CC-220 Is a Potent Cereblon Modulating Agent That Displays Anti-Proliferative, Pro-Apoptotic and Immunomodulatory Activity on Sensitive and Resistant Multiple Myeloma Cell Lines

Abstract Background: CC-220 is a Cereblon (CRBN) binding compound currently under clinical investigation for systemic lupus erythematosus. Comparable to other Cereblon-binding agents, ex vivo treatment of CC-220 on B-cells, T-cells and monocytes leads to the degradation of the hematopoietic transcription factors Ikaros (IKZF1) and Aiolos (IKZF3).(1) Currently, CC-220 is being investigated in a phase Ib/IIa study CC-220-MM-001 (clintrial.gov trial #NCT02773030) as a single agent, or in combination with dexamethasone in relapsed/refractory multiple myeloma (RRMM) in patients who may have previously been exposed to pomalidomide. Here, we provide pre-clinical data and mechanistic rationale for the clinical development of CC-220 in heavily pre-treated RRMM. Results: In order to evaluate the ability of CC-220 effects on MM cells in vitro, we generated a large panel of MM cell lines (~69) that consist of 5 categories, including lenalidomide-sensitive (LS; n=26), intrinsically lenalidomide-resistant (ILR; n=7), acquired lenalidomide-resistant (ALR; n=12), acquired lenalidomide/dexamethasone-dual-resistant (ALDR; n=12), and acquired-pomalidomide-resistant (APR; n=12). Cell proliferation by 3H-thymidine incorporation at concentration between 0.01-100 μM was assessed by the area under the curve (AUC) for both CC-220 and pomalidomide. The average AUC was significantly reduced by 65% vs. 52% (p<0.01) for LS, 33% vs. 20% (p<0.01) for ILR, 30% vs. 20% (p<0.01) for ALR, 25% vs.10% (p<0.01) for ALDR, and 23% vs. 8% (ns) for PR cells for CC-220 vs. pomalidomide respectively. Apoptosis was analyzed by flow cytometry and AnnV+/ToPro3+ staining where CC-220 significantly (p<0.01) induced an average of 36% apoptotic cells compared to 30% for pomalidomide in LS cells, and 18% vs. 6% (p<0.5) in PS cells. Importantly, CC-220 showed anti-proliferative and pro-apoptotic activity in PR cells where Cereblon was still expressed. Additionally, both proliferation inhibition and apoptosis were synergistically enhanced across all cell line categories when CC-220 was used in combination with dexamethasone. We next evaluated the immunmodulatory effects on peripheral blood mononuclear cell (PBMCs)-stimulated killing of MM cells. Following a 72 hr incubation with CD3-stimulated PBMCs, CC-220 significantly induced the death of MM cells (~60%, across all cell type categories) within 4 hr, at concentrations more than 10-fold lower than pomalidomide. The observed CC-220-stimulated PBMC co-culture killing of MM cells closely correlated with dose-dependent increases in IL-2 secretion and Granzyme B release. Notably, CC-220 induced PBMC-mediated death of MM cells lacking observable Cereblon protein expression. Lastly, we evaluated the mechanism of action of CC-220 in MM cells in vitro. In the absence of Cereblon, as shown by shRNA knockdown or downregulation in a subset of PR cells, there is very little if any cell autonomous activity of CC-220, implicating Cereblon-dependency for its effects. Downstream of Cereblon, CC-220 stimulates the complete proteasomal degradation of both Ikaros and Aiolos in as little as 6 hr. Measurement of the half maximal time for 50% degradation of both Ikaros and Aiolos is kinetically faster from 1.9-2.9 vs. 2.4-6.9 hr depending on the MM cell line at a 10-fold lower dose for CC-220 compared to pomalidomide, respectively. CC-220 is also more efficient than pomalidomide at causing downregulation of the c-Myc/IRF4 axis, which has been shown to be essential for the cytotoxic effect of pomalidomide.(2) Conclusions: CC-220 is a potent anti-proliferative and pro-apoptotic compound that shows activity in several MM cell line categories with differing sensitivity to lenalidomide, pomalidomide and dexamethasone. Importantly, CC-220 induces PBMC-mediated killing of all MM cell lines regardless of the level of Cereblon expression and cell autonomous sensitivity. Mechanistically CC-220 acts through binding of Cereblon, leading to the degradation of the hematopoietic transcription factors Ikaros and Aiolos, followed by disruption of the MM promoting c-Myc/IRF4 axis. Taken together, these data support the clinical investigation of CC-220 in relapsed/refractory MM patients,who have previously been exposed to pomalidomide. Disclosures Bjorklund: Celgene Corporation: Employment, Equity Ownership. Kang:Celgene Corporation: Employment, Equity Ownership. Lu:Celgene Corporation: Employment, Equity Ownership. Amatangelo:Celgene: Employment, Equity Ownership. Chiu:Celgene Corporation: Employment, Equity Ownership. Gandhi:Celgene Corporation: Employment, Equity Ownership. Pourdehnad:Celgene Corporation: Employment, Equity Ownership. Klippel:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene: Employment, Equity Ownership.

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EZH2 Inhibitors Are Broadly Efficacious in Multiple Myeloma As Single Agent and in Combination with Standard of Care Therapeutics

Blood ◽

10.1182/blood.v128.22.5672.5672 ◽

2016 ◽

Vol 128 (22) ◽

pp. 5672-5672 ◽

Cited By ~ 1

Author(s):

