6, NFKBIA and B, TRAF2, TSC1 and CSNK2A1, a subunit of CK2, were top synthetically lethal hits; whereas deletion of RB1, SF3B3 and the DNA-binding transcriptional activator TADA2A that regulates RNA-pol II transcription, led to resistance to YKL-5-124. Molecular mechanisms of intrinsic and acquired resistance to CDK7 inhibition are now under investigation and will be presented. In conclusion, our study demonstrates CDK7 as an attractive molecular vulnerability in MM that can be exploited therapeutically alone or in combination. Disclosures Shirasaki: FIMECS: Consultancy. Chesi: Novartis: Consultancy, Patents & Royalties: human CRBN transgenic mouse; Pfizer: Consultancy; Pi Therapeutics: Patents & Royalties: Genetically engineered mouse model of myeloma; Abcuro: Patents & Royalties: Genetically engineered mouse model of myeloma; Palleon Pharmaceuticals: Patents & Royalties: Genetically engineered mouse model of myeloma. Anderson: Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Scientific Founder of Oncopep and C4 Therapeutics: Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mitsiades: Arch Oncology: Research Funding; Karyopharm: Research Funding; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Ionis Pharmaceuticals: Consultancy, Honoraria; Abbvie: Research Funding; FIMECS: Consultancy, Honoraria; Nurix: Research Funding; Sanofi: Research Funding; Novartis: Research Funding; H3 Biomedicine: Research Funding; EMD Serono: Research Funding; Janssen/Johnson & Johnson: Research Funding; Fate Therapeutics: Consultancy, Honoraria; BMS: Research Funding; TEVA: Research Funding. Munshi: Novartis: Consultancy; Legend: Consultancy; Pfizer: Consultancy; Adaptive Biotechnology: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Abbvie: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; Bristol-Myers Squibb: Consultancy.

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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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Activity of Carfilzomib (CFZ) in Acute Myeloid Leukemia (AML) As a Single Agent and in Novel Combinations

Blood ◽

10.1182/blood-2020-141459 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 6-7

Author(s):

Mao Yu Peng ◽

Yasmin Abaza ◽

Martina Mcdermott ◽

Monica Mead ◽

Dennis J. Slamon ◽

...

Keyword(s):

Cell Cycle ◽

Synergistic Effect ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Fatty Acid Synthase ◽

Single Agent ◽

Therapeutic Strategies ◽

Private Company ◽

Advisory Committees

Background:Recent advances in targeted therapy have expanded the available therapeutic optionsfor patients with AML. However, many patients still have suboptimal outcomes, particularly in the relapsed/refractory setting, underscoring the need for novel therapeutic strategies. Proteasome inhibitors (PIs), such as bortezomib, exhibit antitumor activity in AML through inhibition of the nuclear factor κB pathway and induction of apoptosis. CFZ, a second-generation PI, has preferential preclinical activity in AML compared to bortezomib making it an agent of interest in AML therapy. Here we assessed the activity of CFZ as a single agent and in novel combinations with Ara-C and/or other agents targeting potential vulnerabilities in AML cell lines. Methods:20 AML cell lines were treated with a single dose of CFZ for 7 days, proliferation inhibition was measured using an IC50 cutoff for CFZ of 10 nM. 2 sensitive (ML2 and MV411) and 2 resistant (AML193 and NOMO1) cell lines were selected for further analysis. Apoptosis, cell cycle, and cell senescence analysis were performed after 72 hours of CFZ exposure at 10 nM. Combination assays using CFZ 10 nM and Ara-C 200 nM were performed to evaluate for potential interaction in the form of antagonism or potentiation. Proteomic analysis was performed at baseline using reverse phase protein assay (RPPA). Cell lines were aligned according to CFZ IC50. Several proteins involved in various physiological pathways exhibited a potential correlation with CFZ sensitivity. Combination treatments with CFZ and agents targeting these pathways were carried out in selected cell lines. Results:Single-agent CFZ induced apoptosis with apoptotic rates >85% in sensitive cell lines and only 10% in resistant cell lines. Similarly, CFZ resulted in G0/G1 cell cycle arrest in sensitive, but not resistant AML cell lines. Lack of difference in cellular senescence confirmed apoptosis as the major mechanism of CFZ-induced growth inhibition in AML cell lines. No antagonism was noted when CFZ was combined with Ara-C. RPPA revealed that AML cell lines with higher expression of autophagy-related proteins (Atgs) were more resistant to CFZ treatment. Combining autophagy inhibitor hydroxychloroquine (HCQ) or ROC-325 with CFZ produced a synergistic effect to induce apoptosis in several CFZresistant cell lines. RPPA also revealed that lower basal levels of fatty acid synthase (FASN), a key enzyme involved in lipogenesis, correlated with CFZ sensitivity and CFZ resistant lines tendedto have higher basal FASN levels. The combination of CFZ with a FASN inhibitor resulted in a significant synergistic apoptosis-inducing effect that was observed in the AML lines tested. Conclusion:CFZ demonstrated single agent activity in the nanomolar range in human AML cell lines. The addition of standard-of -care chemotherapy to CFZ did not show antagonism. Combining CFZ with agents targeting autophagy or lipid-metabolism showed synergistic effect in apoptosis. These results suggest a role for CFZ in combination therapeutic strategies for AML patients. Disclosures Mcdermott: TORL Biotherapeutics:Current equity holder in private company;1200 Pharma:Current equity holder in private company.Slamon:TORL Biotherapeutics:Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees;1200 Pharma:Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees;Novartis:Consultancy, Research Funding;Eli Lilly:Consultancy;Bayer:Consultancy, Research Funding;Pfizer:Consultancy, Other: stock, Research Funding;Syndax:Research Funding;Aileron:Research Funding;Genetech:Research Funding;Biomarin:Membership on an entity's Board of Directors or advisory committees;Seattle Genetics:Other: Stock;Amgen:Other: Stock.Larson:BMS, Bioline, Celgene, Juno, Janssen:Research Funding;TORL Biotherapeutics:Current equity holder in private company.

