Pre-Clinical Activity of a Novel FcγRIIIa Engineered CD19 Monoclonal Antibody in B Cell Chronic Lymphocytic Leukemia and Acute Lymphoblastic Leukemia.

Abstract CD19 is a B cell lineage-specific transmembrane signaling protein that controls differentiation and proliferation. CD19 is an attractive therapeutic target due to its high level of expression in numerous B cell malignancies, as well as its lack of expression on non-B cells. Here we report the in vitro anti-tumor activity of a novel humanized monoclonal anti-CD19 Ab (CD19-IgG1, aka XENP5603) and its Fc engineered counterpart (XmAb™CD19, aka XENP5574). XENP5603 induced direct apoptosis in normal CD19+ B cells, but not NK cells, T cells, or monocytes, as determined by flow cytometric staining with annexin V and propidium iodide. XENP5603 also induced significant levels of apoptosis in a number of lymphoblastoid cell lines, including Ramos, Raji, 697, NALM6, and RS4;11 cells. Treatment of primary chronic lymphocytic leukemia (CLL) cells with XENP5603 induced significant cell death in all patients tested (mean, 36% apoptotic cells at 24 hours; range, 13–66%, p < 0.001). Similar apoptosis was noted in cells from a subset of patients (4 of 9) with CD19+ primary acute lymphoblastic leukemia (ALL). Apoptosis of CLL cells treated with XENP5603 was not associated with cleavage of caspase-3, caspase-8, caspase-9, or PARP, but was associated with upregulation of Bim, suggesting a caspase-independent mechanism of cell death. NK cells from normal donors exhibited high levels of ADCC in response to B cell lines coated with XENP5603. Furthermore, NK cells from CLL patients mediated significant ADCC against autologous CLL cells in the presence of XENP5603 (mean, 15% specific lysis at an E:T ratio of 25:1; range, 8–24%; p = 0.04 vs. the negative control Ab). ADCC activity was further increased in the presence of XENP5574, which has the same antigen-recognition sequences as XENP5603 but which contains two mutations in the Fc region that increase FcγRIIIa affinity (mean, 39% specific lysis at an E:T ratio of 25:1; range, 29–51%; p = 0.02 vs. the negative control Ab). ADCC mediated by either CD19 Ab was also significantly higher than that mediated by an equivalent concentration of rituximab (mean, 39% specific lysis with XENP5574 vs. 12% with rituximab; p < 0.001). ADCC in the presence of either Ab was further increased in the presence of the NK cell-activating cytokine IL-2, suggesting that these antibodies might be effectively combined with immune stimulatory adjuvants. Furthermore, NK cell ADCC against CLL cells in the presence of CD19 Abs was found to be dependent on perforin/granzyme release, as treatment with 3,4-dichloroisocoumarin (which inhibits granzyme enzymatic activity) or EGTA (which prevents release of cytotoxic vesicles) potently inhibited ADCC activity. Collectively, these studies provide evidence of the autologous innate immune-mediated cytotoxicity and direct apoptotic activity of XENP5603 and XENP5574. In addition, engineering to enhance FcγRIIIa binding enhances autologous ADCC, providing support for further pre-clinical development of XENP5574 in CD19+ malignancies, including CLL and ALL.

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Comparative Study of Obinutuzumab (GA101) Vs. Rituximab Against CD20+ rituximab-Sensitive and -Resistant Burkitt (BL) and Acute Lymphoblastic Leukemia (B-ALL): Potential Targeted Therapy in Patients with High Risk BL and Pre-B-ALL

Blood ◽

10.1182/blood.v124.21.2251.2251 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2251-2251 ◽

Cited By ~ 3

Author(s):

Aradhana Awasthi ◽

Janet Ayello ◽

Carmella van de Ven ◽

Mona Elmacken ◽

Christopher Reggio ◽

...

Keyword(s):