Shilpi Arora ◽

Kaylyn Williamson ◽

Shruti Apte ◽

Srividya Balachander ◽

Jennifer Busby ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Lines ◽

Single Agent ◽

Standard Of Care ◽

Tumor Growth Inhibition ◽

Sequencing Data ◽

Employment Equity ◽

Chip Sequencing ◽

Equity Ownership

Abstract Post-translational modifications of the histone proteins play a key role in regulating processes that require access to DNA. Specifically, methylation of lysine 27 on histone 3 (H3K27) is intimately linked with transcriptional repression. EZH2, a histone lysine methyl transferase is the catalytic component of the PRC2 complex, which catalyzes H3K27 methylation. EZH2 dysregulation has been observed in different malignancies and inhibition of its catalytic activity has emerged as a novel therapeutic approach to treat human cancers. Potent, selective and reversible EZH2 small molecule inhibitors are currently being tested in Ph. 1 clinical trials. We and others have reported EZH2 dependencies across non-Hodgkin Lymphoma subtypes in cancer cell lines, in xenograft mouse models and in lymphoma patients. We identified Multiple Myeloma as potential clinical application for EZH2 inhibitors. Treatment with EZH2 inhibitors such as CPI-360, CPI-169 and CPI-1205 cause apoptosis in multiple myeloma and plasmacytoma cell models and causes tumor growth inhibition in myeloma xenograft models at well tolerated doses. An EZH2-controlled transcriptional signature across various multiple myeloma was identified using integrated RNA-sequencing and ChIP-sequencing data. Combination studies testing EZH2 inhibitors with standard of care (SOC) agents across a panel of multiple myeloma cell lines showed synergistic responses with several of the SOC agents in vitro and in vivo. Disclosures Arora: Constellation Pharmaceuticals: Employment, Equity Ownership. Williamson:Constellation Pharmaceuticals: Employment, Equity Ownership. Apte:Constellation Pharmaceuticals: Employment, Equity Ownership. Balachander:Constellation Pharmaceuticals: Employment, Equity Ownership. Busby:Constellation Pharmaceuticals: Employment, Equity Ownership. Hatton:Constellation Pharmaceuticals: Employment, Equity Ownership. Bryant:Constellation Pharmaceuticals: Employment, Equity Ownership. Trojer:Constellation Pharmaceuticals: Employment, Equity Ownership.

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SL-401, a Targeted Therapy Directed to the Interleukin-3 Receptor (CD123), and SL-801, a Reversible Inhibitor of Exportin-1 (XPO1), Display Synergistic Anti-Tumor Activity Against Hematologic Malignancies in Vitro

Blood ◽

10.1182/blood.v128.22.4724.4724 ◽

2016 ◽

Vol 128 (22) ◽

pp. 4724-4724 ◽

Cited By ~ 1

Author(s):

John Gionco ◽

Janice Chen ◽

Ross Lindsay ◽

Vince Macri ◽

Christopher L. Brooks

Keyword(s):

Cell Line ◽

Cell Lines ◽

Single Agent ◽

Hematologic Malignancies ◽

Clinical Activity ◽

Employment Equity ◽

Equity Ownership ◽

Rpmi 8226 ◽

Anti Tumor Activity

Abstract Background: Novel combination therapies have shown success in combating tumor heterogeneity and drug resistance. SL-401 is a targeted therapy directed to the interleukin-3 receptor (CD123), which is overexpressed on numerous hematologic malignancies. SL-401 has demonstrated high single agent response rates in an ongoing Phase 2 trial of blastic plasmacytoid dendritic cell neoplasm (BPDCN) and is also being evaluated in the clinic for additional cancers, including acute myeloid leukemia (AML) and myeloproliferative neoplasms (MPNs) as a single agent, and multiple myeloma (MM) in combination with other agents. While SL-401 has demonstrated robust single agent clinical activity in patients with BPDCN, its unique mechanism of action and non-overlapping side effect profile with other agents may lend itself to combination therapy as well. Another class of drugs that has demonstrated clinical activity against several hematologic and solid malignancies is Exportin-1 (XPO1) inhibitors. SL-801 is a novel oral small molecule that reversibly inhibits XPO1 and has shown potent in vitro and in vivo anti-tumor activity against a broad range of hematologic and solid malignancies. SL-801 is currently being evaluated in a Phase 1 trial of patients with advanced solid tumors, and a Phase 1 trial in advanced hematologic cancers is planned. Here, we investigated the in vitro effect of combination treatment of SL-401 and SL-801 against cell lines of chronic myeloid leukemia (CML), AML, MM, and Hodgkin's lymphoma (HL). Methods: The human K562 CML cell line, MV4-11 AML cell line, RPMI-8226 MM cell line, and L-428 HL cell line were treated with varying concentrations of SL-401 and SL-801 alone or in combination for 48 hours. Cell viability was assessed by the CellTiter Glo in vitro cytotoxicity assay. Combination index (CI) values were calculated using CompuSyn software by the method of Chou and Talalay, and treatment was considered to be synergistic when CI < 1. Caspase activation was measured using the Caspase-Glo 3/7 assay, and lactate dehydrogenase (LDH) release was measured using the CytoTox 96 Non-Radioactive Cytotoxicity Assay. Results: As single agents, SL-401 and SL-801 demonstrated anti-tumor activity in all four cell lines tested. MV4-11 cells were the most sensitive to both drugs, with an IC50 of 34 pM for SL-401 and 21 nM for SL-801. In the other cell lines, the IC50s for SL-401 were 17 nM in K562 cells, 25 nM in RPMI-8226 cells, and 100 nM in L-428 cells, and the IC50s for SL-801 were 99 nM in K562 cells, 51 nM in RPMI-8226 cells, and 494 nM in L-428 cells. When combined with each other, SL-401 and SL-801 potently inhibited cell growth in all cell lines, and CI calculations indicated that the interaction between the two drugs was synergistic at most dose combinations. Notably, CI values < 0.3 were observed in MV4-11 and L-428 cells, indicative of strong synergy. Consistent with these observations, the combination of SL-401 and SL-801 also induced higher levels of caspase activation and LDH release in MV4-11 and L-428 cells than either drug alone. Conclusion: These findings demonstrate that SL-401 and SL-801, when combined, act synergistically in their in vitro anti-tumor activity against CML, AML, MM, and HL cells. Investigations into the molecular mechanisms underlying the observed synergy are in progress. These promising results provide rationale for further development of SL-401 and SL-801 combination therapy in the treatment of a broad range of hematologic malignancies. Disclosures Gionco: Stemline Therapeutics, Inc.: Employment. Chen:Stemline Therapeutics, Inc.: Employment, Equity Ownership. Lindsay:Stemline Therapeutics, Inc.: Employment, Equity Ownership. Macri:Stemline Therapeutics, Inc.: Employment, Equity Ownership. Brooks:Stemline Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties.

