Abstract: To identify the genetic basis of circulating concentrations of monocyte chemoattractant protein-1 (MCP-1), we conducted genome-wide association analyses for MCP-1 in 3 independent cohorts (n = 9598). The strongest association was for serum MCP-1 with a nonsynonymous polymorphism, rs12075 (Asp42Gly) in DARC, the gene for Duffy antigen receptor for chemokines, a known vascular reservoir of proinflammatory cytokines (minor allele frequency, 45.6%; P 〈 1.0 * 10−323). This association was supported by family-based genetic linkage at a locus encompassing the DARC gene (genome-wide P = 8.0 * 10−13). Asp42Gly accounted for approximately 20% of the variability in serum MCP-1 concentrations and also was associated with serum concentrations of interleukin-8 and RANTES. While exploring a lack of association between this polymorphism and EDTA plasma MCP-1 concentrations (P = .82), we determined that both clotting and exogenous heparan sulfate (unfractionated heparin) released substantial amounts of MCP-1 from Darc. Quantitative immunoflow cytometry failed to identify meaningful Asp42Gly-associated differences in Darc expression, suggesting that a functional change is responsible for the differential cytokine binding. We conclude that Asp42Gly is a major regulator of erythrocyte Darc-mediated cytokine binding and thereby the circulating concentrations of several proinflammatory cytokines. We have also identified for the first time 2 mechanisms for the release of reservoir chemokines with possible clinical implications.

Abstract: Background Chronic myeloid leukemia (CML)-study IV was designed to explore whether treatment with imatinib (IM) at 400mg/day (n=400) could be optimized by doubling the dose (n=420), adding IFN (n=430) or cytarabine (n=158) or using IM after IFN-failure (n=128). Methods From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase were randomized into a 5-arm study. The study was powered to detect a survival difference of 5% at 5 years. The impact of patients' and disease factors on survival was prospectively analyzed. At the time of evaluation, at least 62% of patients still received imatinib, 26.2% were switched to 2nd generation tyrosine kinase inhibitors. Results After a median observation time of 9.5 years, 10-year overall survival was 82%, 10-year progression-free survival 80% and 10-year relative survival 92%. In spite of a faster response with IM800mg, the survival difference between IM400mg and IM800mg was only 3% at 5 years. In a multivariate analysis, the influence on survival of risk-group, major-route chromosomal aberrations, comorbidities, smoking and treatment center (academic vs. other) was significant in contrast to any form of initial treatment optimization. Patients that reached the response milestones 3, 6 and 12 months, had a significant survival advantage of about 6% after 10 years regardless of therapy. The progression probability to blast crisis was 5.8%. Blast crisis was proceeded by high-risk additional chromosomal aberrations. Conclusions For responders, monotherapy with IM400mg provides a close to normal life expectancy independent of the time to response. Survival is more determined by patients' and disease factors than by initial treatment selection. Although improvements are also needed for refractory disease and blast crisis, more life-time can currently be gained by carefully addressing non-CML determinants of survival. Disclosures Hehlmann: Novartis: Research Funding; BMS: Consultancy. Saussele: Pfizer: Honoraria; Incyte: Honoraria; Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Pfirrmann: BMS: Honoraria; Novartis: Honoraria. Krause: Novartis: Honoraria. Baerlocher: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria. Bruemmendorf: Novartis: Research Funding. Müller: Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Jeromin: MLL Munich Leukemia Laboratory: Employment. Hänel: Roche: Honoraria; Novartis: Honoraria. Burchert: BMS: Honoraria. Waller: Mylan: Consultancy, Honoraria. Mayer: Eisai: Research Funding; Novartis: Research Funding. Link: Novartis: Honoraria. Scheid: Novartis: Honoraria. Schafhausen: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Ariad: Honoraria. Hochhaus: Incyte: Research Funding; MSD: Research Funding; Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; ARIAD: Research Funding.

Abstract: Over the last decade, allogeneic HCT has been increasingly administered in the United States to adults aged 70 and older with hematologic malignancies. Allogeneic transplant outcomes were reasonable; high comorbidity and ablative conditioning regimens were associated with inferior outcomes.

