Acquired Hemophilia a Relapse Is Related to Th2 Response, and Increased Expression of B-Cell Activating Factor (BAFF)

Abstract Acquired hemophilia A (AHA) is a rare autoimmune disorder caused by the development of autoantibodies against the factor (F)VIII of coagulation with higher incidence in elderly individuals. The treatment includes immunosuppressive alternatives, and the majority of patients reach complete remission of symptoms. Although the role of immune T and B cells in the physiopathology of several autoimmune diseases is widely established, few studies have explored the T and B cells immune response pathway in AHA. This study aimed to determine the role of T cells through their cytokines expression and B cells through their expression of proteins that activate the B cell receptor (BCR), such as B-cell activating factor (BAFF) and A-proliferation inducing ligand (APRIL), in a longitudinal evaluation of patients with AHA. We included in this study 11 patients, 4 (36%) male, with the diagnosis of AHA, based on the occurrence of low FVIII levels (median FVIII level at the diagnosis was 0.10 IU/dL; range 0-18.8) and anti-FVIII inhibitor titer positive (≥0.6 Bethesda units (BU)/mL) (median inhibitor titer at the diagnosis was 60BU/mL; range 7.6-1000.2). The median age at the diagnosis was 59 years (range 9-75). Idiopathic AHA was evident in 72.7% of cases, while autoimmune diseases (18.2%), and pregnancy (9.1%) were the other underlying etiologies. All patients received immunosuppressive therapy (IST). Eight (72.7%) patients used corticosteroid (CS) plus cyclophosphamide (CP), one (9.1%) received only CP, one (9.1%) used CS plus rituximab and one (9.1%) received CS, CP and three cycles of rituximab. The response to IST was defined as complete remission (CR) with anti-FVIII < 0.6BU/mL and FVIII >50IU/dL, without further IST. Relapse was defined when anti-FVIII titer became >0.6BU/mL after previous remission. In this cohort, we observed 64% of sustained CR and 4(36%) AHA patients had at least one relapse, including two AHA patients considered idiopathic and two with other autoimmune diseases associated. Peripheral blood mononuclear cells (PBMC) were collected from all AHA patients at the diagnosis previously IST (baseline), when patient achieved CR, and at the occurrence of relapse. PBMCs were maintaining frozen in liquid nitrogen. Cells were taw and cultivated with RMPI-1640 medium in 7.5x10 5 cells/well in a 48-well plate. After 24h, cells were stimulated with a 1IU/well of a full-length recombinant FVIII concentrate (rFVIII) or phorbol myristate acetate (PMA) (1µM) with ionomycin (1µM). After 24h incubation, cells were analyzed by flow cytometry at BD FACSCalibur™. To determine T CD4 + cells' cytokine production profile, we stained T cells with anti-CD4, anti-interleukins (IL)-17a, IL-4, and IL-21, anti-TGF-b, and anti-TNF-a. We observed a significant increase of IL-17a production in the rFVIII-stimulated cells isolated at baseline from all patients compared to cells isolated from healthy individuals (P=0.01). However, IL-17a expression at baseline was not different between cells from patients who sustained CR to those who relapsed. Interestingly, when we compared cells isolated at baseline from patients that relapsed after different immunosuppressive attempts, we observed a significant difference for IL-4 (P=0.009), IL-21 (P=0.02), and TGF-b (P=0.01) expression in comparison to cells from healthy individuals. However, this difference was not observed in cells from sustained CR vs. cells from healthy individuals (figure 1). Thus, suggesting that all patients present Th17 response, while only patients that relapsed also showed Th2 response at the diagnosis. We also evaluated B cells' expression of BAFF and APRIL. The cells were stained with anti-CD19, BAFF, and APRIL. Only cells isolated at baseline from AHA relapsed patients after rFVIII stimulation or without any stimuli presented increased expression of BAFF (P=0.01 with rFVIII-stimulated and P=0.007 for unstimulated cells) when compared to PBMCs isolated from healthy individuals (figure 1). BAFF is responsible for controlling B-cell maturation and is associated with autoantibody production of different autoimmune conditions. Our finds reveal an increase in the Th17 response in patients with AHA at the diagnosis. However, the presence of Th2 response and increase of BAFF expression was observed only at the diagnosis of patients with recurrence of autoimmune response to FVIII, which suggests a potential biomarker for AHA evaluation. Figure 1 Figure 1. Disclosures Ozelo: BioMarin: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shire: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer: Speakers Bureau; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Grifols: Other: Grant review.

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Impact of Interim FDG-PET (iPET) in the Outcomes of Patients with Aggressive B-Cell Lymphomas Receiving DA-EPOCH-R

Blood ◽

10.1182/blood-2019-122393 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2898-2898

Author(s):

Vania Phuoc ◽

Leidy Isenalumhe ◽

Hayder Saeed ◽

Celeste Bello ◽

Bijal Shah ◽

...

Keyword(s):