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CC-122 Is a Cereblon Modulating Agent That Is Active in Lenalidomide-Resistant and Lenalidomide/Dexamethasone-Double-Resistant Multiple Myeloma Pre-Clinical Models

Blood ◽

10.1182/blood.v128.22.1592.1592 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1592-1592 ◽

Cited By ~ 2

Author(s):

Chad C Bjorklund ◽

Jian Kang ◽

Ling Lu ◽

Michael Amatangelo ◽

Hsiling Chiu ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Line ◽

Cell Lines ◽

Granzyme B ◽

Single Agent ◽

Proteasomal Degradation ◽

Employment Equity ◽

Clinical Models ◽

Equity Ownership ◽

Maximal Reduction

Abstract Background: CC-122 is a Cereblon (CRBN)-dependent Cul4 E3-ligase complex modulating compound currently being investigated in several hematologic malignancies, including relapsed/refractory multiple myeloma (MM). CC-122 binding to Cereblon results in the selective ubiquitination and subsequent proteasomal degradation of the hematopoietic transcription factors Ikaros (IKZF1) and Aiolos (IKZF3), accounting for its cytotoxic and immunomodulatory effects in diffuse large B-cell lymphoma.(1) In a phase I study CC-122-ST-001 (clintrial.gov trial #NCT01421524), CC-122 showed single agent overall response rates of ~18% in heavily pre-treated (median 6 lines prior therapy) relapsed/refractory MM. CC-122 is currently being explored as a single agent or in combination with dexamethasone in patients who previously failed lenalidomide.(2) Here, we examine the effects of CC-122 in pre-clinical models of MM with varying degrees of sensitivity to lenalidomide and dexamethasone. Results: We established lenalidomide-resistant and lenalidomide/dexamethasone dual-resistant cell lines according to a previously reported protocol.(3) A broad panel of MM cell lines (57) consisting of lenalidomide-sensitive (LS; n=26), intrinsically lenalidomide-resistant (ILR; n=7), acquired lenalidomide-resistant (ALR; n=12), and acquired lenalidomide/dexamethasone-dual-resistant (ALDR; n=12) MM cell lines were investigated for the effects of either lenalidomide or CC-122, with and without dexamethasone. Proliferation analysis by 3H-thymidine incorporation at similar concentrations (0.01-100 μM), showed a greater reduction over the averaged area under the curve (AUC) for CC-122 compared to lenalidomide of 53% to 34% (p<0.01) in LS, 22% to 3% (p<0.05) in ILR, 21% to 7% (p<0.01) in ALR, and 13% to 3% (p<0.05) in ALDR cells, respectively. In combination with dexamethasone (0.001-1 μM), CC-122 also exhibited greater reduction in the AUC compared to lenalidomide at the clinically relevant doses of either compound (~0.1 and 1 μM respectively). CC-122 (1 μM) significantly (p<0.01) induced apoptosis by more than 2-fold over lenalidomide (10 μM) across the entire cell line panel by flow cytometry and AnnexinV+/ToPro3+ staining. Additionally, when incubated with isolated peripheral blood mononuclear cells for 72 hrs, CC-122 induced the killing of all MM cell line types irrespective of their cell-autonomous response when co-cultured for 4 hrs. The anti-MM effect observed in the co-culture assay also correlated well with IL-2 and Granzyme B release, which was significantly (p<0.01) higher for CC-122 than lenalidomide, regardless of Cereblon levels in the MM cell lines. Next we compared the mechanism of action of CC-122 in MM cells by analyzing Ikaros, Aiolos, c-Myc, IRF4 protein expression and Cereblon-dependency. In the presence of CC-122, both Ikaros and Aiolos are targeted for proteasomal degradation within 6 hrs of treatment, where maximal reduction approaches 100% within 10-12 hrs and is sustained over 72 hrs, a previously reported requirement for the anti-proliferative effects of lenalidomide.(4) Half maximal reduction of Ikaros and Aiolos proteins was kinetically accelerated for CC-122 (1 μM) compared to lenalidomide (10 μM) with a time span of 2.7-4 hrs compared to 3.2-8.5 hrs, respectively. Also, the key c-Myc/IRF4 axis is disrupted faster and at 10-fold lower dose for CC-122 compared to lenalidomide. Finally, we evaluated the effects of CC-122 on interferon response genes (ISGs) since Aiolos has previously been shown to act as a repressor of ISGs.(5) Following exposure to CC-122, ISGs including IFIT1/3 and XAF were shown to be stimulated in MM cells, which may also account for some of the anti-MM effects in vitro and in vivo. Conclusions: CC-122 is a Cereblon-dependent Cul4 E3-ligase complex modulating compound that displays superior pre-clinical activity compared to lenalidomide, and is active in a wide range of resistance models. In addition to its direct anti-tumor effects, CC-122 displays anti-MM activity through stimulation of tumor cell killing by co-cultured PBMCs, which tightly correlates with Granzyme B and IL-2 release, regardless of Cereblon expression in MM cells. Together, these data support the clinical rationale to study CC-122 in relapsed/refractory MM patients, who previously failed lenalidomide. Disclosures Bjorklund: Celgene Corporation: Employment, Equity Ownership. Kang:Celgene Corporation: Employment, Equity Ownership. Lu:Celgene Corporation: Employment, Equity Ownership. Amatangelo:Celgene: Employment, Equity Ownership. Chiu:Celgene Corporation: Employment, Equity Ownership. Hagner:Celgene Corporation: Employment, Equity Ownership. Gandhi:Celgene Corporation: Employment, Equity Ownership. Pourdehnad:Celgene Corporation: Employment, Equity Ownership. Klippel:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene: Employment, Equity Ownership.

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A Selective PIM Kinase Inhibitor Is Highly Active In Multiple Myeloma: Mechanism of Action and Signal Transduction Studies

Blood ◽

10.1182/blood.v116.21.4084.4084 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4084-4084 ◽

Cited By ~ 7

Author(s):

