ALBERT

Description: Down-regulation of immune responses by regulatory T (Treg) cells is an important mechanism involved in the induction of tolerance to allo-antigens (Ags). Recently, a novel subset of Ag-specific T-cell receptor (TCR)αβ+ CD4-CD8- (double-negative [DN]) Treg cells has been found to be able to prevent the rejection of skin and heart allografts by specifically inhibiting the function of antigraft-specific CD8+ T cells. Here we demonstrate that peripheral DN Treg cells are present in humans, where they constitute about 1% of total CD3+ T cells, and consist of both naïve and Ag-experienced cells. Similar to murine DN Treg cells, human DN Treg cells are able to acquire peptide–HLA-A2 complexes from antigen-presenting cells by cell contact-dependent mechanisms. Furthermore, such acquired peptide-HLA complexes appear to be functionally active, in that CD8+ T cells specific for the HLA-A2–restricted self-peptide, Melan-A, became sensitive to apoptosis by neighboring DN T cells after acquisition of Melan-A–HLA-A2 complexes and revealed a reduced proliferative response. These results demonstrate for the first time that a sizable population of peripheral DN Treg cells, which are able to suppress Ag-specific T cells, exists in humans. DN Treg cells may serve to limit clonal expansion of allo-Ag–specific T cells after transplantation.

Description: Three NK-like (NKL) homeobox genes, TLX1/HOX11, TLX3/HOX11L2 and NKX2- 5/CSX, have been implicated in T-cell acute lymphoblastic leukemia (T-ALL). Here we screened further NKL genes in 24 T-ALL cell lines by RT-PCR and identified common expression of MSX2, highlighting this homeobox gene as a potential physiological family member in T-cells. Subsequent quantification of MSX2 confirmed expression in primary hematopoietic cells demonstrating higher levels in CD34+ stem cells when compared to peripheral blood cells or mature CD3+ T-cells. Analysis of core thymic factors in T-ALL cell lines, including IL7, BMP4, TGFbeta, NOTCH and T-cell receptor signaling, suggests their involvement in MSX2 regulation during T-cell differentiation. Chromosomal and genomic analysis of the MSX2 locus (at 5q35) uncovered deletion in t(5;14)(q35;q32) positive T-ALL cell lines associated with low expression levels of MSX2 and ectopic activation of TLX3 or NKX2-5, respectively. For functional analysis we lentivirally transduced T-ALL cells for overexpression of either MSX2 or oncogenic TLX1 and NKX2-5. These cells displayed transcriptional activation of NOTCH3-signaling, as indicated by expression array profiling and real-time PCR analysis of NOTCH3, HES1 and HEY1. The sensitivities to gamma-secretase inhibitor analyzed by MTT-assay of cells overexpressing MSX2, TLX1 or NKX2-5, respectively, were consistently decreased. Furthermore, in addition to MSX2, both TLX1 and NKX2-5 proteins interacted with repressor proteins of the NOTCH-pathway, SPEN/MINT and TLE1/GRG1, as shown by co-immunoprecipitation, probably representing one mechanism of (de)regulation. Elevated expression of NOTCH3 and HEY1 mRNA was detected in TLX1/3 positive T-ALL patients, confirming data obtained from cell lines. In conclusion, we have defined expression patterns, regulation and targets of MSX2 in hematopoietic cells, to reveal a novel modulatory activity in T-cell differentiation operating via NOTCH-signaling, and in leukemogenesis when replaced or supplemented by oncogenic NKL homeodomain proteins.