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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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A NOVEL Aurora A Kinase INHIBITOR MLN8237 Induces Cytotoxicity and CELL Cycle Arrest IN MULTIPLE MYELOMA.

Blood ◽

10.1182/blood.v114.22.3830.3830 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3830-3830

Author(s):

Gullu Gorgun ◽

Elisabetta Calabrese ◽

Teru Hideshima ◽

Jeffrey Ecsedy ◽

Giada Bianchi ◽

...

Keyword(s):

Cell Cycle ◽

Board Of Directors ◽

Cell Lines ◽

Mitotic Spindle ◽

Research Funding ◽

Thymidine Incorporation ◽

Aurora A Kinase ◽

Advisory Committees

Abstract Abstract 3830 Poster Board III-766 Multiple myeloma (MM) is an incurable bone marrow derived plasma cell malignancy. Despite significant improvements in treating patients suffering from this disease, MM remains uniformly fatal due to intrinsic or acquired drug resistance. Thus, additional modalities for treating MM are required. Targeting cell cycle progression proteins provides such a novel treatment strategy. Here we assess the in vivo and in vitro anti-MM activity of MLN8237, a small molecule Aurora A kinase (AURKA) inhibitor. AURKA is a mitotic kinase that localizes to centrosomes and the proximal mitotic spindle, where it functions in mitotic spindle formation and in regulating chromatid congression and segregation. In MM, increased AURKA gene expression has been correlated with centrosome amplification and a worse prognosis; thus, inhibition of AURKA in MM may prove to be therapeutically beneficial. Here we show that AURKA protein is highly expressed in eight MM cell lines and primary patient MM cells. The affect of AURKA inhibition was examined using cytotoxicity (MTT viability) and proliferation (3[H]thymidine incorporation) assays after treatment of these cell lines and primary cells with MLN8237 (0.0001 μM – 4 μM) for 24, 48 and 72h Although there was no significant inhibition of cell viability and proliferation at 24h, a marked effect on both viability and proliferation occurred after 48 and 72h treatment at concentrations as low as 0.01 μM. Moreover, MLN8237 inhibits cell growth and proliferation of primary MM cells and cell lines even in the presence of bone marrow stromal cells (BMSCs) or cytokines IL-6 and IGF1. Similar experiments revealed that MLN8237 did not induce cytotoxicity in normal peripheral blood mononuclear cells (PBMCs) as measured by MTT assay, but did inhibit proliferation at 48 and 72h, as measured by the 3[H]thymidine incorporation assay. To delineate the mechanisms of cytotoxicity and growth inhibitory activity of MLN8237, apoptotic markers and cell cycle profiles were examined in both MM cell lines and primary MM cells. Annexin V and propidium iodide staining of MM cell lines cultured in the presence or absence of MLN8237 (1 μM) for 24, 48 and 72h demonstrated apoptosis, which was further confirmed by increased cleavage of PARP, capase-9, and caspase-3 by immunoblotting. In addition, MLN8237 upregulated p53-phospho (Ser 15) and tumor suppressor genes p21 and p27. Cell cycle analysis demonstrated that MLN8237 treatment induces an accumulation of tetraploid cells by abrogating G2/M progression. We next determined whether combining MLN8237 with conventional (melphalan, doxorubucin, dexamethasone) and other novel (VELCADE®) therapeutic agents elicited synergistic/additive anti-MM activity by isobologram analysis using CalcuSyn software. Combining MLN8237 with melphalan, dexamethasone, or VELCADE® induces synergistic/additive anti-MM activity against MM cell lines in vitro (p≤0.05, CI<1). To confirm in vivo anti-MM effects of MLN8237, MM.1S cells were injected s.c. into g-irradiated CB-17 SCID mice (n=40, 10 mice EA group). When tumors were measurable (>100 mm3), mice were treated with daily oral doses of vehicle alone or 7.5mg/kg, 15mg/kg, 30mg/kg MLN8237 for 21 days. Overall survival (defined as time between initiation of treatment and sacrifice or death) was compared in vehicle versus- MLN8237- treated mice by Kaplan-Meier method. Tumor burden was significantly reduced (p=0.02) and overall survival was significantly increased (p=0.02, log-rank test) in animals treated with 30mg/kg MLN8237. In vivo anti-MM effects of MLN8237 were further validated by performing TUNEL apoptosis-cell death assay in tumor tissues excised from control or treated animals. Importantly, a significant dose-related increase in apoptotic cells was observed in tumors from animals that received MLN8237 versus controls. These results suggest that MLN8237 represents a promising novel targeted therapy in MM. Disclosures: Ecsedy: Millennium Pharmaceutical: Employment. Munshi:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Richardson:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees. Anderson:Millennium: Research Funding; Novartis: Research Funding; Celgene: Research Funding.