B Cell ◽

Board Of Directors ◽

Fdg Pet ◽

Research Funding ◽

Cell Lymphoma ◽

B Cell Lymphoma ◽

Advisory Committees ◽

End Of Treatment

Introduction: 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) remains the standard of care for baseline and end of treatment scans for aggressive non-Hodgkin lymphomas (NHLs). However, the role of interim FDG-PET remains not as well defined across aggressive NHLs, especially in the era of high-intensity chemoimmunotherapy. Interim FDG-PET (iPET) can serve as an early prognostic tool, and prior studies evaluating the utility of iPET-guided treatment strategies primarily focused on diffuse large B-cell lymphomas (DLBCL) and frontline R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Classification criteria systems assessing response also differ between studies with no clear consensus between use of Deauville criteria (DC), International Harmonization Project (IHP), and the ΔSUVmax method. Methods: This study evaluates our institutional experience with iPET during treatment with DA-EPOCH ± R (dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin with or without Rituximab) in aggressive NHLs. We retrospectively evaluated 70 patients at Moffitt Cancer Center who started on DA-EPOCH ± R between 1/1/2014 to 12/31/2018 for aggressive NHLs. Response on interim and end-of-treatment (EOT) scans were graded per DC, IHP, and ΔSUVmax methods, and progression free survival (PFS) probability estimates were calculated with chi-square testing and Kaplan Meier method. PFS outcomes were compared between interim negative and positive scans based on each scoring method. Outcomes were also compared between groups based on interim versus EOT positive or negative scans. Results: We identified 70 patients with aggressive NHLs who received DA-EPOCH ± R at our institute. The most common diagnoses were DLBCL (61%) followed by Burkitt's lymphoma (10%), primary mediastinal B-cell lymphoma (9%), plasmablastic lymphoma (7%), gray zone lymphoma (6%), primary cutaneous large B-cell lymphoma (1%), primary effusion lymphoma (1%), and other high-grade NHL not otherwise specified (3%). Of the 43 patients with DLBCL, 21/43 (49%) had double hit lymphoma (DHL) while 7/43 (16%) had triple hit lymphoma (THL), and 3/43 (7%) had MYC-rearranged DLBCL while 2/43 (5%) had double expressor DLBCL. Thirty nine out of 70 (56%) were female, and median age at diagnosis was 58.39 years (range 22.99 - 86.86 years). Most patients had stage IV disease (49/70, 70%), and 43/70 (61%) had more than one extranodal site while 45/70 (64%) had IPI score ≥ 3. Forty-six out of 70 (66%) received central nervous system prophylaxis, most with intrathecal chemotherapy (44/70, 63%). Fifty-five out of 70 (79%) had iPET available while 6/70 (9%) had interim computerized tomography (CT) scans. Fifty-six out of 70 (80%) had EOT PET, and 4/70 (6%) had EOT CT scans. Sustained complete remission occurred in 46/70 (66%) after frontline DA-EPOCH ± R (CR1), and 12/70 (17%) were primary refractory while 5/70 (7%) had relapse after CR1. Four of 70 (6%) died before cycle 3, and 3/70 (4%) did not have long-term follow-up due to transition of care elsewhere. Median follow-up was 15.29 months (range 0.85 - 60.09 months). There was significantly better PFS observed if iPET showed DC 1-3 compared to DC 4-5 (Χ2=5.707, p=0.0169), and PFS was better if iPET was negative by IHP criteria (Χ2=4.254, p=0.0392) or ΔSUVmax method (Χ2=6.411, p=0.0113). Comparing iPET to EOT PET, there was significantly better PFS if iPET was negative with EOT PET negative (iPET-/EOT-) compared to iPET positive with EOT negative (iPET+/EOT-), and iPET+/EOT+ and iPET-/EOT+ had worse PFS after iPET-/EOT- and iPET+/EOT- respectively. This pattern in iPET/EOT PFS probability remained consistent when comparing DC (Χ2=30.041, p<0.0001), IHP (Χ2=49.078, p<0.0001), and ΔSUVmax method (Χ2=9.126, p=0.0104). These findings fit clinical expectations with positive EOT scans indicating primary refractory disease. There was no significant difference in PFS when comparing DLBCL versus non-DLBCL (Χ2=3.461, p=0.0628) or DHL/THL versus non-DHL/THL diagnoses (Χ2=2.850, p=0.0914). Conclusion: Our findings indicate a prognostic role of iPET during treatment with DA-EPOCH ± R for aggressive NHLs. Significant differences in PFS were seen when graded by DC, IHP, and ΔSUVmax methods used in prior studies and when comparing interim versus EOT response. Larger studies are needed to confirm these findings. Disclosures Bello: Celgene: Speakers Bureau. Shah:Novartis: Honoraria; AstraZeneca: Honoraria; Spectrum/Astrotech: Honoraria; Adaptive Biotechnologies: Honoraria; Pharmacyclics: Honoraria; Jazz Pharmaceuticals: Research Funding; Incyte: Research Funding; Kite/Gilead: Honoraria; Celgene/Juno: Honoraria. Sokol:EUSA: Consultancy. Chavez:Janssen Pharmaceuticals, Inc.: Speakers Bureau; Genentech: Speakers Bureau; Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

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Waldenström's Macroglobulinemia (WM) Is Preceded By Clonal Lymphopoiesis Including MYD88 L265P in Progenitor B Cells

Blood ◽

10.1182/blood-2019-126889 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1527-1527

Author(s):

Sara Rodríguez ◽

Cirino Botta ◽

Jon Celay ◽

Ibai Goicoechea ◽

Maria J Garcia-Barchino ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Somatic Mutations ◽

Advisory Committees ◽

Normal Cells ◽

Cell Clones ◽

B Cell Precursors ◽

Myd88 L265p

Background: Although MYD88 L265P is highly frequent in WM, by itself is insufficient to explain disease progression since most cases with IgM MGUS also have mutated MYD88. In fact, the percentage of MYD88 L265P in CD19+ cells isolated from WM patients is typically <100%, which questions if this mutation initiates the formation of B-cell clones. Furthermore, a few WM patients have detectable MYD88 L265P in total bone marrow (BM) cells and not in CD19+ selected B cells, raising the possibility that other hematopoietic cells carry the MYD88 mutation. However, no one has investigated if the pathogenesis of WM is related to somatic mutations occurring at the hematopoietic stem cell level, similarly to what has been shown in CLL or hairy cell leukemia. Aim: Define the cellular origin of WM by comparing the genetic landscape of WM cells to that of CD34 progenitors, B cell precursors and residual normal B cells. Methods: We used multidimensional FACSorting to isolate a total of 43 cell subsets from BM aspirates of 8 WM patients: CD34+ progenitors, B cell precursors, residual normal B cells (if detectable), WM B cells, plasma cells (PCs) and T cells (germline control). Whole-exome sequencing (WES, mean depth 74x) was performed with the 10XGenomics Exome Solution for low DNA-input due to very low numbers of some cell types. We also performed single-cell RNA and B-cell receptor sequencing (scRNA/BCRseq) in total BM B cells and PCs (n=32,720) from 3 IgM MGUS and 2 WM patients. Accordingly, the clonotypic BCR detected in WM cells was unbiasedly investigated in all B cell maturation stages defined according to their molecular phenotype. In parallel, MYD88p.L252P (orthologous position of the human L265P mutation) transgenic mice were crossed with conditional Sca1Cre, Mb1Cre, and Cγ1Cre mice to selectively induce in vivo expression of MYD88 mutation in CD34 progenitors, B cell precursors and germinal center B cells, respectively. Upon immunization, mice from each cohort were necropsied at 5, 10 and 15 months of age and screened for the presence of hematological disease. Results: All 8 WM patients showed MYD88 L265P and 3 had mutated CXCR4. Notably, we found MYD88 L265P in B cell precursors from 1/8 cases and in residual normal B cells from 3/8 patients, which were confirmed by ASO-PCR. In addition, CXCR4 was simultaneously mutated in B cell precursors and WM B cells from one patient. Overall, CD34+ progenitors, B-cell precursors and residual normal B cells shared a median of 1 (range, 0-4; mean VAF, 0.16), 2 (range, 1-5; mean VAF, 0.14), and 4 (range, 1-13; mean VAF, 0.26) non-synonymous mutations with WM B cells. Some mutations were found all the way from CD34+ progenitors to WM B cells and PCs. Interestingly, concordance between the mutational landscape of WM B cells and PCs was <100% (median of 85%, range: 25%-100%), suggesting that not all WB B cells differentiate into PCs. A median of 7 (range, 2-19; mean VAF, 0.39) mutations were unique to WM B cells. Accordingly, many clonal mutations in WM B cells were undetectable in normal cells. Thus, the few somatic mutations observed in patients' lymphopoiesis could not result from contamination during FACSorting since in such cases, all clonal mutations would be detectable in normal cells. Of note, while somatic mutations were systematically detected in normal cells from all patients, no copy number alterations (CNA) present in WM cells were detectable in normal cells. scRNA/BCRseq unveiled that clonotypic cells were confined mostly within mature B cell and PC clusters in IgM MGUS, whereas a fraction of clonotypic cells from WM patients showed a transcriptional profile overlapping with that of B cell precursors. In mice, induced expression of mutated MYD88 led to a moderate increase in the number of B220+CD138+ plasmablasts and B220-CD138+ PCs in lymphoid tissues and BM, but no signs of clonality or hematological disease. Interestingly, such increment was more evident in mice with activation of mutated MYD88 in CD34+ progenitors and B-cell precursors vs mice with MYD88 L252P induced in germinal center B cells. Conclusions: We show for the first time that WM patients have somatic mutations, including MYD88 L265P and in CXCR4, at the B cell progenitor level. Taken together, this study suggests that in some patients, WM could develop from B cell clones carrying MYD88 L265P rather than it being the initiating event, and that other mutations or CNA are required for the expansion of B cells and PCs with the WM phenotype. Disclosures Roccaro: Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Transcan2-ERANET: Research Funding; AstraZeneca: Research Funding; European Hematology Association: Research Funding; Transcan2-ERANET: Research Funding; Associazione Italiana per al Ricerca sul Cancro (AIRC): Research Funding; Associazione Italiana per al Ricerca sul Cancro (AIRC): Research Funding; European Hematology Association: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Paiva:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau.