Cell Death ◽

Acute Lymphoblastic Leukemia ◽

B Cell ◽

Children And Adolescents ◽

Nk Cells ◽

Tumor Cells ◽

Lymphoblastic Leukemia ◽

Tumor Burden

Abstract Background: Aggressive non-Hodgkin lymphoma (NHL) represents >90% of all NHL that occur in children and adolescents. Among all NHLs, Burkitt Lymphoma (BL) is the most common NHL in children and adolescents and has an excellent prognosis (≥80% 5 yrs, EFS) following short but intense multi-agent chemotherapy (Cairo et al. Blood, 2007). Patients who relapse with CD20+ B-NHL and B cell Acute lymphoblastic leukemia (B-ALL) have a dismal prognosis, often associated with chemotherapy resistance and may require alternative therapeutic strategies (Cairo et al. JCO, 2012, Barth/Cairo et al. BJH, 2013). Rituximab (RTX) in combination with FAB 96 chemotherapy is a safe and well-tolerated and is associated with >90% EFS in children with newly diagnosed and advanced mature B-Cell NHL (Goldman/Cairo et al. Leukemia, 2013). Resistance to RTX, however, may predispose patients with CD20+ B-NHL/ALL to an increase risk of relapse and/or disease progression (Barth/Cairo et al. BJH, 2012; Tsai et al. Cl. Can. Res, 2012,). Obinutuzumab, a novel glycoengineered type II CD20 antibody, has been shown to enhance cell death and ADCC vs. RTX (Herter et al, Clinc Canc Res, 2013), and was recently approved by FDA and EMA for first line treatment of CLL in combination with chlorambucil. Objective: To evaluate anti-tumor activity of obinutuzumab vs RTX against RTX resistant and sensitive BL and pre-B-ALL tumor targets in-vitro and in-vivo in xenografted NSG mice. Methods: Raji (CD20+) and Loucy (T-ALL, CD20-), (ATCC, Manhass, VA), U698-M (CD20+, DSMZ, Germany) and Raji-4RH (provided by M. Barth, Roswell Park Cancer Institute) were cultured in RPMI with 10% FBS. For in-vitro studies, tumor cells were incubated with 100 µg/ml obinutuzumab (supplied by Christian Klein, PhD, Roche Research & Early Development, Zurich), and/or RTX for 24 hrs. Cell death was evaluated by staining with AnnexinV/7AAD and analysis by flow-cytometry. Loucy cells (CD20-) were used as the negative control. ADCC were performed with K562-IL-15-41BBL expanded NK cells (Ayello/Cairo et al. ASH, 2010) at 20:1 effector: target ratio (E: T, n=3) using an europium release assay (Perkin-Elmer).The lentiviral construct, pSico PolII-eGFP-Luc2, was transfected into Raji, Raji 4RH (RTX resistant), U698M and Loucy for in vivo evaluation by BLI. Six to 8 week old female NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ), mice, bred in-house under pathogen free conditions, were divided into 5 groups: PBS only (control), isotype control (IgG), obinutuzumab 10 mg/kg, obinutuzumab (30 mg/kg), and RTX (30 mg/kg). Mice were xenografted with intravenous injections of Luc+ Raji, Raji4RH, U698M and Loucy cells at 5x106 tumor cells/mouse. 6-8 days after tumor cell injection, mice were then injected every 7 days with the respective therapy for 8 weeks. Mice were monitored for tumor burden and survival for up to 12 weeks ( approx. 80 days) via bioluminescent imaging (BLI) using the IVIS Spectrum system. Results: Obinutuzumab compared to RTX (100 mg/ml, 24hrs), significantly enhanced cell death in Raji 45.1±3.3% vs 32.7±6.8%, (p=0.005), Raji4RH 15.8±2.2% vs 2.1±1.5% (p=0.001) and U698-M 40.5±2.9 % vs 26.36±2.6% (p=0.001) n=6. Obinutuzumab vs RTX also elicited a significant increase ADCC with K562-IL15-41BBL expanded NK cells, in Raji 73.8±8.1% vs 56.81±4.6% (p=0.001), Raji-4RH 40.0±1.6% vs 0.5±1.1%, (p=0.001), and U-698-M 70.0±6 % vs. 45.56± 0.1% (p=0.001) n=3. Further, we found that, in vivo, obinutuzumab was significantly more effective than RTX when administered at the same doses in BL (RTX resistant/sensitive) and pre-B-ALL xenografts. Overall survival in mice receiving 30 mg/kg of obinutuzumab was significantly increased when compared to mice receiving 30 mg/kg of RTX in BL; Raji (p=0.05), Raji4RH (p=0.024) and U698-M (p=0.03) (Figure1: A, B and C). Conclusion: Obinutuzumab significantly enhances cell death and NK mediates ADCC in sensitive and RTX resistant CD20+ B-NHL and B-ALL compared to RTX. These preliminary studies also demonstrate that RTX sensitive/resistant BL and pre-B-ALL xenografted mice display significantly increased survival when given 30 mg/kg of obinutuzumab and decreased tumor burden in BL and Pre-B-ALL xenografts compared to an equal dose of RTX. Obinutuzumab may be a novel agent to investigate as adjuvant therapy in patients with relapsed refractory CD20+ B-NHL and/or B-ALL. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Interleukin-4 induces programmed cell death (apoptosis) in cases of high-risk acute lymphoblastic leukemia

Blood ◽

10.1182/blood.v83.7.1731.1731 ◽

1994 ◽

Vol 83 (7) ◽

pp. 1731-1737 ◽

Cited By ~ 54

Author(s):

A Manabe ◽

E Coustan-Smith ◽

M Kumagai ◽

FG Behm ◽

SC Raimondi ◽

...

