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Supplementary Figures S1-6. Figure S1: Histological staging criteria for acute GvHD Figure S2: Ruxolitinib does not impair post-transplant donor myeloid reconstitution and full donor chimerism. Figure S3: GVT effect against myeloid leukemia RMB-1 cell line is maintained in the presence of ruxolitinib Figure S4: Ruxolitinib at the dose of 90 mg/Kg prevents acute GVHD without affecting T cell alloreactivity Figure S5: Ruxolitinib effect at 45 mg/Kg on absolute numbers of alloreactive T cells, Th17 and Treg cells. Figure S6: Representative Images of Ruxolitinb effect on T cells and macrophage infiltration of GVHD organs

Purpose: Immune-mediated graft-versus-tumor (GVT) effects can occur after allogeneic hematopoietic stem cell transplantation (HSCT), but GVT is tightly linked to its main complication, graft-versus-host disease (GVHD). Strategies aimed at modulating GVHD, while maintaining the GVT effect, are needed to improve the cure rate of transplant. Given the emerging role of Janus-activated kinase (JAK) signaling in lymphoproliferative and myeloproliferative diseases and its established function at dictating T-cell differentiation, we postulated that JAKs might be potential therapeutic targets through a pharmacologic approach.Experimental Design: We examined the effect of JAK1/JAK2 modulation by ruxolitinib in a mouse model of fully MHC mismatched bone marrow transplant comprising in vivo tumor inoculation.Results: JAK1/JAK2 inhibition by ruxolitinib improved both overall survival (P = 0.03) and acute GVHD pathologic score at target organs (P ≤ 0.001) of treated mice. In addition, treatment with ruxolitinib was associated with a preserved GVT effect, as evidenced by reduction of tumor burden (P = 0.001) and increase of survival time (P = 0.01). JAK1/JAK2 inhibition did not impair the in vivo acquisition of donor T-cell alloreactivity; this observation may account, at least in part, to the preserved GVT effect. Rather, JAK1/JAK2 inhibition of GVHD was associated with the modulation of chemokine receptor expression, which may have been one factor in the reduced infiltration of donor T cells in GVHD target organs.Conclusions: These data provide further evidence that JAK inhibition represents a new and potentially clinically relevant approach to GVHD prevention. Clin Cancer Res; 21(16); 3740–9. ©2015 AACR.

Novel treatments for multiple myeloma (MM) have increased rates of complete response, raising interest in more accurate methods to evaluate residual disease. Cell-free tumor DNA (cfDNA) analysis may represent a minimally invasive approach complementary to multiparameter flow cytometry (MFC) and molecular methods on bone marrow aspirates. A sequencing approach using the Ion Torrent Personal Genome Machine was applied to identify clonal IGH gene rearrangements in tumor plasma cells (PCs) and in serial plasma samples of 25 patients with MM receiving second-line therapy. The same clonal IGH rearrangement identified in tumor PCs was detected in paired plasma samples, and levels of IGH cfDNA correlated with outcome and mirrored tumor dynamics evaluated using conventional laboratory parameters. In addition, IGH cfDNA levels reflected the number of PCs enumerated by MFC immunophenotyping even in the complete response context. Patients determined by MFC to be free of minimal residual disease were characterized by low frequencies of tumor clonotypes in cfDNA and longer survival. This pilot study supports the clinical applicability of the noninvasive monitoring of tumor levels in plasma samples of patients with MM by IGH sequencing.

BACKGROUND The authors describe a family with a high penetrance of plasma cell dyscrasias, suggesting inheritance of an autosomal dominant risk allele. METHODS The authors performed whole-exome sequencing and reported on a combined approach aimed at the identification of causative variants and risk loci, using the wealth of data provided by this approach. RESULTS The authors identified gene mutations and single-nucleotide polymorphisms of potential significance, and pinpointed a known risk locus for myeloma as a potential area of transmissible risk in the family. CONCLUSIONS To the authors' knowledge, the current study is the first to provide a whole-exome sequencing approach to such cases, and a framework analysis that could be applied to further understanding of the inherited risk of developing plasma cell dyscrasias. Cancer 2017. © 2017 American Cancer Society.

Novel treatments for multiple myeloma (MM) have increased rates of complete response, raising interest in more accurate methods to evaluate residual disease. Cell-free tumor DNA (cfDNA) analysis may represent a minimally invasive approach complementary to multiparameter flow cytometry (MFC) and molecular methods on bone marrow aspirates. A sequencing approach using the Ion Torrent Personal Genome Machine was applied to identify clonal IGH gene rearrangements in tumor plasma cells (PCs) and in serial plasma samples of 25 patients with MM receiving second-line therapy. The same clonal IGH rearrangement identified in tumor PCs was detected in paired plasma samples, and levels of IGH cfDNA correlated with outcome and mirrored tumor dynamics evaluated using conventional laboratory parameters. In addition, IGH cfDNA levels reflected the number of PCs enumerated by MFC immunophenotyping even in the complete response context. Patients determined by MFC to be free of minimal residual disease were characterized by low frequencies of tumor clonotypes in cfDNA and longer survival. This pilot study supports the clinical applicability of the noninvasive monitoring of tumor levels in plasma samples of patients with MM by IGH sequencing.

Purpose: Immune-mediated graft-versus-tumor (GVT) effects can occur after allogeneic hematopoietic stem cell transplantation (HSCT), but GVT is tightly linked to its main complication, graft-versus-host disease (GVHD). Strategies aimed at modulating GVHD, while maintaining the GVT effect, are needed to improve the cure rate of transplant. Given the emerging role of Janus-activated kinase (JAK) signaling in lymphoproliferative and myeloproliferative diseases and its established function at dictating T-cell differentiation, we postulated that JAKs might be potential therapeutic targets through a pharmacologic approach. Experimental Design: We examined the effect of JAK1/JAK2 modulation by ruxolitinib in a mouse model of fully MHC mismatched bone marrow transplant comprising in vivo tumor inoculation. Results: JAK1/JAK2 inhibition by ruxolitinib improved both overall survival (P = 0.03) and acute GVHD pathologic score at target organs (P ≤ 0.001) of treated mice. In addition, treatment with ruxolitinib was associated with a preserved GVT effect, as evidenced by reduction of tumor burden (P = 0.001) and increase of survival time (P = 0.01). JAK1/JAK2 inhibition did not impair the in vivo acquisition of donor T-cell alloreactivity; this observation may account, at least in part, to the preserved GVT effect. Rather, JAK1/JAK2 inhibition of GVHD was associated with the modulation of chemokine receptor expression, which may have been one factor in the reduced infiltration of donor T cells in GVHD target organs. Conclusions: These data provide further evidence that JAK inhibition represents a new and potentially clinically relevant approach to GVHD prevention. Clin Cancer Res; 21(16); 3740–9. ©2015 AACR.

Myeloid-derived suppressor cells (MDSCs) are powerful immunomodulatory cells that in mice play a role in infectious and inflammatory disorders, including acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Their relevance in clinical acute GVHD is poorly known. We analyzed whether granulocyte colony-stimulating factor (G-CSF) administration, used to mobilize hematopoietic stem cells, affected the frequency of MDSCs in the peripheral blood stem cell grafts of 60 unrelated donors. In addition, we evaluated whether the MDSC content in the peripheral blood stem cell grafts affected the occurrence of acute GVHD in patients undergoing unrelated donor allogeneic stem cell transplantation. Systemic treatment with G-CSF induces an expansion of myeloid cells displaying the phenotype of monocytic MDSCs (Linlow/negHLA-DR−CD11b+CD33+CD14+) with the ability to suppress alloreactive T cells in vitro, therefore meeting the definition of MDSCs. Monocytic MDSC dose was the only graft parameter to predict acute GVHD. The cumulative incidence of acute GVHD at 180 days after transplantation for recipients receiving monocytic MDSC doses below and above the median was 63% and 22%, respectively (P = .02). The number of monocytic MDSCs infused did not impact the relapse rate or the transplant-related mortality rate (P > .05). Although further prospective studies involving larger sample size are needed to validate the exact monocytic MDSC graft dose that protects from acute GVHD, our results strongly suggest the modulation of G-CSF might be used to affect monocytic MDSCs graft cell doses for prevention of acute GVHD.