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Chromosomal Translocation t(11;14) Induced By the Cre-Loxp System in Normal B Cell-Derived Ips Cells for the Study of Myeloma-Initiating Cells

Blood ◽

10.1182/blood-2020-134572 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 18-19

Author(s):

Misaki Sugai ◽

Naohiro Tsuyama ◽

Yu Abe ◽

Yusuke Azami ◽

Kenichi Kudo ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Board Of Directors ◽

B Lymphocytes ◽

Research Funding ◽

Chromosomal Translocation ◽

Stem Cell Differentiation ◽

Advisory Committees ◽

Myeloma Cells ◽

Company Limited

The cellular origin of multiple myeloma (MM) has not yet been identified. Based on immunoglobulin heavy chain (IgH) gene analysis, myeloma cells are derived from mature B cells. Chromosomal aberrations such as trisomy and chromosomal translocation (cTr) play a critical role in the early tumorigenesis of MM. We hypothesized that the abnormal cells from which myeloma cells originate might be mature B lymphocytes with chromosomal or genetic changes in the reprogrammed state that enable them to acquire the potential to become tumors in the process of redifferentiation into B lymphocytes. We established induced pluripotent stem cells (iPSs) from normal B lymphocytes (BiPSCs: BiPSC13 & MIB2-6); these BiPSCs have the same VDJ rearrangement of IgH as the original B lymphocytes and differentiate into CD34+/CD38- hematopoietic progenitor cells co-culture with stromal cells, AGM-S3 (Sci Rep, 2017). We then established a method to induce reciprocal cTr t(11;14), which is a reciprocal cTr between IgH and CCND1 and the most frequent cTr in MM, using the CRISPR/Cas9 system; cTr was induced by infection of IgH-CCND1 lentiCRISPRv2 lentivirus, which targets the human IgH Eµ region and 13kb upstream of the CCND1 coding sequence, to BiPSCs (Oncol Lett, 2019). Subsequently, we established cell lines carrying reciprocal cTr t(11;14) between CCND1 and either an allele in which VDJ rearrangement of IgH had been completed or an allele in which VDJ rearrangement had not been completed (stopped at DJ joining) in BiPSC13 t(11;14) (AZ & AX) and MIB2-6 t(11;14) (BC & BG), respectively. These BiPSCs differentiated into CD34+/CD38-/CD45+/-/CD43+/- hematopoietic progenitors cells in co-culture with AGM-S3 or in stem cell differentiation medium; this was subsequently confirmed by the differentiation into granulocytes, macrophages, and erythroblasts in a colony-formation assay. We are now trying to produce BiPSCs in which cTr t(11;14) is induced when they differentiate into mature B cells expressing CD27. First, we used the Cre-loxP recombination system to induce cTr t(11;14) in BiPSCs. BiPSCs were transfected with IgH loxP-Neo-loxP knock-in vector and IgH lentiCRISPRv2 vector. Subsequently, G418-resistant BiPSCs carrying loxP-Neo-loxP in IgH were transfected with iCre-EGFP. After removing the loxP-Neo site from EGFP-positive cells, BiPSCs carrying IgH-loxP were transfected with CCND1 loxP-FRT3-Neo-FRT3 knock-in vector and CCND1 lentiCRISPRv2 vector. Subsequently, G418-resistant BiPSCs carrying IgH-loxP in IgH and loxP-FRT3-Neo-FRT3 in CCND1 were transfected with Flpo-EGFP. After removing the FRT3-Neo site from EGFP-positive cells, BiPSCs carrying IgH-loxP in IgH and CCND1-loxP-FRT3 in CCND1 were transfected with iCre-HygR. Hygromycin B-resistant cells were picked, the reciprocal cTr t(11;14) was confirmed by polymerase chain reaction, and we established BiPSCs with der(11)t(11;14) and BiPSCs with der(14)t(11;14). We also developed a system in which Cre is expressed along with CD27 expression in the B cell lymphoma cell line Raji. These BiPSCs could be useful for the study of myeloma-initiating cells, but whether they would be able to be redifferentiated into B lymphocyte is important. Disclosures Hanamura: Mundipharma K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi K.K.: Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; SHIONOGI Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis Pharma K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; DAIICHI SANKYO COMPANY, LIMITED: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eisai Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; NIPPON SHINYAKU CO.,LTD.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer Japan Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda Pharmaceutical Company Limited: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen Pharmaceutical K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Ono Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

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The Influence Of KIR Haplotype In ITP Incidence, Treatment Response and Bleeding Symptoms

Blood ◽

10.1182/blood.v122.21.2316.2316 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2316-2316

Author(s):

Bethan Psaila ◽

Nayla Boulad ◽

Emily Leven ◽

Naznin Haq ◽

Christina Soo Lee ◽

...