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LSD1 Inhibitor CPI-482 Shows Efficacy and Prolongs Survival in Mouse Models of AML and Post-MPN AML in the Context of Constitutive JAK-STAT Pathway Activation

Blood ◽

10.1182/blood-2020-140186 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 50-51

Author(s):

Raajit K. Rampal ◽

John P. McGrath ◽

Aishwarya Krishnan ◽

Bing Li ◽

Wenbin Xiao ◽

...

Keyword(s):

Bone Marrow ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Myelogenous Leukemia ◽

Publicly Traded ◽

Private Company ◽

Advisory Committees ◽

Pathway Activation ◽

Stat Pathway

Several novel mechanism-based therapeutic modalities are currently being clinically investigated for the treatment of patients with acute myelogenous leukemia (AML), including agents that exploit genomic vulnerabilities, attenuate leukemia stem cell populations and/or or synergize with anti-leukemic cytotoxic/epigenetic therapies. Lysine-specific demethylase 1 (LSD1) is an enzyme that functions in transcriptional repression by catalyzing the removal of histone H3 lysine 4 methylation, a histone modification associated with transcriptionally competent gene enhancers and transcriptional start sites. Small molecule mediated inhibition of LSD1 alters the chromatin state and the transcriptional output of LSD1 target genes. Transcriptional 'reprogramming' by LSD1 inhibitors either causes a direct impact on cell fate and/or renders malignant cells more susceptible to the treatment with other cancer therapeutic agents. LSD1 inhibitors have shown encouraging phenotypic effects in myelogenous leukemia (AML) models but the key molecular determinants governing LSD1 inhibitor sensitivity remain to be further investigated. Here, we explored the in vitro sensitivity of 350 cancer cell lines to our LSD1 inhibitor CPI-482 to identify potential hyper-responder cell contexts. Four AML cell lines showed high sensitivity with low nanomolar concentration GI50s, each of which contained either a JAK2V617F mutation or a genetic aberration that resulted in JAK-STAT pathway activation. Oral administration of LSD1 inhibitor CPI-482 on a once daily or a once weekly dosing schedule resulted in significant tumor growth inhibition in SET-2 and HEL 92.1.7 JAK2 mutant AML xenograft mouse models. Given the unmet need and poor prognosis in post-MPN secondary AML (sAML) we then explored CPI-482 in a tertiary transplant post-MPN AML retroviral transduction murine model (Jak2V617F retrovirus transduced intoTp53 null bone marrow). Jak2V617F/Tp53 null spleen cells were transplanted into lethally irradiated recipient mice along with wild-type donor support whole bone marrow cells. Mice were randomized to treatment with vehicle, Ruxolitinib (60mg/kg twice daily) or CPI-482 (60mg/kg weekly). Once-weekly treatment with CPI-482 significantly improved survival compared to vehicle (p<0.001) or ruxolitinib (p<0.043) (Figure 1A). Spleen weights were significantly reduced by CPI-482 compared to ruxolitinib (p<0.05;Figure 2B). The white blood cell count was unchanged in mice treated with CPI-482 but increased in both vehicle and ruxolitinib treated mice. Evaluation at the time of terminal take-down of mice demonstrated a significant increase in the proportion of lineage positive cells in both the bone marrow and spleen (compared to vehicle, p<0.05) consistent with restoration of normal hematopoiesis (Figure 1D). Histopathologic evaluation of the spleen demonstrated marked reduction in infiltration by blast cells, restoration of lymphoid follicles, emergence of megakaryocytes (Figure 1E), and modest reductions in reticulin fibrosis in CPI-482 treated mice, which was not observed in ruxolitinib treated mice. Mice tolerated treatment with CPI-482 well, with no changes in weights of treated mice (Figure 1F). Treatment of the JAK2V617F mutant AML cell lines SET-2 and HEL with CPI-482 resulted in specific transcriptional effects, including increased expression of the myeloid differentiation markers LY96 and CD86 and inflammatory response genes. CPI-482 also resulted in upregulation of genes that are repressed by the HOXA9 oncogene in other leukemia contexts. The induction of specific CPI-482 mediated gene expression and phenotypic changes was recapitulated by knockdown of the transcription factor GFI1B, suggesting that, consistent with prior findings in other leukemia contexts, LSD1 functionally cooperates with GFI1B in JAK2V617F mutant AML cells. These data provide support for a potential therapeutic impact of the LSD1 inhibitor CPI-482 in AML and sAML in the context of the JAK2V617F mutation, and thus extend the previous findings that LSD1 inhibitors may have utility in JAK2V617F mutated malignant proliferative neoplasms. Given the pressing need for new therapies for sAML which evolves from a pre-existing MPN, we believe these data form the rationale for a mechanism based clinical trial in this adverse risk myeloid malignancy. Figure Disclosures Rampal: Pharmaessentia: Consultancy; Galecto: Consultancy; Abbvie: Consultancy; Stemline: Consultancy, Research Funding; Constellation: Research Funding; Incyte: Consultancy, Research Funding; Celgene: Consultancy; Promedior: Consultancy; CTI Biopharma: Consultancy; Jazz Pharmaceuticals: Consultancy; Blueprint: Consultancy. McGrath:Constellation Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Xiao:Stemline Therapeutics: Research Funding. Nikom:Constellation Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Wang:Constellation Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Levine:Imago: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Isoplexis: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding; Lilly: Consultancy, Honoraria; Janssen: Consultancy; Astellas: Consultancy; Morphosys: Consultancy; Novartis: Consultancy; Amgen: Honoraria; Gilead: Honoraria; Prelude Therapeutics: Research Funding; Qiagen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Loxo: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Trojer:Constellation Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company.

