Pre-Adipocytes Differentiate Into Megakaryocytes (MK) by a Paracrine Thrombopoietin (TPO) Loop

Abstract Abstract 4742 The regulation of megakaryopoiesis and thrombopoiesis are incompletely understood. Better understanding of the underlying mechanisms would be of biological import, but may also lead to novel approaches for generating of platelets for clinical application. One cell line that undergoes terminal differentiation into megakaryocytes is pre-adipocytes. These cells represent a potential candidate cell for ex vivo generation of megakaryocytes. Here we demonstrate that pre-adipocytes differentiate into MKs and platelets by using an endogenous paracrine loop involving TPO, the primary cytokine involved in megakaryopoiesis, and its receptor c-mpl. We previously reported that pre-adipocytes differentiate into MKs and form platelets when the culture medium is switched from maintenance medium to MK lineage induction (MKLI) medium. Neither media include TPO. Based on these observations, the present study tested the hypothesis that pre-adipocytes might differentiate into MKs and platelets by endogenous TPO and c-mpl expression of sufficient magnitude to drive megakaryopoiesis. We used primary mouse pre-adipocytes (CD45-, CD117-, Sca1+, CD29+, CD73+, CD90+, CD105+, CD106+) from subcutaneous adipose tissues and also the mouse pre-adipocyte line 3T3-L1 cells. The TPO levels, as assessed by ELISA, in the supernatant from 106 pre-adipocytes cultured in 2 ml MKLI medium without exogenous TPO (TPO-) were unmeasurable level on Day 0, 29±14 pg/ml on Day 7 and 8±2 pg/ml on Day 12. Similar results were obtained in the supernatant from 3T3-L1 during MK differentiation. We did not observe measureable TPO in supernatants from pre-adipocytes and 3T3-L1 cells cultured in maintenance medium on Days 0, 7 and 12. We then compared MK differentiation from pre-adipocytes in MKLI media in the absence (TPO-) or addition (final concentration, 50 ng/ml; TPO+) of TPO. The frequency of CD41-postive pre-adipocytes in culture after 6 days was 58±11% for TPO+ and 70±7% for TPO- (p>0.05), consistent with endogenous TPO being sufficient under these circumstances to stimulate MK differentiation of pre-adipocytes. DNA ploidy and c-mpl expression assessed by immunohistochemistry were also similar with or without added exogenous TPO. We next examined the number of CD41-expressing large-sized (>15 μm) cells beginning with 1.2 × 104 preadipocytes in the absence or presence of the c-mpl inhibitor rat anti-mouse c-mpl inhibitor AMM2 (final concentration, 10 μg/ml). In the absence of AMM2, 10-fold more CD41-positive, large cells were seen (6.8±1.7×103) than in its presence (0.6±0.2×103, p<0.05). These observations support that pre-adipocytes differentiate into MKs using endogenous TPO stimulation via c-mpl. We next examined the ability to release platelets from these treated pre-adipocytes in each experimental condition (pre-adipocytes and 3T3-L1 cells, each ± exogenous TPO). Infusion of 2 × 105 carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled MKs into irradiated thrombocytopenic mice (7 days post-2.0Gy exposure) led to a time-dependent appearance of CFSE+/CD41+ platelet-sized particles with a peak at 4 hours after the infusion reaching ∼2.5% of the total circulating platelet population (∼30 platelets/infused MK) under all tested experimental conditions. For platelet function, blood samples from each of these mice were perfused over a collagen-coated chip for 10 minutes, and the incorporation of CFSE+ particles into thrombi on the chip was determined (Total Thrombus-formation Analyzing System). A similar degree of platelet incorporation was observed under all experimental conditions and each was with an efficiency similar to that seen when CFSE+ control platelets were infused. These findings demonstrate that pre-adipocytes differentiate into MKs and subsequent platelets by an endogenous TPO release and a paracrine loop involving c-mpl. We propose that such pre-adipocytes could be used as a model of a continuously replicating cell line that upon switching media simultaneous expresses TPO and its receptor c-mpl to establish a paracrine loop leading to terminal differentiation into functional MKs. The basis of why this media switch induces this change needs to be clarified to further develop this pre-adipocyte strategy as a donor-independent source for platelet transfusion as well as for studying mechanism underlying megakaryopoiesis and thrombopoiesis. Disclosures: Matsubara: Medico's Hirata: Honoraria; Advisory Committees on VerifyNow: Membership on an entity's Board of Directors or advisory committees. Murata:Medico's Hirata: Honoraria; Advisory Committees on VerifyNow: Membership on an entity's Board of Directors or advisory committees.

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

Blood ◽

10.1182/blood.v114.22.1729.1729 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1729-1729

Author(s):

Melissa G Ooi ◽

Robert O'Connor ◽

Jana Jakubikova ◽

Justine Meiller ◽

Steffen Klippel ◽

...

Keyword(s):

Lung Cancer ◽

Multiple Myeloma ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Significant Activity ◽

Cancer Resistance ◽

Advisory Committees ◽

Bortezomib Treatment

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

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Induced Resistance to Bortezomib in Preclinical Model of Waldenstrom Macroglobulinemia Is Associated with Bcl-2 Upregulation.

Blood ◽

10.1182/blood.v114.22.4919.4919 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4919-4919 ◽

Cited By ~ 1

Author(s):

Kasyapa Chitta ◽

Jean-Gabriel Coignet ◽

Sakina Sojar ◽

Pushpankur Ghoshal ◽

Kiersten M. Miles ◽

...