Keyword(s):

Platelet Count ◽

B Cells ◽

Nk Cells ◽

Board Of Directors ◽

Research Funding ◽

Nk Cell ◽

Advisory Committees ◽

Kir Genes ◽

Number Of Patients

Abstract The pathogenesis of immune thrombocytopenia (ITP) is multifactorial, with both cellular and humoural immune dysfunction. The role of NK cells has not been well defined in ITP but in other diseases NK cells have a role in rejecting “foreign” eg transplanted organ or tumor, and also acting against self as occurs in autoimmunity. NK cell activity is orchestrated by the balance of activating vs. inhibitory signalling, in particular via the killer cell immunoglobulin-like receptor (KIR) family of receptors. Significant variation exists in KIR allelic subtype and copy number for the KIR between individuals, and associations have been made with certain haplotypes and a number of autoimmune disorders including rheumatoid arthritis, scleroderma and diabetes. Previous reports have demonstrated a reduction in natural killer (NK) cell number and function in ITP and expression of inhibitory KIR genes is increased in patients in remission vs. active ITP. Methods To explore whether a particular KIR haplotype might predispose to ITP, and also affect response to ITP treatment, we performed KIR genotyping using the Invitrogen SSP kit on 92 patients attending a haematology centre in New York and compared the results to data from 213 controls taken from the USA Eastern Database. Genomic DNA was typed for the inhibitory KIR genes KIR2DL1, KIR2DL2, KIR2DL5A (alleles 001 and 002), KIR2DL5B (alleles 002-004, 06, and 007), KIR3DL1, KIR3DL3; the activating KIR genes KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, KIR3DS1; the framework genes KIR2DL3, KIR2DL4, KIR3DL2, KIR3DP1; and the pseudogene KIR2DP1. The patients with ITP had been or were receiving treatment with IVIG (n=64), corticosteroids (72) and rituximab (37). Bleeding symptoms were recorded. Response to treatment was defined as complete - platelet count increase to > 100 x 109/mL; partial - platelet count increase to > 50 x 109/mL; or no response. For the purpose of analysis, PRs and CRs were combined. A comprehensive database allowed a logistic regression, assessing both responses to treatments, platelet counts, neutrophil counts, CRP, lymphocyte subsets and bleeding symptoms. Results The expression of two inhibitory KIR genes, 2DL1 and 3DL1, was significantly lower in the patients with ITP as compared to controls (87% 2DL1 and 87% 3DL1 compared to 99% in controls - P < 0.02). Response to rituximab was strongly related to KIR haplotype expression. 2DL1 expression was higher among nonresponders to Rituximab (100% of non responders compared to 82% of responders), whereas 2DL3 expression was significantly lower (79% compared to 90%) (P < 0.05, Figure 1B). Separately, patients with the 2DS3 allele, an activatory KIR, were 5.5 times more likely to have experienced significant bleeding. Conclusions Although these findings are preliminary and require further investigation, these data suggest that increased cytotoxic autoimmunity due to reduced KIR inhibition may be associated with the development of ITP and possibly contribute importantly to the pathogenesis. Anti-CD20 targeting therapy directed at B cells was strongly influenced by 2 different KIRs (1 upregulated and one down-regulated) emphasizing the potential role of NK cells in elimination of tissue-based (nodal) B cells. Finally a more pronounced clinical phenotype with a markedly higher incidence of severe bleeding associated with an increased activatory KIR expression demonstrates the role of NK cells in bleeding presumably via their effects on either endothelial cells or platelet function. These exciting findings will be pursued for confirmation in a larger number of patients. Disclosures: Bussel: Amgen: Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Genzyme: Research Funding; GlaxoSmithKline: Family owns stock, Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; IgG of America: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity’s Board of Directors or advisory committees.

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Phase I/Ib Study of the Novel Immunotoxin MT-3724 in Relapsed/Refractory Non-Hodgkin's B-Cell Lymphoma (NHL)

Blood ◽

10.1182/blood.v126.23.5112.5112 ◽

2015 ◽

Vol 126 (23) ◽

pp. 5112-5112

Author(s):

Paul A Hamlin ◽

Catherine S. Diefenbach ◽

David J. Valacer ◽

Jack Higgins ◽

Michelle A. Fanale

Keyword(s):

B Cells ◽

Phase I ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

B Cell Lymphoma ◽

Advisory Committees ◽

Dose Cohort ◽

Mixed Response

Abstract Background CD20 is selectively expressed on the surface of early pre-B-cells, remains throughout B-cell development, and is then lost from plasma cells. Because CD20 is present on the majority of B-cell lymphomas, anti-CD20 monoclonal antibody (MAb) therapy is widely employed in the treatment of NHL. However a majority of NHL patients eventually become refractory to CD20 MAb(s). Resistance mechanisms may include increased MAb catabolism, initial or post treatment selection of low CD20 expressing tumor cells, trogocytosis of surface CD20, failure of MAb effector mechanisms and/or impaired patient immune cell function. MT-3724 is a recombinant fusion protein consisting of a CD20 binding variable fragment (scFv) fused to the enzymatically active Shiga-like toxin-I A1 subunit (SLT-I A1). SLT-I A1 is an N-glycosidase that catalytically inactivates 60S ribosomal subunits causing inhibition of protein synthesis. Upon its scFv binding to cell surface CD20 in vitro, SLT-I A1 forces MT-3724 internalization which then routes in a predictable fashion to the cytosol and irreversibly inactivates the cell ribosomes triggering cell death. MT-3724 has been shown to specifically bind and kill CD20+ malignant human B-cells in vitro and non-human primate (NHP) B-cells in vivo. MT-3724 was tested for safety in healthy NHPs: 6 intravenous (IV) doses of MT-3724 were given over 12 days at doses of 50, 150, and 450 mcg/kg. There were no deaths or effects on serum chemistries in the NHP studies. The major observed toxicity (inappetence) resolved within 48 hours of last dose. There was a significant, dose-dependent NHP B-cell depletion by Day 3 at all doses. Given the preclinical activity and mechanism of action, a Phase I/Ib study of MT-3724 was initiated in NHL. Methods MT-3724 is being tested for safety and tolerability in a first-in-human, open label, ascending dose study (3 + 3 design) in sequential cohorts of 5, 10, 20 and 50 mcg/kg/dose. Eligible subjects who previously responded to a CD20 MAb containing therapy followed by relapse/recurrence of NHL receive 6 doses by 2 hour IV infusions over the first 12 days of a 28 day cycle (first cycle). With continued safety, tolerability and lack of tumor progression, subjects may receive up to 4 additional 6-dose cycles (21 days) with tumor assessments after cycles 2, 4 and 5. Dose escalation is based on < 33% dose limiting toxicities (DLTs) observed during the first 28 day cycle. Results Three NHL subjects (2 transformed DLBCL, 1 FL) have completed at least one cycle in the 5 mcg/kg/dose cohort with no protocol DLTs or infusion related reactions and are evaluable for safety. Non-DLTs included grade (Gr) 2-3 transient hyperglycemic episodes related to pre-infusion corticosteroid therapy (n=1); transient Gr 4 neutropenia, possibly related to MT-3724 during cycle 1, week 4 (n=1); Gr 4 hypercalcemia and acute kidney injury with Gr 3 hypophosphatemia during cycle 1, week 4 due to leukemic disease progression (n=1). Subject 1 completed 5 cycles of therapy, with a partial response achieved post cycle 2 sustained through cycle 5; Subject 3 had a mixed response (both subjects had transformed DLBCL). Three subjects have now initiated treatment in the 10 mcg/kg/dose cohort with updated data to be presented at the meeting. Conclusions MT-3724 at 5 mcg/kg/dose has been safely administered for up to 5 cycles in this first-in-human study in relapsed/refractory NHL subjects. Treatment with the 10 mcg/kg cohort has commenced with continuing dose ascension planned. There is early evidence of clinical activity. Disclosures Diefenbach: Gilead: Equity Ownership, Research Funding, Speakers Bureau; Jannsen Oncology: Consultancy; Idera: Consultancy; Immunogen: Consultancy; Incyte: Research Funding; Genentech: Research Funding; Celgene: Consultancy; Molecular Templates: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Valacer:Molecular Templates: Employment. Higgins:Molecular Templates: Employment. Fanale:Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Research Funding; Infinity: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Research Funding; Genentech: Research Funding; Medimmune: Research Funding; Novartis: Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Molecular Templates: Research Funding; ADC Therapeutics: Research Funding; Onyx: Research Funding; Gilead: Research Funding.