Keyword(s):

Bone Marrow ◽

Cell Death ◽

Acute Lymphoblastic Leukemia ◽

High Risk ◽

Programmed Cell Death ◽

B Cell ◽

Lymphoblastic Leukemia ◽

Fatal Outcome ◽

Interleukin 4 ◽

B Lineage

Abstract We investigated the effects of interleukin-4 (IL-4) on the survival of leukemic and normal B-cell progenitors cultured on bone marrow stroma. IL-4 (at 100 U/mL) was cytotoxic in 16 of 21 cases of B-lineage acute lymphoblastic leukemia, causing reductions in CD19+ cell numbers that ranged from 50% to greater than 99% (median 83.5%) of those in parallel cultures not exposed to the cytokine. All nine cases with the t(9;22)(q34;q11) or the t(4;11)(q21;q23), chromosomal features that are often associated with multidrug resistance and a fatal outcome, were susceptible to IL-4 toxicity. IL-4 cytotoxicity resulted from induction of programmed cell death (apoptosis); there was no evidence of cell killing mediated by T, natural killer, or stromal cells. IL-4 cytotoxicity extended to a proportion of normal B-cell progenitors. After 7 days of culture with IL-4 at 100 U/mL, fewer CD19+, CD34+ normal lymphoblasts (the most immature subset) survived: in five experiments the mean (+/- SEM) reduction in cell recoveries caused by IL-4 was 60.0% +/- 6.0%. By contrast, reductions in recovery of more differentiated bone marrow B cells (CD19+, CD34-, surface Ig+) were low (6.6% +/- 2.2%; P < .001 by t-test). Our findings indicate that IL-4 is cytotoxic for human B-cell precursors and support clinical testing of IL-4 in cases of high-risk lymphoblastic leukemia resistant to conventional therapy.

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PTEN as a tumor promoter

Science Signaling ◽

10.1126/scisignal.aaf8449 ◽

2016 ◽

Vol 9 (423) ◽

pp. ec84-ec84

Author(s):

Wei Wong

Keyword(s):

Cell Death ◽

Acute Lymphoblastic Leukemia ◽

B Cells ◽

Tumor Suppressor ◽

B Cell ◽

Negative Selection ◽

Lymphoblastic Leukemia ◽

Pharmacological Inhibition ◽

Link Type ◽

Factor C

PTEN is generally considered to be a tumor suppressor because it limits the activity of the PI3K-Akt pathway, which usually promotes cell survival. However, in pre-B cells transformed with BCR-ABL1 or NRASG12D, oncogenes common to acute lymphoblastic leukemia (ALL), Shojaee et al. found that deletion of Pten resulted in cell death, and mice transplanted with the transformed pre-B cells in which Pten was also deleted did not develop leukemia. Pten deletion in transformed pre-B cells resulted in increased phosphorylation of Akt, which is activated downstream of the pre-B cell receptor through the tyrosine kinase Syk. Pharmacological inhibition of Akt or Syk reduced cell death caused by Pten deletion; it also prevented the cell death of autoreactive B cells, which are eliminated through negative selection because the pre-BCR binds to self-antigen. Pten deletion did not affect the abundance of the tumor suppressor p53 or the survival of BCR-ABL1–transformed chronic myeloid leukemia (CML) cells. In contrast, Pten deletion in BCR-ABL1–transformed pre-B ALL cells triggered the phosphorylation of p53 and its accumulation, effects that required Akt activity. Overexpression of the myeloid transcription factor C/EBP-α converts cells of the B cell lineage to the myeloid lineage, and Pten deletion increased glycolysis to a greater extent in pre-B ALL cells than in myeloid-reprogrammed cells, as indicated by increased glucose consumption and lactate production and depletion of ATP. Analysis of a genetic database of human cancers indicated that PTEN deletions or point mutations were not detected in pre-B ALL patient samples, and PTEN abundance was increased in pre-B ALL patient samples compared to that in patient samples of other types of lymphomas and leukemias. PTEN knockdown reduced cell viability in four different patient-derived pre-B ALL cell lines, and pharmacological inhibition of PTEN increased AKT signaling; the phosphorylation and accumulation of p53; and glycolytic metabolism in human pre-B ALL cells. Thus, PTEN may be a potential therapeutic target for the treatment of pre-B ALL (see also Fortin et al.). S. Shojaee, L. N. Chan, M. Buchner, V. Cazzaniga, K. N. Cosgun, H. Geng, Y. H. Qiu, M. Dühren-von Minden, T. Ernst, A. Hochhaus, G. Cazzaniga, A. Melnick, S. M. Kornblau, T. G. Graeber, H. Wu, H. Jumaa, M. Müschen, PTEN opposes negative selection and enables oncogenic transformation of pre-B cells. Nat. Med. 22,379–387 (2016). [PubMed] J. Fortin, C. Bassi, T. W. Mak, PTEN enables the development of pre-B acute lymphoblastic leukemia. Nat. Med. 22, 339–340 (2016). [PubMed]