Abstract: Abstract 68 Early T-cell precursor acute lymphoblastic leukemia (ETP ALL) is characterized by an immature T-lineage immunophenotype (cCD3+, CD1a-, CD8- and CD5dim) aberrant expression of myeloid and stem cell markers, a distinct gene expression profile and very poor outcome. The underlying genetic basis of this form of leukemia is unknown. Here we report results of whole genome sequencing (WGS) of tumor and normal DNA from 12 children with ETP ALL. Genomes were sequenced to 30-fold haploid coverage using the Illumina GAIIx platform, and all putative somatic sequence and structural variants were validated. The frequency of mutations in 43 genes was assessed in a recurrence cohort of 52 ETP and 42 non-ETP T-ALL samples from patients enrolled in St Jude, Children's Oncology Group and AEIOP trials. Transcriptomic resequencing was performed for two WGS cases, and whole exome sequencing for three ETP ALL cases in the recurrence cohort. We identified 44 interchromosomal translocations (mean 4 per patient, range 0–12), 32 intrachromosomal translocations (mean 3, 0–7), 53 deletions (mean 4, 0–10) and 16 insertions (mean 1, 0–5). Three cases exhibited a pattern of complex rearrangements suggestive of a single cellular catastrophe (“chromothripsis”), two of which had mutations targeting mismatch and DNA repair (MLH3 and DCLRE1C). While no single chromosomal alteration was present in all cases, 10 of 12 ETP ALLs harbored chromosomal rearrangements, several of which involved complex multichromosomal translocations and resulted in the expression of chimeric in-frame novel fusion genes disrupting hematopoietic regulators, including ETV6-INO80D, NAP1L1-MLLT10, RUNX1-EVX1 and NUP214-SQSTM1, each occurring in a single case. An additional ETP case with the ETV6-INO80D fusion was identified in the recurrence cohort. Additionally, 51% of structural variants had breakpoints in genes, including those with roles in hematopoiesis and leukemogenesis, and genes also targeted by mutation in other cases (MLH3, SUZ12, RUNX1). We identified a high frequency of activating mutations in genes regulating cytokine receptor and Ras signalling in ETP ALL (67.2% of ETP compared to 19% of non-ETP T-ALL) including NRAS (17%), FLT3 (14%), JAK3 (9%), SH2B3 (or LNK; 9%), IL7R (8%), JAK1 (8%), KRAS (3%), and BRAF (2%). Seven cases (5 ETP, 2 non-ETP) harbored in frame insertion mutations in the transmembrane domain of IL7R, which were transforming when expressed in the murine cell lines, and resulted in enhanced colony formation when expressed in primary murine hematopoietic cells. The IL7R mutations resulted in constitutive Jak-Stat activation in these cell lines and primary leukemic cells expressing these mutations. Fifty-eight percent of ETP cases (compared to 17% of non-ETP cases) harbored mutations known or predicted to disrupt hematopoietic and lymphoid development, including ETV6 (33%), RUNX1 (16%), IKZF1 (14%), GATA3 (10%), EP300 (5%) and GATA2 (2%). GATA3 regulates early T cell development, and mutations in this gene were observed exclusively in ETP ALL. The mutations were commonly biallelic, and were clustered at R276, a residue critical for binding of GATA3 to DNA. Strikingly, mutations disrupting chromatin modifying genes were also highly enriched in ETP ALL. Genes encoding the the polycomb repressor complex 2 (EZH2, SUZ12 and EED), that mediates histone 3 lysine 27 (H3K27) trimethylation were deleted or mutated in 42% of ETP ALL compared to 12% of non-ETP T-ALL. In addition, alterations of the H3K36 trimethylase SETD2 were observed in 5 ETP cases, but not in non-ETP ALL. We also identified recurrent mutations in genes that have not previously been implicated in hematopoietic malignancies including RELN, DNM2, ECT2L, HNRNPA1 and HNRNPR. Using gene set enrichment analysis we demonstrate that the gene expression profile of ETP ALL shares features not only with normal human hematopoietic stem cells, but also with leukemic initiating cells (LIC) purified from patients with acute myeloid leukemia (AML). These results indicate that mutations that drive proliferation, impair differentiation and disrupt histone modification cooperate to induce an aggressive leukemia with an aberrant immature phenotype. The similarity of the gene expression pattern with that observed in the LIC of AML raises the possibility that myeloid-directed therapies might improve the outcome of ETP ALL. Disclosures: Evans: St. Jude Children's research Hospital: Employment, Patents & Royalties; NIH & NCI: Research Funding; Aldagen: Membership on an entity's Board of Directors or advisory committees.