Keyword(s):

Multidrug Resistance ◽

Cell Line ◽

Board Of Directors ◽

Induced Resistance ◽

Wild Type Cell ◽

Preclinical Model ◽

Wild Type ◽

Advisory Committees ◽

Proteasomal Activity ◽

Resistant Cells

Abstract Abstract 4919 Waldenstrom's macroglobulinemia (WM) is characterized by the presence of lymphoplasmacytic cells in the bone marrow and the secretion of IgM monoclonal antibody in the serum. Several conventional therapies are available but the disease remains incurable. Recently, bortezomib (a proteasomal inhibitor) has shown promising anti-WM activity with enhanced responses when combined with traditional therapies. Resistance to bortezomib therapy is an important event that is associated with continued treatment. In order to understand the mechanism of bortezomib resistance in WM we exposed BCWM.1 (a known WM cell line) in vitro to increasing concentrations of bortezomib over prolonged periods of time and isolated the bortezomib resistant clone (BCWM.1/BR). This clone was compared with its parent wild type cell line (BCWM.1/WT). Investigation to understand the susceptibility of BCWM.1/Br cells to various therapeutic agents showed that these cells are resistant to many of the agents such as melaphalan, fludarabine or doxorubicin. Interestingly, verapamil, a broad spectrum inhibitor of multidrug resistance, failed to reverse the resistance induced by bortezomib indicating that bortezomib resistance is not because of an activation of multidrug resistance in these cells. While BCWM.1/WT cells showed an IC50 of 7.8nM when treated for 72h with bortezomib, the BCWM.1/BR cells were not inhibited at any concentration of the compound up to 100nM. Furthermore, the cells with the acquired resistance showed a 4 fold increase in the proteasomal activity as measured by the release of a fluorescent product (7-Amino-4-methylcoumarin (AMC)) from its peptide substrate, suc-LLVY-AMC. Biochemical analysis further revealed that many of the proteasomal components are altered in BCWM.1/BR cells as compared to their parental control cells. Interestingly, protein levels of two of the proteasomal catalytic subunits, PSMB5 and PSMB9 are upregulated in resistant cells suggesting a reason for the enhanced proteasomal activity of these cells. The resistant cells showed an altered gene expression profile that indicates a transformation of the parental wild type cell line to acquire resistance. A comparative analysis of the signal transduction pathways operated in these cells showed that many of the activation and cell survival pathways that are present in BCWM.1 cells are inhibited in the resistant cells. For example, BCWM.1 cells show a constitutive activation of AKT and ERK1/2 which are inhibited in the resistant cells thus making them insensitive to the inhibitors of these pathways. Similarly, HSP27 which was earlier shown to contribute to bortezomib induced resistance was completely inhibited in BCWM.1 resistant cells. Interestingly, there is an increase in Bcl-2 protein in BCWM.1/BR cells as compared to WT cells indicating that the resistant cells might be dependent on Bcl-2 family for their survival. Inhibition of Bcl-2 induced potent apoptosis in BCWM.1/BR cells. Thus the results presented here indicate that acquired bortezomib resistance in BCWM.1 cells alters their proteasomal activity, cellular signaling pathways to make them resistant to many of the known therapies but these cells retain the Bcl-2 mediated pathway for targeting thus inhibitors of Bcl-2 may be used in therapy against bortezomib-resistant WM. Disclosures Chanan-Khan: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immunogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

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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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Decitabine Priming Enhances The Antileukemic Effects Of The Selective Inhibitor Of Nuclear Export (SINE) CRM1/XPO1 Antagonist (Selinexor) In Acute Myeloid Leukemia (AML)

Blood ◽

10.1182/blood.v122.21.1453.1453 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1453-1453 ◽

Cited By ~ 2

Author(s):

Parvathi Ranganathan ◽

Xueyan Yu ◽

Jessica Hofstetter ◽

Ramasamy Santhanam ◽

Sharon Schacham ◽

...

Keyword(s):

Cell Proliferation ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Nuclear Export ◽