Veerendra Munugalavadla ◽

Leanne Berry ◽

Yung-Hsiang Chen ◽

Gauri Deshmukh ◽

Jake Drummond ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Lines ◽

Combination Treatment ◽

Kinase Inhibitor ◽

Single Agent ◽

Myeloma Cell ◽

Negative Regulator ◽

Combination Drug ◽

Employment Equity ◽

Equity Ownership

Abstract Abstract 4084 Related work from our group has shown the therapeutic utility of PIM inhibition in multiple myeloma cell lines, xenografts, and primary patient samples (Ebens A. et al., ASH 2010 submitted abstr.). In this study we provide detailed mechanistic findings to show that PIM kinase inhibition co-regulates several important elements of the PI3K/AKT/mTOR pathway, resulting in significant synergy for combination drug treatments. The PIM kinases are a family of 3 ser/thr growth factor- & cytokine-induced proteins hypothesized to have redundant survival and growth functions. GNE-652 is a pan-PIM kinase inhibitor with picomolar biochemical potencies and an excellent kinase selectivity profile. Myeloma cell lines exhibit sensitivity to single agent PIM inhibition and a striking synergy in combination with the PI3K inhibitor GDC-0941. Cells respond to this combination with cell cycle arrest and marked apoptosis in vitro. We tested a panel of selective PI3K/AKT/mTOR inhibitors and found PI3K and AKT inhibitors showed the greatest extent of synergy with GNE-652, whereas mTOR inhibitors were synergistic to a lesser extent. These results suggest that PIM signaling converges on both TORC1 and AKT to generate these differential synergies. BAD is a negative regulator of both Bcl-2 and Bcl-XL, and we were able to confirm previous reports that AKT and PIM cooperate to inactivate BAD (Datt et al., 1997; Yan et al., 2003). Pim has been shown to potentially inactivate PRAS40, a negative regulator of TORC1 (Zhang et al., 2009). We demonstrate that PIM or PI3K inhibition caused a loss of phosphorylation on PRAS40 and results in a physical association of PRAS40 and TORC1 and a decrease in phosphorylated p70S6K and S6RP. These reductions were apparent in 7 of 7 cell lines assayed and enhanced by the combination of PI3K and PIM inhibition in these cell lines. Consistent with prior reports (Hammerman et al., 2005), we show that a second node of convergence between PIM and TORC1 is 4E-BP1. Both GDC-0941 and GNE-652 treatments reduced phosphorylation of 4E-BP1 in 7 of 7 myeloma cell lines. Since dephosphorylated 4E-BP1 competes with eIF4G for the mRNA cap binding factor eIF4E, we assayed immunoprecipitates of eIF4E for the presence of eIF4G and 4E-BP1 and observed increased BP1 and decreased 4G. The combination treatment significantly enhanced the loss of 4G relative to either single agent, and importantly, even at 5× the IC50 concentrations for single agents, combination drug treatment achieved greater extent of effect than single agent treatment. Thus PI3K and PIM pathways are redundant at the level of cap-dependent translational initiation mediated by eIF4E. It has been hypothesized a subset of mRNAs are particularly sensitive to inhibition of cap-dependent translation, and that this includes a number of oncogenes such as cyclin D1. We assayed global protein synthesis in MM1.s cells using 35S-methionine and as expected we observed only a modest ≂∼f20% decrease caused by either GNE-652 or GDC-0941 and this decrease was not enhanced by combination treatment. However, we noted across 7 different myeloma cell lines, strong decreases in levels of cyclin D1 that were enhanced by combination treatment. In summary, we have identified several points at which PIM and PI3K/AKT/mTOR converge to provide synergistic apoptosis in multiple myeloma cell lines. These results provide the rationale for further preclinical development of PIM inhibitors and provide the basis for a possible clinical development plan in multiple myeloma. Disclosures: Munugalavadla: Genentech: Employment, Equity Ownership. Berry:Genentech: Employment, Equity Ownership. Chen:Genentech: Employment, Equity Ownership. Deshmukh:Genentech: Employment, Equity Ownership. Drummond:Genentech: Employment, Equity Ownership. Du:Genentech: Employment, Equity Ownership. Eby:Genentech: Employment, Equity Ownership. Fitzgerald:Genentech: Employment, Equity Ownership. S.Friedman:Genentech: Employment, Equity Ownership. E.Gould:Genentech: Employment, Equity Ownership. Kenny:Genentech: Employment, Equity Ownership. Maecker:Genentech: Employment, Equity Ownership. Moffat:Genentech: Employment, Equity Ownership. Moskalenko:Genentech: Employment, Equity Ownership. Pacheco:Genentech: Employment, Equity Ownership. Saadat:Genentech: Employment, Equity Ownership. Slaga:Genentech: Employment, Equity Ownership. Sun:Genentech: Employment, Equity Ownership. Wang:Genentech: Employment, Equity Ownership. Yang:Genentech: Employment, Equity Ownership. Ebens:Genentech Inc: Employment, Equity Ownership.

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Coltuximab Ravtansine (SAR3419) Demonstrates Enhanced Activity in Combination with Bendamustine, Gemcitabine and Novel Targeted Agents Such As PI3K Inhibitors in Pre-Clinical Models of Relapsed and/or Refractory Non-Hodgkins Lymphoma (NHL)

Blood ◽

10.1182/blood.v126.23.5125.5125 ◽

2015 ◽

Vol 126 (23) ◽

pp. 5125-5125

Author(s):

Callum M Sloss ◽

Katie O'Callaghan ◽

Jutta Deckert ◽

Jenny Tsui ◽

Leanne Lanieri ◽

...

Keyword(s):