Abstract: TP53-mutated myeloid malignancies are associated with complex cytogenetics and extensive structural variants, which complicates detailed genomic analysis by conventional clinical techniques. We performed whole-genome sequencing (WGS) of 42 acute myeloid leukemia (AML)/myelodysplastic syndromes (MDS) cases with paired normal tissue to better characterize the genomic landscape of TP53-mutated AML/MDS. WGS accurately determines TP53 allele status, a key prognostic factor, resulting in the reclassification of 12% of cases from monoallelic to multihit. Although aneuploidy and chromothripsis are shared with most TP53-mutated cancers, the specific chromosome abnormalities are distinct to each cancer type, suggesting a dependence on the tissue of origin. ETV6 expression is reduced in nearly all cases of TP53-mutated AML/MDS, either through gene deletion or presumed epigenetic silencing. Within the AML cohort, mutations of NF1 are highly enriched, with deletions of 1 copy of NF1 present in 45% of cases and biallelic mutations in 17%. Telomere content is increased in TP53-mutated AMLs compared with other AML subtypes, and abnormal telomeric sequences were detected in the interstitial regions of chromosomes. These data highlight the unique features of TP53-mutated myeloid malignancies, including the high frequency of chromothripsis and structural variation, the frequent involvement of unique genes (including NF1 and ETV6) as cooperating events, and evidence for altered telomere maintenance.

Abstract: Introduction: The majority of patients with classical Hodgkin lymphoma (cHL) will be cured with anthracycline-containing chemotherapy regimens. However, 10-20% of patients with early-stage disease and 30-40% of patients with advanced-stage cHL will relapse. The standard treatment for patients with relapsed cHL is salvage chemoimmunotherapy followed by high-dose chemotherapy (HDT) and autologous hematopoietic cell transplantation (auto-HCT) in chemotherapy-sensitive patients. Patients with primary treatment failure (PTF), i.e. patients who have progressive disease while on therapy or who fail to achieve complete remission (CR) at the end of initial therapy, or experience early relapse after CR1 are expected to have a worse prognosis than patients with late relapse. Since 2011 newer treatments, namely Brentuximab vedotin and PD1/PDL1 blockers have been introduced for the treatment of relapsed and refractory cHL. It is unknown whether changes in disease monitoring and management, including the availability of new agents, impacted survival of patients with cHL and PTF. Methods: Fifteen US academic medical centers contributed cases to the ECLIPSE study (Evaluation of Classical Hodgkin Lymphoma patients wIth Primary treatment failure and analySis of outcomEs). ECLIPSE retrospectively captured patient, disease and treatment characteristics and treatment response as assessed by treating physicians. Eligible patients were ≥ 15 years diagnosed with cHL on or after 2005, who received treatment with curative intent with anthracycline-containing chemotherapy regimens, and developed one of the 3 patterns of PTF: detection of progressive disease during or within 6 weeks of completion of chemotherapy (PP cohort, primary progression), partial response (PR) or stable disease (SD) by functional imaging at completion of chemotherapy (PR/SD cohort), or disease progression detected within 12 months of completion of chemotherapy after prior documentation of CR (ER cohort, early relapse). Patients were divided into two "eras" based on year of diagnosis, 2005-2010 (era1) and 2011-2018 (era2), with the latter expected to reflect changes in salvage therapy for cHL. Results: Patient characteristics for the 553 cases are summarized in Table. Median follow up of survivors was 58.7 and 31.2 months for patients diagnosed in era1 and era2, respectively. ABVD was the upfront treatment for 97.6% of cases. Nearly all patients (98.5%) received salvage therapy after PTF and 60.9% underwent auto-HCT. Patients who relapsed or progressed post auto-HCT received a median of 1 (range 0 to 3) salvage regimens. Five-year overall survival (OS) from time of PTF was 70.3% (95% CI=63.4-77.2%) for patients diagnosed in era1, and 77.6% (95% CI=70.3-84.8%, p = 0.018) for patients diagnosed in era2 (Figure A). While there was no difference in OS among the PP, PR/SD and ER cohorts in the era1 (Figure B), the PR/SD and ER cohorts had better OS than PP cohort in era2 (Figure C). On