The authors describe a family with a high penetrance of plasma cell dyscrasias, suggesting inheritance of an autosomal dominant risk allele.The authors performed whole-exome sequencing and reported on a combined approach aimed at the identification of causative variants and risk loci, using the wealth of data provided by this approach.The authors identified gene mutations and single-nucleotide polymorphisms of potential significance, and pinpointed a known risk locus for myeloma as a potential area of transmissible risk in the family.To the authors' knowledge, the current study is the first to provide a whole-exome sequencing approach to such cases, and a framework analysis that could be applied to further understanding of the inherited risk of developing plasma cell dyscrasias. Cancer 2017;123:3701-3708. © 2017 American Cancer Society.

Haploidentical hematopoietic stem cell transplantation provides an option for patients with advanced hematologic malignancies lacking a compatible donor. In this prospective phase 1/2 trial, we evaluated the role of reduced-intensity conditioning (RIC) followed by early add-backs of CD8-depleted donor lymphocyte infusions (DLIs). The RIC regimen consisted of thiotepa, fludarabine, cyclophosphamide, and 2 Gy total body irradiation. Twenty-eight patients with advanced lymphoproliferative diseases (n = 24) or acute myeloid leukemia (n = 4) were enrolled. Ex vivo and in vivo T-cell depletion was carried out by CD34+ cell selection and alemtuzumab treatment. The 2-year cumulative incidence of nonrelapse mortality was 26% and the 2-year overall survival (OS) was 44%, with a better outcome for patients with chemosensitive disease (OS, 75%). Overall, 54 CD8-depleted DLIs were administered to 23 patients (82%) at 3 different dose levels without loss of engraftment or acute toxicities. Overall, 6 of 23 patients (26%) developed grade II-IV graft-versus-host disease, mainly at dose level 2. In conclusion, our RIC regimen allowed a stable engraftment with a rather low nonrelapse mortality in poor-risk patients; OS is encouraging with some long-term remissions in lymphoid malignancies. CD8-depleted DLIs are feasible and promote the immune reconstitution.

Background: Current criteria used to assess response lag behind the extraordinary evolution in the treatment of multiple myeloma (MM) patients (pts), and more sensitive techniques are being explored to detect true minimal residual disease (MRD) for new complete remission (CR) definitions. In recent years, next generation sequencing (NGS) technologies have emerged. NGS of immunoglobulin (IgH) gene rearrangements are very sensitive and also allow the identification of small subclonal population that can be monitored over time during treatment, something not possible with flow cytometry or PCR. However, the patchy pattern of bone marrow infiltration observed in MM leads to some degree of uncertainty regarding MRD-negative results, irrespectively of the technique adopted. This highlights the value of applying "liquid biopsy" as a non-invasive strategy for monitoring MRD through the analysis of circulating cell-free tumor DNA (ctDNA). The objective of the current study was to measure residual tumor burden in sequential plasma samples of a cohort of MM pts by NGS of the IgH gene rearrangements. Methods: We retrospectively analyzed 14 MM pts homogeneously treated between 2011 and 2015 with all clinical data available. We obtained serial tumor and plasma samples at diagnosis and at specified time points during treatment cycles and up to 24 months of follow-up. Genomic DNA (gDNA) was extracted from immunomagnetically selected CD138+ plasma cells at diagnosis (n=14). ctDNA was extracted from 500uL of plasma (Qiagen) at diagnosis (n=14) and at follow-up time points (n=58). IgH gene rearrangements were amplified, quality assessed (Agilent hsDNA kit) and sequenced on Ion Torrent PGM as previously described (Gimondi et al., ASH 2015). Raw reads were filtered for quality, length (>250bp) and presence of both forward and reverse primers. Reads were subsequently aligned using IgBlast against IMGT germline database and aggregated into clonotypes based on identity of CDR3, V and J segments (MigMap). Post-processing analyses were performed using VDJtools and customized R scripts. Results: PCR products quality assessment from ctDNA amplification of the entire IgH-VDJ region revealed the presence of both short (150-250bp) and long amplicons (310-360bp). Raw reads were subjected to filtering using our custom bioinformatic workflow to retain only complete IgH-VDJ gene rearrangements and discard low-quality reads. Three pts could not be evaluated due to low quality sequencing reads in all samples. At least 3 follow-up time points were available for all the remaining 11 pts whereas 6 pts had 4 time points. At diagnosis, both plasma and tumor samples revealed a high level of heterogeneity (range 1980-7753 clonotypes) with only a small fraction of shared clonotypes (346±262, mean±SD). Among the shared ones, the clonotype with the highest frequency in plasma corresponded to the tumor-associated one identified in CD138+ cells. Interestingly, in the plasma of 3 pts, additional clonotypes were detected at relatively high frequencies (range 1-16%) suggesting the presence of subclones. IgH-NGS at follow-up time points revealed that the clonotype identified at diagnosis (range 4-31% of total reads) could be easily tracked over time in plasma samples, at frequencies as low as 0.00001%. Frequencies of the tumor-associated IgH gene rearrangement in plasma showed a patient-specific modulation and reflected the tumor burden assessed according to the International Myeloma Working Group-Uniform Response Criteria. At the time of CR, the tumor-associated clonotype was undetectable in the plasma of pts who would not subsequently relapse. In patients that would lately experience progressive disease, the tumor specific clonotype was still detectable at low frequencies (range 0.00001-0.03%) in all plasma samples suggesting that liquid biopsy can be used for MRD monitoring. Conclusions: Despite the limited number of pts and follow-up samples analyzed, we demonstrate that NGS of IgH gene rearrangements from ctDNA can be used for MM disease monitoring, thus representing a non-invasive alternative strategy for clinical management. The analysis of retrospectively collected plasma samples revealed that ctDNA quality is essential for a NGS characterization of IgH gene rearrangements. Plasma samples collection and processing represent critical steps that need to be considered designing prospective liquid biopsy studies. Disclosures No relevant conflicts of interest to declare.

Background: Approximately 50% of patients with peripheral T-cell lymphoma (PTCL) enter long-term remission after standard chemotherapy and stem cell transplantation. Patients who do not respond to chemotherapy have few treatment options highlighting the critical need for new effective and targeted therapeutics. Aberrant T cell receptor (TCR) and tyrosine kinase (TK) signaling have been described in PTCL (Agostinelli 2014;Netchiporouka 2014). Single-agent TK inhibitors (TKIs) have significantly improved patient outcomes across multiple tumor subtypes. However, TKI therapy is rarely curative. The recent discovery of a subgroup of PTCL characterized by high levels of GATA3 and c-Myc expression and poor prognosis (Iqbal 2014; Manso 2016), establishes the rationale of targeting c-Myc in PTCLs. Based on the demonstration that pharmacologic inhibition of c-Myc is achievable through targeting bromodomain and extra terminal (BET) family of chromatin adapters, the therapeutic potential of BET inhibition was assessed in a panel of T cell lymphoma and leukemia cell lines. Since expression of c-Myc is regulated by the TCR, we also hypothesized that simultaneous targeting of c-Myc and TCR would significantly enhance the antiproliferative effects of BET inhibitors (BETis) and TKI alone in preclinical models of PTCL. Methods: Five T-cell lymphoma and leukemia cell lines (Jurkat, HD-MAR-2, Karpas 299, Sup-T1, HH) were incubated with escalating doses of JQ1 (a small-molecule BETi with the highest affinity for BRD4) and OTX-015 (a BETi with a broader affinity for BRD2, BRD3, BRD4) and the tyrosine-kinase-inhibitor Dasatinib. Analysis of cell viability, cell cycle distribution, apoptosis and mitochondrial depolarization was performed using flow cytometry. Effects of treatments were assessed using gene expression profiling (GEP) and western blotting (WB). Combinations were evaluated using the Chou-Talalay Combination Index (CI), calculated with CompuSyn software (CompuSyn Inc, Paramus, NJ). Results: JQ1 and OTX-015 show antiproliferative activity with IC50 at nanomolar concentrations in all cell lines. As assessed determining viable cells by PI exclusion and flow cytometry, JQ1 and OTX-015 are similarly active in a dose-dependent manner in all cell lines. To understand the activity of JQ1 and OTX-015, we analyzed cell-cycle distribution using flow cytometry. JQ1 and OTX-015 induce a cell cycle arrest with G1-phase accumulation and decrease S-phase with the exception of SUPT1 cells that are characterized by a cell cycle arrest in G2-phase. Minimal increase in the sub-G1 population is observed in all cell lines, suggesting that JQ1 and OTX-015 mainly exert a cytostatic effect. We then examined GATA3 and c-Myc protein levels in all cell lines: varying amounts of GATA3 and c-Myc proteins were observed but a strong correlation between GATA3 and c-Myc expression was detected. After JQ1 and OTX-015 exposure, c-Myc protein level decrease in all cell lines apart from SUP-T1 cell line. Here c-Myc level do not change significantly upon BETis exposure, suggesting that BETis target other pathways relevant for SUP-T1 survival. Dasatinib efficiently inhibits the proliferation in all cell lines at micromolar concentrations in a dose-dependent manner. Dasatinib induces G0/G1-phase arrest and an increase in sub-G1 population indicating a modest induction of apoptosis confirmed by caspase-9 activation and mitochondrial depolarization. Compared to all single agents, combined treatments with sub-optimal concentrations of Dasatinib and JQ1 or OTX-015 exert synergistic lethal activity against all tested cell lines (C.I. Conclusions: The experiments presented here support the combination of BET inhibitors with the TK inhibitor Dasatinib for PTCLs. Our data suggest a synergistic interaction for the combination of both BETis and Dasatinib in vitro. Mechanistically, combined treatments exert synergistic anti-tumor effects in all cell lines through growth inhibitory effects, direct induction of cell death by promotion of caspase-dependent apoptosis and mitochondrial depolarization. Disclosures No relevant conflicts of interest to declare.