Cell Lines ◽

Single Agent ◽

Targeted Agents ◽

Employment Equity ◽

Pi3k Inhibitors ◽

Xenograft Models ◽

Equity Ownership ◽

Chemotherapy Agents

Abstract Introduction: Relapsed/refractory B-cell NHL remains an area of significant medical need. CD19 is broadly expressed on B-cell malignancies making it an ideal target for antibody-drug conjugate (ADC) based therapy. Coltuximab ravtansine is a CD19-targeting ADC consisting of a CD19-targeting antibody conjugated to the maytansinoid anti-mitotic DM4. In preclinical studies, coltuximab ravtansine has shown potent, targeted activity against NHL cell lines and xenograft models. In early clinical trials, it has been well tolerated and has shown promising signs of efficacy as both a single agent and in combination with rituximab. In the STARLYTE Phase 2 trial coltuximab ravtansine monotherapy resulted in an ORR of 44% in R/R-DLBCL that included an ORR of 21% in hard-to-treat primary refractory patients (NCT01472887). Here we describe studies aimed at the identification of combination partners for coltuximab ravtansine to further optimize clinical benefit to R/R-NHL patients. We are employing a dual approach where we investigate combination of coltuximab ravtansine with multiple, novel targeted therapy partners whilst in parallel also investigating the combination of coltuximab ravtansine with chemotherapies commonly used in the late stage R/R-NHL setting. Methods: Coltuximab ravtansine and the DM4 payload were evaluated in a high throughput screen both as single agents and in combination with a selection of novel, emerging targeted agents across a panel of twenty NHL cell lines. The combinations were evaluated in a dose-response matrix and a statistical method was used to identify combination synergies significantly superseding baseline additivity values. The in vivo efficacy of coltuximab ravtansine was additionally assessed in combination with various clinically relevant chemotherapy agents in subcutaneous xenograft models of NHL. Results: Coltuximab ravtansine and DM4 both showed potent single agent activity against the entire panel of NHL cell lines with median GI50's of 770pM and 100pM, respectively. We observed a significant correlation in the cell line sensitivity of the two compounds suggesting that sensitivity to coltuximab ravtansine is driven, at least in part, by inherent sensitivity of cells to the cytotoxic effects of the DM4 payload. In vitro combination studies for coltuximab ravtansine were performed to identify targets or pathways that result in the most prominent combination effects across the cell line panel. Analysis of the in vitro combination dose-matrix revealed particularly strong synergy between coltuximab ravtansine and various inhibitors of the PI3K/AKT/mTOR axis. Studies to examine the synergism between coltuximab ravtansine and PI3K inhibitors in in vivo models of NHL are ongoing. In order to further determine the utility of coltuximab ravtansine as part of a potential combination regimen for the treatment of R/R-NHL, we assessed the combination of coltuximab ravtansine with the chemotherapy agents bendamustine and gemcitabine in vivo. As gemcitabine is typically used in combination we assessed the efficacy of a coltuximab ravtansine with rituximab and gemcitabine in vivo. In both cases the combination with coltuximab ravtansine was significantly more efficacious than the standard-of-care alone arms. Conclusions: Coltuximab ravtansine demonstrates synergistic activity in combination with multiple PI3K pathway inhibitors across a large panel of NHL cell lines. Additionally, we have shown that combination of coltuximab ravtansine with clinically relevant late stage treatments such as bendamustine and rituximab + gemcitabine is more efficacious than the chemotherapy regimens alone. These results support the continued development of coltuximab ravtansine in R/R-NHL in combination with chemotherapy regimens and suggest that a combination of coltuximab ravtansine with PI3K inhibitors may also be of interest in the clinical setting. Disclosures Sloss: ImmunoGen, Inc.: Employment, Equity Ownership. O'Callaghan:ImmunoGen, Inc.: Employment, Equity Ownership. Deckert:ImmunoGen, Inc.: Employment, Equity Ownership. Tsui:ImmunoGen, Inc.: Employment, Equity Ownership. Lanieri:ImmunoGen, Inc.: Employment, Equity Ownership. Romanelli:ImmunoGen, Inc.: Employment, Equity Ownership.

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Inecalcitol and Decitabine Synergize to Inhibit Cell Proliferation and to Induce Differentiation of Human Acute Myeloid Leukemia Cell Lines

Blood ◽

10.1182/blood-2018-99-118125 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 5234-5234

Author(s):

Enguerran Mouly ◽

Emilie Rousseau ◽

Cecile Planquette ◽

Remi Delansorne

Keyword(s):

Cell Proliferation ◽

Cell Line ◽

Cell Lines ◽

Myeloid Leukemia ◽

Employment Equity ◽

Elderly Aml ◽

Equity Ownership ◽

Inhibit Cell Proliferation ◽

Stimulation Of

Abstract Decitabine (DAC) is a hypomethylating agent indicated as front-line therapy for de novo or secondary acute myeloid leukemia (AML) in newly diagnosed patients aged 65 years or older unfit for standard induction chemotherapy (Kantarjian et al., 2012, Malik & Cashen, 2014, Nieto et al., 2016, He et al., 2017). Its mechanism of action at the DNA level mostly results in inhibition of cell proliferation. Cellular differentiation can also be involved in some extent in a fraction of the leukemic cell population, as reported in initial pharmacological studies (Creusot et al., 1982; Pinto et al., 1984). Overall survival advantage is nevertheless limited to several more months and the next challenge is to combine DAC with other drugs to improve it further (Kubasch & Platzbecker, 2018). Inecalcitol (INE: 14epi-,19nor-,23yne-,1,25dihydroxy-cholecalciferol) is a vitamin D receptor agonist characterized by potent anti-proliferative and pro-differentiating general properties on cancer cells and by a low calcemic potential (Okamoto et al., 2012; Ma et al., 2013; Medioni et al. 2014), and especially on AML cell lines (AACR 2017, 2018). INE is currently being tested in combination with DAC in this category of elderly AML patients unfit for standard chemotherapy. The aim of the present report was to look for synergies in vitro between DAC and INE on four non-APL human AML cell lines (MOLM-13, U-937, THP-1, OCI-AML2) both on inhibition of proliferation and induction of differentiation. After 72 hours of incubation, cells were counted and labeled for CD11b and CD14 at the cell surface as biomarkers of monocytic/macrophagic differentiation. The range of DAC concentrations had to adapted to each cell line to avoid maximal cytotoxicity: 1.2 nM to 100 nM on MOLM-13, 3 nM to 250 nM on U-937 and THP-1, and 31 nM to 500 nM on OCI-AML2. The same range of 0.12 to 10 nM INE concentrations was tested on each cell line. Each concentration of INE was tested in combination with each concentration of DAC. Synergy was calculated as the excess over the highest single agent (HSA) using the open source Combenefit software (Di Veroli et al., 2016). The highest concentration of DAC alone (MOLM-13: 100 nM, U-937 and THP-1: 250 nM; OCI-AML2: 500 nM) induced a decrease in cell count of 30% of THP-1 cells, 50% of OCI-AML2 cells, 65% of U-937 cells and 80% of MOLM-13 cells. The highest concentration of INE alone (10 nM) induced a decrease in cell count of 20% of U-937 and THP-1 cells, 60% of OCI-AML2 cells and 70% of MOLM-13 cells. The antiproliferative effects of DAC and INE were at least additive in all combinations tested. Significant HSA synergy indexes were found for the decrease in cell number in all four cell lines, ranging from 12% to 23% depending on cell lines and combinations of concentrations. The highest concentration of DAC alone had no (U-937, THP-1) or limited activity (<+12% of labeled MOLM-13 or OCI-AML2 cells) to induce either CD11b or CD14 on the cell surface. By contrast, the highest concentration of INE alone (10 nM) stimulated the expression of CD11b and CD14 in up to 70% to 95% of the cells depending on the cell line (except the CD14 labeling of U-937 cells which remained < 8%). The respective EC50 of INE for CD11b and CD14 induction was 1 and 3 nM on THP-1 cells, 4 and 3 nM on MOLM-13 cells, 3 and 3 nM on OCI-AML2 cells and 1 nM on U-937 cells (50% not reached for CD14). There was no antagonistic effect of DAC towards the pro-differentiating properties of INE. A significant HSA synergy index in the 16% to 26% range was observed for both CD11b and CD14 in MOLM-13 cells and for CD14 in OCI-AML2 cells. A very high HSA synergy index of 75% was observed for the stimulation of CD14 in U-937 cells. In summary, DAC exerted more antiproliferative activity than INE which was more potent to induce monocytic/macrophagic differentiation of four non-APL human AML cell lines. The combination of DAC and INE systematically resulted in a synergy to inhibit cell proliferation, and the strong stimulation of cell differentiation induced by INE alone was in some cases boosted by DAC. These in vitro results provide the mechanistic basis for the potential interest of treating elderly AML patients with INE in addition to DAC in the ongoing double-blind placebo-controlled Phase II clinical trial (NCT02802267). Disclosures Mouly: Hybrigenics: Employment. Rousseau:Hybrigenics: Employment. Planquette:Hybrigenics: Employment, Equity Ownership, Patents & Royalties: inventor, but no royalties. Delansorne:Hybrigenics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: inventor, but no royalties.