comparing the OS for each of the 3 cohorts between era1 and era2, there was an improvement in OS in the PR/SD (Figure E) and ER cohorts (Figure F) but no improvement among the PP cohort (D). Multivariable analysis of patients in era 2 identified only age (HR 1.05, 95% CI=1.03-1.07, P & lt;0.001) and PP pattern of PTF (HR 2.45, 95% CI=1.11-5.40, P=0.03) as predictors of worse survival. Conclusions: Though there has been an improvement in survival among cHL cases with PTF treated in the most recent years, the outcome of patients with PP did not change significantly across eras. Patients with PP disease should be prioritized for clinical trials incorporating newer agents and innovative cellular therapy to current available effective treatments. Disclosures Epperla: Pharmacyclics: Honoraria; Verastem Oncology: Speakers Bureau. Costa:Abbvie: Consultancy; Karyopharm: Consultancy; Fujimoto Pharmaceutical Corporation Japan: Other: Advisor; Sanofi: Consultancy, Honoraria, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding. Cashen:Novartis: Other: Speaker's Bureau; Seattle Genetics: Other: Speaker's Bureau; Celgene: Other: Speaker's Bureau. Hamadani:Otsuka: Research Funding; Takeda: Research Funding; Pharmacyclics: Consultancy; ADC Therapeutics: Consultancy, Research Funding; Merck: Research Funding; Sanofi Genzyme: Research Funding, Speakers Bureau; Celgene: Consultancy; Janssen: Consultancy; Medimmune: Consultancy, Research Funding. Barta:Mundipharma: Honoraria; Celgene: Research Funding; Takeda: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Research Funding; Bayer: Consultancy, Research Funding; Mundipharma: Honoraria; Merck: Research Funding; Celgene: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees. Reddy:Celgene: Consultancy; BMS: Consultancy, Research Funding; Genentech: Research Funding; Abbvie: Consultancy; KITE Pharma: Consultancy. Karmali:Gilead/Kite; Juno/Celgene: Consultancy, Speakers Bureau; Takeda, BMS: Other: Research Funding to Institution; Astrazeneca: Speakers Bureau. Bello:Celgene: Speakers Bureau. Chavez:Novartis: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Svoboda:AstraZeneca: Consultancy; Celgene: Research Funding; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; Kyowa: Consultancy; Merck: Research Funding; BMS: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding. Glenn:BMS: Research Funding; Merck: Research Funding; Genentech: Research Funding. Cohen:Lymphoma Research Foundation: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding; ASH: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; Bristol-Meyers Squibb Company: Research Funding; Genentech, Inc.: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy; LAM Therapeutics: Research Funding; UNUM: Research Funding; Hutchison: Research Funding; Astra Zeneca: Research Funding.

Abstract: Acquired immunodeficiency syndrome–related non-Hodgkin lymphomas (AIDS-NHL) are thought to arise because of loss of Epstein-Barr Virus (EBV)-specific cellular immunity. Here, an investigation was done to determine whether cellular immunity to EBV is lost because of physical loss or dysfunction of EBV-specific cytotoxic T cells. Data on EBV-specific cellular immunity were correlated with EBV load. For comparison, individuals who progressed to AIDS with opportunistic infections (AIDS-OI) and long-term asymptomatics (LTAs) were studied. The number of virus-specific T cells was detected using tetrameric HLA–EBV-peptide complexes; function of these EBV-specific T cells was determined using the interferon-γ (IFN-γ) Elispot assay. It was observed that EBV-specific CD8+ T cells were present in normal numbers in human immunodeficiency virus (HIV)-infected individuals. However, their functional capacity was decreased compared with HIV− individuals. In AIDS-NHL patients, EBV-specific T cells were not physically lost in the course of HIV-1 infection but showed progressive loss of their capability to produce IFN-γ in response to EBV peptides. This loss of function correlated with lower CD4+ T-cell numbers and was accompanied by increasing EBV load. In HIV-1–infected LTA individuals, in whom CD4+T-cell numbers were maintained, and progressors to AIDS-OI, IFN-γ–producing EBV-specific T cells were stable and EBV load remained stable or decreased in the course of HIV infection, suggestive of immune control. Our data indicate that functional loss of EBV-specific CD8+ T cells with a concomitant increase in EBV load may play a role in the pathogenesis of AIDS-NHL.