Objectives The efficacy of a novel vaccine against influenza virus A (H1N1) in patients with hematologic malignancies is largely unknown. Methods We prospectively evaluated the humoral and cellular immune responses after one injection of monovalent adjuvanted 2009 H1N1 vaccine in 47 adults with hematologic malignancies and 77 controls by hemagglutination-inhibition assay and flow-cytometry analysis on day 0, 28, 50, and 90. Results On day 28 postvaccination, patients had lower seroprotection (95.2% vs. 75.2%, P

Background: The achievement of complete remission is an important therapeutic goal and prognostic factor for overall survival in patients with B-cell malignancies. Molecular monitoring of disease with PCR-based strategies is used to assess the depth of treatment response, detect minimal residual disease (MRD), and identify patients at increased risk of relapse. Immunoglobulin heavy chain (IGH) gene rearrangements are used as molecular marker in approximately 80% of lymphoma and multiple myeloma (MM) patients since they represent lineage-specific markers and the third complementarity determining region (CDR3) is unique to each clone. We and others have demonstrated that next generation sequencing (NGS) technologies provide the opportunity to identify and quantify clonotypes with consensus primers combining the benefits of high sensitivity and universal applicability thus overcoming ASO-PCR and RQ-PCR limitations. Very recently, NGS has been applied to characterize the tumor-specific VDJ recombination of the immunoglobulin genes in the serum of patients with diffuse large B-cell lymphoma and used as a novel non-invasive strategy to predict clinical disease recurrence after first-line treatment (Roschewski et al., Lancet Oncology 2015). The present study was designed to assess whether the Ion Torrent Personal Genome Machine (IT-PGM)-based sequencing and analysis we established (Gimondi et al., ASH 2014), could be used to detect circulating tumor DNA encoding the clonal immunoglobulin gene sequence in the plasma of patients with Multiple Myeloma. Methods: Genomic DNA (gDNA) was extracted from CD138+ plasma cells immunomagnetically selected from the bone marrow blood of six MM patients and amplified using seven different family-specific IgH-V primers and a consensus JH primer (Voena et al., Leukemia 1997). IgH clonality was assessed by Sanger sequencing in order to define the patient specific DNA rearrangement. Plasma samples of the six MM patients were collected and cell free DNA (cfDNA) extracted (Qiagen). The total amount of cfDNA was estimated by fluorometric measurement (median 105 ng, range 37-171 ng).For library construction and NGS, paired samples of gDNA (500ng) and cfDNA (at least 37ng) were amplified as previously described (Gimondi et al., ASH 2014). PCR products were evaluated for quality and length by high-sensitivity dsDNA chips (Agilent).PCR amplicons were barcoded, pooled and sequenced on the Ion Torrent PGM.NGS data were analyzed by using the IMGT-High V-Quest web server tool and the statistical software R. Results: Rearranged IGHV-D-J loci from cfDNA of each MM patient could be amplified using 7 different IGHV family primers and a consensus JH primer, despite the limited abundance of DNA recovered from plasma samples. PCR products were sequenced on an IT-PGM 316 chip, yielding at least 110K reads per sample (mean 280K reads) with an average coverage of 130x (at least 50x). Clonal IgH sequences were quantified as a fraction of the complete IGHV-D-J rearranged reads. The clonality of our samples was assessed by determining the percentage of reads identical to the most abundant CDR3 sequence in each sample. The number of clonal sequences corresponding to the highest expressed IGH clonotype in gDNA was consistent with those identified in cfDNA samples (range 74%-82% and range 65%-73% respectively). Furthermore, the clonotypes identified by high-throughput sequencing of gDNA and cfDNA samples demonstrated a 100% sequence identity with the patient-specific IGHV-D-J clonal rearrangement identified by Sanger sequencing. Conclusions: We demonstrate that next generation sequencing of cfDNA from the plasma of Multiple Myeloma patients is feasible, accurate, and sensitive in identifying the tumor-derived VDJ recombination of the immunoglobulin genes without prior knowledge of the tumor clonotype and might represent an alternative when bone marrow biopsies are unavailable. Moreover, given the patchy bone infiltration of malignant plasma cells, cfDNA analysis is a non-invasive approach that might give a more precise quantification of disease burden. In addition, NGS analysis of the IGHV-D-J rearranged sequences provides a deep and detailed characterization of the patient immune repertoire, thus possibly allowing clonal evolution evaluations and monitoring of MRD in follow-up samples. Disclosures No relevant conflicts of interest to declare.

Background The graft-versus-leukemia effect is able to induce clinical responses in patients with chronic lymphocytic leukemia treated with a reduced intensity conditioning regimen, followed by allogeneic stem cell transplantation. We investigated whether molecular remissions could be attained after reduced intensity conditioning and allogeneic stem cell transplantation in patients with relapsed chronic lymphocytic leukemia and whether the assessment of minimal residual disease might be used to predict the clinical outcome. Design and Methods Minimal residual disease was monitored by polymerase chain reaction using the immunoglobulin heavy-chain gene rearrangement as a molecular marker in 29 relapsed patients who achieved complete remission following reduced intensity conditioning and allogeneic stem cell transplantation. A nested-polymerase chain reaction with patient-specific primers derived from complementarity determining regions (CDR2 and CDR3) was carried out in all the patients. Real-time polymerase chain reaction was performed in patients whose nested reaction gave positive or mixed results. Results Three patterns of minimal residual disease were observed: negative (31%), mixed (24%), and always positive (45%). The cumulative incidence of relapse according to the minimal residual disease status at 6 and 12 months after transplantation was significantly different between polymerase chain reaction-negative and -positive patients ( p =0.031 and p =0.04, respectively). Two-year disease-free survival was 93% and 46% for polymerase chain reaction-negative and -positive patients at 6 months after transplantation, respectively ( p =0.012). Similarly, 2-year disease-free survival was 100% and 57% for polymerase chain reaction-negative and -positive patients at 12 months, respectively ( p =0.037). No clinical or biological factors were predictive of the achievement of polymerase chain reaction negativity after allogeneic stem cell transplantation. Graft-versus-host disease was more frequent in patients who did not relapse ( p =0.04). Quantitative monitoring of minimal residual disease was able to identify polymerase chain reaction-positive patients with a higher risk of relapse. Conclusions These findings demonstrate that relapsed patients can achieve molecular remission after reduced intensity conditioning and allogeneic stem cell transplantation and suggest a minimal residual disease-driven intervention that might be useful to prevent overt hematologic relapse.