Description: Epstein-Barr virus (EBV) infection may result in a spectrum of diseases in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT), especially post-transplant lymphoproliferative disease (PTLD). Furthermore, the clinical course of EBV-associated diseases often superimposes with graft-versus-host disease (GVHD) and that increases the difficulty of treatment. Adoptive immunotherapy with EBV-specific cytotoxic T lymphocytes (EBV-CTL) is recommended as one of the first-line therapy for PTLD. Engineering of T cell receptor (TCR)-transferred T lymphocytes could be an attractive strategy to obtain sufficient T cells with an antigen specificity of choice. But TCR-modified alpha beta T cells are restricted by major histocompatibility (MHC) class I expression and low affinity. Because gamma delta T cells (GD T cells) recognize target cells independent of human leukocyte antigen (HLA), the alpha beta TCR engineering of GD T cells forms a feasible strategy to generate antigen-specific effector T cells without HLA restriction. And regulatory GD T cells (GD Tregs) (one of the novel subset of GD T cells), which express Foxp3 and primarily belong to CD27+CD25high phenotype, might have application prospect in the treatment of GVHD. In order to investigate a novel strategy with potential therapeutic benefits in EBV-associated diseases after allo-HSCT, we obtained the monoclonal EBV-CTL clone HLA-A*0201/GLCTLVAML from the PROIMMUNE company (U.K.) and detected peptide-specific CTL activity in chromium release assays, then identified the EBV-CTL associated - TCR Valpha 15 and TCR Vbeta 1 chain genes, and subsequently cloned into the eukaryotic expression vector pIRES to construct the recombinant plasmid; We transferred the EBV specific recombinant plasmid to GD T cells and GD Tregs (generated in vitro by stimulating with anti-TCR gamma delta in the presence of TGF-beta and IL-2). The TCR gene-transduced groups had special TCR Vbeta 1 expression in fluorescence detection, quantitative PCR and western Blot analysis. TCR gene-transduced GD T cells had significant cytotoxicity against the EBV+ target cell lines (including toledo cells (HLA-A2 positive) (38.17±0.86%) and daudi cells (HLA-A2 negative) (61.74±1.84%)) compared with empty vector transfected GD T cells (toledo cells (30.15±0.89%); daudi cells (53.91±4.33%)) (P

Description: Background: 6 cycles CHOP-like chemotherapy plus rituximab (6x R-CHOP) are the standard treatment for young patients with DLBCL. The MInT trial established a subgroup with favourable prognosis as defined as aaIPI=0 and no bulky disease [Pfreundschuh et al., Lancet Oncol 2006; 7: 379-391] with a 3-year EFS of 89%, PFS of 95% and OS of 98%. We hypothesized that 4 cycles of CHOP plus 6 applications of rituximab are non-inferior to the standard treatment of 6x R-CHOP in this population. Patients and Methods: 18 to 60 year-old patients, aaIPI =0 without bulky (≥7.5 cm) disease were randomized to receive 6x R-CHOP or 4x R-CHOP+2xR at 21-day cycles. Radiotherapy was not planned to be given except for prophylactic radiotherapy of the contralateral testis in patients with testicular lymphoma. The primary endpoint was progression free survival (PFS) with events defined as progressive disease, relapse or death. Assuming a 93% 3-years PFS for the 6x R-CHOP arm, it was planned to tolerate an impairment of 5.5% by reducing the number of courses to 4x R-CHOP+2xR to prove non-inferiority with a power of 80% and an alpha-error of 5% (one-sided). Results: Between 12/2005 and 10/2016, 592 patients were randomized in the international multi-center FLYER trial and 588 patients were evaluable for this final analysis. 