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The PI3K Inhibitor GDC-0941 Synergizes with Standard of Care Therapies to Induce Growth Inhibition and Apoptosis of Multiple Myeloma Cells.

Blood ◽

10.1182/blood.v114.22.3788.3788 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3788-3788

Author(s):

Veerendra Munugalavadla ◽

Leanne Berry ◽

Changchun Du ◽

Sanjeev Mariathasan ◽

Dion Slaga ◽

...

Keyword(s):

Multiple Myeloma ◽

Research Funding ◽

Single Agent ◽

Standard Of Care ◽

Rational Approach ◽

Current Standard ◽

Employment Equity ◽

Specific Flow ◽

Equity Ownership

Abstract Abstract 3788 Poster Board III-724 Multiple myeloma (MM) is a malignancy characterized by clonal expansion and accumulation of long-lived plasma cells within the bone marrow. Phosphatidylinositol 3' kinase (PI3K) -mediated signaling is frequently dysregulated in cancer and controls fundamental cellular functions such as cell migration, growth, survival and development of drug resistance in many cancers, including MM, and therefore represents an attractive therapeutic target. Here, we demonstrate in vitro, that a potent and selective pan-isoform PI3Kinhibitor, GDC-0941, modulates the expected pharmacodynamic markers, inhibits cell-cycle progression and induces apoptosis; overcomes resistance to apoptosis in MM cells conferred by IGF-1 and IL-6; and is additive or synergistic with current standard of care drugs including dexamethasone, melphalan, lenolidamide and bortezomib. In cell lines we find sensitivity to GDC-0941 is positively correlated with pathway activation as determined by phospho-AKT-specific flow-cytometry and Western-blot analysis. Preliminary results indicate apoptosis of MM cells is correlated with increased expression of the proapoptotic BH3-only protein BIM; mechanisms of increased apoptosis in MM will be further explored and an update presented. We further extend these in vitro findings to show that GDC-0941 has activity as a single agent in vivo and combines well with standard of care agents in several murine xenograft models to delay tumor progression and prolong survival. Our results suggest that GDC-0941 may combine well with existing therapies, providing a framework for the clinical use of this agent, and a rational approach to improving the efficacy of myeloma treatment. Disclosures: Munugalavadla: Genentech: Employment, Patents & Royalties. Berry:Genentech: Employment, Patents & Royalties. Du:Genentech, Inc.: Employment, Equity Ownership. Mariathasan:Genentech: Employment, Patents & Royalties. Slaga:Genentech: Employment, Patents & Royalties. Sun:Genentech Inc.: Employment. Chesi:Genentech, Inc.: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Merck: Research Funding. Bergsagel:Genentech: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Merck: Research Funding. Ebens:Genentech, Inc.: Employment, Equity Ownership, Patents & Royalties.

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Expression of Bcl-2 Pro-Survival Family Proteins Predicts Pharmacological Responses to ABT-199, a Novel and Selective Bcl-2 Antagonist, in Multiple Myeloma Models

Blood ◽

10.1182/blood.v120.21.5028.5028 ◽

2012 ◽

Vol 120 (21) ◽

pp. 5028-5028 ◽

Cited By ~ 1

Author(s):

Deepak Sampath ◽

Elizabeth Punnoose ◽

Erwin R. Boghaert ◽

Lisa Belmont ◽

Jun Chen ◽

...

Keyword(s):