Sequential Treatment ◽

Great Promise ◽

Treatment Schedule ◽

Advisory Committees ◽

Novel Therapeutic

Abstract AML is a clonal hematopoietic disorder characterized by genetic and epigenetic alterations. The prognosis of AML is poor highlighting the urgent need for novel therapeutic approaches. Targeting aberrant DNA hypermethylation by using hypomethylating drugs such as decitabine has been recently investigated in AML. Our group reported a relatively effective (47% complete response) single agent decitabine treatment schedule for older AML patients. These results suggested the opportunity to capitalize on this relatively effective and non-toxic treatment by incorporating this compound into novel molecularly targeted approaches. Recent data indicate that targeting nuclear exporter proteins is a novel therapeutic strategy to overcome cancer. In particular, CRM1/XPO1 is the only nuclear exporter involved in the active transport of the majority of tumor suppressor proteins (TSP) [e.g. p53 and FOX03A] out of the nucleus resulting in their inactivation. We recently reported the anti-leukemic activity of oral SINE CRM1/XPO1 Antagonists in AML. SINEs displayed potent anti-proliferative properties, induced apoptosis, cell-cycle arrest and myeloid differentiation in AML cell lines and patient blasts. In addition, treatment of leukemic mice with oral SINE significantly prolongs their survival. By crossing the lists of genes known to be regulated by DNA methylation in AML with the ones whose nuclear transport is XPO1 dependent, we identified important TSPs such as FOXO3A and p21. Here we hypothesize that treatment of AML cells with decitabine will increase the transcription and expression of a subset of TSPs (including FOX03A and p21) whose nuclear anti-leukemic effects could be enhanced by blocking their XPO1 mediated nuclear export using the clinical stage oral SINE (Selinexor). Thus, we expect that the sequential treatment of decitabine followed by Selinexor will be more effective than each drug alone. To confirm this hypothesis first we treated the AML line OCI-AML3 cells with decitabine (500nM) overnight (ovn) followed by Selinexor (200nM, 2 fold lower than IC50) for an additional 24 hours (hrs) and measured cell proliferation using WST-1 assay. Controls include: 1) DMSO ovn +DMSO 24 hours, 2) Selinexor ovn +selinexor 24 hours (200 nM) and 3) decitabine ovn + decitabine 24 hrs (500nM). AML cells that were treated first with decitabine followed by Selinexor exhibited a higher cytotoxicity (absorbance (Abs) 0.7) than cells treated with either decitabine (Abs 1.36), Selinexor (Abs 1, p=0.006) or DMSO (Abs 1.7). Similar results were observed with the MV4-11 cell line. Next we measured the candidate TSPs (FOX03A and p21) mRNA and protein expression in OCI-AML-3 and MV4-11 cell lines after 24 hrs of decitabine treatment. We found a significant up-regulation of p21 in decitabine versus DMSO treated cells (MV4-11, Fold change (FC) 4.67±1.4; OCI-AML3, FC 3.98±1.19, p<0.05). We also detected a modest up-regulation of FOXO3A in both cell lines treated with decitabine when compared to the DMSO controls (MV4-11, FC 2.56±0.74 and OCI-AML3, FC 1.5±0.23, p<0.05). These results were confirmed also at the protein level by using western blot. Next, we asked whether ectopic up-regulation of p21 (mimicking decitabine effects) in OCI-AML3 cells could re-capitulate the decitabine enhancing antileukemic effects of Selinexor. Overexpression of p21 followed by Selinexor (200nM) for 24 hrs resulted in a larger decrease of cell proliferation (Abs 0.5) with respect to controls (Abs 0.7, p<0.05) using the WST assay. Similar results were observed for the MV4-11 cell line. Finally, we tested the efficacy of the sequential decitabine–Selinexor in vivo using the MV4-11 xenograft model. Treatment began one week after leukemic cell inoculation in 4 different cohorts; 1) Vehicle, 2) decitabine i.p. twice weekly (BIW) (0.4mg/kg); 3) Selinexor BIW (20mg/kg by oral gavage) and 4) decitabine BIW i.p (0.4 mg/kg) followed by Selinexor (10 mg/kg BIW). We found no difference in median survival time (MST) between vehicle and decitabine only treated mice. As expected, Selinexor alone treated mice have significantly improved MST at 36.5 days vs. 28.5 days, vehicle, p=<0.01). Most importantly, the sequential treatment of decitabine followed by Selinexor significantly improved MST compared to Selinexor alone 47 vs 36.5, p=0.008). These pre-clinical results hold great promise for the use of this combination in human clinical trials in AML. Disclosures: Schacham: Karyopharm: Membership on an entity’s Board of Directors or advisory committees. Kauffman:Karyopharm Therapeutics Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties. Garzon:Karyopharm: Research Funding.

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An Update On The Clinical Activity Of Resimmune, a Targeted Therapy Directed To CD3 Receptor, In Patients With Cutaneous T Cell Lymphomas--CTCL

Blood ◽

10.1182/blood.v122.21.4381.4381 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4381-4381 ◽

Cited By ~ 2

Author(s):

Arthur E. Frankel ◽

Jung H Woo ◽

Jeremy P Mauldin ◽

Francine M. Foss ◽

Madeleine Duvic ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Pichia Pastoris ◽

Cell Line ◽

Board Of Directors ◽

Research Funding ◽

Response Rate ◽

The United States ◽

Advisory Committees ◽

Systemic Therapies

Abstract Cutaneous T cell lymphoma—CTCL is a malignancy of skin-tropic T cells. CTCL cells have ubiquitous overexpression of CD3. Although uncommon, CTCL has been estimated to affect 1,500 patients per year in the United States. There are multiple approved systemic therapies for CTCL, but responses are brief lasting months. Allogeneic stem cell transplantation may provide long-term remissions, but is suitable for only rare CTCL patients. Overall, CTCL has a long clinical course with relentless progression over months to years with estimated median survival of 3-5 years for stage IB-IIB patients. The CD3 targeted agent, Resimmune, was synthesized and prepared for clinical use. It consists of the catalytic and translocation domains of diphtheria toxin fused to two anti-human CD3 Fv fragments. DNA encoding Resimmune protein was integrated into the Pichia pastoris genome, and recombinant protein was produced in Pichia pastoris via the secretory route (Woo, Protein Expr Purif 25, 270, 2002). Protein was purified by anion exchange and size exclusion chromatography. The CD3+ Jurkat cell line incubated with Resimmune yielded an IC50 for protein synthesis inhibition of 0.017pM. The CD3- Vero cell line incubated with Resimmune showed an IC50 >10pM. Mice, rats, and monkeys given total doses of >200mg/kg over four days showed only transient transaminasemia without histopathologic tissue injury or clinical signs or symptoms (Woo, Cancer Immunol Immunother 57, 1225, 2008). In a mouse model with human CD3e transfected lymphocytes, four logs of antigen positive cells were reproducibly depleted from nodes and spleen with 100mg/kg total dose of Resimmune (Thompson, Protein Eng 14, 1035, 2001). Based on these findings, a phase 1 study was initiated and this report serves to update the results of a single cycle of Resimmune given at 2.5-11.25mg/kg 15 min IV infusion twice daily for 8 doses to 18 CTCL patients. There were 10 females and 8 males with ages 20-81 years. Two patients were naïve to systemic therapies, and all others had failed 1-4 prior treatments including interferon, bexarotene, gemcitabine, vorinostat, chlorambucil, etoposide, pralatrexate, doxil, romidepsin, methotrexate, CHOP, and brentuximab vedotin. None of the Resimmune treated CTCL patients had dose-limiting toxicities. Side effects were mild-moderate and transient with fevers, chills, nausea, transaminasemia, hypoalbuminemia, lymphopenia, reactivation of EBV and CMV, and hypophosphatemia. Toxicities responded to antipyretics, anti-emetics, albumin infusions, rituximab treatment and valgancyclovir. Among measured patients, there was a 3 log decline in normal, circulating T cells by day 5 that recovered by day 14. Because of vascular leak syndrome toxicities in non-CTCL patients, the MTD was defined as 7.5mg/kg x 8 doses. Cmax ranged from 1.9-40.7ng/mL and half-life from 5-66min. Pretreatment anti-DT titers were 0.9-251mg/mL and day 30 post-therapy increased to 5-4059 mg/mL. 17 CTCL patients were evaluable for response. There were six responses for a response rate of 35%. There were four CRs (24% CR rate). Three of the CRs are over 4-years duration. Patients with IB or IIB disease and mSWAT<50 had an overall response rate of 86% and CR rate of 56%. The long time required to convert from a PR to a CR in the absence of any additional therapy beyond the four treatment days suggest an additional anti-tumor mechanism beyond immunotoxin-induced killing such as immunomodulation. Accrual of patients with mSWAT scores of 50 or less is ongoing. Disclosures: Woo: Angimmune: Patents & Royalties, Research Funding. Foss:celgene: Honoraria, Research Funding; millenium: Honoraria, Membership on an entity’s Board of Directors or advisory committees; eisai: Membership on an entity’s Board of Directors or advisory committees; spectrum: Research Funding; merck: Research Funding; seattle genetics: Research Funding. Neville:Angimmune: Employment, Equity Ownership, Patents & Royalties.