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Natural Killer Cells In Pediatric Acute Lymphoblastic Leukemia Patients At Diagnosis Demonstrate An Inhibitory Phenotype and Reduced Cytolytic Capacity

Blood ◽

10.1182/blood.v122.21.1397.1397 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1397-1397 ◽

Cited By ~ 1

Author(s):

Rayne H. Rouce ◽

Takuya Sekine ◽

Gerrit Weber ◽

Claude Chew ◽

Katayoun Rezvani ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Nk Cells ◽

Nk Cell ◽

Lymphoblastic Leukemia ◽

Target Cells ◽

Healthy Controls ◽

Cytokine Release ◽

Absolute Count ◽

Flow Cytometric ◽

Pediatric All

Abstract Background Natural killer (NK) cells are a key component of innate immunity, with the potential to recognize and kill transformed malignant cells without prior sensitization. A balance between activating and inhibitory signals from cell surface receptors determines NK cell cytotoxicity and cytokine release. Therapeutic approaches to augmenting NK cell function are being explored in various malignancies. Little is known about NK phenotype and function in patients with childhood acute lymphoblastic leukemia (ALL), the most common childhood cancer. Here we describe an inhibitory phenotype and impaired cytolytic function in NK cells from pediatric ALL patients at diagnosis, compared with healthy pediatric controls. Restoring NK function may be a useful therapeutic approach in ALL. Methods Peripheral blood mononuclear cells (PBMCs) were isolated from 25 patients with newly diagnosed B-ALL, age 1-16 years, and 7 healthy controls, age 2-13 years, in order to compare NK cell frequency, immunophenotype, and functional activity. NK frequency was assessed by flow cytometric staining for CD56+CD3- cells. NK phenotype was assessed by surface expression of activating receptors NKp30, NKp44, NKp46 and NKG2D and inhibitory receptors KIR2DL1/S1, KIR2DL2/S2, KIR3DL1 and NKG2A. Functional activity was determined by incubation of NKs with target cells, followed by flow cytometric measurement of degranulation (surface CD107a) and cytokine release (intracellular IFNg and TNFa). Targets included the MHC class I deficient K562 cell line and, where available, autologous ALL blasts. Results ALL patients demonstrated significantly lower absolute NK cell counts compared with healthy controls (mean absolute count 168 vs. 406 cells/uL, p = 0.0002). They also exhibited significantly fewer NK cells expressing the activating marker NKp46 (mean absolute count 70 vs. 165, p = 0.016); and a significantly higher percentage of cells expressing the inhibitory marker NKG2A (mean 20.5% vs. 1.95% in controls, p = 0.012) (Fig 1A). In co-culture assays with K562 target cells, ALL patients' NK cells demonstrated inferior degranulation and cytokine release compared to healthy controls (representative data in Fig 1B; mean IFNγ production of 1.2% vs. 4.8%, p = 0.02; mean TNFα production of 1.8% vs. 3.8%, p = 0.06; and mean surface CD107a of 5.4% vs. 15.1%, p = 0.08). ALL samples (n = 3) demonstrated little to no cytokine release when incubated with autologous blasts compared with the response elicited by PMA-ionomycin (representative data in Fig 1C; mean CD107a 0.92% vs. 7.85%, p = 0.04; mean IFNγ 0.26% vs 40.47%, p = 0.10; mean TNFα 0.2% vs 41%, p = 0.008). Conclusion At diagnosis, pediatric ALL patients exhibit a lower frequency of NK cells, an inhibitory phenotype, and decreased cytolytic activity compared to healthy pediatric controls, particularly against autologous leukemic blasts. These results suggest that augmentation of the NK response may be useful therapeutically to improve outcomes in childhood ALL. Disclosures: No relevant conflicts of interest to declare.

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The PI3K∂-Selective Inhibitor Idelalisib Induces T- and NK-Cell Dysfunction Independently of B-Cell Malignancy-Associated Immunosuppression

Frontiers in Immunology ◽

10.3389/fimmu.2021.608625 ◽

2021 ◽

Vol 12 ◽

Author(s):

Lisa Rohrbacher ◽

Bettina Brauchle ◽

Ana Ogrinc Wagner ◽

Michael von Bergwelt-Baildon ◽

Veit L. Bücklein ◽

...