295 patients were assigned to receive 6x R-CHOP and 293 were assigned to receive 4x R-CHOP+2xR. There were no relevant differences in demographics (median age: 48 years, 99% aaIPI=0, 1% aaIPI=1, 0.3% bulky disease), protocol adherence and toxicity between the two arms. PFS, EFS and OS after 4x R-CHOP+2xR were as good as after 6x R-CHOP. After 66 months median observation, the 3-year PFS rate of the patients receiving 4x R-CHOP+2xR was 96% vs. 94% of patients receiving 6x R-CHOP (p=0.760). The lower limit of the 95% CI of the difference between treatment arms was 0% and excludes -5.5% demonstrating the non-inferiority. The 3-year EFS was identical (89%) in both treatment arms. The 3-years OS was 99% in patients receiving 4x R-CHOP+2xR and 98% in patients receiving 6x R-CHOP. In a multivariable analysis adjusting for strata (stage and E-involvement), the hazard ratio of 4x R-CHOP+2xR compared to 6x R-CHOP was 1.0 (95% CI: 0.7-1.6; p=0.896) for EFS, 0.9 (95% CI: 0.5-1.6; p=0.797) for PFS, and 0.8 (95% CI: 0.4-1.9; p=0.671) for OS. With respect to relapse rate there was also no significant difference between the two treatment arms. 4% (95% CI 2-7%) of the patients in the 4x R-CHOP+2xR arm relapsed vs. 5% (95% CI 3-8%) of the patients in the 6x R-CHOP arm. 33% of relapses occurred in the first two years after study inclusion but continue to be seen with longer follow-up in both arms. Conclusion: In young patients with favourable prognosis DLBCL outcome after 4x R-CHOP+ 2xR is non-inferior compared to the previous standard 6x R-CHOP. Thus, chemotherapy can be spared without compromising prognosis in this population. Supported by Deutsche Krebshilfe Figure. Figure. Disclosures Poeschel: Roche: Other: Travel grants; Amgen: Other: Travel grants. Held:BMS: Consultancy, Other: Travel grants, Research Funding; Amgen: Research Funding; Roche: Consultancy, Other: Travel grants, Research Funding; MSD: Consultancy; Spectrum: Research Funding. Holte:Roche, Norway: Research Funding; Novartis Pharmaceuticals Corporation: Membership on an entity's Board of Directors or advisory committees. Viardot:Roche: Consultancy, Honoraria; Amgen: Consultancy; Gilead Kite: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria. Borchmann:Novartis: Consultancy, Honoraria. Keller:Celgene: Research Funding; BMS: Consultancy; Takeda: Consultancy, Research Funding; Janssen-Cilag: Consultancy, Equity Ownership; Roche: Consultancy; MSD: Consultancy. Schmidt:Gilead: Honoraria, Other: Travel Grants; Celgene: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grants. Marks:Merck: Honoraria; BMS: Honoraria; Servier: Honoraria. Stilgenbauer:Boehringer-Ingelheim: 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; Celgene: 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; Pharmcyclics: 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; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: 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; 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; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Schmitz:Riemser: Honoraria, Other: Travel grants; Kite/Gilead: Honoraria, Other: Travel grants; Novartis: Honoraria, Other: Travel grants; Celgene: Other: Travel grants; Roche: Honoraria. Murawski:Takeda: Consultancy; Janssen: Other: Travel grants.

Description: Background: The clinical course of follicular lymphoma (FL) is characterized by a slow progression over years with continuous relapses despite good response to initial treatment. The median overall survival is 10 to more than 15 years. Standard therapy for patients requiring treatment consists of an anti-CD 20 antibody combined with chemotherapy followed by antibody maintenance. With this combination a 1-year-PFS of 93% was seen in the GLSG-2000 trial (Hiddemann et al, Blood 2005). Because of the substantial side effects of chemotherapy such as infections, secondary malignancies and impairment of the stem cell reserve novel "chemotherapy-free" treatment approaches could substantially improve the treatment tolerability in FL. The BTK-inhibitor ibrutinib has demonstrated promising activity in patients with iNHL, CLL and MCL. Anticipating the recent reports on a superior activity of obinutuzumab as compared to rituximab in the GALLIUM trial (Marcus et al., NEJM 2017), the GLSG initiated a phase II study combining ibrutinib and obinutuzumab to explore the efficacy and safety of this "chemotherapy-free" alternative. Methods: ALTERNATIVE is a prospective multicenter single-arm phase 2 study of the combination of ibrutinib and obinutuzumab in 98 patients with previously untreated FL and a high tumor burden (defined by modified GELF criteria) in need of treatment. Induction comprises 6 cycles of obinutuzumab at a dose of 1000 mg by intravenous