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Identifying Mechanisms Associated with Venetoclax Resistance in Multiple Myeloma (MM)

Blood ◽

10.1182/blood-2021-153747 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 2668-2668

Author(s):

Yuan Xiao Zhu ◽

Laura Ann Bruins ◽

Joseph Ahmann ◽

Cecilia Bonolo De Campos ◽

Esteban Braggio ◽

...

Keyword(s):

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Acquired Resistance ◽

Resistant Cell ◽

Resistant Cell Line ◽

Sensitive Cell ◽

Advisory Committees ◽

Bcl2 Family ◽

Family Regulation

Abstract Venetoclax (VTX) is a selective small-molecule inhibitor of BCL-2 that exhibits antitumoral activity against MM cells presenting lymphoid features and those with translocation t(11;14). Despite its impressive clinical activity, VTX therapy for a prolonged duration can lead to drug resistance. Therefore, it is important to understand the underlying mechanisms of resistance in order to develop strategies to prevent or overcome resistance. In the present study, we established four VTX resistant human myeloma cell lines (HMCLs) from four sensitive HMCLs, including three with t(11;14), in culture with a stepwise increase in treatment dose with VTX. To identify the molecular basis of acquired VTX resistance, whole exon sequencing (WES), mRNA-sequencing (mRNAseq), and protein expression assays were performed in the four isogenic VTX-sensitive/resistant HMCLs and three MM patients with samples collected before VTX administration and after clinical resistance to the drug. Compared with sensitive cell lines and patient samples collected before VTX administration, mRNAseq analysis identified downregulation of BIM and upregulation of BCLXL in both resistant cell lines and MM cells from relapse patients. Other transcriptional changes detected included upregulation of AURKA, BIRC3, BIRC5, and IL32. Enrichment analysis of differentially expressed genes suggested involvement of PI3K and MAPK signaling, likely associated with cytokines, growth factors (EGF, FGF and IGF family members), and receptor tyrosine kinase (EGF and FGF). Western blot analysis was performed to compare BCL2 family expression in resistant cell lines versus sensitive cell lines and it showed upregulation of BCL2 survival members (such as MCL-1 and BCLXL), and downregulation of pro-apoptotic BH3 members (such as BIM and PUMA). BIM expression was completely lost in one resistant cell line, and introduction of exogenous BIM into this cell line enhanced VTX sensitivity. Interestingly, BCL2 was upregulated in some resistant cell lines generated after a long-term treatment with VTX, suggesting BCL2 expression level may not be suitable as a marker of VTX sensitivity for acquired resistance. Unlike in CLL, BCL2 mutations were not identified through WES in any resistant cell lines or primary patient sample harvested after relapse. While 8 genes were mutated in two resistant samples , no clear mutational pattern emerged . Based on the above, we further tested some specific inhibitors in in vitro or ex vivo cell models to help understanding resistant mechanism and identify strategies to overcome VTX resistance. We found that inhibition of MCL-1, with the compound S68345, substantially enhanced VTX sensitivity in three resistant HMCLs and in primary cells from one relapsed MM patient. A BCLXL inhibitor (A155463) only significantly enhanced VTX sensitivity in one resistant cell line after co-treatment with VTX. Co-treatment of the other three resistant cell lines with VTX, S68345 and A155463 resulted in the most synergistic anti-myeloma activity, suggesting those cell lines are co-dependent on MCL-1, BCLXL, and BCL2 for survival, although they are more dependent on MCL-1. We also found that inhibition of PI3K signaling, IGF1, RTK (EGF and FGF) and AURKA significantly increased VTX sensitivity, partially through downregulation of MCL-1, and BCLXL, and upregulation of BIM. Conventional anti-MM drugs such as dexamethasone, bortezomib and lenalidomide, were shown to have little activity on augmenting VTX sensitivity in most resistant cell lines. In summary, we find that acquired resistance to VTX in MM is largely associated with BCL2 family regulation, including upregulation of survival members such as MCL-1, BCLXL, BCL2, and downregulation of pro-apoptotic members, especially BIM. Our study also indicates that upstream signaling involved in BCL2 family regulation during acquired resistance is likely related to cytokine, growth factor, and/or RTK-induced cell signaling such as PI3K. Co-inhibition of MCL-1, or BCLXL, as well as the upstream PI3K, RTK (FGF and EGF), IGF-1 mediated signaling were effective in overcoming VTX resistance. Disclosures Fonseca: Mayo Clinic in Arizona: Current Employment; Amgen: Consultancy; BMS: Consultancy; Celgene: Consultancy; Takeda: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Merck: Consultancy; Juno: Consultancy; Kite: Consultancy; Aduro: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; AbbVie: Consultancy; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees.