Keyword(s):

B Cell ◽

Nk Cells ◽

Nk Cell ◽

Selective Inhibitor ◽

Lymphocytic Leukemia ◽

Leukemic Cells ◽

Potential Contribution ◽

B Cell Malignancy ◽

Increased Risk ◽

Cell Malignancy

B-cell receptors, multiple receptor tyrosine kinases, and downstream effectors are constitutively active in chronic lymphocytic leukemia (CLL) B cells. Activation of these pathways results in resistance to apoptosis and enhanced survival of the leukemic cells. Idelalisib is a highly selective inhibitor of the PI3K p110∂ isoform and is approved for the treatment of CLL in patients with relapsed/refractory disease or in those harboring 17p deletions or tp53 mutations. Despite the initial excitement centered around high response rates in clinical trials of idelalisib, its therapeutic success has been hindered by the incidence of severe opportunistic infections. To examine the potential contribution of idelalisib to the increased risk of infection, we investigated the effects of idelalisib on the immune cell compartments of healthy donors (HDs) and CLL patients. PI3K∂ blockade by idelalisib reduced the expression levels of inhibitory checkpoint molecules in T cells isolated from both HDs and CLL patients. In addition, the presence of idelalisib in cultures significantly decreased T-cell-mediated cytotoxicity and granzyme B secretion, as well as cytokine secretion levels in both cohorts. Furthermore, idelalisib reduced the proliferation and cytotoxicity of HD NK cells. Collectively, our data demonstrate that both human T and NK cells are highly sensitive to PI3K∂ inhibition. Idelalisib interfered with the functions of T and NK cell cells from both HDs and CLL patients. Therefore, idelalisib might contribute to an increased risk of infections regardless of the underlying B-cell malignancy.

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Effects of Rituximab on JAK-STAT and NF-κB signaling pathways in acute lymphoblastic leukemia and chronic lymphocytic leukemia

Turkish Journal of Biochemistry ◽

10.1515/tjb-2018-0321 ◽

2019 ◽

Vol 44 (4) ◽

pp. 499-509 ◽

Cited By ~ 1

Author(s):

Ayşegül Dalmızrak ◽

Nur Selvi Günel ◽

Burçin Tezcanlı Kaymaz ◽

Fahri Şahin ◽

Güray Saydam ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Chronic Lymphocytic Leukemia ◽

B Cell ◽

Signaling Pathways ◽

Cell Lines ◽

B Lymphocyte ◽

Lymphoblastic Leukemia ◽

Lymphocytic Leukemia ◽

Protein Expressions ◽

Apoptotic Effect

AbstractObjectivesRituximab is a monoclonal antibody that targets the B-lymphocyte surface antigen CD20. It is used in the treatment of some diseases including B-cell chronic lymphocytic leukemia (B-CLL). There are a lot of data regarding effect of Rituximab on lymphoma cells. But, there is no satisfactory information about the effect of Rituximab on the signaling pathways in leukemia cells. In this study, it was aimed to understand the effect of Rituximab on JAK-STAT and NF-κB signaling pathways in B-cell acute lymphoblastic leukemia (B-ALL) and B-CLL.Material and methodsApoptotic effect of Rituximab in the TANOUE (B-ALL) and EHEB (B-CLL) cell lines were evaluated by using the Annexin V method. mRNA expression levels of STAT3 and RelA were analysed by quantitative RT-PCR (Q-PCR). Alterations in STAT3 and RelA protein expressions were detected by using a chromogenic alkaline phosphatase assay after Western Blotting.ResultsRituximab had no apoptotic effect on both cell lines. Complement-mediated cytotoxicity was only detected in EHEB cells. mRNA and protein expressions of STAT3 and RelA genes were decreased following Rituximab treatment.ConclusionOur preliminary results suggest that the use of Rituximab might be effective in B-ALL though both signaling pathways.

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A Novel Method for Propagating Primary Natural Killer (NK) Cells Allows Highly Efficient Expression of Anti-CD19 Chimeric Receptors and Generation of Powerful Cytotoxicity Against NK-Resistant Acute Lymphoblastic Leukemia Cells.

Blood ◽

10.1182/blood.v104.11.306.306 ◽

2004 ◽

Vol 104 (11) ◽

pp. 306-306

Author(s):

Chihaya Imai ◽

Shotaro Iwamoto ◽

Dario Campana

Keyword(s):