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Modeling of the Epigenome of the Cell-of-Origin Identifies Cancer-Specific DNA Methylation Patterns in CLL

Blood ◽

10.1182/blood-2018-99-115941 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3885-3885

Author(s):

Justyna Anna Wierzbinska ◽

Reka Toth ◽

Naveed Ishaque ◽

Jan-Phillip Mallm ◽

Karsten Rippe ◽

...

Keyword(s):

Dna Methylation ◽

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

B Cell Differentiation ◽

Advisory Committees ◽

Normal Differentiation ◽

Methylation Patterns

Abstract Normal B cells undergo extensive epigenetic programming during normal differentiation and distinct B cell differentiation stages represent unique DNA methylation patterns. Chronic Lymphocytic Leukemia (CLL) originates from rapidly differentiating B cells and their DNA methylation signature is stably propagated in CLL. Consequently, CLL methylome data can be used to infer the putative cell-of-origin (COO) for each individual CLL case. We define the COO of CLL as the cell that has acquired a first oncogenic hit and which will initiate tumorigenic growth if one or more additional hits have been acquired. This means that two factors contribute to the epigenetic profile of CLL cells: first, the epigenetic profile of the founder B cell at the time of malignant transformation and second, CLL-specific epigenetic alterations that are acquired during leukemogenesis and progression of the disease. Previous studies using peripheral blood CD19+ B cells as a reference for aberrant methylation calls completely neglected the massive epigenetic programming that occurs during normal B cell differentiation. Thus, novel strategies aiming at identifying truly CLL-specific methylation changes considering the highly dynamic methylome during normal B cell differentiation were urgently needed. Here we outline a new analytical framework to delineate CLL-specific DNA methylation. We demonstrate how this approach can be applied to detect epigenetically deregulated transcripts in CLL. Firstly, we modeled the epigenome dynamics occurring during normal B cell differentiation using linear regression. The DNA methylomes of CLL cells were then precisely positioned onto the normal B cell differentiation trajectory to define the closest normal B cell methylome for every CLL patient, the COO. The epigenome of the COO then served as a reference for aberrant DNA methylation calls. We dissected two categories of CLL-specific methylation events: those occurring at sites undergoing epigenetic programming during B cell differentiation and those that normally do not change during B cell differentiation. The first group was further subdivided into class A and B, displaying exaggerated methylation loss or gain, respectively, and class C showing both hyper- and hypomethylation relative to the normal differentiation. The second group was classified into class D displaying hypo- and class E showing hypermethylation. Overall, only 1.6% of the CpG-sites (7,248 CpGs) represented on the Illumina 450k array were affected by disease-specific methylation programming, mostly hypomethylation (6,680 CpGs). Next, the molecular programs underlying the CLL-specific methylation patterns were investigated. We tested enrichment of chromatin states and of transcription factor binding sites (TFBS) as identified in an immortalized B cell line (GM12878). This indicated that disease-specific methylation events target transcriptionally relevant cis-regulatory elements in CLL (enhancers, weak and poised promoters and insulator regions). In line with this, CLL-specific differentially methylated regions affected TFBS associated with signaling pathways known to be important in normal B-cell differentiation (i.e. BATF, EBF1). We also observed altered methylation at CTCF binding sites suggesting their involvement in CLL pathogenesis. In the present work, we dissected CLL methylomes to distinguish between normal B cell differentiation-associated methylation patterns and CLL-specific methylation events. We showed that this approach is indispensable to identify key pathogenic events driving CLL pathogenesis. The relevance of our approach was demonstrated by contrasting the number of epigenetically deregulated miRNAs and protein-coding genes to those determined with a classic analysis using CD19+ B cells as controls. This highlights the extent of overcalling of CLL-specific methylation patterns in previous studies (~30-fold for protein-coding genes and ~10-fold for miRNAs) and stresses the importance to consider normal differentiation trajectories for the identification of aberrant DNA methylation events. Here we propose 11 protein-coding genes (e.g. DOK2, CLLU1) and 4 miRNAs (e.g. miR-486, miR-195) as being epigenetically deregulated in CLL. Our analytical approach provides a general framework for the identification of disease-specific epigenomic changes that should be applicable to other cancers in the future. Disclosures Küppers: the Takeda Advisory Board: Membership on an entity's Board of Directors or advisory committees. Stilgenbauer:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genzyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer-Ingelheim: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmcyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Hoffmann La-Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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The Tigit/CD226/CD155 Immunomodulatory Axis Is Deregulated in CLL and Contributes to B-Cell Anergy

Blood ◽

10.1182/blood-2021-150183 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3718-3718

Author(s):

Francesca Arruga ◽

Andrea Iannello ◽

Nikolaos Ioannou ◽

Alberto Maria Todesco ◽

Marta Coscia ◽

...

Keyword(s):