Bone Marrow ◽

Cell Death ◽

Cell Lines ◽

Single Agent ◽

Employment Equity ◽

Bone Marrow Biopsies ◽

Xenograft Models ◽

Equity Ownership

Abstract Abstract 5028 Multiple myeloma (MM) is a hematological malignancy of the bone marrow caused by the dysregulated proliferation of monoclonal antibody producing plasma cells. A hallmark feature of cancer is the ability to evade cell death signals induced by stress response cues. The Bcl-2 family of proteins regulates the intrinsic apoptosis pathways and consists of pro-apoptotic (Bax, Bak, Bad, Bim, Noxa, Puma) and pro-survival (Bcl-2, Bcl-xL, Mcl-1); the balance of which dictates the life or death status of MM tumor cells. Thus, there is a strong rationale to target members of the Bcl-2 proteins for the treatment of MM. ABT-199 is a potent BH3-only mimetic that selectively antagonizes Bcl-2 and is currently in phase I clinical trials for the treatment of hematological malignancies. Therefore, we evaluated the efficacy of ABT-199 as a single agent and in combination with standard of care drugs such as Velcade (bortezomib) in preclinical models of MM. A panel of 21 human MM cell lines was evaluated in vitro for to sensitivity to ABT-199. ABT-199 potently inhibited cell viability in a sub-set of MM cell lines (7/21) with EC50 values less than 1 μM. Expression of Bcl-2, Bcl-xL, Mcl-1, Bim and other Bcl-2 family proteins were evaluated by protein and mRNA. Cell line modeling identified thresholds for expression of Bcl-2, Bcl-xL and Mcl-1 that best predicted sensitivity and resistance to ABT-199 and the dual Bcl-2/Bcl-xL antagonist, navitoclax. Consistent with the target inhibition profile of these drugs, we found that MM lines that were Bcl-2high/Bcl-xLlow/Mcl-1low are the most sensitive to ABT-199 treatment. Whereas cell lines that are Bcl-xLhigh remain sensitive to navitoclax but not ABT-199. MM cell lines that are Mcl-1high are less sensitive to both ABT-199 and navitoclax, suggesting that Mcl-1 is a resistance factor to both drugs. Utilizing a novel Mesoscale Discovery based immunoassay we determined that levels of Bcl-2/Bim complexes also correlated with sensitivity of ABT-199 in the MM cell lines tested. In addition, the t(11;14) status in these cell lines associated with sensitivity to ABT-199. The clinical relevance of the Bcl-2 pro-survival expression pattern in MM cell lines, was determined by a collection of bone marrow biopsies and aspirates (n=27) from MM patients by immunohistochemistry for prevalence of Bcl-2 and Bcl-xL. Similar to our in vitro observations, the majority (75%) of the MM bone marrow biopsies and aspirates had high Bcl-2 levels whereas 50% had high Bcl-xL expression. Therefore, a subset of patient samples (33%) were identified with a favorable biomarker profile (Bcl-2high/Bcl-xLlow) that may predict ABT-199 single agent activity. ABT-199 synergized with bortezomib in decreasing cell viability in the majority of MM cell lines tested in vitro based on the Bliss model of independence analyses (Bliss score range = 10 to 40). However the window of combination activity was reduced due to high degree of sensitivity to bortezomib alone. Therefore, the combination efficacy of ABT-199 and bortezomib was further evaluated in vivo in MM xenograft models that expressed high levels of Bcl-2 protein (OPM-2, KMS-11, RPMI-8226, H929 and MM. 1s). Bortezomib treatment alone at a maximum tolerated dose resulted in tumor regressions or stasis in all xenograft models tested. ABT-199 at a maximum tolerated dose was moderately efficacious (defined by tumor growth delay) as a single agent in xenograft models that expressed high protein levels of Bcl-2 but relatively lower levels of Bcl-xL. However, the combination of ABT-199 with bortezomib significantly increased the overall response rate and durability of anti-tumor activity when compared to bortezomib, resulting in increased cell death in vivo. Treatment with bortezomib increased levels of the pro-apoptotic BH3-only protein, Noxa, in MM xenograft models that expressed high levels of Mcl-1. Given that the induction of Noxa by bortezomib results in neutralization of Mcl-1 pro-survival activity in MM models [Gomez-Bougie et al; Cancer Res. 67:5418–24 (2007)], greater efficacy may be achieved when Bcl-2 is antagonized by ABT-199 thereby inhibiting pro-survival activity occurring through either Bcl-2 or Mcl-1 and increasing cell death. Thus, our preclinical data support the clinical evaluation of ABT-199 in combination with bortezomib in MM patients in which relative expression of the Bcl-2 pro-survival proteins may serve as predictive biomarkers of drug activity. Disclosures: Sampath: Genentech: Employment, Equity Ownership. Punnoose:Genentech: Employment, Equity Ownership. Boghaert:Abbott Pharmaceuticals: Employment, Equity Ownership. Belmont:Genentech: Employment, Equity Ownership. Chen:Abbott Pharmaceuticals: Employment, Equity Ownership. Peale:Genentech: Employment, Equity Ownership. Tan:Genentech: Employment, Equity Ownership. Darbonne:Genentech: Employment, Equity Ownership. Yue:Genentech: Employment, Equity Ownership. Oeh:Genentech: Employment, Equity Ownership. Lee:Genentech: Employment, Equity Ownership. Fairbrother:Genentech: Employment, Equity Ownership. Souers:Abbott Pharmaceuticals: Employment, Equity Ownership. Elmore:Abbott Pharmaceuticals: Employment, Equity Ownership. Leverson:Abbott Pharmaceuticals: Employment, Equity Ownership.

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Iberdomide (CC-220) Has Synergistic Anti-Tumor and Immunostimulatory Activity Against Multiple Myeloma in Combination with Both Bortezomib and Dexamethasone, or in Combination with Daratumumab in Vitro

Blood ◽

10.1182/blood-2018-99-113383 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1935-1935 ◽

Cited By ~ 7

Author(s):

Michael Amatangelo ◽

Chad C. Bjorklund ◽

Jian Kang ◽

Ann Polonskaia ◽

Sridevi Viswanatha ◽

...

Keyword(s):

Multiple Myeloma ◽

Nk Cells ◽

Cell Lines ◽

Immune Cells ◽

Antiproliferative Activity ◽

Mononuclear Cells ◽

Interleukin 2 ◽

Immunomodulatory Activity ◽

Employment Equity ◽

Equity Ownership

Abstract Despite significant progress in the treatment of multiple myeloma (MM), the disease remains incurable. Multiple targeted and biologics-based therapies, including immunomodulatory agent IMiD® compounds (lenalidomide and pomalidomide), proteasome inhibitors (bortezomib and carfilzomib), and monoclonal antibodies (daratumumab and elotuzumab) have shown impressive activity in treating advanced MM. Moreover, triplet regimens combining these agents have consistently proven to be more efficacious than doublets in heavily pretreated patients with limited additional toxic effects. Iberdomide (CC-220) is a novel compound being investigated in a phase I/II study (clinicaltrials.gov NCT02773030) for treatment of lenalidomide- and pomalidomide-relapsed/refractory MM (RRMM) in combination with dexamethasone. Preclinical studies of iberdomide have shown that it more potently binds to cereblon than other cereblon-binding compounds, is more efficient at degrading Aiolos and Ikaros, and has enhanced immunomodulatory activity, inducing greater interleukin-2 secretion and granzyme-b degranulation in immune cells (Matyskiela et al and Bjorklund et al, submitted abstract). Clinical studies of bortezomib and daratumumab in combination with other cereblon-binding agents have demonstrated high tolerability with notable efficacy in the RRMM setting; however, these combinations with iberdomide have not been investigated. Here we show in MM cell lines that iberdomide induces deep Aiolos and Ikaros degradation in the presence of bortezomib at clinically relevant concentrations as determined in healthy volunteers. Furthermore, iberdomide treatment in combination with bortezomib produced synergistic antiproliferative activity and deeper induction of apoptosis than combinations of other clinically approved cereblon-binding compounds with bortezomib across multiple cell lines. In addition, adding dexamethasone resulted in further synergistic antiproliferative activity. In combination with daratumumab, iberdomide also had synergistic anti-MM activity in Complement-Dependent Cytotoxicity (CDC) assays. In co-culture systems using myeloma and immune cells, iberdomide significantly increased the antibody-dependent cellular cytotoxic activity of daratumumab. While iberdomide treatment of MM cell lines resulted in increased CD38 surface expression, combinations were more effective when peripheral blood mononuclear cells (PBMCs) were pretreated, suggesting that iberdomide immunomodulatory activity is a significant contributor to the synergy observed. Interestingly, pretreatment of PBMCs with daratumumab resulted in reduced efficacy of the combination. We observed that the treatment of PBMCs with daratumumab resulted in killing of natural killer (NK) cells in the PBMC culture. In contrast, treatment of PBMCs with iberdomide resulted in proliferation of NK cells, possibly helping to rescue the antagonistic effect of daratumumab on NK cell-mediated antibody‐dependent cellular cytotoxicity. Taken together, these preclinical data support further investigation of iberdomide in combination with both bortezomib/dexamethasone and daratumumab in the clinic. Disclosures Amatangelo: Celgene Corporation: Employment, Equity Ownership. Bjorklund:Celgene Corporation: Employment, Equity Ownership. Kang:Celgene Corporation: Employment, Equity Ownership. Polonskaia:Celgene Corporation: Employment, Equity Ownership. Viswanatha:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene Corporation: Employment, Equity Ownership.