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Role of TORC1 and TORC2 in Multiple Myeloma

Blood ◽

10.1182/blood.v118.21.1815.1815 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1815-1815

Author(s):

Patricia Maiso ◽

Yi Liu ◽

Abdel Kareem Azab ◽

Brittany Morgan ◽

Feda Azab ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Board Of Directors ◽

Cell Lines ◽

Stromal Cells ◽

Research Funding ◽

Plasma Cells ◽

Advisory Committees ◽

Cycle Arrest

Abstract Abstract 1815 Mammalian target of rapamycin (mTOR) is a downstream serine/threonine kinase of the PI3K/Akt pathway that integrates signals from the tumor microenvironment. Mechanistically, mTOR operates in two distinct multi-protein complexes, TORC1 (Raptor) and TORC2 (Rictor). TORC1 leads to the phosphorylation of p70S6 kinase and 4E- BP1, while TORC2 regulates phosphorylation of Akt and other kinases. In multiple myeloma (MM), PI3K/Akt plays an essential role enhancing cell growth and survival and is activated by the loss of the tumor suppressor gene PTEN and by the bone marrow microenvironment. Rapamycin and its analogues have not shown significant activity in MM, likely due to the lack of inhibition of TORC2. In this study, we dissected the baseline activity of the PI3K/Akt/mTOR pathway TORC1/2 in MM cell lines with different genetic abnormalities. Methods: Eight different MM cell lines and BM samples from MM patients were used in the study. The mechanism of action was investigated by MTT, Annexin V, cell cycle analysis, immunochemistry, Western-blotting and siRNA assays. For the in vivo analyses, Luc+/GFP+ MM.1S cells (2 × 106/mouse) were injected into the tail vein of 30 SCID mice and tumor progression was detected by bioluminescence imaging. In vivo homing was checked by in vivo flow. Nanofluidic proteomic immunoassays were performed in selected tumors. Results: Raptor (TORC1) and Rictor (TORC2) knockdowns led to significant inhibition of proliferation of MM cells even in the presence of bone marrow stromal cells, this effect was also accompanied by inactivation of p-Akt, p-rS6 and p-4EBP1. We used INK128, a dual and selective TORC1/2 kinase inhibitor with similar effects to Raptor plus Rictor knockdown. We examined the protein expression levels of both mTOR complex and their downstream effectors in MM plasma cells from patients and cell lines. mTOR, Akt, pS6R and 4E-BP1 are constitutively activated in all samples. We showed that dual TORC1/2 inhibition is much more active than TORC1 inhibition alone (rapamycin) even in the presence of cytokines or stromal cells. INK128 induced cell cycle arrest, autophagy and apoptosis in cell lines and primary plasma cells even in the presence of bone marrow stromal cells (BMSCs). INK128 also showed a significant effect inhibiting cell adhesion in our in vivo homing model. Oral daily treatment with INK128 highly decreased the percentage of CD138+ tumor plasma cells in mice implanted with MM cells and reduced the levels of p-Akt and p-4EBP. These results suggest that potent and complete blockade of mTOR as part of TORC1 and TORC2 is potential therapeutic strategy to induce cell cycle arrest, apoptosis and disruption of MM cells interaction with the BM microenvironment. Conclusion: Dual inhibition of TORC1 and TORC2 represent a new and promising approach in the treatment of MM and its microenvironment. The ability of INK128 to inhibit both TORC1 and TORC2 strongly supports the potential use of this compound in MM patients. Disclosures: Liu: Intellikine: Employment. Roccaro:Roche: Research Funding. Rommel:Intellikine: Employment. Ghobrial:Celgene: Consultancy; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Noxxon: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Targeting MYD88-Mutant DLBCL with IRAKIMiDs: A Comparison to IRAK4 Kinase Inhibition and Evaluation of Synergy with Rational Combinations