Abstract: Introduction: Salvage immunochemotherapy (IC), followed by high-dose chemotherapy with autologous stem cell transplantation if chemosensitive is standard-of-care second-line (2L) therapy (tx) for fit patients (pts) with relapsed/refractory (R/R) diffuse large B cell lymphoma (DLBCL) when treated with first-line (1L) R-CHOP as shown in the CORAL study. Outcomes following receipt of salvage IC in the 2L setting for pts with DLBCL or high grade B cell lymphoma/B cell lymphoma unclassifiable (HGBL/BCLU) receiving intensive 1L tx remain unknown, and may be worse than those reported in CORAL given prior exposure to higher-dose IC in 1L setting. Here we report the results of a multicenter retrospective analysis of R/R DLBCL and HGBL/BCLU pts treated with intensive 1L tx who receive standard salvage 2L tx. Methods: Inclusion criteria were histologic diagnosis of DLBCL or HGBL/BCLU, R/R disease following 1L tx with R-EPOCH, R-HyperCVAD or R-CODOX-M/IVAC and receipt of 2L tx with R-ICE, R-DHAP, R-DHAC, R-ESHAP or R-GDP. Exclusion criteria were HIV positivity, post-transplant lymphoproliferative disorder, prior chronic lymphocytic leukemia and inadequate data. Therapy was given at the discretion of the treating physician. Progression free survival (PFS) was defined as the interval between time of first relapse or primary refractory disease and disease progression, change in therapy if no disease response or last follow-up in remission, and overall survival (OS) between time of first relapse or primary refractory disease and death or last follow-up while alive. Pts were treated from 2007-2017 and data were censored on 10/15/17. Results: A total of 195 pts treated at 20 US and Canadian academic medical centers were included. Clinicopathologic characteristics at time of R/R disease were 39% age 〉 60 years, 62% male, 77% stage III-IV, 72% elevated LDH, 24% bone marrow (BM) involvement, 28% B symptoms present, 44% extranodal (EN) disease at 〉 1 site, 19% ECOG performance status (PS) 〉 1, 49% with International Prognostic Index score (IPI) ≥3, 46% HGBL/BCLU histology, 49% Ki67 ≥90%, and 61% germinal center (GCB) cell of origin (COO) by Hans algorithm. Of pts with available fluorescence in situ hybridization (FISH) data, 51%, 45% and 30% demonstrated MYC, BCL2 and BCL6 rearrangements (-R), respectively, and 37% were double hit lymphoma (DHL). Tx received in 1L were R-EPOCH in 82%, R-HyperCVAD in 16% and R-CODOX-M/IVAC in 2% of pts. R-ICE was received by 64% and other platinum-containing regimens by 36% as 2L tx. Most (86%) pts relapsed within 12 months (mo) of completion of 1L tx (early) and 58% of pts had primary refractory disease. For all pts, the median length of follow-up was 25.0 mo with a median PFS of 3.0 mo and median OS of 8.0 mo. Overall response rate to 2L tx among all pts was 44% (23% complete response [CR] and 21% partial response [PR] ), and 48% with progressive disease. Pts achieving CR had significantly longer median PFS (32.0 vs 4.0 mo, p = 0.0001) and OS (not reached vs 13.0 mo, p = 0.0004) as compared to pts achieving PR. In pts who achieved CR or PR following 2L tx, 64% received consolidative transplant (42 autologous and 13 allogeneic) and achieved a median PFS and OS of 18.3 mo and 62.0 mo, respectively. As compared to pts relapsing ≥12 mo after completion of 1L tx (late), pts relapsing early were less likely to achieve CR (17% vs. 61%, p=0.0001) and experienced significantly shorter median PFS (2.8 vs. 23.0 mo, p 〈 0.0001) and median OS (6.0 mo vs. not yet reached, p 〈 0.0001). Univariate analysis incorporating clinicopathologic characteristics at the time of relapse demonstrated elevated LDH, stage III-IV disease, IPI ≥3, BM involvement, GCB COO, HGBL/BCLU histology, MYC-R, BCL2-R, DHL and early relapse to have a statistically significant increased hazard ratio (HR) for progression. All of these factors, as well as EN disease at 〉 1 site, B symptoms, ECOG PS 〉 1 and Ki67 ≥90%, but not BCL2-R, demonstrated a statistically significant increased HR for death. Multivariate analysis demonstrated only early relapse to have a statistically significant increased HR for progression (HR 2.47, p=0.024) and death (HR 5.90, p=0.001). Conclusion: Relapse 〈 12 mo from completion of intensive 1L tx is associated with extremely poor outcomes in pts with DLBCL and HGBL/BCLU treated with standard salvage 2L tx. Novel therapeutics, including chimeric antigen receptor-modified T cell (CART) tx, should be investigated as 2L tx in this pt population. Figure. Figure. Disclosures Maddocks: Pharmacyclics: Research Funding; BMS: Research Funding; Teva: Honoraria; AstraZeneca: Honoraria; Novartis: Research Funding; Pharmacyclics/Janssen: Honoraria; Merck: Research Funding. Wagner-Johnston:Novartis: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; ASTEX: Research Funding; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Merck: Research Funding; JUNO: Honoraria, Membership on an entity's Board of Directors or advisory committees. Karmali:Gilead: Speakers Bureau; AstraZeneca: Speakers Bureau. Kahl:Genentech: Consultancy; Juno: Consultancy; Celgene: Consultancy; Seattle Genetics: Consultancy; ADC Therapeutics: Consultancy; Gilead: Consultancy; Acerta: Consultancy; CTI: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy. Cohen:AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding; Infinity Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees; BioInvent: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Reddy:MEI Pharma: Research Funding. Ramchandren:Seattle Genetics: Consultancy, Research Funding; Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Merck: Research Funding; Janssen: Consultancy, Research Funding. Diefenbach:Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Incyte: Research Funding; Trillium: Research Funding; Millenium/Takeda: Research Funding; Denovo: Research Funding; Acerta: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy. Olszewski:TG Therapeutics: Research Funding; Genentech: Research Funding; Spectrum Pharmaceuticals: Consultancy, Research Funding. Barta:Janssen: Membership on an entity's Board of Directors or advisory committees; Merck, Takeda, Celgene, Seattle Genetics, Bayer: Research Funding. Hill:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Assouline:Roche: Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding; BMS: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Landsburg:Curis: Consultancy, Research Funding; Takeda: Consultancy.

Abstract: The process of proplatelet formation (PPF) requires coordinated interaction between megakaryocytes (MKs) and the extracellular matrix (ECM), followed by a dynamic reorganization of the actin and microtubule cytoskeleton. Localized fluxes of intracellular calcium ions (Ca2+) facilitate MK-ECM interaction and PPF. Glutamate-gated N-methyl-D-aspartate receptor (NMDAR) is highly permeable to Ca2+. NMDAR antagonists inhibit MK maturation ex vivo; however, there are no in vivo data. Using the Cre-loxP system, we generated a platelet lineage–specific knockout mouse model of reduced NMDAR function in MKs and platelets (Pf4-Grin1−/− mice). Effects of NMDAR deletion were examined using well-established assays of platelet function and production in vivo and ex vivo. We found that Pf4-Grin1−/− mice had defects in megakaryopoiesis, thrombopoiesis, and platelet function, which manifested as reduced platelet counts, lower rates of platelet production in the immune model of thrombocytopenia, and prolonged tail bleeding time. Platelet activation was impaired to a range of agonists associated with reduced Ca2+ responses, including metabotropic like, and defective platelet spreading. MKs showed reduced colony and proplatelet formation. Impaired reorganization of intracellular F-actin and α-tubulin was identified as the main cause of reduced platelet function and production. Pf4-Grin1−/− MKs also had lower levels of transcripts encoding crucial ECM elements and enzymes, suggesting NMDAR signaling is involved in ECM remodeling. In summary, we provide the first genetic evidence that NMDAR plays an active role in platelet function and production. NMDAR regulates PPF through a mechanism that involves MK-ECM interaction and cytoskeletal reorganization. Our results suggest that NMDAR helps guide PPF in vivo.