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) represents a potential curative strategy for patients with hematological malignancies. Despite recent improvements in transplantation procedurs and supportive care, acute graft versus host disease (aGvHD) remains the most significant barrier to the success of allo-HSCT. In this contest, strategies directed against GvHD adversely affect survival because they increase malignancy relapse and infections. Approaches aimed at separating graft-versus-tumor (GvT) effect from GvHD are warranted, but difficult to achieve because of their shared biology. Given that JAK signaling dictates T cell differentiation, we postulated that JAKs might be potential therapeutic targets in allo-HSCT through a pharmacological approach. The relative importance of JAK2 signaling in myeloid and lymphoid malignancies drew our attention to the usage of INCB18424 (Ruxolitinb), a JAK1/JAK2 specific inhibitor that was recently shown to be an effective treatment for patients with myelofibrosis. We tested our hypothesis in a mouse model of aGvHD in order to abrogate GvHD, while maintaining a GvT effect. Methods: A major histocompatibility complex (MHC) mismatched HSCT mouse model was set up. Lethally irradiated BALB/c mice received spleen (SC) and bone marrow (BM) cells from donors C57BL/6 (B6) mice, and were treated with INCB18424 for 14 days at the dose of 90mg/kg/day (INC90), 45mg/kg/day (INC45) or 22.5mg/kg/day (INC22.5). Syngeneic transplants (B6-B6) and BALB/c recipients treated with B6 BM cells only were also used. To determine the GvT activity, allo-HSCT recipients were co-injected with either a B-cell lymphoma cell line (A20) or a myeloid leukemia cell line (RMB-1) and treated or not with INCB18424 at the dose of 45mg/kg/day. Mice were monitored for overall survival (OS) and weight loss. GvHD was histologically scored in tissues harvested on day 14, 30 and 60 and cytokine production by ELISA. Immune reconstitution and tumor cells were monitored by flow cytometry. Results: Significantly less GvHD, as determined by survival (INC45, p Conclusions: The inhibition of Jak/STAT signalingusing the sensitive and specific inhibitor of Jak1/Jak2, INCB18424 conferred effective protection from lethal acute GvHD in a MHC mismatched HSCT mouse model while sparing the GvT effect. Our work provides novel evidences of the mechanisms implied in INCB18424-mediated prevention of acute GvHD, demonstrating a significant inhibition of T cell trafficking into GvHD target tissues associated with reduced expression of CXCR3. We expect that these experimental observations may be readily translated into a prospective clinical trial evaluating INCB18424 (Ruxolitinb) for aGvHD prophilaxis after allo-HSCT for patients with hematologic malignancies. Disclosures No relevant conflicts of interest to declare.

Background: Minimal residual disease (MRD) detection is of high clinical relevance in patients with B-cell malignancies and is generally a surrogate parameter to evaluate treatment response and long-term prognosis. IgH gene rearrangements can be used as molecular marker in approximately 80% of lymphoma and myeloma patients since they represent lineage-specific markers and the complementarity determining region 3 (CDR3) is unique to each clone. To date, allele specific oligonucleotide polymerase chain reaction (ASO-PCR) and real-time quantitative polymerase chain reaction (RQ-PCR) are considered the most sensitive and widely applicable methods for MRD detection. A major disadvantage of ASO-PCR and RQ-PCR assays, is the use of specific primers and probes for every individual patient. Clone-specific primers and probes are not only expensive but also time-consuming to design and to test, which limits their wide applicability in the clinical setting. The recent major improvements in next generation sequencing (NGS) technologies, provide the opportunity to identify and quantify clonotypes with consensus primers combining the benefits of high sensitivity and universal applicability. The present work was designed to overcome ASO-PCR and RQ-PCR limitations by developing a feasible method for rearranged IgH genes amplification, NGS and analysis using Ion Torrent Personal Genome Machine (IT-PGM). Methods: To define a multiplex PCR protocol, DNA from 7 CLL patients, previously shown to bare a family specific clonal VDJ rearrangement, was amplified with a pool of the seven different family-specific IgH-V primers, and a consensus JH primer (Voena et al., Leukemia 1997). After Sanger sequencing, results were compared to the ones obtained with singleplex PCR protocol. Once validated, the multiplex PCR protocol was used to amplify DNA from patients and serially diluted (up to 10-8 ) DNA from Namalwa cell line (bearing a known IgH rearrangement) and subsequently sequenced on the IT-PGM using the 316 Ion-chip. NGS data were analyzed by using the IMGT-High V-Quest web server tool and the statistical software R. RQ-PCR was used to quantify the specific VDJ rearrangement in the serially diluted Namalwa DNA solutions and in DNA from patients as previously described (Farina et al, Haematologica 2009). RQ-PCR data were analyzed through a relative quantification procedure. Results: The multiplex PCR reactions we have tested, demonstrated the same specificity as the standard singleplex PCR protocol and therefore was used to construct the DNA library required for IT-PGM-based sequencing. The IT-PGM sequencing output is represented by at least 400000 reads per sample with a minimum average coverage of the VDJ repertoire of 500x. The IMGT-High V-quest tool allows a user-friendly web based analysis and a deep molecular characterization of the IgH recombinatorial repertoire. Namalwa clonal CRD3 sequences were detected up to a dilution of 10-5 without the need for specific CDR3 primers. Comparability of NGS and ASO RQ-PCR results was assessed. The use of CDR3 specific primers, along with the specific IgH-V family fluorescent probe, enabled the identification of clonal VDJ rearrangements with a sensitivity up to 10-5 (2/3 replicates) and 10-6 (just 1/3 replicates) in Namalwa Cell Line. Similar results were obtained when we characterized the IgH recombination repertoire of two CLL patients over time. Conclusions: IgH sequencing with the IT-PGM platform showed at least the same level of sensitivity as ASO RQ-PCR, without the need for patient-specific reagents. It also allows specific and detailed molecular characterization of the clonal rearrangements and could be easily incorporated into clinical laboratories for routine testing of MRD in B-cell malignancies. Disclosures No relevant conflicts of interest to declare.

Background: Peripheral T-cell lymphomas (PTCLs) represent approximately 10-15% of all non-Hodgkin lymphomas (NHL) in the Western world, and their incidence is increasing. Cases of PTCL tend to have an aggressive clinical course, with poor patient responses to conventional chemotherapy and poor long-term survival. So far, treatment approaches have mirrored diffuse large B-cell lymphoma (DLBCL) and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and CHOP-like chemotherapy are commonly used despite suboptimal results. Histone deacetylase inhibitors (HDACs) have been approved for the treatment of relapsed or refractory PTCLs given their single-agent activity in these diseases. To continue to improve responses in patients with PTCL, it is important to assess the utility of romidepsin as frontline therapy and as a component of combination therapies. Aim: Interactions between romidepsin (R) and bendamustine (B), a potent cytotoxic alkylating drug active against a panel of other lymphoproliferative disorders, was investigated in in preclinical models of T-cell Lymphoma. Experimental Design: Assays for cytotoxicity on 5 different T-cell lymphoma and leukemia cell lines (Jurkat, HD-MAR2, Karpas, Sup-T1, HH), mathematical analysis for synergism (Chou-Talalay equation), flow cytometry, and the Itk-Syk transgenic mouse model (K. Pechloff, 2010) were used to explore the in vitro and in vivo activities of R and B alone and in combination in T-cell lymphoid malignancies. Results: In vitro, romidepsin and bendamustine exhibited concentration- and time-dependent cytotoxicity against all the 5 different T-cell lymphoma and leukemia cell lines. Romidepsin showed synergism when combined with bendamustine in all cell lines studied. Romidepsin also induced potent apoptosis and caspase activation when combined with bendamustine across the panel. The impact of schedule on the activity of the combination was determined by assessing cell viability after treatment with B and R as follows: (1) simultaneous exposure; (2) B pretreatment followed by exposure to R; and (3) R pretreatment followed by exposure to B. In a new mouse model of PTCL in which a status of permanent T cell activation mediated by the Itk-Syk transcript induces highly malignant PTCLs with 100% penetrance that resemble the human disease, the combination of romidepsin and bendamustine enhanced efficacy compared with either drug alone. Conclusions: Collectively, these data strongly support the potential therapeutic role of romidepsin in combination with bendamustine for PTCLs and might constitute the basis for future phase I-II clinical trials. Citation Format: Cristiana Carniti, Silvia Gimondi, Antonio Vendramin, Sara Rizzitano, Paolo Corradini. The combination of romidepsin and bendamustin is synergistically cytotoxic and reverses the malignant phenotype in preclinical models of T-cell lymphoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1693. doi:10.1158/1538-7445.AM2014-1693