Blood ◽

10.1182/blood-2020-135898 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 12-12

Author(s):

Jennifer Kimberly Lue ◽

John S Manavalan ◽

Christine Klaus ◽

Rahul Kanik ◽

Andre M. Grilo ◽

...

Keyword(s):

Flow Cytometry ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Kinase Inhibitors ◽

Dual Function ◽

Rna Seq ◽

Publicly Traded ◽

Advisory Committees ◽

Ic50 Values

Introduction: MYD88 mutations are found in 25% of DLBCL and are associated with an inferior survival. MYD88 is an adapter molecule, forming the core of the Myddosome complex. MYD88 mutations constitutively activate pathways such as NFқB, leading to lymphomagenesis. Essential to the Myddosome-dependent signaling pathway is the recruitment of IRAK4 which complexes with MYD88 to activate downstream effects. Targeting IRAK4 is therefore a rational therapeutic approach in MYD88-mutant lymphomas. First-in-class IRAKIMiDs, novel heterobifunctional degraders that target IRAK4 as well as the IMiD substrates Ikaros and Aiolos to enable the inhibition of both the NFkB and IRF4 pathways activated by MYD88 mutations, demonstrate potent efficacy in MYD88-mutant lymphomas (KTX-475, KTX-582, Walker D et al. AACR 2020). Herein, we compare the activity of IRAKIMiDs to IRAK4 kinase inhibitors and IMiDs alone in MYD88-mutant DLBCL, and evaluate rational combinations of IRAKIMiDs and other active agents in DLBCL for synergy. Methods: MYD88-mutant (n=4) and wild type (n=4) DLBCL cell lines were exposed to a panel of single agents (KTX-475, KTX-582, BAY1830839, CA-4948, CC-220, lenalidomide, pomalidomide, ibrutinib, umbralisib, venetoclax) in order to establish the drug concentration:cytotoxicity effect relationship. Cell viability was assessed using Celltiter-Glo assay at 24-hour intervals. IC50 values were computed. MYD88-mutant DLBCL cells were co-exposed to combinations of KTX-475 with venetoclax, ibrutinib, or umbralisib at concentrations representing their respective IC10-40 in order to determine synergy using the excess over bliss (EOB) method. Venetoclax, ibrutinib, and umbralisib were selected for combinational studies in order to target adverse pathways known to be associated in DLBCL biology. To confirm IRAK4 degradation, western blot and flow cytometry was performed. Apoptosis was evaluated with flow cytometry. Pre-treatment RNA-seq libraries were developed for the purpose of identifying GSEA and mutational analysis to predict response to IRAKIMiDs. Results: Exposure to IRAKIMiDs led to potent activity in MYD88-mutated DLBCL with IC50s in the low nanomolar range. IRAK4 degradation occured in a dose- and time-dependent manner and was observed as early as four hours after exposure. IRAKIMiDs induced superior cytotoxicity compared to two IRAK4 kinase inhibitors, including CA-4948 (Curis), which is currently under clinical investigation for relapsed/refractory NHL, as determined by lower IC50s in all cell lines. IRAKIMiD IC50s were also lower compared to pomalidomide, lenalidomide, and CC-220. KTX-475 was selected for synergy assessments based on IC50 values. Synergy was observed after exposure to KTX-475 in conjunction with venetoclax, ibrutinib, or umbralisib as determined by EOB >0 in the MYD88-mutant OCI-LY10 model, with maximum values peaking at 72-96 hours. After dual drug exposure, IRAK4 degradation was validated by flow cytometry demonstrating that the addition of venetoclax, ibrutinib or umbralisib to KTX-475 did not impair IRAK4 degradation capabilities. RNA-seq interpretation is currently underway. Conclusions: Collectively, our results demonstrate that dual-function degraders targeting both IRAK4 and the IMiD substrates Ikaros and Aiolos can serve as a potential therapeutic option for poor prognosis MYD88-mutant DLBCL. Our data thus far demonstrate improved efficacy of IRAKIMiDs compared to IRAK4 kinase inhibitors or IMiDs alone in vitro, as well as synergy with other active agents in combination regimens. A promising lead IRAKIMiD candidate has been identified, with initiation of a first-in-human clinical trial in B-cell lymphomas planned for 2021. Disclosures Lue: Daiichi Sankyo: Honoraria; AstraZeneca: Speakers Bureau; Astex Pharmaceuticals: Honoraria; Kymera Therapeutics: Honoraria, Research Funding; Kura Oncology: Honoraria. Klaus:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kanik:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. McDonald:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Gollob:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. Walker:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company. O'Connor:Kymera Therapeutics: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Current Employment, Current equity holder in publicly-traded company; Servier: Consultancy; Mundipharma: Other: Consulting; Astex Pharmaceuticals: Honoraria, Research Funding; Merck: Research Funding; Nomocan: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Other: Data Safety Monitoring Committee, Research Funding. Mainolfi:Kymera Therapeutics: Current Employment, Current equity holder in publicly-traded company.