infusion on days 1, 8, 15 of cycle 1 and on day 1 of cycles 2-6 to be given every 21 days. Ibrutinib is administered orally at a dose of 560 mg once daily throughout all 6 cycles. In patients with at least partial response (defined by Cheson Response Criteria 2007) after the end of induction, maintenance with obinutuzumab (1000mg every 8 weeks) plus ibrutinib (560mg daily) is given for an additional 24 months. In patients remaining MRD positive at 30 months ibrutinib is continued for another 12 months in an extended maintenance setting without obinutuzumab. The primary efficacy endpoint is the rate of investigator-assessed PFS one year after registration. Response rates at end of induction, after one year and after end of maintenance, duration of response, percentage of progression during induction and maintenance, time to treatment failure, overall survival, duration of molecular remission in MRD negative patients and safety are key secondary endpoints. Results: 98 patients with advanced stage FL were included, The median age was 59 years (29-81), 60% were male and 40% had a high risk FLIPI, 90% stage III/IV disease and 10% were stage II with a high tumor burden. Response to in induction was 90% (87/97) with 85% (82/97) PR and 5% (5/97) CR. 5 patients (5%) progressed during induction. Of the 82 patients with PR after end of induction, 8 patients achieved a CR during the first 6 months of maintenance treatment. 95 patients were evaluable for the primary endpoint of 1-year-PFS and 76 patients (80%) remained alive and free of progression at this timepoint. 18 patients progressed in the first year, two of whom died due to progressive disease. One additional death was caused by a non-lymphoma related event. An MRD-marker was found in 65 patients. MRD at the end of induction was evaluable for 63 patients. 44 patients (70%) were MRD negative after induction treatment. Of the 42 patients with follow-up MRD peripheral blood or bone marrow samples, 35 (83%) were MRD negative one year after registration. Therapy was generally well tolerated. Most common adverse events were diarrhea in 30% of patients, rash in 25% and fatigue and nasopharyngitis (common cold) in 23% and 20%, respectively. Concerning hematotoxicity grade 3-4 neutropenia and thrombopenia were seen in 8% and 4% of patients, respectively. Severe (〉=grade 3) infectious complications were rare (6% pneumonia/bronchitis, 2% sepsis, 7% other infections). Conclusions: The chemotherapy - free combination of ibrutinib and obinutuzumab showed high anti-lymyphoma activity with high overall response rates and a high proportion of MRD negativity at one year. While the combination of ibrutinib and obinutuzumab was associated with a low toxicity profile, the combination was inferior to the published results of conventional immunochemotherapies in terms of the primary efficacy endpoint (1-year-PFS). Further evaluations might demonstrate whether subgroups exist which particularly benefit clinically from this low toxicity regime. Figure Figure. Disclosures Schmidt: Celgene: Honoraria; Gilead: Honoraria, Other: Travel Grants; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grants. Buske:Bayer: Research Funding; Roche: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Viardot:Amgen: Consultancy; Gilead Kite: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Keller:BMS: Consultancy; Roche: Consultancy; Takeda: Consultancy, Research Funding; Janssen-Cilag: Consultancy, Equity Ownership; MSD: Consultancy; Celgene: Research Funding. Graeven:Roche: Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria. Marks:Merck: Honoraria; BMS: Honoraria; Servier: Honoraria. Hänel:Novartis: Honoraria; Roche: Honoraria; Amgen: Honoraria; Takeda: Honoraria. Liersch:Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria. Dürig:Celgene: Honoraria; Roche: Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria. Hoster:Roche Pharma AG: Other: Travel support, Research Funding; F. Hoffman-La Roche: Other: Travel support, Research Funding. Unterhalt:F. Hoffman-La Roche: Other: Travel support. Hiddemann:Janssen: 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; F. Hoffman-La Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Research Funding.