Introduction Allogeneic stem cell transplantation (alloSCT) is an effective salvage therapy for relapsed B-cell lymphomas. Different studies have shown that Rituximab (R) is implicated in the pathophysiology of acute and chronic GVHD. Methods: We analyzed 153 adult patients who received alloSCT for relapsed/refractory B-cell lymphomas. All patients received the same preparative conditioning consisting of thiotepa/cyclophosphamide/fludarabine, and GVHD prophylaxis consisting in cyclosporine and short course methotrexate. ATG (7 mg/kg) was added to patients allografted from class I antigen mismatched sibling or unrelated donors. Eighty-two patients (group A) received high-dose Rituximab (R 500 mg/ms on day -6) and were enrolled in a prospective multicenter study, whereas 71 consecutive patients (group B, control group) were part of a previous study without R. The two groups were not significantly different in terms of diagnosis (p=0.10), donor types (p=0.74), rate of complete remission at transplant (p=0.51). Results: The cumulative incidence (CI) of non-relapse mortality (NRM) at 2-years was 16% in group A and 18% in group B (p=0.84). Main cause of death were infections without GVHD in group A (7/13) and extensive GVHD in group B (6/14). Deaths associated to acute or chronic GVHD were significantly lower in group A (5 of 13) as compared to group B (13 of 14) (p=0.004). The CI of grade II-IV and III-IV acute GVHD was 23% versus 35% (p=0.11) and 7% versus 14% (p=0.11) in group A versus B, respectively. The CI of chronic GVHD was 48% versus 47% (p=0.73) in group A versus group B, respectively. The CI of acute GVHD and chronic GVHD in unrelated recipients was 20% versus 31% (p=0.41) and 32% versus 40% (p=0.83) in patients who received R in the conditioning comparing to group B. A delayed immune reconstitution of B-cells was still evident at 2 years after alloSCT in group A versus B [median value CD19+: 126/µL versus 300/µL with a significant higher percent of IgD+CD27- in group A and reduced immunoglobulin production: 502 versus 778 mg/dL of IgG (p=0.04)]. Progression free survival (PFS) and overall survival (OS) at 3-years were similar in group A and group B [PFS: 54% versus 58% (p=0.50); OS: 64% versus 67% (p=0.51)]. PFS at 3-years in indolent and aggressive lymphomas was 66% versus 75% and 42% versus 43% with and without R; OS at 3-years in indolent and aggressive lymphomas was 74% versus 78% and 55% versus 57% with and without R. In multivariate analysis, acute GVHD, extensive chronic GVHD and aggressive hystotype were associated to a lower OS [HR=3.6, p=0.0003; HR=2.3,p=0.03;HR=2.1,p=0.01] and only acute GVHD and aggressive hystotype to lower PFS [HR=2.7, p=0.002; HR=2.3, p=0.001]. Rituximab in the conditioning regimen, year of transplant and donor type did not influence the outcome. Conclusions: Rituximab administration in the setting of alloSCT is associated with reduced GVHD-related deaths and increased infection-related deaths, likely due to delayed B-cell immune-reconstitution. Disclosures: No relevant conflicts of interest to declare.

Background Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative option for patients with hematological malignancies. However, its success is limited by life-threatening graft-versus-host disease (GvHD). Strategies to control GvHD are often associated with suppression of the immune system leading to the impairment of the beneficial graft versus tumor (GvT) effect. The ideal approach to prevent and treat GvHD would limit alloantigen-specific reactivity while preserving immunity against malignant cells and pathogens. This study extends our previous findings on the beneficial effect of the inhibition of JAK signaling on acute GvHD (aGvHD) (Carniti et al, ASH2012), evaluating whether INCB18424 (Ruxolitinb) treatment preserved the GvT effect in a mouse model of aGvHD. Methods A major histocompatibility complex (MHC) mismatched HSCT mouse model was set up. Lethally irradiated BALB/c mice received spleen (SC) and bone marrow (BM) cells from donors C57BL/6 (B6) mice, and were treated with INCB18424 for 14 days at the dose of 90mg/kg/day (INC90), 45mg/kg/day (INC45) or 22.5mg/kg/day (INC22.5). Syngeneic transplants (B6-B6) and BALB/c recipients treated with B6 BM cells only were also used. To determine the GvT activity, allo-HSCT recipients were co-injected with either a B-cell lymphoma cell line (A20) or a myeloid leukemia cell line (RMB-1) and treated or not with INCB18424 at the dose of 45mg/kg/day. Mice were monitored for overall survival (OS) and weight loss. GvHD was histologically scored in tissues harvested on day 14, 30 and 60 and cytokine production by ELISA. Immune reconstitution and tumor cells were monitored by flow cytometry. Results INCB18424 treatment caused significantly less GvHD when compared to untreated animals, as determined by survival (INC45, p

Abstract 2997 Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for patients with hematological malignancies. However, its success is limited by a life-threatening complication: the graft-versus-host disease (GvHD). Although numerous studies have described immunosuppression protocols to mitigate acute GVHD (aGvHD), novel approaches are needed. Chemokines are well known inducers of leukocyte trafficking and activation. Stimulation of the chemokine receptor signaling pathway leads to initiation of the Janus Kinase (JAK)/Signal Transducer and Activator of Transcription (STAT) pathway that contributes to the pathogenesis of GvHD. The key role of JAK signaling in normal and abnormal lymphocyte development and function, along with the cytotoxic effects of its inhibitor INCB18424 (Ruxolitinib) on leukemia cells, prompted us to hypothesize that this selective JAK1 and 2 inhibitor could be useful as anti-GvHD agent while maintaining antitumor activity. Since CP-690550, a more selective JAK3 inhibitor, was recently shown to protect against GvHD in mouse models, we also tested whether blocking the JAK1/JAK2 pathway could be more effective in preventing GvHD. Methods: To assess the therapeutic effect of pharmacologic modulation of JAK1 and 2 on GvHD, a major histocompatibility complex (MHC) mismatched HSCT mouse model was used. Recipient BALB/c mice were lethally irradiated and treated either with spleen and bone marrow (BM) cells from C57BL/6 (B6) donors (GvHD cohort, n=8), or with spleen and BM cells from B6 donors along with INCB18424 90mg/kg/day at days -1 to 13 (INCB18424 cohort, n=10) or with CP-690550 15mg/kg/day (CP-690550 cohort, n=8) at days -1 to 13. Syngeneic transplants (B6-B6, n=6) and BALB/c recipients treated with B6 BM cells only (control cohort, n=8) were also included as controls. Mice were characterized for GvHD by monitoring overall survival and weight loss. Recipient mice were sacrificed and tissues harvested on day 14 and 30 post transplant and GvHD confirmed by histology. Results: All mice in the GvHD cohort had clinical evidence of GvHD (weight loss, generalized erythema of the skin and poor fur quality) by day 14. The INCB18424 treated mice showed markedly reduced weight loss along the time of observation when compared to the GvHD cohort. Animals in the CP-690550 cohort tended to gain weight during the time of treatment (day-1 to 13), but thereafter they exhibited reduced body weight similar to that observed in the GvHD cohort. The histological examination of the stomach, liver, skin and intestine obtained at day 14 revealed no sign of GvHD in the control group as well as in the INCB18424 group. On the other hand, mild to moderate signs of GvHD were present in the tissues of CP-690550 treated mice and extensive inflammation and disruption of the normal architecture of the tissues was observed in the GvHD group. To determine whether INCB18424 treatment affected alloreactive CD4+ T cells, total spleen T cells were harvested at day 14 from the GvHD cohort and from recipients either of INCB18424 or CP-690550. Total spleen T cells were co-cultured with BM derived BALB/c (recipient-derived) or C57BL/6 (donor-derived) dendritic cells (DCs). After 24h, T cells alloreactivity was determined by IFN-γ production assessed by intracellular staining. As expected, T cells from GvHD mice showed significantly higher alloreactivity against BALB/c DCs compared to the reactivity observed against syngeneic B6 DCs (5.24% and 0.84% respectively, p Conclusions: The inhibition of Jak/STAT signaling using the sensitive and specific inhibitor of Jak1/Jak2, INCB18424, conferred effective protection from aGvHD in a HSCT mouse model. INCB18424 treatment was more effective than the targeting of JAK3 with CP-690550. In fact, CP-690550 administered during GvHD induction was not completely sufficient to restore the normal weight and to prevent the histological appearance of GvHD whereas INCB18424 was. INCB18424 protected mice against acute GvHD by significantly decreasing alloreactive CD4 T cells. Disclosures: No relevant conflicts of interest to declare.