T Cells ◽

Acute Lymphoblastic Leukemia ◽

T Lymphocytes ◽

Nk Cells ◽

Treatment Option ◽

Nk Cell ◽

Lymphoblastic Leukemia ◽

Chimeric Receptors ◽

Membrane Bound

Abstract Despite intensive chemotherapy, acute lymphoblastic leukemia (ALL) recurs in approximately 20% of children and 65% of adults. For most of these patients, allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment option but risk of relapse after transplantation is high. Donor lymphocyte infusions can suppress leukemia relapse but they are generally ineffective in ALL. We and others have shown that T lymphocytes transduced with anti-CD19 chimeric receptors have remarkable anti-ALL capacity in vitro and in vivo, suggesting the clinical testing of receptor-modified autologous T cells in patients with persistent minimal residual disease. However, the use of allogeneic receptor-modified T lymphocytes after HCT might carry the risk of severe graft-versus-host disease (GvHD). In this setting, the use of CD3-negative NK cells is attractive because they should not cause GvHD. Spontaneous cytotoxicity of NK cells against ALL is weak, if measurable at all. To test whether anti-CD19 chimeric receptors could enhance it, we developed a method to specifically expand human primary NK cells and induce high levels of receptor expression. Specific NK cell expansion has been problematic to achieve with established methods, because CD3+ T cells expand preferentially; even with T-cell depletion, residual T cells typically become prominent after stimulation. We overcame this obstacle by generating a genetically-modified K562 myeloid leukemia cell line that expresses membrane-bound interleukin-15 (IL-15) and 4-1BB ligand (CD137L) (K562-mb15-137L). Peripheral blood mononuclear cells from 8 donors were cultured with K562-mb15-137L in the presence of 10 IU/mL IL-2. After 1 week of culture with K562-mb15-137L, CD3- CD56+ NK cells expanded by 16.3 ± 5.9 fold, whereas CD3+ T cells did not expand. The stimulatory effect of K562-mb15-137L was much higher than that of K562 cells transduced with control vectors, K562 expressing membrane-bound IL-15 or CD137L alone, or K562 expressing wild-type IL-15 instead of membrane-bound IL-15. NK cell exposed to K562-mb15-137L were transduced with a retroviral vector and the anti-CD19-BB-ζ receptor, consisting of the single-chain variable domain of an anti-CD19 monoclonal antibody, the hinge and transmembrane domains of CD8α, and the signaling domains of CD3ζ and 4-1BB. 4-1BB mediates signals that are crucial for immune response to tumors in vivo and significantly improves chimeric receptor signaling. In 27 experiments, mean (± SD) transduction efficiency after 7–14 days was 67.5% ± 16.7%. Seven days after transduction, 92.3% (range 84.7%–99.4%) of cells were CD3- CD56+ NK cells; expression of receptors on the cell surface was high. NK cells expressing anti-CD19-BB-ζ had powerful cytotoxicity against NK-resistant B-lineage ALL cell lines and primary ALL cells. NK cells transduced with anti-CD19-BB-ζ had consistently higher cytotoxicity than those transduced with receptors lacking 4-1BB. The method described here allows specific expansion of primary NK cells and highly efficient transduction of chimeric receptors. Expression of anti-CD19-BB-ζ receptors in NK cells markedly enhances their anti-ALL activity. This approach could be a valuable treatment option for patients with refractory or relapsed B-cell malignancies after HCT.

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The Anti-CD20 Monoclonal Antibody GA101 Displays More Robust Anti-Tumor Activity Versus Rituximab In Waldenstrom's Macroglobulinemia (WM)

Blood ◽

10.1182/blood.v116.21.4904.4904 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4904-4904 ◽

Cited By ~ 2

Author(s):

Guang Yang ◽

Christina Hanzis ◽

Sigitas Verselis ◽

Lian Xu ◽

Zachary Hunter ◽

...

Keyword(s):

Monoclonal Antibody ◽

Cell Death ◽

B Cell ◽

Nk Cells ◽

Healthy Donor ◽

B Cell Depletion ◽

Adcc Activity ◽

Direct Cell ◽

Anti Cd20

Abstract Abstract 4904 Background: Rituximab is an IgG class CD20-directed monoclonal antibody used in the treatment of B-cell malignancies, including WM. We and others have previously demonstrated dependence for IgG class therapeutic antibodies on polymorphisms at FcγRIIIA-158. Approximately half of WM patients express V/V or V/F, and the remainder half express F/F at this polymorphic locus. Patients with WM expressing FcγRIIIA-158 V/V or V/F show improved rituximab single agent activity, as well as attainment of deeper responses (VGPR or CR) with combination Rituximab therapy. GA101 is a novel humanized anti-CD20 antibody with a glyco-engineered Fc domain that exhibits increased Fcg receptor binding and ADCC activity. Methods: In this study, we examined the in vitro activity of GA101 and Rituximab against WM cells, and also examined the activity of these antibodies in context of FcγRIIIA-158 polymorphisms. ADCC activity for GA101 and Rituximab was assessed using genotyped healthy donor derived NK cells against BCWM.1 WM cells, as well autologous NK cells against the patient's own lymphoplasmacytic cells. In vitro B-cell depletion and direct cell death induction assays were also performed. Results: We observed significantly greater ADCC activity against WM cells for GA101 versus Rituximab in both healthy donor, as well as autologous NK cell assays. GA101 mediated ADCC activity was particularly more robust versus Rituximab in patients expressing FcγRIIIA-158 F/F versus V/V or V/F (Figure 1). In addition, GA101 induced significant direct cell death against WM lymphoplasmacytic cells, as well as in vitro B-cell depletion assays in comparison to Rituximab, which exhibited little direct cell death induction activity. Nuclear translocation of apoptosis inducing factor (AIF) was observed following GA101 by immunofluorescence microscopy. Conclusions: GA101 is associated with enhanced ADCC activity relative to Rituximab by NK cells, particularly for those subjects expressing FcγRIIIA-158 F/F. In addition, GA101 demonstrated direct cell death in WM lymphoplasmacytic cells through an AIF mediated caspase-independent pathway. These studies provide the framework for the investigation of GA101 in WM, and suggest particular benefit for those patients who express FcγRIIIA-158 F/F. Disclosures: No relevant conflicts of interest to declare.