Description: Introduction & Objectives: Primary Cutaneous Follicle Center Lymphoma (PCFCL) is a very indolent mature B-cell lymphoma that shares germinal center morphology with follicular lymphoma (FL) but lacks the characteristic t(14;18). Unlike FL, immunohistochemistry fails to detect expression of BCL2, CD10, and immunoglobulin in PCFCL. Therefore, we investigated expression of B-cell receptor (BCR) transcripts to gain insight into the immunobiology of PCFCL. Materials & Methods: Full-length heavy and light chain BCR transcripts of 13 histologically confirmed PCFCL were amplified using ARTISAN PCR and sequenced on the PacBio RSII system. BCR from 4 cases were sequenced to a depth of 〉2000 sequences per BCR transcript; the remaining cases to a median depth of 1663 sequences (range: 626-5301). BCR from 51 cases of FL and from peripheral B cells of 12 healthy donors were used as controls. Whole genome sequencing (WGS) and RNAseq were performed on 5 PCFCL on the Illumina HiSeq platform. Results: No PCFCL case carried a t(14;18). In addition to previously described CD79B mutations, an L265P mutation in MYD88 was identified in one case, and two PCFCL carried amplifications in chromosome 2 involving the proto-oncogene REL. ARTISAN PCR demonstrated expression of potentially functional VDJ and VJ genes with heavily mutated V regions (VDJ: 5.9-24.0%; VJ: 4.7-17.9%) in all PCFCL cases, which could be confirmed by RNAseq-based de novo BCR assembly. One PCFCL case expressed IgM, another IgA, and the remaining ten cases expressed IgG. PCFCL VDJ carried relatively long heavy chain CDR3 regions with a median of 19 amino acids (versus 17 in healthy donor PBMCs). In contrast to FL, only minimal intraclonal sequence variation (comparable to the known error rate of the used sequencing method) was observed in PCFCL VDJ and VJ sequences, indicating absence of ongoing somatic hypermutation (SHM). VDJ and/or VJ of 11 PCFCL (85%) carried at least one acquired N-linked glycosylation motifs, six PCFCL (46%) at least two, and one case four such motifs. 75% of acquired N-linked glycosylation motifs were found in different positions than the N-linked glycosylation motifs found in FL BCR (Figure). In contrast, only 17.5% and

Description: Abstract 3755 Altered expression, mutation, disruption, or rearrangement of the B-cell chronic lymphocytic leukemia (CLL)/lymphoma 11B gene (BCL11B) has been associated with T-cell malignancies. BCL11B overexpression occurs primarily in T-cell malignancies, suggesting that it may be a target gene for cancer therapy. Our previous study showed that the inhibition of BCL11B expression by siRNA led to apoptosis in human T-cell acute lymphoblastic leukemia cell lines (Jurkat, huT78, and Molt-4), but not in normal, mature T cells. To confirm the potential of BCL11B siRNA as a therapeutic agent and to determine its safety, the present study further analyzed the effects of BCL11B suppression on hemopoietic stem/progenitor cells, CD34+ cells were collected from three samples of umbilical cord blood using magnetic-activated cell sorting. BCL11B expressions in mRNA level of umbilical cord blood CD34+ cells were analyzed by the real-time quantitative PCR with TaqMan technique. For nucleofection of CD34+ cells, BCL11B-siRNA935 and the U-001 program were used of a Nucleofection Device II. Mock-transfected cells nucleofected without siRNA were used as a negative control. To evaluate the role of differentiation and proliferation in CD34+ cells after BCL11B-siRNA935 transfection, erythroid burst-forming units (BFU-E), granulocyte/macrophage colony-forming units (CFU-GM), and megakaryocyte colony-forming units (CFU-Meg) from BCL11B siRNA935-, mock-CD34+ cells were performed using methylcellulose assays. Colonies were assessed 14 days after plating. The BCL11B mRNA expression level in the CD34+ cells was significantly lower than that in Molt-4 cells and in peripheral blood mononuclear cells from eight healthy individuals. There was no significant difference between BCL11B siRNA935-transfected and mock-transfected CD34+ cells with respect to the formation of BFU-E, CFU-GM, or CFU-Meg (P 〉 0.05). We speculate that the BCL11B gene, because of its very low expression level, may not play a major role in proliferation and differentiation of hematopoietic stem/progenitor cells, but we cannot rule out another anti-apoptotic mechanism. Nevertheless, BCL11B gene silencing alone does not affect the proliferation and differentiation of hematopoietic stem/progenitor cells in vitro. In conclusion, our findings provide evidence for an anti-apoptotic function of BCL11B in T-cell malignancies, but not in hemopoietic stem/progenitor cells, suggesting that BCL11B siRNA is safe and may be considered a new targeted therapeutic strategy for T-cell malignancies. * National Natural Science Foundation(30771980)& Guangdong Science and Technology Project (2007B030703008) Grants Disclosures: Li: National Natural Science Foundation (30771980) and Guangdong Science and Technology Project (2007B030703008, 2009B050700029) Grants: Research Funding.