Abstract 1898 Background: In mice, graft-versus-host disease (GvHD) can be abrogated by ex vivo expanded, bone marrow derived myeloid-derived suppressor cells (MDSCs) generated in the presence of GM-CSF, G-CSF and IL-13 (Highfill et al). Whether MDSCs play a role in human allogeneic hematopoietic stem cell transplantation (allo-HSCT) is still unclear. We hypothesized that G-CSF stem cell mobilization may be protective from acute GvHD (aGvHD) by increasing MDSC frequencies. Methods: G-CSF-mobilized peripheral blood (PB) samples were collected from 40 healthy unrelated donors (median age 34, range 20–43, male/female 31/9) who received G-CSF (Filgrastim) at 10 μg/kg/day for 5 days. Donor selection had been performed according to standard criteria, including molecular typing for HLA-A,-B,-C, DRB1, and DQB1. Donors were 10/10 HLA-matched (MUD) in 20 cases, 9/10 in 13 cases and 8/10 in the remaining 7 cases (MMUD). Patients (median age 46, range 18–67) received reduced intensity conditioning based or low-dose total body irradiation (TBI 2Gy) (8), Fludarabine-Rabbit Antithymocyte Globulin (ATG) (9) or Thiotepa-ATG (23). Diagnosis were lymphomas (29), myelomas (8), acute myeloid leukemia (3). GvHD prophylaxis was cyclosporine plus either methotrexate (36) or mycophenolate mofetil (4). As controls, PB samples were collected from 10 healthy adults. Informed consent was obtained from all subjects. Cells were characterized using flow cytometry with Abs against CD3;CD14;CD16;CD19;CD20;CD56;CD11b;HLADR;CD33. The frequencies of MDSCs and T regulatory cells (Tregs, CD4+CD25+CD127-FoxP3+) in the grafts were correlated with the clinical characteristics and outcome of the 40 patients. To verify that G-CSF treatment increases the number of MDSCs that are transferred with the graft and prevent GvHD, a major histocompatibility complex (MHC) mismatched HSCT mouse model was also used. After lethal irradiation, recipient BALB/c mice received spleen and bone marrow (BM) cells from C57BL/6 (B6) donors (GvHD cohort, n=5) or BM cells only (negative control, n=3). To generate MDSC enriched allografts, donor mice were treated with G-CSF (5 μg/d for 5 days) and thereafter BM cells and spleen cells were transferred in recipient mice (MDSC cohort, n=5). Results: Expansion of MDSCs (Lin-/LoHLADR−CD33+CD11b+) in the PB of G-CSF-treated unrelated donors was found with respect to steady state control individuals (p< 0.03, Mann Whitney-U). Acute GvHD occurred in 16 of 40 patients (40%). There was no significant correlation between the incidence of aGvHD and the degree of HLA incompatibility or the presence of donor-recipient sex mismatches. Neither the conditioning regimens nor the GvHD prophylaxis had effect on risk of aGvHD. There was no correlation between the number of Tregs infused and the occurrence of GvHD.Conversely, aGvHD patients received grafts containing significantly lower number of MDSCs when compared to non- aGvHD patients (p < 0.006, Mann Whitney-U). The ability of MDSC levels in the graft to predict the occurrence of aGvHD was determined by the receiver operating characteristic (ROC) curve: sensitivity was 100%, specificity 60%, AUC=0.768. The immunosuppressive activity of the MDSCs on activated T lymphocytes was confirmed in vitro. To confirm these results, we set up a MHC mismatched HSCT mouse model. G-CSF treatment induced a significant increase in MDSCs (up to four fold, p Conclusions: G-CSF mobilization significantly increases circulating MDSC both in Matched Unrelated Donors and in mice. In humans, a significant correlation between the frequencies of MDSC present in the graft and the incidence of aGvHD was found. This result was further confirmed using a MHC mismatched HSCT mouse model. Mice treated with G-CSF received grafts containing higher numbers of MDSCs and developed less severe aGvHD than the untreated mice. Taken together, these findings strongly suggest that G-CSF stem cell mobilization is protective against aGvHD through MDSCs augmentation and might be relevant to modify GvHD prophylaxis. Disclosures: No relevant conflicts of interest to declare.

Abstract 311 Background: Acute graft-versus-host disease (aGVHD) results in significant morbidity and mortality and remains the main complication of alloHSCT. Noninvasive, diagnostic and prognostic tests for aGVHD are currently lacking but essential to predict GVHD and to improve the safety and accessibility of alloHSCT. We hypothesized that the prospective analysis of miRNA expression profile in the plasma of allografted patients could allow for the detection of specific miRNAs with predictive role for aGVHD. Methods: After informed consent, we collected plasma samples from 10 healthy donors and 22 patients (median age: 59 and 41 years) who received unmanipulated alloHSCT (18 from Matched Unrelated Donors and 4 from HLA-matched siblings). Blood samples were collected weekly after HSCT and patients were monitored to assess aGVHD onset. MicroRNAs were isolated from the plasma and the miRNA expression profile examined using a quantitative PCR-method (TaqMan® Human microRNA Cards, Applied Biosystems). The results obtained were subsequently validated with specific miRNA Single Assays (Applied Biosystems). To verify whether the miRNAs emerged from the human studies represent markers of aGVHD and provide information regarding the involvement of specific target organs, a major histocompatibility complex (MHC) mismatched HSCT mouse model was used. Recipient BALB/c mice were lethally irradiated and treated either with spleen and bone marrow (BM) cells from C57BL/6 (B6) donors (GVHD cohort, n=22) or with BM cells only (negative control, n=18). Syngeneic transplants (B6àB6, n=6 were also included. Mice were characterized for GVHD onset by monitoring overall survival and weight loss. Recipient mice were sacrificed and tissues harvested on day 9, 14 and 18 post transplant and GVHD confirmed by histology and scored according to Foley et al, 2008. MiRNAs expression profile have been characterized in the plasma, skin, liver, colon and lymphocytes of GVHD and non-GVHD control cohorts Results: Three of 22 patients developed intestinal GVHD (grade 2) and 9 of 22 patients developed cutaneous GVHD (grade 2–3). By comparing the circulating miRNAs expression profiles of GVHD patients and non GVHD patients, we identified a group of 8 differentially expressed miRNAs (miR-136, 194, 203, 367, 148b, 196b, 26a, 340) (p Conclusions: Considering the noninvasive characteristics of plasma sampling and the reproducible and easy detection of miRNAs, our results indicate that circulating miRNAs might represent a promising tool for the early diagnosis of aGVHD thus enhancing therapeutic success and increasing life expectancy of allografted patients. In addition the miRNA profiling of the target organs and lymphocytes of GVHD mice, allowed the identification of several deregulated genes that might play a role in the modulation of aGVHD and warrant further investigations. Disclosures: No relevant conflicts of interest to declare.