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Tolinapant (ASTX660), a Non-Peptidomimetic Antagonist of cIAP1/2 and XIAP, and the HDAC Inhibitor Romidepsin Are Synergistic in in Vitro Models of T Cell Lymphoma

Blood ◽

10.1182/blood-2021-153451 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 4356-4356

Author(s):

John S Manavalan ◽

Ipsita Pal ◽

Aidan Pursley ◽

George A. Ward ◽

Tomoko Smyth ◽

...

Keyword(s):

T Cell ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Cell Lymphoma ◽

T Cell Lymphoma ◽

Tnf Alpha ◽

Sensitive Cell ◽

Advisory Committees

Abstract Background: The PTCL are a heterogeneous group of non-Hodgkin lymphomas originating from mature T-lymphocytes. They are aggressive diseases, often resistant to conventional chemotherapy. Despite the fact that a number of new agents have been approved, treatment paradigms tailored to the biology of the disease have yet to emerge. Tolinapant (ASTX660) is a potent antagonist of both cellular and X-linked inhibitors of apoptosis proteins (cIAP1/2 and XIAP), and is presently in phase I/II trials in patients with advanced solid tumors and lymphomas (NCT02503423). IAP antagonists enhance tumor necrosis factor (TNF) receptor superfamily mediated apoptosis (Ward GA, et al. Mol Cancer Ther. 2018), are potent anti-tumor immune enhancers and induce markers of immunogenic cell death such as damage associated molecular patterns (DAMPs; Ye W, et al, Oncoimmunology, 2020). Objectives: We explored the sensitivity of a range of T-cell lymphoma (TCL) cell lines to tolinapant. We establish the synergy coefficient between tolinapant and the HDAC inhibitor, romidepsin, and interrogated the molecular basis of their synergistic interaction. Methods: A panel of human T-cell lymphoma cell lines were tested in proliferation assays (CellTiterGlo) for sensitivity to tolinapant in the presence or absence of 10ng/ml of TNF alpha. For combination studies, with tolinapant and romidepsin, each drug was tested at the IC10 and IC40 concentrations in the presence or absence of TNF alpha. Synergy scores using the Excess over Bliss (EOB) model were calculated using SynergyFinder (Aleksandr Ianevski et al; Nucleic Acids Research, 2020). Additionally, the effects of tolinapant and romidepsin on the IAPs and caspases were analyzed by western blots. TNFR1 receptor expression and induction of DAMPs were also analyzed by flow cytometry. Results: TCL Lines demonstrated varying sensitivities to tolinapant in the presence or absence of TNF alpha. The most sensitive cell lines, ALK+ ALCL and SUP-M2, had IC50 concentrations ranging from 200nM ± 100nM to 20nM ± 1nM in the absence or presence of TNF alpha, respectively, at 24, 48 and 72hrs, while a resistant CTCL cell line HH had an IC50 concentration of over 20mM, even in the presence of TNF alpha. Interestingly, using western blot analysis, we found that the presence of TNF alpha increased the levels of cIAP1 in the tolinapant sensitive SUP-M2 cell line, but not in the resistant HH cell line. However, there was a concentration dependent decrease in cIAP1 but not in XIAP in both cell lines treated with tolinapant. Flow cytometry analysis demonstrated that tolinapant increases the expression of TNFR1 and DAMPs in a dose dependent manner on the sensitive SUP-M2, but not in the resistant HH cells. In combination experiments, using the EOB model, tolinapant plus romidepsin was found to be synergistic in the absence of TNF alpha, at 36hrs, in both the sensitive cell line SUP-M2 and the resistant cell line HH. In the presence of TNF alpha, synergism was seen only in the sensitive cell line SUP-M2 and antagonistic in the HH cell line (Fig. 3). In the tolinapant plus romidepsin treated samples, cIAP1 levels decreased in the SUP-M2 cell line, in the absence of TNF alpha, however, addition of TNF alpha did not alter the levels of cIAP1 in the SUP-M2 cells. The cIAP1 levels decreased in the HH cells treated with the combination, in both the presence or absence of TNF alpha (Figure). Our findings indicate that the synergy of the tolinapant plus romidepsin is not dependent on the presence of TNF alpha. Conclusion: Tolinapant has demonstrated potent cytotoxic effects against a broad range of TCL lines both as a monotherapy and in combination with the HDAC Inhibitor, romidepsin. In in vitro studies, T cell lymphoma cell lines demonstrated varying sensitivity to tolinapant with certain cell lines being more resistant, even in the presence of TNF alpha. Interestingly, the addition of romidepsin appeared to overcome the intrinsic resistance to tolinapant in the absence of TNF alpha. These data provide the rationale to continue to explore the combination of tolinapant and romidepsin in vivo and to investigate additional combinations with T-cell specific agents (e.g. pralatrexate, belinostat, azacitidine and decitabine). Figure 1 Figure 1. Disclosures Smyth: Astex Pharmaceuticals: Current Employment. Sims: Astex Pharmaceuticals: Current Employment. Loughran: Kymera Therapeutics: Membership on an entity's Board of Directors or advisory committees; Bioniz Therapeutics: Membership on an entity's Board of Directors or advisory committees; Keystone Nano: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Marchi: Kyowa Kirin: Honoraria; Myeloid Therapeutics: Honoraria; Astex: Research Funding; BMS: Research Funding; Merck: Research Funding; Kymera Therapeutics: Other: Scientific Advisor.

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Molecular Characterization By Immune Profiling of Paired Blood and Bone Marrow in Multiple Myeloma and Its Precursor States

Blood ◽

10.1182/blood-2018-99-118281 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4461-4461 ◽

Cited By ~ 1

Author(s):

Manisha Bhutani ◽

David M. Foureau ◽

Nury M Steuerwald ◽

Sally Trufan ◽

Fei Guo ◽

...