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Sensitizing shRNA Screen for Molecular Targets in CDK4/CDK6-Based Combination Therapy in Multiple Myeloma

Blood ◽

10.1182/blood.v124.21.3440.3440 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3440-3440 ◽

Cited By ~ 1

Author(s):

Xiangao Huang ◽

Maurizio Di Liberto ◽

David Chiron ◽

Ruben Niesvizky ◽

Anna C. Schinzel ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Clinical Trial ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Proteasome Inhibitors ◽

Advisory Committees ◽

Myeloma Cells ◽

Shrna Screen

Abstract CDK4 and CDK6 are rarely mutated but are overexpressed or hyperactivated at a very high frequency in human cancers. By inhibiting CDK4/CDK6 with an exceptionally selective and reversible inhibitor, palbociclib (PD 0332991), we have developed a novel strategy to reprogram cancer cells for cytotoxic killing through induction of prolonged early G1 arrest (pG1). We have demonstrated that pG1 sensitizes cancer cells expressing Rb, the substrate of CDK4 and CDK6, to cytotoxic killing by forcing an imbalance in gene expression because only genes scheduled for early G1 are expressed. This sensitization is exacerbated after palbociclib withdrawal due to incomplete restoration of gene expression despite S phase synchronization (pG1-S). This study aims to identify genes that mediate pG1-S sensitization to two clinically-relevant agents for myeloma, the proteasome inhibitors carfilzomib and bortezomib, in model cell lines by a sensitizing pool genome-wide shRNA screen, and by validating the hits in a clinical trial of palbociclib in combination with bortezomib and dexamethasone. We ranked the hits based on the enrichment of target shRNAs, and representation in replica of each cell lines and among different human myeloma cell lines (HMCLs) as well as functional analyses. In myeloma cells, cell cycle control by palbociclib was intact in all hits, demonstrating that CDK4 and CDK6 are indispensable for myeloma replication. Among the top ranking 20 candidates, we found that NEDD4L was essential for proteasome inhibitor killing, FTH1 modulated the threshold of killing by diverse agents especially in pG1-S, and IL10RAappeared to be required for pG1-S sensitization to proteasome inhibitors. Moreover, RNA-sequencing analysis of primary myeloma cells from a phase II clinical trial targeting CDK4/CDK6 with palbociclib in combination with bortezomib in myeloma revealed that a higher level of FTH1 expression in myeloma cells in vivo correlated with sensitivity to this therapy, suggesting a role for FTH1 in differential sensitivity to this CDK4/CDK6-based therapy in myeloma. Selective inhibition of CDK4/CDK6 with palbociclib, or another specific inhibitor such as LY2835219 or LEE011, in combination therapy has now achieved unprecedented clinical efficacy in diverse human cancers. Most notably, palbociclib more than doubled the progression free survival of metastatic breast cancer patients when it was combined with letrozole, and has been designated a “breakthrough therapy” by the FDA for breast cancer. Our work provides the first insight into genes that mediate cell cycle sensitization to cytotoxic killing through selective CDK4/CDK6 inhibition. It provides an exciting potential for further investigation in a clinical context, such as the ongoing phase I clinical trial combining palbociclib with the immunomodulatory drug lenalidomide in patients with relapsed/refractory myeloma. Disclosures Huang: Celgene: Research Funding. Off Label Use: PD 0332991 (palbociclib) is a specific CDK4/CDK6 inhibitor used to stop the cell cycle.. Niesvizky:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Chen-Kiang:Celgene: Consultancy, Research Funding.