Abstract 4546 Background: Reduced-intensity conditioning (RIC) followed by allogeneic stem cell transplantation (alloSCT) is an effective salvage therapy for relapsed lymphomas. The present GITMO study is a prospective multicenter phase II trial for patients affected by relapsed CD20 positive lymphomas. Compared with the previous thiotepa/fludarabine/cyclophosphamide GITMO protocol (Leukemia 2007), the thiotepa dose is increased, and high-dose Rituximab is included in the regimen to improve the outcome and possibly modulate the incidence of acute GVHD. Aims: Primary end-point was 1-year progression-free survival; secondary endpoints were non-relapse mortality and incidence of acute and chronic GVHD. Methods: Fifty-seven patients (pts) were enrolled so far in the study and 49 are evaluable for analysis. Treatment plan consisted of high-dose R (500 mg/ms on day -6) followed by thiotepa (12 mg/kg), fludarabine (60 mg/kg) and cyclophosphamide (60 mg/kg). Graft-versus-host disease (GVHD) prophylaxis included cyclosporine and mini-methotrexate; ATG (7.5 mk/kg) was only added for pts allografted from one antigen mismatched sibling or unrelated donors. Histopathological subtypes included 24 aggressive (HG) (n= 17 diffuse large B-cell lymphomas, n= 7 mantle cell lymphomas) and 25 indolent lymphomas (LG) (n= 13 follicular lymphomas, n= 12 small lymphocytic/chronic lymphocytic leukemia). Patients were allografted from related siblings (SIB) (n= 32 matched, n=1 one single mismatched) or unrelated donors (UD) (n=11 matched, n=5 mismatched). All the pts had chemosensitive disease (n=20, 41% in complete remission) and 26 (53%) came from a failed autoSCT. Results: At a median follow-up of 13 months (range, 5–44 months), 36 pts are alive [n=27 (75%) in CR] and 13 died from any cause [n=6 for non-relapse mortality (NRM), n=7 for disease progression]. All the patients engrafted (94% had full donor chimerism at 3 months). The cumulative incidence (CI) of NRM was 13% at 1 year: 9% vs 19% for SIB and MUD (p=0.3), and 9% versus 16% for for LG and HG (p=0.3), respectively. In total only 11 of 49 pts had acute GVHD (n=8 grade II, n=3 grade III) with an estimated CI of 21% at 100 days. In the previous GITMO study the incidence was 35% with SIB only. Forty pts are evaluable for chronic GVHD with an estimated CI of 41% and 47% at 1 and 2 year, respectively (n=11 limited, n=3 extensive). Infections after engraftment requiring hospitalization or intravenous treatment were evaluable in 46 pts (n=3 excluded for early death). The overall incidence of infections was 58% (n=27) including 5 pts experienced sepsis and 10 pts pneumonia. Preliminary data on immune-reconstitution at 1 year showed: 1) low number of circulating B cells (median CD19+/ul: 129/ul) with an expansion of naive cells (IgD+, CD27-); 2) the median value of IgM was 89 mg/dl whereas IgG and IgA remained at low levels. The CI of relapse was 26% and 37% at 1 year and 2 years, respectively. In the indolent and aggressive groups, OS estimates at 2 years were 79% (95%CI, 52%-91%) and 61% (95 CI, 38%-77%) and PFS estimates were 53% (95%CI, 23%-76%) and 48% (95% CI, 27%-66%), respectively. Conclusions: The present data suggest that the administration of high-dose R is feasible and causes an unexpected reduction of the incidence of acute GVHD without increasing the NRM and the incidence of severe infections complications. Complete data evaluating the effects of R on immune reconstitution are ongoing. Disclosures: No relevant conflicts of interest to declare.

Abstract 2308 Introduction: Allogeneic haemopoietic-stem-cell transplantation (HSCT) is the treatment of choice for many malignant and non-malignant disorders. Despite the recent advances in post-transplant immunosuppressive therapy, Graft-versus-Host Disease (GVHD) still represents the major life-threatening complication, developing in a substantial number of HSCT patients and resulting in poor outcome. Recent studies have indicated that microRNAs (miRNAs) circulate in a stable, cell-free form in the bloodstream and that the abundance of specific miRNAs in plasma or serum can serve as biomarkers of cancer and other diseases. We examined plasma microRNA (miRNA) expression levels from patients transplanted from matched unrelated donor (MUD) to assess their clinical application for diagnosing and monitoring GVHD. Methods: Having obtained an informed consent, we collected plasma samples from 11 patients who received unmanipulated HSCT from MUDs. After HSCT, 5 of 11 patients developed acute GVHD. Blood samples were collected serially at day +30, +60, +90, +150 after HSCT. MicroRNAs were isolated from the peripheral blood (PB) plasma using a modified mirVana™ miRNA Isolation Kit (Ambion Inc). The miRNAs expression profile was examined using a quantitative PCR-method (TaqMan ® Human microRNA cards, Applied Biosystems) that allows the analysis of 384 human miRNAs by low density array technology. Plasma samples of normal subjects have been included in the study. Relative quantification of miRNA expression was calculated with the 2-ΔΔCt method. The data were normalized respect to hsa-mir-122 and relative to a calibrator sample (average of normal subjects plasma samples). Results: Initial analysis showed that miRNAs are stable and detectable in all plasma samples from MUD transplanted patients. Among the 384 mirRNAs analyzed we identified a panel of mirRNAs that may have a predictive role for GVHD. Among these, we have identified mir203 which is upregulated in patients prior to the onset of GVHD and its expression decreases upon therapy. Mir203 acts downregulating SOCS3, the endogenous regulator of cytokine signaling through JAK-STAT3 which is involved in the activation of the immune response. The importance of SOCS3 in the pathogenesis of GVHD has been recenly demonstrated (Hill et al. Blood, 2010) confirming the potential regulatory role of mir203 in this disease. Of interest, the evaluation of mir203 expression levels at day +30 after HSCT is able to clearly classify the patients who will develop GVHD from those who will not (p-value Conclusions: Profiling of mir203 in a wider and heterogeneous group of patients receiving allo-HSCT is ongoing to extend and confirm the present findings. Although preliminary, these results indicate that the detection of circulating miRNAs might provide new complementary markers of GVHD. In particular the elevated plasma level of mir203 at day +30 after HSCT may be used to predict the risk of developing GVHD. Disclosures: No relevant conflicts of interest to declare.

Abstract 4494 1.Background Mismatches of minor Histocompatibility antigens (mHAg) have been considered as an important immunogenetic factor influencing outcomes and immune responses following allogeneic stem-cell transplantation (alloSCT) despite fully matched HLA of donor and recipient. 2. Aim Aim of this study was to assess whether mHAg incompatibilities may affect overall survival (OS), progression free survival (PFS) and GVHD incidence (acute and chronic, aGVHD and cGVHD) in patients receiving alloSCT for lymphoid malignancies. 3. Methods Sixty-four consecutive patients with B-cell lymphomas who underwent alloSCT were studied. Ten patients had chronic lymphocytic leukemia (CLL, 15.8%), 3 had follicular lymphoma (FCL, 4.7%), 1 had diffuse large B cell lymphoma (DLBCL, 1,5%), 17 had Hodgkin's lymphoma (26.5%) and 33 had multiple myeloma (51.5%). All underwent peripheral blood stem-cells allograft with non-myeloablative (13 patients, 20%) or reduced intensity (51 pts, 80%) Fludarabine-based conditioning; GVHD prophylaxis included methotrexate and oral cyclosporine +/- micomofetil fenolate in case of matched unrelated donors. Median age was 51 years (range 18-66); 35 patients were male (55%), median number of previous chemotherapies was 3 (0-7), 49 patients had a previous autologous transplant (76%). Twenty-five patients were in complete remission (CR, 39%), 30 and 9 were in partial response and progression (PR 47% and PD 14%). Karnofsky performance status (PS) was >80% in 50 patients (78%). Forty-four patients allografted from HLA-matched siblings (69%), 20 from matched unrelated donor (31%): all were matched at allelic level for HLA-A, -B, -Cw, -DRB1 and -DQB1 loci. Allelic mHAs typing was performed by PCR with sequence-specific primers for 14 autosomic mHAg and H-Y. Host versus Graft or Graft versus Host direction of immune responses in donor/recipient pairs was analyzed with use of the minor Histocompatibility Database of Leiden University Medical Center. OS and PFS were analyzed with Kaplan-Meier method and log-rank test. aGVHD and cGVHD were analyzed with a multivariate logistic regression including as covariates age, sex, previous lines of chemotherapy, disease, pre-transplant status, PS and mHAs mismatches; grade >=2 aGVHD and extensive cGVHD were considered events. 4. Results Median follow-up was 34 months (2-83). One-year OS was 85%, 2- and 3-years OS were 82% and 77%. One-year PFS was 61%, 2- and 3-years PFS were 49% and 41%. The univariate analysis which considered transplant characteristics showed that OS and PFS were significantly affected by disease status at transplant (p80, p 5. Conclusions This study showed that in the non-myeloablative and RIC setting, mHAg mismatches may have a significant role in determining aGVHD. Assessing mHAg mismatches may be a useful tool to choose patient-specific GVHD prophylaxis in conditioning regimens and in post transplant follow-up. Larger prospective data are needed in order to confirm these results. Disclosures: No relevant conflicts of interest to declare.