Keyword(s):

Multiple Myeloma ◽

T Cell ◽

Board Of Directors ◽

Mononuclear Cells ◽

Plasma Cells ◽

Terminal Differentiation ◽

Advisory Committees ◽

Cell Mobilization ◽

Precursor States ◽

Immune Profiling

Abstract INTRODUCTION: Progression from precursor states, MGUS and smoldering multiple myeloma (SMM), to multiple myeloma (MM) is dependent upon adaptive and innate immune contexture shaped by cross-talk between malignant plasma cells and bone marrow (BM) milieu. The complexity and heterogeneity of interactions between the immune system and plasma cells in BM triggers alterations in peripheral blood (PB) immune cell subsets. The advantage of using PB as a surrogate is that dynamic changes in the immune cells can be measured at various time points during disease progression or therapeutic intervention. Here, we performed a comprehensive analysis of immune repertoire to identify immune signatures in PB and BM associated with MM or its precursor states. We also performed T cell receptor (TCR) clonotyping to quantify clonal expansion specific to each immunotype. METHODS: Paired PB and BM specimens were collected from patients with MGUS/SMM (n=12) and MM (n=16) through an IRB-approved biospecimen protocol. PB mononuclear cells and BM mononuclear cells were isolated for immune profiling. A total of 59 immune variables were analyzed by flow cytometry surveying 6 cell lineages' [NK, NK-T, Th, CTL, Treg and ɣδ T cells] distribution and functional status [activation, differentiation and anergy]. In addition, ArcherDx Immunoverse TCR αδ-βɣ CDR3 targeted NGS assay was performed to study clonal distributions of Vα24Jα18 NK-T, βα and ɣδ T cell. Univariate analyses (ANOVA) were performed using p<0.15 cutoff. Each set of variables (PB or BM) was then validated by multivariate analyses (Wilk's lambda) and used for unsupervised hierarchical analysis by WPGMA methods. Innate (NK-T, ɣδ T) and adaptive (βα T) mobilization for each cluster were finally confirmed by calculating Shannon's TCR clonal diversity index (SI). RESULTS: PB immunotyping identified 1 marker of innate inflammation and 9 markers of adaptive T mobilization that differentiated precursor states and MM (p=0.005). This model generated 3 PB immune clusters (Figure): cluster #1 [8 precursor states, 1 MM] showed a lack of innate inflammation and low Th/CTL mobilization, cluster #2 [2MGUS, 5MM] showed low innate inflammation and, cluster #3 [2SMM, 10MM] showed strong innate inflammation (Vɣ9-Vδ2-NKG2D+), Th terminal differentiation (central memory phenotype) and CTL anergy (Tim3+). TCR clonotyping confirmed increased innate inflammation (TCRδ SI 3.99±0.3 vs 4.75±0.15, p<0.05) and T cell mobilization (TCRα SI 7.12±0.3 vs. 8.20± 0.2, p<0.05) in PB cluster #3 compared with PB cluster #1. BM immunotyping identified 3 markers of innate inflammation and 2 markers of adaptive T mobilization (p=0.0274) distinguishing precursor states from MM. This model generated 3 BM immune clusters: cluster #1 [6 precursor states, 6 MM] showed innate inflammation (ɣδ T) and CTL terminal differentiation (central memory phenotype); cluster #2 [4 SMM, 8 MM] showed innate inflammation (NK-T, ɣδ T) and CTL effector anergy; and cluster #3 [2 MGUS, 2 MM] showed low NK cell cytotoxicity (KIR3DL1+) and CTL terminal differentiation. TCR clonotyping confirmed qualitative differences in innate inflammation between BM cluster #1 and #2 with higher NK-T (%Vα24Jα18 p<0.01) but lower ɣδ T (TCRδ SI 3.36±0.2 vs 4.57±0.2, p<0.05). In addition, CTL mobilization whether resulting in terminal differentiation or anergy in BM cluster #1 and #2, respectively was associated with similar clonal expansion of T cells (TCRα SI 7.21±0.26 vs. 7.87± 0.4, ns). Comparisons showed associations between PB and BM ɣδ T cell involvement in 13/13 patients. High PB Th/CTL mobilization (terminal differentiation) was associated with high T cell anergy in BM in 9/12 patients; conversely low PB Th/CTL mobilization was associated with low BM T cell involvement in 6/7 patients. CONCLUSION: This pilot study shows immune clustering of MGUS, SMM and MM patients based on BM and PB immunotypes. This is the first study to demonstrate two very distinct MM immunotypes based on low vs. high inflammatory states. We also show a high correlation between innate immune inflammation status in both PB and BM, specifically pertaining to ɣδ T cell, conventional T cell mobilization or lack thereof. Additional studies including a larger cohort for validation and longer follow up to establish correlation with clinical outcomes are currently underway. Figure. Figure. Disclosures Foureau: Teneobio Inc.: Research Funding. Berlin:ArcherDx: Employment. Johnson:ArcherDx: Employment. Williams:ArcherDx: Employment. Voorhees:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Other: served on an IRC; Amgen Inc.: Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: served on an IRC; Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: served on an IRC; TeneoBio: Consultancy, Membership on an entity's Board of Directors or advisory committees. Usmani:Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding; Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy.

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Genotype-Phenotype Relationships and Therapeutic Targets in Acute Erythroid Leukemia

Blood ◽

10.1182/blood-2020-141750 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 17-18

Author(s):

June Takeda ◽

Kenichi Yoshida ◽

Akinori Yoda ◽

Lee-Yung Shih ◽

Yasuhito Nannya ◽

...