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Targeting Hypersumoylation in Mantle Cell Lymphoma

Blood ◽

10.1182/blood-2019-127363 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4060-4060 ◽

Cited By ~ 1

Author(s):

Walter Hanel ◽

Liudmyla Tsyba ◽

Dennis Huszar ◽

Alex Prouty ◽

Xiaoli Zhang ◽

...

Keyword(s):

Cell Cycle ◽

Cell Death ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Advisory Committees ◽

Human B Cells ◽

Mantle Cell ◽

Normal Human ◽

Protein Sumoylation

Mantle cell lymphoma (MCL) is an aggressive and incurable subtype of B-cell Non-Hodgkin's lymphoma (NHL) characterized by genetic dysregulation of CyclinD1. Despite the improvement in response rates with current therapies, MCL patients inevitably relapse and outcomes remain poor. This is particularly true for MCL patients progressing on novel targeted therapies such as ibrutinib, highlighting the continued need for new therapeutic approaches. SUMOylation is a post-translational modification regulated by SUMO Activating Enzymes 1 and 2 (SAE1/2) affecting function, stability, and subcellular localization of a multitude of proteins such as Cyclin D1 and regulating multiple cellular functions such as cell cycle control and DNA damage response. While not yet explored in MCL, it is known that hyper-SUMOylation is associated with augmented cell proliferation and tumor growth of a number of cancers including B-cell NHL. We evaluated the expression levels of SAE1/2, total SUMO1, and SUMO 2/3 in normal human B cells, primary MCL patient samples, and a panel of 8 MCL cell lines via immunoblotting. We found significantly increased levels of SAE1/2 and total protein SUMOylation in 4 out of 5 MCL patient samples and all MCL cell lines compared to normal human B-cells. To validate the SAE complex as a potential therapeutic target in MCL, we performed genetic knockdown of SAE1 and SAE2 using both shRNA and an inducible CRISPR/Cas9 system and found significant reduction in viability of MCL cells (p < 0.001) thus confirming that SUMOylation is essential for MCL survival. TAK-981 (Takeda Pharmaceuticals) is a potent and selective inhibitor of the SAE1/2 complex currently in a phase 1 clinical trial (NCT036483). We found that treatment of MCL cell lines with TAK-981 resulted in time- and dose-dependent cell death in 7 of 8 MCL cell lines (IC50 17 - 62.5 nM at 72 hr) which was associated with relevant decrease in protein sumoylation. MCL cells were sensitive to TAK regardless of ATM or p53 mutations. Finally, TAK-981 treatment prolonged the survival of SCID mice engrafted with a human MCL cell line (Jeko) compared with placebo control [median overall survival (OS): TAK-981, 34 days; placebo, 29 days, p = 0.008] and also extended the survival of a novel patient derived xenograft (PDX) mouse model of ibrutinib-resistant MCL (median OS: TAK-981, 60 days; placebo, 55 days, p = 0.001), thus establishing the in vivo efficacy of TAK-981 in models of aggressive MCL. Mechanistically, 24 hours of treatment with TAK-981 resulted in a profound G2M cell cycle arrest in 6 out of 7 TAK-981-sensitive MCL cell lines. Cell synchronization with palbociclib followed by release into TAK-981 showed significant apoptosis upon G2M re-entry. In addition, in p53-deficient MCL cell lines, we found rapid accumulation of polyploid and aneuploid cells followed by rapid cell death following 48 hours of drug exposure. These findings strongly support mitotic catastrophe as a significant mechanism of tumor cell death mediated by TAK-981. Upon fractionation of cells at distinct phases of the cell cycle, we found significantly increased levels of protein SUMOylation by both SUMO1 and SUMO2/3 at the G2M transition. Further mechanistic data will be presented at the meeting. Given the multiple immune dampening mechanisms of SUMOylation, we are currently studying the anti-MCL immune effects of TAK-981. To do this, we are employing a novel immunocompetent mouse model of MCL in which murine lymphoma cells from Eμ-SOX11/CCND1 double transgenic animals are adoptively transferred into syngeneic mice. These mice develop a systemic lymphoma with morphological, molecular, and phenotypic features characteristic of MCL resulting in death within 3-4 weeks. Preliminary results with this model show that treatment with TAK-981 leads to decrease in lymphoma burden and significant prolongation of survival. Studies into the immune mediated anti-lymphoma effects of TAK-981 using this model are ongoing and will be presented at the meeting. Together, our data strongly support further development of TAK-981 as a novel MCL therapeutic. Disclosures Huszar: Takeda Pharmaceuticals: Employment, Equity Ownership. Parekh:Karyopharm Inc.: Research Funding; Foundation Medicine Inc.: Consultancy; Celgene Corporation: Research Funding. Maddocks:BMS: Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Merck: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees. Baiocchi:Prelude: Consultancy.