T Cell ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Cell Receptor ◽

Tcr Signaling ◽

Advisory Committees ◽

Cell Responses ◽

Blocking Antibodies

Abstract BACKGROUND. T cell immunoreceptor with Ig and ITIM domains (TIGIT) is an inhibitory receptor expressed on T, NK and NKT cells, sharing structural and mechanistic similarities with PD-1 and CTLA-4. TIGIT competes with CD226, its partner receptor, for the binding to CD155 ligand: signaling triggered upon CD155 binding to CD226 potentiates T cell receptor (TCR) signaling and CD8 + T cell cytotoxicity against tumor cells (positive signaling). On the contrary, concomitant TIGIT expression on the cell surface prevents CD226 activation either by sequestering CD155 or by impeding CD226 homodimerization and phosphorylation (negative signaling). Recently, TIGIT was shown to be expressed on the surface of normal memory B cells, where it could directly act to suppress T cell responses. No data are available on TIGIT or CD226 expression by chronic lymphocytic leukemia (CLL) cells. AIM AND METHODS. Our aim was to investigate expression of the TIGIT and CD226 receptors and of the CD155 ligand in a cohort of clinically and molecularly annotated CLL patient samples. To this end, we designed a multiparametric panel of antibodies for flow cytometry and examined expression of the TIGIT/CD226/CD155 axis in peripheral blood mononuclear cells (PBMC) from our patient cohort. To investigate the impact of TIGIT/CD226 engagement on B cell responses, purified leukemic B cells were activated either through the B cell receptor (BCR) using an αIgM polyclonal antibody or with CpG oligonucleotide and interleukin 15 (IL-15) to induce proliferation. In selected experiments, we added recombinant human (Rh) TIGIT-Fc or CD155-Fc chimeras and αTIGIT or αCD226 blocking antibodies to interfere with this axis. RESULTS. Surface expression of TIGIT, CD226 and CD155 was evaluated in a cohort of 115 CLL samples and compared to age- and sex-matched healthy subjects. Both TIGIT and CD226 were upregulated on leukemic B cells compared to normal B lymphocytes, while CD155 was expressed at lower levels. A similar trend was observed on CD4 + and CD8 + T lymphocytes. High-risk CLLs (unmutated IgV genes, unfavorable cytogenetics and advanced stage) were predominantly TIGIT low and CD226 high, indicating an unbalance towards "positive signaling". Results were confirmed by confocal microscopy analyses on lymph node (LN) biopsies, which showed i) an overall higher TIGIT expression in CLL compared to reactive LNs and ii) among CLL LNs a stronger TIGIT positivity in mutated vs unmutated cases, confirming flow cytometry data. In line with these findings, Richter's syndrome samples and patient-derived xenografts models showed the lowest TIGIT and the highest CD226 levels. We next examined TIGIT axis expression during the follow up of CLL cases who underwent treatment with BTK inhibitor (BTKi). While CD226 levels remained unmodified upon treatment, a sharp decrease in surface TIGIT was detected soon after BTKi initiation. Since TIGIT acts by decreasing TCR signaling to shut down T cell responses, we hypothesized similar functions in B cells. By crosslinking the BCR with an αIgM antibody in a selected cohort of IGHV UM CLL cells, we found that BTK phosphorylation was induced to a lesser extent in TIGIT high compared to TIGIT low samples, suggesting that TIGIT is a marker of CLL cell anergy. Accordingly, interruption of receptors/ligand interactions with RhTIGIT-Fc chimera or with αTIGIT or αCD226 blocking antibodies, modulated BCR signaling capacity. Specifically, in TIGIT high samples, preventing receptor engagement by CD155 increased αIgM-induced BTK phosphorylation; in contrast, in TIGIT low samples, blocking CD155 interaction affected mostly CD226 signaling, thereby depotentiating BCR activation. Similar results were obtained when stimulating CLL cells with CpG/IL-15. Interestingly, we observed a significant upregulation of surface CD226 in CLL cells cultured for 6 days in the presence of CpG/IL-15. CONCLUSIONS. These results show for the first-time expression of TIGIT by CLL cells. Furthermore, they indicate that TIGIT is a marker of CLL cells anergy, whereas activated CLL cells express high levels of CD226. Inhibition of TIGIT binding to CD155 partially restores B cell signaling and activation. Future studies are needed to gain insights on the mechanisms behind its deregulation and to obtain a complete functional characterization of the axis. Disclosures Coscia: AbbVie: Honoraria, Other; Janssen: Honoraria, Other, Research Funding; AstraZeneca: Honoraria; Gilead: Honoraria. Gaidano: Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astrazeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Allan: Genentech: Consultancy, Research Funding; Epizyme: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; BeiGene: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Celegene: Research Funding; AstraZeneca Pharmaceuticals LP, Genentech, a member of the Roche Group, Janssen Biotech Inc, TG Therapeutics Inc.: Research Funding; AbbVie Inc, AstraZeneca Pharmaceuticals LP, BeiGene, Janssen Biotech Inc, Pharmacyclics LLC: Consultancy; AbbVie Inc, Ascentage Pharma, Epizyme, Genentech, a member of the Roche Group, Janssen Biotech Inc, Pharmacyclics LLC: Other: Advisory Committee; TG Therapeutics: Research Funding. Furman: Oncotracker: Consultancy; Verastem: Consultancy; Abbvie: Consultancy, Honoraria, Other: Expert testimony; Sunesis: Consultancy; Incyte: Consultancy; Beigene: Consultancy; Acerta/AstraZeneca: Consultancy; Loxo Oncology: Consultancy; Genentech: Consultancy; Morphosys: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; TG Therapeutics: Consultancy; X4 Pharmaceuticals: Consultancy; Janssen: Consultancy, Honoraria; AstraZeneca: Honoraria. Deaglio: Heidelberg Pharma: Research Funding; Astra Zeneca: Research Funding.

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First-in-Human, Phase 1/2 Trial to Assess the Safety and Clinical Activity of Subcutaneous GEN3013 (DuoBody®-CD3×CD20) in B-Cell Non-Hodgkin Lymphomas

Blood ◽

10.1182/blood-2019-121460 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 758-758 ◽

Cited By ~ 4

Author(s):

Pieternella Lugtenburg ◽

Rogier Mous ◽

Michael Roost Clausen ◽

Martine E.D. Chamuleau ◽

Peter Johnson ◽

...

Keyword(s):