Keyword(s):

Cell Line ◽

Board Of Directors ◽

Research Funding ◽

Pharmaceutical Research ◽

Private Company ◽

Advisory Committees ◽

Otsuka Pharmaceutical ◽

Group A ◽

Genetic Profiles ◽

Stat Pathway

Background: Acute erythroid leukemia (AEL) is a rare subtype of AML characterized by erythroid predominant proliferation and classified into two subtypes with pure erythroid (PEL) and myeloid/erythroid (MEL) phenotypes. Although gene mutations in AEL have been described in several reports, genotype phenotype correlations are not fully understood with little knowledge about the feasible molecular targets for therapy. Methods: To understand the mechanism of the erythroid dominant phenotype of AEL and identify potential therapeutic targets for AEL, we analyzed a total of 105 AEL cases with the median age of 60 (23-86), using targeted-capture sequencing of commonly mutated genes in myeloid neoplasms, together with 1,279 SNPs for copy number measurements. Among these 105 cases, 13 were also analyzed by RNA sequencing. Genetic profiles of these 105 AEL cases were compared to those of 775 cases with non-erythroid AML (NEL) including 561 cases from The Cancer Genome Atlas and Beat AML study. An immature erythroid cell line (TF1) and three patient-derived xenografts (PDX) established from AEL with JAK2 and/or EPOR amplification. Cell line and samples from patients were inoculated into immune-deficient mice and tested for their response to JAK1/2 inhibitor. Results: According to unique genetic alterations, AEL was classified into 4 subgroups (A-D). Characterized by TP53 mutations and complex karyotype, Group A was the most common subtype and showed very poor prognosis. Remarkably, all PEL cases were categorized into Group A. Conspicuously, 80% of PEL cases had amplifications of JAK2 (6/10; 60%), EPOR (7/10;70%), and ERG (6/10;60%) loci on chromosomes 9p, 19q, and 21q, respectively, frequently in combination, although they were rarely seen in NEL cases. All cases in Group B (n=19, 18%), another prevalent form of AEL, had STAG2 mutations and classified in MEL. To further characterize this subgroup, we compared genetic profiles of STAG2-mutated AEL and NEL. Prominently, 70% (14/20) of STAG2-mutated cases in AEL had KMT2A-PTD, whereas it was found only in 8.8% (3/34) of NEL. CEBPA mutations were also more common in AEL (6/21; 29%) than NEL (4/34; 12%). While Group C was characterized by frequent NPM1 mutations, in contrast to the frequent co-mutation of FLT3 in the corresponding subgroup of NPM1-mutated cases in NEL, NPM1-mutated patents in this subgroup lacked FLT3 mutations but had frequent PTPN11 mutations (8/16; 50%), which were much less common in NEL (25/209; 12%). The remaining cases were categorized into Group D, which was enriched for mutations in ASXL1, BCOR, PHF6, U2AF1 and KMT2C. Recurrent loss-of-function mutations in USP9X were unique to this subtype, although USP9X mutations have been reported in ALL with upregulation of JAK-STAT pathway. In RNA sequencing analysis, AEL cases exhibited gene expression profiles implicated in an upregulated STAT5 signaling pathway, which was seen not only those cases with JAK2 or EPOR amplification, but also those without, suggesting that aberrantly upregulated STAT5 activation might represent a common defect in AEL. Based on this finding, we evaluated the effect of a JAK inhibitior, ruxolitinib, on an AEL-derived cell line and three PDX models established from AEL having TP53 mutations and JAK2 and EPOR mutation/amplification. Of interest, ruxolitinib significantly suppressed cell growth and prolonged overall survival in mice engrafted with TF1 and 2 PDX models with STAT5 downregulation, although the other model was resistant to JAK2 inhibition with persistent STAT5 activation. Conclusion: AEL is a heterogeneous group of AML, of which PEL is characterized by frequent amplifications/mutations in JAK2, EPOR and/or ERG. Frequent involvement of EPOR/JAK/STAT pathway is a common feature of AEL, in which a role of JAK inhibition was suggested. Disclosures Yoda: Chordia Therapeutics Inc.: Research Funding. Shih:Novartis: Research Funding; Celgene: Research Funding; PharmaEssentia: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees. Ishiyama:Alexion: Research Funding; Novartis: Honoraria. Miyazaki:Astellas Pharma Inc.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; NIPPON SHINYAKU CO.,LTD.: Honoraria; Celgene: Honoraria; Otsuka Pharmaceutical: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma KK: Honoraria; Kyowa Kirin Co., Ltd.: Honoraria. Nakagawa:Sumitomo Dainippon Pharma Co., Ltd.: Research Funding. Takaori-Kondo:Celgene: Honoraria, Research Funding; Ono Pharmaceutical: Research Funding; Thyas Co. Ltd.: Research Funding; Takeda: Research Funding; CHUGAI: Research Funding; OHARA Pharmaceutical: Research Funding; Sanofi: Research Funding; Novartis Pharma: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Pfizer: Research Funding; Otsuka Pharmaceutical: Research Funding; Eisai: Research Funding; Astellas Pharma: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Nippon Shinyaku: Research Funding; MSD: Honoraria. Kataoka:Asahi Genomics: Current equity holder in private company; Otsuka Pharmaceutical: Research Funding; Takeda Pharmaceutical Company: Research Funding; CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding. Usuki:Alexion: Research Funding, Speakers Bureau; Apellis: Research Funding; Novartis: Research Funding, Speakers Bureau; Chugai: Research Funding. Maciejewski:Novartis, Roche: Consultancy, Honoraria; Alexion, BMS: Speakers Bureau. Ganser:Novartis: Consultancy; Celgene: Consultancy. Thol:Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Ogawa:Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Otsuka Pharmaceutical Co., Ltd.: Research Funding; Asahi Genomics Co., Ltd.: Current equity holder in private company; Eisai Co., Ltd.: Research Funding; Chordia Therapeutics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; KAN Research Institute, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Ruxolitinib is used for drug efficacy test using patient-derived xenografts established from acute erythroid leukemia.