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Overcoming the Supportive Stroma-Induced Proliferation in Waldenstrom's Macroglobulinemia By Selective Inhibition of the FGF/FGF-Receptor Axis

Blood ◽

10.1182/blood-2019-126554 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1822-1822

Author(s):

Cinzia Federico ◽

Antonio Sacco ◽

Katia Todoerti ◽

Arianna Giacomini ◽

Gaia C Ghedini ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Cell Growth ◽

Board Of Directors ◽

Tumor Cells ◽

Cell Lines ◽

Research Funding ◽

Significant Inhibition ◽

Advisory Committees ◽

Dose Dependent

The human fibroblast growth factor receptor (FGF-R) family plays an essential role in a wide range of cellular processes, such as cell growth, proliferation, differentiation, migration and survival. It has been reported that FGF-Rs are expressed in hematopoietic cells; and FGF/FGFR signaling deregulation is largely involved in hematologic malignancies, including Waldenström macroglobulinemia (WM). WM is still an incurable disease, and patients succumb due to disease progression. Therefore, novel therapeutics designed to specifically target deregulated signaling pathways in WM are required. We aimed to investigate the role of FGF/FGF-R system in FGF-dependent WM cell lines by using an anti-pan FGF trap molecule (NSC12), responsible for FGF/FGF-R blocking. We first interrogated the GSE9656 dataset in order to confirm the expression of FGFs and FGF-Rs in WM cells, demonstrating an enrichment of several FGF- and FGF-R-isoforms in primary WM patients' derived tumor cells compared to the normal cellular counterpart (P<0.05); and demonstrated the ability of NSC12 to inhibit FGF-secretion within the conditioned media of NCS12-treated WM cells, as shown by ELISA. Wide-transcriptome profiling of NSC12-treated WM cells (BCWM.1; MWCL1) revealed a significant inhibition of Myc-target related genes, coupled with silencing of genes involved in cell cycle progression, cell proliferation, PI3K-AKT-mTOR signaling, oxidative phosphorylation (Hallmark; FDR<0.25; P<0.05). This prompted us to evaluate the anti-tumor functional sequelae exerted by NSC12 in WM cells: NSC12 induced significant inhibition of WM cell growth (BCWM1 and WMCL1) in a dose-dependent fashion (0.1-10μM; IC50 ~3μM), even in the presence of bone marrow microenvironment. In addition, a significant effect was also observed in primary tumor cells from WM patients; while no effect was observed on healthy donor-derived peripheral blood mononuclear cells. The growth inhibitory effect was associated with induction of apoptotic cell death, caspase activation and PARP cleavage, as demonstrated by flow cytometry and western blot, respectively. Moreover, we also observed a NSC12 dose-dependent increase of mitochondrial reactive oxigen species (ROS), at protein level. Cell cycle analysis revealed a reduction of the S-phase and increase of G0/G1 phase. Mechanistically, NSC12 targeted WM cells by inhibiting MAPK, JAK/STAT3 and PI3K-Akt pathways known to be FGFRs-activated signaling cascades. Importantly, the same effect was maintained in WM cells even in the presence of the supporting BM microenvironment. Functional studies demonstrated the ability of NSC12 to impair the adhesion of both cell lines to the supportive primary bone marrow stromal cells, in vitro. NCS12-dependnet anti-WM activity was also tested in combination with bortezomib, carfilzomib, everolimus and ibrutinib: the combinatory treatment (48h) resulted in a more significant dose-dependent inhibition of WM cell survival and proliferation (P<0.05), thus suggesting the rational for combining FGF-blockade with proteasome-, mTOR-, or BTK-inhibitors. In vivo studies are being performed, in order to further corroborate the anti-WM activity of NSC12 using WM animal models. Disclosures Ronca: Associazione Italiana per la Ricerca sul Canctro (AIRC): Research Funding. Rossi:Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Mundipharma: Honoraria; BMS: Honoraria; Sandoz: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Roccaro:AstraZeneca: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Associazione Italiana per al Ricerca sul Cancro (AIRC): Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; European Hematology Association: Research Funding; Associazione Italiana per al Ricerca sul Cancro (AIRC): Research Funding; Transcan2-ERANET: Research Funding; AstraZeneca: Research Funding; European Hematology Association: Research Funding; Transcan2-ERANET: Research Funding.

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