Description: Introduction: Advanced follicular lymphoma (FL) is a clinically and molecularly heterogeneous disease. About 20% of patients have early progression of disease (POD) and short overall survival (OS). We have previously shown that integration of lymphoma-specific gene mutations and clinical factors improves pretreatment risk stratification (Pastore, 2015) and prediction of early POD (i.e., within 24 months, POD24; Jurinovic, 2016). Recently, we have shown that high-dose therapy (HDT) followed by autologous stem-cell transplantation (ASCT) is an effective treatment option for eligible patients with high-risk disease as defined by POD24 (Jurinovic, 2018). Here, we aimed to explore whether HDT/ASCT is an effective frontline therapy for patients identified to be high-risk by clinical (i.e., FLIPI) or clinicogenetic risk models (i.e., m7-FLIPI, POD24-PI). Methods: We performed targeted DNA deep-sequencing of 〉150 genes in available diagnostic FL biopsies from 165 patients ≤60 years with advanced FL from the GLSG2000 trial who uniformly received R-CHOP as frontline treatment. Of these, 87 patients (53%) were randomized to receive consolidative HDT/ASCT, 78 (47%) were randomized to interferon maintenance. We performed intention-to-treat (ITT) survival and regression analyses to explore whether known clinical and clinicogenetic risk factors can be overcome by ASCT. Results: The HDT/ASCT and no-HDT/ASCT cohorts were balanced regarding age (48 vs 50 years), sex (49% vs 64% male patients), high-risk FL International Prognostic Index (FLIPI; 25% vs 29%), Eastern Cooperative Oncology Group Performance Score 〉1 (6% vs 5%) and mutation status of EZH2 (23% vs 18%) and TP53 (3% vs 3%). The incidence of POD24 was not significantly lower in the HDT/ASCT cohort (8% vs 14%, p=0.32). After a median follow-up of 7.5 years, 5-year failure-free survival (FFS) rates in the HDT/ASCT and no-HDT/ASCT cohorts were 77% and 69% (HR 0.7, p=0.16), 5-year OS rates were 95% and 90% (HR 0.6, p=0.21), respectively. The high-risk cohorts identified by FLIPI, m7-FLIPI, and POD24-PI comprised 27% (n=45), 18% (n=29) and 22% (n=37) of patients, respectively (Fig. A). The m7-FLIPI reclassified 10% (n=16) of patients from high-risk FLIPI to low-risk m7-FLIPI. The POD24-PI reclassified 5% (n=9) of patients from high-risk FLIPI to low-risk POD24-PI; one patient was reclassified from low-risk FLIPI to high-risk POD24-PI. Patients identified to be high-risk by all three indices had shorter FFS (FLIPI: HR 2.8, p=0.0002; m7-FLIPI: HR 3.0, p=0.0003; POD24-PI: HR 2.5, p=0.0013), but OS was not different (FLIPI: HR 1.4, p=0.47; m7-FLIPI: HR 1.5, p=0.45; POD24-PI: HR 1.5, p=0.47). The risk to develop POD24 was increased in high-risk patients (FLIPI: OR 4.4, p=0.007; m7-FLIPI: OR 4.8, p=0.005; POD24-PI: OR 4.3, p=0.008). Consolidative HDT/ASCT did not prolong FFS in high-risk patients as defined by FLIPI (HR 1.2, p=0.67), m7-FLIPI (HR 1.2, p=0.70; Fig. B) and POD24-PI (HR 1.3, p=0.63; Fig. B). Similarly, OS was not significantly improved in all three high-risk cohorts (FLIPI: HR 0.2, p=0.13; m7-FLIPI: HR n/a, p〉0.99; and POD24-PI: HR 0.3, p=0.22). In low-risk patients, HDT/ASCT was associated with a non-significant trend towards prolonged FFS (FLIPI: HR 0.5, p=0.061; m7-FLIPI: HR 0.6, p=0.16; POD24-PI: HR 0.5, p=0.068; Fig. B), but again OS was not significantly different (FLIPI: HR 0.8, p=0.69; m7-FLIPI: HR 0.8, p=0.66; and POD24-PI: HR 0.7, p=0.52). Conclusions: Our ITT-analysis confirms that consolidative HDT/ASCT should not be offered to unselected cohorts of patients with previously untreated, advanced FL after R-CHOP. Also, our current clinicogenetic risk models are not optimized to select high-risk patients who may benefit from frontline HDT/ASCT. The fraction of patients identified to be high-risk by FLIPI, m7-FLIPI and POD24-PI is low when applied to younger, medically fit patients. Moreover, the fraction of patients being reclassified by integrating gene mutation data is low in this patient cohort. Therefore, we are developing specific stratification algorithms for younger, medically fit