Abstract: Hemophagocytic lymphohistiocytosis (HLH; hemophagocytic syndrome) is a rare syndrome of potentially fatal, uncontrolled hyperinflammation. Allogeneic stem cell transplantation (alloSCT) is indicated in familial, recurrent or progressive HLH. Additional recommendations include central nervous system involvement and unknown triggering factor. While data for alloSCT outcome are available for the pediatric setting, information for adults is very limited. The aim of this study was to retrospectively analyze the information from the EBMT databases about adult HLH patients who underwent allogeneic stem cell transplantation. We obtained data of 67 adult (≥18 years of age) patients transplanted due to HLH. The first reported transplantation was in 1995. Due to the rise of HLH awareness, the number was steadily growing. Until 2006 only 12 transplants were performed, while in the next 10 years it was 55. Median age at transplantation was 28 (range: 18-65). There was a slight male predominance 43/67 (64%). The majority of patients were reported with secondary HLH 33/67 (49%), the familial disease was reported in 29/67 (43%) patients. In two patients triggering factor was attributed to malignancy. The majority of patients received stem cells obtained from the peripheral blood (52/67; 78%) while for the remaining ones it was bone marrow. Reduced intensity conditioning was used since 2004 in 23/63 (37%)of patients. Thirteen (19%) patients received TBI. Donor choice was: matched unrelated 33 (50%), mismatched unrelated 7 (11%), identical sibling 26 (39%). Engraftment was observed in 55/61 (77%); 7/61 (12%) patients suffered from primary and 2/61 (3%) from secondary graft failure. The cumulative incidence of acute graft versus host disease (GvHD) at 100 days was 26% (95% CI 15-37%). The cumulative incidence of chronic GvHD at 1 year after alloSCT was 13% (95% CI 2-23%) and increased to 31% at 3 years (95% CI 16-47%). The overall survival until three years is shown in Fig.1. The median survival time was 8 months. The three year OS was 41% (95% CI 28-55%). For patients who survived until 3 months, this proportion was more favorable with an OS of 62% (95% CI 45-78%) at 3 years after transplantation. Among 19 patients with observation times longer than 15 months, only one patient died (in the 48th month after alloSCT due to relapse which occurred in the 12th month). Main causes of death in the described group were: relapse or progression 10/36 (28%), infection 9/36 (25%) and GvHD 6/36 (17%). After 12 months no more relapses of HLH were recorded - the cumulative incidence reached 19%. The non-relapse mortality reached 42% after 15 months. The familial disease was associated with a better prognosis than secondary HLH (p=0.04). Unlike the pediatric population, where reduced intensity conditioning (RIC) was associated with higher survival, in adult patients there was no difference between the conditioning types. The choice of donor: matched related versus matched unrelated did not alter the survival. To our knowledge, this is the largest group of adult patients with HLH who underwent allogeneic stem cell transplantation. Relatively low relapse incidence shows that alloSCT can effectively cure HLH. Patients who survive the first period after this procedure can expect a long disease-free survival. Figure Overall survival after allogeneic stem cell transplantation for adult HLH patients until 36 months (95% Confidence Intervals are shown in grey). The number of patients at risk is indicated below the time axis at the corresponding time points. Figure. Overall survival after allogeneic stem cell transplantation for adult HLH patients until 36 months (95% Confidence Intervals are shown in grey). The number of patients at risk is indicated below the time axis at the corresponding time points. Disclosures Jedrzejczak: Celgene: Consultancy; Roche: Consultancy, Research Funding; Jansen-Cilag: Consultancy; Novartis: Consultancy, Research Funding; Amgen: Research Funding; BMS: Research Funding; Angelini: Consultancy; Sandoz: Consultancy. Kobbe:Jansen: Honoraria, Other: travel support; Celgene: Honoraria, Other: travel support, Research Funding. Kroeger:Sanofi: Honoraria, Research Funding.