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CC-92480, a Novel Cereblon E3 Ligase Modulator, Is Synergistic with Dexamethasone, Bortezomib, and Daratumumab in Multiple Myeloma

Blood ◽

10.1182/blood-2019-124345 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1815-1815

Author(s):

Lilly Wong ◽

Rama Krishna Narla ◽

Jim Leisten ◽

Daniel Bauer ◽

Matthew Groza ◽

...

Keyword(s):

Multiple Myeloma ◽

Synergistic Effect ◽

Cell Viability ◽

Cell Lines ◽

E3 Ligase ◽

Proteasome Activity ◽

Employment Equity ◽

Equity Ownership

Introduction: CC-92480 is a novel cereblon E3 ligase modulator (CELMoD) with enhanced autonomous cell-killing and immunomodulatory activity against multiple myeloma (MM) cells. CC-92480 is currently in phase 1 development in a late-line myeloma patient population (NCT03374085). Here, we sought to characterize the antitumor activity of CC-92480 in combination with dexamethasone (DEX), bortezomib (BORT), or daratumumab (DARA) in MM cell lines in vitro and xenograft mouse models in vivo. Methods: CC-92480 activity in combination with DEX was evaluated in MM cell lines. Apoptosis was measured by quantification of caspase-3 activation. The effect of BORT on CC-92480-induced Ikaros and Aiolos degradation was determined by concurrent treatment of MM cells with BORT and CC-92480. β5-site proteasome activity was also determined in the same experiment. The in vitro activity of CC-92480 in combination with BORT was characterized using washout experiments to more faithfully model the short in vivo exposure but more prolonged, gradually diminishing proteasome inhibitory activity of BORT. Apoptosis and cell viability of CC-92480 with BORT were analyzed by flow cytometry. The effect of CC-92480 on CD38 expression was also evaluated across a panel of MM cell lines. The effect of CC-92480 in combination with DARA was characterized with antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) assays. CC-92480 in combination with DEX or BORT was tested in a lenalidomide-resistant (H929-1051) xenograft mouse model. Female SCID mice were inoculated with H929-1051 cells in the right hind leg. For the DEX combination, groups of tumor-bearing mice (n = 9-10) were dosed with vehicle, DEX, or CC-92480 once daily (QD), or CC-92480 in combination with DEX throughout the study, starting when the tumor volumes reached approximately 115 mm3. For combination with BORT, mice (n = 9-10/group) were dosed with vehicle, CC-92480, or BORT, or the CC-92480 and BORT combination starting when the tumor volumes reached approximately 500 mm3. CC-92480 was administered orally QD for 3 days and BORT as a single intravenous dose. Tumor volumes were measured twice a week for the duration of the studies. Results: CC-92480 synergized with DEX in reducing cell viability and potentiated DEX-induced apoptosis in a concentration-dependent manner in MM cell lines. Of note, the combination showed activity at concentrations of both DEX and CC-92480 that had minimal activity as single agents. In the xenograft model with H929-1051 cells, the combination of CC-92480 and DEX significantly inhibited tumor growth (−84%) when compared with either agent alone (−34% and −20% for CC-92480 and DEX, respectively) and was classified as a synergistic effect using the fractional product method. Although proteasome activity is required for CC-92480-induced degradation of Ikaros and Aiolos, CC-92480 nevertheless maintained its ability to efficiently degrade Ikaros and Aiolos in the presence of doses of BORT that cause clinically relevant levels of proteasome inhibition. The in vitro combination of CC-92480 with BORT resulted in greater cytotoxic activity on MM cells than either single agent alone. The in vivo efficacy of CC-92480 and BORT, administered concurrently, showed a strongly synergistic effect with a near complete or complete tumor regression in every animal, and 6 of 9 animals remained tumor-free through an observation period extending 157 days after the control group was terminated. Anti-CD38 therapies, including DARA and isatuxumab, target CD38-expressing MM cells for killing by immune cells through cytotoxic and phagocytic mechanisms. In a panel of MM cell lines, CC-92480 treatment caused increased cell surface expression of CD38 (2-3 times that of control). Pretreatment of MM cells with CC-92480 resulted in increased DARA-mediated ADCC and ADCP compared with DMSO-treated controls. Conclusions: The strong preclinical synergy in MM cell killing exhibited by CC-92480 in combination with DEX, BORT, and with an anti-CD38 antibody (DARA), highlights its potential to bring clinical benefit to patients with MM in combination with these agents and supports the rationale for testing these combinations in clinical studies. Disclosures Wong: Celgene Corporation: Employment, Equity Ownership. Narla:Celgene Corporation: Employment, Equity Ownership. Leisten:Celgene Corporation: Employment. Bauer:Celgene Corporation: Employment, Equity Ownership. Groza:Celgene Corporation: Employment, Equity Ownership. Gaffney:Celgene: Employment. Havens:Celgene: Equity Ownership; Pfizer: Employment, Equity Ownership. Choi:AnaptysBio Inc: Employment, Equity Ownership; Celgene Corporation: Equity Ownership, Other: Formerly Employed. Lopez-Girona:Celgene Corporation: Employment. Hansen:Celgene Corporation: Employment. Cathers:Celgene Corporation: Equity Ownership; Global Blood Therapeutics (GBT): Employment. Carmichael:Celgene plc: Employment, Equity Ownership. Pierce:Celgene Corporation: Employment, Equity Ownership.

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