patients who are eligible for dose-intensified approaches. Figure. Figure. Disclosures Klapper: F.Hoffman-La Roche: Honoraria, Research Funding; HTG Molecular Diagnostics, Inc.: Research Funding; Regeneron: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Takeda: Honoraria, Research Funding. Schmitz:Riemser: Honoraria, Other: Travel grants; Kite/Gilead: Honoraria, Other: Travel grants; Novartis: Honoraria, Other: Travel grants; Celgene: Other: Travel grants; Roche: Honoraria. Hess:CTI: Research Funding; Celgene: Consultancy, Honoraria, Other: travel expenses, Research Funding; Roche: 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; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Unterhalt:F. Hoffman-La Roche: Other: Travel support. Dreyling:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sandoz: Membership on an entity's Board of Directors or advisory committees. Schmidt:Gilead: Honoraria, Other: Travel Grants; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grants; Celgene: Honoraria. Hoster:F. Hoffman-La Roche: Other: Travel support, Research Funding; Roche Pharma AG: Other: Travel support, Research Funding. Hiddemann:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffman-La Roche: 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; Bayer: Consultancy, Research Funding. Weigert:Roche: Research Funding; Novartis: Research Funding.

Description: Despite combinations of different therapeutic strategies have significantly increased survival, acute leukemia is still not curable. To further improve outcome, specific immunotherapy might be one of the best choice. DNA vaccines have been showed leading to strong and persistent cell-mediated and humoral immune response to the antigen encoded by the plasmid. However, little data exist regarding the DNA vaccines in acute leukemia, there are few studies reported that PML-RARα DNA vaccines were developed, but the host immune response were weakly, due to the weak immunogenicity of tumor antigens. In order to improve the effect of DNA vaccine for acute promyelocytic leukemia (APL) therapy, we have used a full-length human GM-CSF (hGM-CSF) sequence fused to PML-RARα breakpoint-drived sequence and develop a vector coexpressing PML-RARα gene and hGM-CSF gene, which was expected to to promote T cells response in host. PML-RARα fusion gene segment and the hGM-CSF gene were amplified from NB4 cells or pORF-hGM-CSF plasmid. Both PCR products were cloned into PIRES plasmid respectively to construct a recombinant plasmid PML-RARα-IRES-hGM-CSF. The recombinant plasmids were then transfected into K562 or A549 cells respectively. The expression of the PML-RARα/GM-CSF mRNA and protein in transfected cells were identified by RT-PCR, dot blotting, ELISA and Western-Blot respectively. By in vivo assays, BALB/c mice were vaccinated at 6–8 week of age with a total of 200 μg DNA in normal saline, injected into two sites in the quadriceps muscles on day 0, 7 and 21. The plasmid containing the same PML-RARα segment and blank plasmid served as controls. Two weeks after the final DNA boost, both PML-RARα/GM-CSF mRNA and protein, serum INF-γ and anti-NB4 cells specific cytotoxicity of splenocytes following 7 days of stimulation in vitro with freeze thawing NB4 cells and recombinant human IL-2 were assessed by ELISA and LDH assays. The results showed that the sequence of the fragments inserted in multi-clone site (MCS) A and MCS B of PIRES plasmid were absolutely correct by double restriction enzyme cutting analysis (Xba I/Sal I) and sequence analysis, the PML-RARα/GM-CSF mRNA and protein could be identified in transfected K562 or A549 cells and in mice quadriceps muscles. The level of serum INF-γ and cytotoxicity of splenocytes against NB4 cells from immunized mice was significant increased than that from control groups. In conclusions, the vector expressing PML-RARα and hGM-CSF was successfully constructed, which can more effective immune response and anti-APL cells effect in animal models than that from plasmid containing single PML-RARα segment. It could be farther used in the research as PML-RARα DNA vaccine for APL.