Purpose: Haploidentical hematopoietic stem cell transplantation (haplo-SCT) provides an option for cancer patients lacking a compatible donor. However, the delayed immune reconstitution increases incidence of opportunistic infections and disease relapse. We conducted a phase I-II prospective trial to evaluate the effect of escalating doses of CD8-depleted (Miltenyi Device) donor lymphocyte infusions (DLIs) following RIC haplo-SCT. Here, we present the data on the immune reconstitution. Patients and Methods: Twenty-eight patients (pts) with advanced lymphoproliferative diseases (n=24) or acute myeloid leukaemia (n=4) were enrolled in this study. Fifteen (54%) of 28 pts had refractory disease. All pts received a thiotepa-fludarabine based RIC regimen, with an ex vivo and in vivo T-cell depletion performed by CD34+ cell selection and alemtuzumab infusion. Fifty-four CD8-depleted DLIs were administered to 23 pts [dose level 1 (n=4): 1×104/kg on days + 45, +75, +105; dose level 2 (n=11): 5×104/kg on days + 45, +75, +105; dose level 3 (n=8): 1×104/kg on day+ 45, 5x104/kg on days +75 and +105]. Results: At a median follow-up of 29 months, 12 pts are alive (n=3 Hodgkin Lymphoma, n=6 Non-Hodgkin Lymphoma, n=1 Multiple Myeloma, n=2 Acute Myeloid Leukemia) and 16 died from any cause [n=6 for non-relapse mortality (NRM), n=10 for disease progression] with a 2-year estimates of overall survival of 39%. The 2-year cumulative incidence of NRM and relapse were 26% and 51%, respectively. Six pts (26%) developed grade II-IV acute graft-versus-host disease (GVHD) (dose level 1: no GVHD; dose level 2: 5 cases; dose level 3: 1 case). Following CD8-depleted DLIs, the major findings were:(i) a significant expansion of memory CD4+ cells and CD19+ cells (median value 107/μL and 135/μL, respectively) at 120 days after haplo-SCT; (ii) de-novo T-cell responses to cytomegalovirus (CMV) peptides performed by activation-induced CD137 expression: the median frequency of CMV-specific CD8+/CD137+ and CD4+/CD137+ cells were 2% and 0.4% at 200 days after haplo-SCT, respectively, as evaluated in a subset of pts at risk for CMV reactivation (R CMVpos/D CMVpos/neg); this frequency was associated to a clearance of CMV antigen; (iii) recovery of thymopoiesis: 10 of 20 (50%) pts showed measurable TREC at 1 year after haplo-SCT; (iv) the increase of CD19+ cells was associated to reconstitution of B lymphocyte repertoire as analysed by Immunoglobulin heavy chain (IgH) CDR3 spectratyping: median number peaks in normal donors and pts, at day 360 after haplo-SCT, were 17 (range, 14–21) versus 12 (range, 7–14), respectively. Conclusions: Our study showed that CD8-depleted DLIs are a feasible procedure with low acute GVHD when using dose level 3. Long-term disease remissions can be observed in advanced lymphoid malignancies. Escalated doses of CD8-depleted DLIs exert complex effects on immune reconstitution: (i) provide help to expansion of CD8 T-cell clones, as suggested by the occurrence of the anti-CMV reactivity; (ii) support B-cell recovery, as demonstrated by a partial recovery of CDR3 polyclonality.

Reduced intensity allogeneic stem cell transplantation (RIC alloSCT) is a therapeutic option for poor risk relapsed chronic lymphocytic leukemia (CLL) and can lead to 50% of progression-free survivors. The aims of this study were: to assess the “molecular quality” of clinical remission after RIC alloSCT in CLL patients; to investigate whether molecular remission (MR) can correlate with a lower relapse risk; to understand the clinical role of molecular monitoring in post-transplant immunotherapy. Twenty-nine patients with a molecular marker (heavy chain gene immunoglobulin rearrangement, IgH) were monitored for minimal residual disease (MRD). All patients had a relapsed disease; 75% had an unmutated IgH; cytogenetic analysis was available in 13 patients at first relapse, and 5 of them (38%) showed a 17p deletion. Median age at transplant was 60 years (range, 44–69). Median number of previous chemotherapy was 3 (range, 1–6) and 29% of patients failed autologous transplant. Eleven patients (38%) were chemorefractory before transplant. The conditioning regimen included thiotepa-cyclophosphamide-fludarabine in HLA identical sibling transplants (n=21), and an in vivo T cell depletion in haploidentical and unrelated alloSCT (n=8). Molecular monitoring was performed by nested-PCR on bone marrow using CDR-2 and CDR-3-derived patient-specific primers. For real-time PCR a FR3-derived probe was used. Post-transplant samples were amplified including the pre-transplant sample as positive control, and ΔCT was calculated after normalization for GAPDH gene. Eight patients (28%) were PCR-negative: 4 of them (14%) have been always PCR-negative while 4 patients (14%) experienced a delayed clearance of MRD during the first year after transplant. All these patients are alive and in CR at the median follow-up of 24 months (range, 3–71). Seven patients (24%) showed a mixed pattern of PCR positivity and negativity: one patient died of secondary acute leukemia, another patient had a nodal relapse, the others are in CR at a median follow-up of 30 months (range, 6–60). Fourteen patients (48%) were always PCR-positive: 7 of them relapsed after a median time of 9 months (range, 3–12); 2 patients died of TRM in MR; 5 patients are alive and in CR after a median follow-up of 15 months (range, 3–24). Relapse risk was higher for PCR-positive patients compared to PCR-mixed/negative patients (p=0.014). Eighty percent of PCR-mixed/negative patients experienced GVHD compared to 43% of PCR-positive patients (p=0.06). In 5 PCR-positive patients real-time PCR was carried out. In 3 patients that did not relapse a decreasing tumor load was detected; these patients were affected by extensive chronic GVHD. In the other 2 patients after an initial reduction, the tumor load increased on day +300 and +270: both patients relapsed on days +420. In conclusion, in poor risk relapsed CLL clinical and molecular remission can be achieved in a sizeable fraction of patients after RIC alloSCT. Persistent PCR positivity correlates with a high incidence of relapse and requires novel treatments, while a mixed-PCR pattern can be observed without clinical relapse.

Acute graft-versus-host disease (aGVHD) results in significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Noninvasive diagnostic and prognostic tests for aGVHD are currently lacking, but would be beneficial in predicting aGVHD and improving the safety of allo-HSCT. Circulating microRNAs exhibit marked stability and may serve as biomarkers in several clinical settings. Here, we evaluated the use of circulating microRNAs as predictive biomarkers of aGVHD in lymphoma patients after allo-HSCT from matched unrelated donors (MUDs). After receiving informed consent, we prospectively collected plasma samples from 24 lymphoma patients before and after unmanipulated MUD allo-HSCT; microRNAs were then isolated. Fourteen patients developed aGVHD symptoms at a median of 48 days (range: 32–90) post-transplantation. Two patients developed intestinal GVHD, eight cutaneous GVHD, and four multiorgan GVHD. The microRNA expression profile was examined using quantitative real-time polymerase chain reaction (qRT-PCR). MicroRNAs 194 and 518f were significantly upregulated in aGVHD samples compared with samples taken from non-aGVHD patients. Remarkably, these upregulated microRNAs could be detected before the onset of aGVHD. Pathway prediction analysis indicated that these microRNAs may regulate critical pathways involved in aGVHD pathogenesis. Considering the noninvasive characteristics of plasma sampling and the feasibility of detecting miRNAs after allo-HSCT using real-time polymerase chain reaction, our results indicate that circulating microRNAs have the potential to enable an earlier aGVHD diagnosis and might assist in individualizing therapeutic strategies after MUD allo-HSCT. Nevertheless, standardization of blood sampling and analysis protocols is mandatory for the introduction of miRNA profiling into routine clinical use.