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In Vitro Effects of PI3Kδ Inhibitor GS-1101 (Cal-101) in Acute Lymphoblastic Leukemia (ALL)

Blood ◽

10.1182/blood.v120.21.3534.3534 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3534-3534 ◽

Cited By ~ 1

Author(s):

Nathalie Y Rosin ◽

Stefan Koehrer ◽

Ekaterina Kim ◽

Susan O'Brien ◽

William G. Wierda ◽

...

Keyword(s):

Cell Cycle ◽

Acute Lymphoblastic Leukemia ◽

Cell Growth ◽

B Cell ◽

Cell Lines ◽

Lymphoblastic Leukemia ◽

Lymphocytic Leukemia ◽

P Value ◽

B Cell Malignancies ◽

Growth Experiments

Abstract Abstract 3534 Acute lymphoblastic leukemia (ALL) is a highly heterogeneous disease. B-cell acute lymphoblastic leukemia (B-ALL) is characterized by uncontrolled proliferation of immature lymphoid blasts with suppression of normal hematopoiesis. Phosphoinositide 3-kinases (PI3K) transmit activation signals from diverse transmembrane receptors, leading to generation of phosphatidylinositol- 3,4,5-trisphosphate (PIP3) which promotes proliferation, differentiation, migration, and survival in lymphocytes and various other cell types. A knockout mouse model of the PI3K isoform p110δ demonstrates a unique role of p110δ (PI3Kδ) in B cell receptor (BCR) signaling. This is corroborated by clinical efficacy of the PI3Kδ inhibitor GS-1101 in mature B cell malignancies, especially in chronic lymphocytic leukemia (CLL). In contrast to mature B cell malignancies, expression and function of PI3Kδ in B-ALL has not been well characterized. We therefore analyzed PI3Kδ expression and effects of the PI3Kδ inhibitor GS-1101 in B-ALL. To screen efficacy of GS-1101 in B-ALL subsets, we performed viability and proliferation assays, using a panel of B-ALL cell lines, derived from different B-cell development stages (Pro-B: REH, RS4;11, Nalm-20, Nalm-21, TOM-1; Pre-B: Nalm-6, Kasumi-2, KOPN-8, SMS-SB, RCH-ACV, 697; Mature: Tanoue, Ball-1 unknown: CCRF-SB). A key downstream effector of PI3K is the serine/threonine kinase Akt, whose phosphorylation is used as a common readout of PI3K activation status. Western Blot analysis of the 15 cell lines showed almost identical levels of phospho-Akt (Ser473) in all tested cell lines, suggesting constitutive PI3K activity. To investigate the ability of GS-1101 to inhibit B-ALL cell proliferation, we performed cell growth experiments. Among the pre-B cell lines 4 of 6 showed a marked decrease in proliferation, 2 other pre-B cell lines showed a minor decrease. In contrast, none of the pro-B or mature B-ALL cell lines were affected by GS-1101. To explore the effects of GS-1101 on cell cycle of B-ALL cells, cell lines were treated with GS-1101 at concentrations ranging from 0.5μM to 5μM. In accordance with the cell growth experiments, G1 phase arrest and reduced numbers of S phase cells were detected in pre-B cell lines after GS-1101 treatment, but not in the pro-B or mature B cell lines. Next, we examined GS-1101 effects on metabolism of B-ALL cells via XTT (sodium 2,3,-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazolium inner salt) staining. Cell lines were treated with GS-1101 concentrations between 0.1μM and 5μM for 3 days prior to XTT measurement. Pre-B cells showed a significant (p-value <0.0001) decrease in normalized absorbance compared to the control (without treatment) indicating a decrease in cellular viability. Finally, preliminary co-culture experiments of primary B-ALL samples and KUSA-H1 bone marrow stromal cells revealed significantly reduced B-ALL cell viability after GS-1101 treatment, signifying that GS-1101 can overcome microenviromental-mediated B-ALL cell protection; this is similar to that in other B cell malignances. In summary, these experiments demonstrate that GS-1101 inhibits growth, cell cycle progression and metabolic activity of pre-B ALL cells. Validation of these data with primary patient samples is ongoing. Disclosures: Lannutti: Gilead Sciences Inc: Employment.

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Obinutuzumab (GA101) Significantly Enhances Cell Death and ADCC Compared to Rituximab Against CD20+ sensitive and Rituximab Resistant B-Cell Non-Hodgkin Lymphoma (NHL) and Lymphoblastic Leukemia (BLL)

Blood ◽

10.1182/blood.v120.21.4865.4865 ◽

2012 ◽

Vol 120 (21) ◽

pp. 4865-4865 ◽

Cited By ~ 1

Author(s):

Aradhana Awasthi Tiwari ◽

Janet Ayello ◽

Carmella van de Ven ◽

Danielle Glassman ◽

Anthony Sabulski ◽

...