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CD38low Natural Killer Cells Transiently Expressing CD16F158V m-RNA Potentiates the Therapeutic Activity of Daratumumab Against Multiple Myeloma with Minimal Effector NK Cell Fratricide

Blood ◽

10.1182/blood-2018-99-118926 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3199-3199 ◽

Cited By ~ 2

Author(s):

Subhashis Sarkar ◽

Sachin Chauhan ◽

Arwen Stikvoort ◽

Alessandro Natoni ◽

John Daly ◽

...

Keyword(s):

Nk Cells ◽

Cell Line ◽

Board Of Directors ◽

Cell Lines ◽

Research Funding ◽

Nk Cell ◽

Ex Vivo ◽

Advisory Committees ◽

Cd38 Expression ◽

Rpmi 8226

Abstract Introduction: Multiple Myeloma (MM) is a clonal plasma cell malignancy typically associated with the high and uniform expression of CD38 transmembrane glycoprotein. Daratumumab is a humanized IgG1κ CD38 monoclonal antibody (moAb) which has demonstrated impressive single agent activity even in relapsed refractory MM patients as well as strong synergy with other anti-MM drugs. Natural Killer (NK) cells are cytotoxic immune effector cells mediating tumour immunosurveillance in vivo. NK cells also play an important role during moAb therapy by inducing antibody dependent cellular cytotoxicity (ADCC) via their Fcγ RIII (CD16) receptor. Furthermore, 15% of the population express a naturally occurring high affinity variant of CD16 harbouring a single point polymorphism (F158V), and this variant has been linked to improved ADCC. However, the contribution of NK cells to the efficacy of Daratumumab remains debatable as clinical data clearly indicate rapid depletion of CD38high peripheral blood NK cells in patients upon Daratumumab administration. Therefore, we hypothesize that transiently expressing the CD16F158V receptor using a "safe" mRNA electroporation-based approach, on CD38low NK cells could significantly enhance therapeutic efficacy of Daratumumab in MM patients. In the present study, we investigate the optimal NK cell platform for generating CD38low CD16F158V NK cells which can be administered as an "off-the-shelf"cell therapy product to target both CD38high and CD38low expressing MM patients in combination with Daratumumab. Methods: MM cell lines (n=5) (MM.1S, RPMI-8226, JJN3, H929, and U266) and NK cells (n=3) (primary expanded, NK-92, and KHYG1) were immunophenotyped for CD38 expression. CD16F158V coding m-RNA transcripts were synthesized using in-vitro transcription (IVT). CD16F158V expression was determined by flow cytometry over a period of 120 hours (n=5). 24-hours post electroporation, CD16F158V expressing KHYG1 cells were co-cultured with MM cell lines (n=4; RPMI-8226, JJN3, H929, and U266) either alone or in combination with Daratumumab in a 14-hour assay. Daratumumab induced NK cell fratricide and cytokine production (IFN-γ and TNF-α) were investigated at an E:T ratio of 1:1 in a 14-hour assay (n=3). CD38+CD138+ primary MM cells from newly diagnosed or relapsed-refractory MM patients were isolated by positive selection (n=5), and co-cultured with mock electroporated or CD16F158V m-RNA electroporated KHYG1 cells. CD16F158V KHYG1 were also co-cultured with primary MM cells from Daratumumab relapsed-refractory (RR) patients. Results: MM cell lines were classified as CD38hi (RPMI-8226, H929), and CD38lo (JJN3, U266) based on immunophenotyping (n=4). KHYG1 NK cell line had significantly lower CD38 expression as compared to primary expanded NK cells and NK-92 cell line (Figure 1a). KHYG1 electroporated with CD16F158V m-RNA expressed CD16 over a period of 120-hours post-transfection (n=5) (Figure 1b). CD16F158V KHYG1 in-combination with Daratumumab were significantly more cytotoxic towards both CD38hi and CD38lo MM cell lines as compared to CD16F158V KHYG1 alone at multiple E:T ratios (n=4) (Figure 1c, 1d). More importantly, Daratumumab had no significant effect on the viability of CD38low CD16F158V KHYG1. Moreover, CD16F158V KHYG1 in combination with Daratumumab produced significantly higher levels of IFN-γ (p=0.01) upon co-culture with CD38hi H929 cell line as compared to co-culture with mock KHYG1 and Daratumumab. The combination of CD16F158V KHYG1 with Daratumumab was also significantly more cytotoxic to primary MM cell ex vivo as compared to mock KHYG1 with Daratumumab at E:T ratio of 0.5:1 (p=0.01), 1:1 (p=0.005), 2.5:1 (p=0.003) and 5:1 (p=0.004) (Figure 1e). Preliminary data (n=2) also suggests that CD16F158V expressing KHYG1 can eliminate 15-17% of primary MM cells from Daratumumab RR patients ex vivo. Analysis of more Daratumumab RR samples are currently ongoing. Conclusions: Our study provides the proof-of-concept for combination therapy of Daratumumab with "off-the-shelf" CD38low NK cells transiently expressing CD16F158V for treatment of MM. Notably, this approach was effective against MM cell lines even with low CD38 expression (JJN3) and primary MM cells cultured ex vivo. Moreover, the enhanced cytokine production by CD16F158V KHYG1 cells has the potential to improve immunosurveillance and stimulate adaptive immune responses in vivo. Disclosures Sarkar: Onkimmune: Research Funding. Chauhan:Onkimmune: Research Funding. Stikvoort:Onkimmune: Research Funding. Mutis:Genmab: Research Funding; OnkImmune: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Research Funding; Celgene: Research Funding; Novartis: Research Funding. O'Dwyer:Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; BMS: Research Funding; Glycomimetics: Research Funding; Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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