T Cell ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Dose Escalation ◽

Research Funding ◽

Clinical Activity ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Introduction: CD20-specific monoclonal antibodies (mAbs) have demonstrated efficacy in the treatment of B-cell non-Hodgkin lymphomas (B-NHL); however, a significant proportion of patients (pts) present with refractory disease or will experience relapse. GEN3013 (DuoBody®-CD3×CD20) is the first subcutaneously administered IgG1 bispecific antibody (bsAb) that targets the T-cell surface antigen CD3 and the B-cell surface antigen CD20, triggering T-cell-mediated killing of B cells. In vitro, GEN3013 efficiently activates and induces cytotoxic activity of CD4+ and CD8+ T cells in the presence of B cells (Hiemstra et al. Blood 2018), and results in long-lasting depletion of B cells in cynomolgus monkeys. Subcutaneous (SC) GEN3013 in cynomolgus monkeys resulted in lower plasma cytokine levels, and similar bioavailability and B-cell depletion, compared with intravenous administration. GEN3013 has higher potency in vitro than most other CD3×CD20 bsAbs in clinical development (Hiemstra et al. HemaSphere 2019). SC GEN3013 in pts with B-NHL is being evaluated in a first-in-human, Phase 1/2 trial (NCT03625037), which comprises a dose-escalation part and a dose-expansion part. Here we report preliminary dose-escalation data. Methods: Pts with CD20+ B-NHL with relapsed, progressive, or refractory disease following anti-CD20 mAb treatment, and ECOG PS 0-2 were included. During dose escalation, pts received SC GEN3013 flat dose in 28-day cycles (q1w: cycle 1-2; q2w: cycle 3-6; q4w thereafter) until disease progression or unacceptable toxicity. Risk of cytokine release syndrome (CRS) was mitigated with the use of a priming dose and premedication with corticosteroids, antihistamines, and antipyretics. Primary endpoints were adverse events (AEs) and dose-limiting toxicities (DLTs). Secondary endpoints included pharmacokinetics (PK), immunogenicity (anti-drug antibodies [ADA]), pharmacodynamics (PD) (cytokine measures; laboratory parameters), and anti-tumor activity (tumor size reduction; objective and best response). Results: At data cut-off (June 28, 2019), 18 pts were enrolled into the dose-escalation part of the trial, with safety data available for pts receiving doses starting at 4 µg. Most pts had diffuse large B-cell lymphoma (DLBCL; n=14) and were heavily pre-treated; 10 pts had received ≥3 prior lines of therapy (overall median [range]: 3 [1-11]). The median age was 58.5 years (range: 21-80), and 13 pts were male. At a median follow-up of 1.9 months, pts received a median of 5 doses (range: 1-14); treatment is ongoing in 6 pts. Twelve pts discontinued treatment due to progressive disease. Six pts died (2 during treatment, 4 during survival follow-up), all due to disease progression and unrelated to treatment. The most common (n≥5) treatment-emergent AEs were pyrexia (n=8), local injection-site reactions (n=7), diarrhea (n=5), fatigue (n=5), and increased aspartate aminotransferase (n=5). The most common Grade (G) 3/4 AEs were anemia (n=3) and neutropenia (n=3). Despite increasing GEN3013 doses, all CRS events were non-severe (initial observation: 3/8 pts, G1: n=1, G2: n=2; following modification of premedication plan [corticosteroids for 3 days]: 6/10 pts, G1: n=4, G2: n=2). Increases in peripheral cytokine (IL6, IL8, IL10, IFNγ, TNFα) concentrations after GEN3013 dosing correlated with clinical symptoms of CRS in most pts. No pts had tumor lysis syndrome or neurological symptoms. No DLTs were observed. GEN3013 PK profiles reflect SC dosing; Cmax occurred 2-4 days after dosing. No ADAs were detected. PD effects following GEN3013 dosing were observed at dose levels as low as 40 µg and included rapid, complete depletion of circulating B cells (if present after prior anti-CD20 therapy) and peripheral T-cell activation and expansion. The first evidence of clinical activity was observed at a dose level of 120 µg, with complete metabolic response observed in a pt with DLBCL. Conclusions: Subcutaneously administered GEN3013, a potent CD3×CD20 bsAb, shows good tolerability and early evidence of clinical activity at low dose levels in heavily pretreated pts with relapsed or refractory B-NHL. All CRS events were non-severe and did not lead to discontinuation. No DLTs were observed. Dose escalation is ongoing; updated data will be presented. Dose expansion will begin upon determining the recommended Phase 2 dose (RP2D) (NCT03625037). Disclosures Lugtenburg: Janssen Cilag: Honoraria; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria; Servier: Consultancy, Honoraria, Research Funding; Genmab: Consultancy, Honoraria; BMS: Consultancy; Takeda: Consultancy, Honoraria, Research Funding. Mous:Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Sandoz: Honoraria; Roche: Honoraria; Abbvie: Honoraria; Takeda: Honoraria, Research Funding; Janssen Cilag: Consultancy, Honoraria; MSD: Honoraria; Gilead: Consultancy, Honoraria, Research Funding. Clausen:Abbvie: Other: Travel grant to attend ASH 2019. Johnson:Boehringer Ingelheim: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Honoraria; Epizyme: Honoraria, Research Funding; Incyte: Honoraria; Takeda: Honoraria; Genmab: Honoraria; Bristol-Myers Squibb: Honoraria; Kite: Honoraria; Novartis: Honoraria. Rule:Janssen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding; Astra-Zeneca: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Napp: Consultancy; Kite: Consultancy. Oliveri:Genmab: Employment, Equity Ownership. DeMarco:Genmab: Employment, Equity Ownership. Hiemstra:Genmab: Employment, Equity Ownership, Other: Warrants. Chen:Genmab: Employment. Azaryan:Genmab: Employment. Gupta:Genmab: Employment, Equity Ownership. Ahmadi:Genmab Inc: Employment, Other: stock and/or warrants. Hutchings:Incyte: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Genmab: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Janssen: Research Funding; Pfizer: Research Funding.

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Axl Regulates Fibroblast Growth Factor Receptor Signaling in B-Cell Chronic Lymphocytic Leukemia: Dual Targeting in CLL Therapy

Blood ◽

10.1182/blood.v124.21.831.831 ◽

2014 ◽

Vol 124 (21) ◽

pp. 831-831

Author(s):

Sutapa Sinha ◽

Justin Boysen ◽

Charla Secreto ◽

Steven L. Warner ◽

Neil E. Kay ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Advisory Committees ◽

High Affinity ◽

Fgfr Signaling ◽

Cell Chronic Lymphocytic Leukemia

Abstract B-cell chronic lymphocytic leukemia (CLL) is an incurable disease and represents a significant health problem in the western world. We and others have reported that primary CLL B-cells spontaneously produce increased levels of proangiogenic basic fibroblast growth factor (bFGF) in vitro and that most CLL plasma contains elevated levels of bFGF. However, the precise role of bFGF in CLL pathobiology is not clearly understood. In this study we investigated the functional implication of the FGF/FGF receptor (FGFR) signaling axis in CLL B-cell biology. We have detected expression of FGFR1 and FGFR3 with comparatively higher levels of the latter receptor tyrosine kinase (RTK), but no or notably low levels of FGFR2/FGFR4, by flow cytometry and Western blot analyses in primary CLL B-cells. This observation was further supported by detection of FGFR1/FGFR3 transcripts in CLL B-cells by semi-quantitative reverse transcriptase polymerase chain reaction. Although both FGFR1 and FGFR3 in CLL B-cells remain as constitutively phosphorylated, we found significantly higher levels of phosphorylation on FGFR3 and thus this latter receptor is likely the predominant RTK of the FGFR family in these leukemic B-cells. Of note, in vitro stimulation of FGFRs with recombinant bFGF was unable to increase total phosphorylation on FGFRs from their constitutive basal levels in CLL B-cells. Further analysis using a bFGF neutralizing antibody suggested that FGFR phosphorylation in CLL B-cells is likely independent of bFGF ligation. We then interrogated the mechanism of how FGFRs were being phosphorylated and/or maintained at the observed constitutive levels of phosphorylation in CLL B-cells. Our previous studies established that Axl is a critical RTK in CLL B-cells since it acts as a docking site for multiple cellular kinases/lipase, an observation supported by earlier literatures in human malignancies. Given this, Axl is likely capable of cross talk with other RTKs including FGFRs to regulate FGFR-signaling in CLL B-cells. Therefore, in an effort to determine whether Axl is functionally associated with FGFR, we examined if these two RTKs exist in the same molecular complex in CLL B-cells. Indeed, immunoprecipitation assays demonstrated that Axl formed a complex with FGFR3 in CLL B-cells, suggesting that Axl is likely functionally linked to the FGFR signaling. In this regard we found that Axl inhibition, using a high-affinity Axl inhibitor (TP-0903; Tolero Pharmaceuticals), resulted in significant reduction of total FGFR phosphorylation in CLL B-cells. Additionally, siRNA-mediated partial depletion of Axl in CLL B-cells reduced total FGFR phosphorylation. In contrast, inhibition of FGFR phosphorylation using a high-affinity FGFR inhibitor could not alter phosphorylation levels on Axl RTK in CLL B-cells. Together, these findings suggest that Axl has a dominant role in the regulation of FGFR signaling in CLL B-cells. To find out if inhibition of FGFR can induce apoptosis in CLL B-cells we used a specific inhibitor for FGFR (TKI-258; Novartis) to treat CLL B-cells. Here we found a substantial level of apoptosis induction in the leukemic B-cells with a mean LD50 dose of ~2.5 μM. Interestingly, Axl inhibition by TP-0903 induced a robust level of apoptosis in CLL B-cells in the nanomolar dose range with a mean LD50 dose of 0.14 mM. Thus Axl inhibition exerts a very robust cytotoxic effect on CLL B-cell survival likely targeting both Axl and FGFR signaling pathways via Axl inhibition. In conclusion, we have detected expression of constitutively active FGFR1 and 3 in primary CLL B-cells and that inhibition of FGFR signaling induces considerable levels of CLL B-cell apoptosis albeit lower than that observed on Axl RTK inhibition. Interestingly, our findings here suggest that Axl forms an active RTK complex with FGFR and that Axl inhibition modifies FGFR phosphorylation levels. Thus it is likely that Axl RTK can regulate FGFR signaling in the CLL B-cells. In total these observations suggest that the finding of robust induction of apoptosis in CLL B-cells is as a result of targeting two signaling pathways with Axl inhibition: Axl and FGFR. These studies further support investigation of Axl inhibition as a way to develop a more effective and efficient therapeutic intervention for CLL patients. Disclosures Warner: Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Kay:Genetech: Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees.