Keyword(s):

Cell Death ◽

B Cell ◽

Nk Cells ◽

Cell Lines ◽

Caspase 3 ◽

Conflicts Of Interest ◽

Lymphoblastic Leukemia ◽

Dismal Prognosis

Abstract Abstract 4865 Background: Patients who relapse with CD20+ B-NHL and B cell lymphoblastic leukemia (B-LL) have a dismal prognosis, often associated with chemotherapy resistance (Cairo et al. JCO, 2012,Mils/Cairo et al. BJH,2012) and often require alternative therapeutic strategies. Rituximab (RTX) in combination with FAB 96 chemotherapy is a safe, well-tolerated treatment that is associated with > 90% EFS in children with newly diagnosed and advanced mature B-Cell NHL (Cairo M.S. et al. ASCO, 2010). Resistance to RTX, however, may predispose patients with CD20+ NHL to an increase risk of relapse and or disease progression (Barth/Cairo et al. BJH, 2012; Tsai et al. Cl. Can. Res, 2012). Obinutuzumab (GA101), a novel type II glycoengineered CD20 antibody of the IgG1 isotype, mediates enhanced cell death vs RTX and has a glycoengineered Fc region that induces significantly enhanced ADCC (Mössner et al. Bld, 2010; Niederfellner G. et al. Bld, 2011; Bologna L et al. JI, 2012). Objective: To evaluate the in-vitro efficacy of GA101 compared to RTX against RTX sensitive and resistant CD20+ B-NHL and B-LL cell lines. Methods: Raji (CD20+,ATCC, Manhass, VA), U698-M (CD20+, DSMZ, Germany), Loucy cells (CD20−) (T-ALL) (ATCC, Manhass, VA) and Raji-2R and Raji-4RH (generously supplied by M. Barth, Roswell Park Cancer Institute) were cultured in RPMI with 10% FBS and incubated with GA101 and/or RTX at 100 μg/ml for 24 hrs (n=6), 48 and 72 hrs (n=5). Cell death was evaluated by staining with AnnexinV/7AAD and flow-cytometry. Loucy cells (CD20−) were used as the negative control. The caspase 3/7 activity was measured by FAM caspase 3/7 assay kit by FLICA™ methodology. RSCL, RRCL, U698-M and Loucy were incubated with GA101 and RTX treatment for 24, 48 and 72 hrs, and caspase3/7 activity was detected by FACS using 488 nm excitation and emission filter (n=3). ADCC were performed with K562-IL-15–41BBL expanded NK cells (Ayello/Cairo et al. ASH, 2010) as well as IL-2 expanded NK cells, at 20:1 effector: target ratio (E: T, n=3) using europium release assay (Perkin-Elmer). Results: GA101 induced significantly more cell death compared to RTX in B-NHL and BLL cell lines. (Table-1) GA101 vs RTX shows a significantly increase in caspase 3/7 activity in Raji 16.92±0.84% vs 11.76±0.08% compared to Raji2R 6.7±0.62% vs 2.8±0.7%, Raji4RH 5.8±0.35% vs 2.0±0.3% and U698-M 12.54±0.44% vs 9.6±0.95% compared to Loucy 3.22±0.45% vs 2.59±0.05%, respectively, at 24 hrs of treatment (p<0.0001). GA101 vs RTX also elicited a significant increase a ADCC with K562-IL15–41BBL expanded NK cells, in Raji 73.8±8.1% vs 56.81±4.6% compared to Raji-2R 38.0±2.0% vs 21.6±1.2%, Raji-4RH 40.0±1.6% vs 0.5±1.1% and U698-M 70.0±1.6% vs 45.56±0.1%, compared to Loucy 21.67±0.48% vs 15.92±0.52%, respectively (p<0.001) at day 7.The IL-2 alone expanded Hu-NK cells demonstrated a reduction of 10–20% cytotoxicity compared to K562-IL15–41BBL Hu-NK cells at day 7 against BLL, RSCL and RRCL, in-vitro. Conclusion: Obinutuzumab compared to RTX significantly enhanced cell death, caspase3/7 activity and NK mediated ADCC in sensitive and RTX resistant B-NHL and B-LL. Obinutuzumab represents a promising candidate for treating RTX sensitive and resistant CD20+ B-Cell Lymphomas and lymphoblastic leukemia. Further studies will investigate the combination of activated NK cells or chemotherapy that may enhance or synergize with the efficacy of GA101 (Obinutuzumab) both in -vitro and in-vivo in xenografted NOD/SCID mice. Disclosures: No relevant conflicts of interest to declare.

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