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Single-Cell RNA-Seq Identifies Potentially Pathogenic B Cell Populations That Uniquely Circulate in Patients with Chronic Gvhd

Blood ◽

10.1182/blood-2019-130928 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 874-874

Author(s):

Jonathan C Poe ◽

Dadong Zhang ◽

Jichun Xie ◽

Rachel A. DiCioccio ◽

Xiaodi Qin ◽

...

Keyword(s):

Cell Cycle ◽

B Cells ◽

B Cell ◽

Single Cell ◽

Board Of Directors ◽

Research Funding ◽

Ex Vivo ◽

Rna Seq ◽

Advisory Committees ◽

B Cell Subsets

While B cells are known to contribute to the pathogenesis of chronic graft-versus-host disease (cGVHD) in mice, it has been challenging to elucidate intrinsic mechanisms of tolerance loss in patients. To identify distinct and potentially targetable B-cell subsets in cGVHD, we employed single-cell RNA-Seq along with an unsupervised hierarchical clustering analysis, targeting 10,000 single B cells from each of eight patients who were >12 months post-allogeneic hematopoietic stem cell transplantation (HCT) and either had active cGVHD manifestations (n=4) or never developed cGVHD (n=4). Bioinformatics analysis of pooled cell data (using R with Seurat extension package) identified 6 major B cell clusters common to all patients (Figure 1A). "Intra-cluster" gene comparison (using R package DESeq2, false-discovery rate 0.05) revealed numerous differentially expressed genes between patient groups. The greatest number of differentially-expressed genes occurred in a cluster referred to herein as 'Cluster 6' (Figure 1A, in yellow with asterisk). Within Cluster 6, B cells from active cGVHD patients expressed significantly increased ITGAX (CD11c, Padj =0.007), TNFRSF13B (TACI, a receptor for BAFF, Padj =0.003), IGHG1 (IgG1, Padj =9.3e-06) and IGHG3 (IgG3, Padj =1.7e-12), along with 44 additional genes (to be discussed). Thus, Cluster 6 in cGVHD patients may represent a CD11cpos, BAFF-responsive B cell subset primed to undergo isotype switching in response to alloantigen. Flow cytometry analysis on PBMCs from an independent HCT patient cohort (n=10) confirmed that CD11cpos B cells were indeed significantly expanded in cGVHD (P < 0.01, Figure 1B), and revealed these B cells were also TACIpos, CD19high, forward scatter high (FSChigh) blast-like cells (Figure 1C). We found that these CD11cpos B cells had mixed expression of CD21, CD27, IgD and CD24 (Figure 1C). Remarkably, other recent studies on bulk patient B cells have suggested that similar CD11cposCD21negCD19highT-BETpos cells are critical drivers of humoral autoimmunity in diseases including systemic lupus erythematosus (SLE; Scharer et al. 2019; Rubtsova et al. 2017; Rubtsov et al. 2011). This subset now identified by single-cell RNA-Seq is consistent with a population of TACIhigh B cells that produced IgG in response to BAFF treatment ex vivo (Sarantopoulos 2009). Data suggest we have identified functionally distinct and potentially targetable B cell subpopulations. We are employing functional assays to determine whether the additional molecular pathways now elucidated account for our previous work showing greater ex vivo B cell survival rates and hyper-responsiveness to surrogate antigen (Allen et al. 2012, 2014), certain TLR agonists (Suthers et al. 2017), and NOTCH ligand (Poe et al. 2017). In addition to more deeply characterizing B-cell subsets in cGVHD, our single-cell RNA-Seq analyses identified several genes significantly altered across multiple B cell clusters in the cGVHD group, implicating more broad alterations of some genes in this disease. Among these is CKS2, a critical cell cycle regulator, which was significantly increased in cGVHD B cells (Padj 1.0e-10 to 0.018, depending on the cluster evaluated). Increased CKS2 expression was validated by qPCR analysis on B cells from a separate HCT patient cohort with or without cGVHD (P < 0.001, Figure 1D), suggesting that the majority of cGVHD B cells are primed to enter the cell cycle at multiple stages of differentiation when exposed to the proper stimuli. In summary, we used an unbiased approach to identify and further characterize an extrafollicular CD11cposTACIposCD19high B cell population in cGVHD patients that appears to be activated and undergoing active IgG isotype switching. This plasmablast-like B cell population is potentially amenable to therapeutic intervention to prevent pathogenic antibody production. Importantly, we also identify gene alterations across the cGVHD peripheral B cell compartment that potentially underpin promotion of hyperactivated B cells in this disease. Therapeutic strategies to target these pathways will also be discussed. This work was supported by a National Institutes of Health grant, R01HL129061. Disclosures Ho: Omeros Corporation: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Consultancy. Horwitz:Abbvie Inc: Membership on an entity's Board of Directors or advisory committees. Rizzieri:Celgene, Gilead, Seattle Genetics, Stemline: Other: Speaker; AbbVie, Agios, AROG, Bayer, Celgene, Gilead, Jazz, Novartis, Pfizer, Sanofi, Seattle Genetics, Stemline, Teva: Other: Advisory Board; AROG, Bayer, Celgene, Celltron, Mustang, Pfizer, Seattle Genetics, Stemline: Consultancy; Stemline: Research Funding.

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