ALBERT

Description: Background: Separating graft versus leukemia (GvL) from graft versus host disease (GvHD) is a critical issue in allogeneic bone marrow transplantation (allo BMT) for malignant hematopoietic cancers. Vasoactive intestinal peptide (VIP) is capable of inducing tolerogenic dendritic cells (DC) from bone marrow progenitors that limit GvHD (Blood 2006 107:3787). We have published that use of donor mice deficient in VIP or pharmacological blockade of VIP-signaling both increased cellular anti-viral activity in murine allo BMT models of CMV infection (JI 2011 187:1057, Blood 2013 121:2347). We hypothesized that blockade of VIP could enhance GvL activity without increasing GvHD in recipients of allo BMT. Methods: We used the B10BR to B6 and B6 to B10BR murine allo BMT models, with luciferase-expressing C1498 acute myeloid leukemia and LBRM acute T-lymphoblastic lymphoma tumor cells, respectively, to study the effect of VIP-signaling on GvL and GvHD. Murine recipients of WT TCD-BM plus splenic allografts (5 x106 TCD-BM plus 0, 0.5, 1.0 and 3.0 x106 splenocytes) were treated with 7 daily s.c. injections of VIPhyb, a VIP antagonist, on d-1 to d+5 (early treatment) or d+6 to d+12 (late treatment), or PBS. Tumor cells were administered by i.v. injection one day before transplant (d-1), and tumor burden was monitored by bioluminescence imaging (BLI). Expression of activation immune cell markers, intracellular cytokines, and ex vivo cytolytic activity against tumor were measured by flow cytometry. TCR-β clono-types were analyzed by TCR-β CDR3 deep sequencing. Results: Recipients of VIP-KO donor cells and VIPhyb-treated recipients of WT donor cells did not have more GvHD than untreated recipients of equivalent numbers of splenocytes from WT donors. VIPhyb-treatment significantly increased survival of transplant tumor recipients in the B10.BR to B6 model with C1498 (2 replicate experiments, n= 10 in VIPhyb early-treatment, p

Description: Background: Acute graft-versus-host disease (aGvHD) remains a critical barrier to the success of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nearly all patients who undergo allo-HSCT receive red blood cell (RBC) transfusions during the first 30 days post-transplant, but the long-term effects of transfusions on post-transplant outcomes remain unclear. Preclinical and clinical studies indicate that RBC transfusions can activate dendritic cells (DCs) sensitizing transplant recipients to minor histocompatibility antigens (miHA). Initial interactions between donor T cell and DC regulate donor T cell activation and proliferation. We hypothesized that RBC transfusion may contribute to aGvHD in allo-HSCT patients by activating DC and stimulating allo-reactive T cells or other inflammatory pathways. Methods: We conducted a retrospective study of 336 adult allo-HSCT patients at Emory University Hospital from 2007 to 2013. In cases involving multiple transplants, only data relevant to the first allo-HSCT was included. Graft sources were restricted to bone marrow and G-CSF mobilized peripheral blood (excluded cord blood and T cell depleted grafts). 181 patients (54%) were male and 155 (46%) were female. Patients received transplants from matched related donors (n=123, 37%) or matched unrelated donors (n=213, 63%) for treatment of AML (n=132), ALL (n=40), acute leukemia (n=5), MDS (n=41), CML (n=22), CLL (n=15), HD (n=6), NHL (n=33), AA (n=10), MM (n=7) or other diseases (n=25). aGvHD with onset of up to 150 days after allo-HSCT was the primary end-point. Leuko-reduced and irradiated RBC transfusions administered during the week prior to transplant and 30 days post-transplant (while patients were closely monitored at the transplant center) were provided by a single Blood Bank. The median follow up time was 14.6 months post transplantation (range, 0.3 to 65.1 months). The relationship of RBC transfusions to aGvHD was determined as a time-dependent variable or as a function of the total number of RBC units transfused. Results: 306 patients (91%) received RBC transfusions during the observation timeframe, while 30 (9%) did not require transfusion (median 6). 221 patients (66%) developed grade I-IV aGvHD with a distribution of 85 (25%), 72 (21%), 47 (14%), and 11 (3%) of patients with maximum grade of I, II, III and IV, respectively, while 115 (34%) patients did not show any signs of aGvHD. We compared transfusion history, prior to the diagnosis of GvHD, in patients who developed grade 0-II aGvHD (n=272, 81%) vs. grade III-IV aGvHD (n=64, 19%). Patients with grade III-IV aGvHD received more RBC units (median 8) than patients with grade 0-II aGvHD (median 4). In univariable Cox regression analysis, factors significantly associated with grade III-IV acute GvHD were HLA match (HR 2.22, p=0.004), number of RBC units per week (HR=1.26, p

Description: Background: With existing anti-tubercular therapies, treatment success rates for multi- and extensively-drug resistant tuberculosis (MDR-TB, XDR-TB) are dismal, highlighting the urgent need for new drugs. Ratios of myeloid to lymphoid cells are important predictors of TB disease susceptibility and vaccine efficacy. Imatinib mesylate (Gleevec), a cancer drug used in humans for chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors (GISTs), is a potential "host- directed therapeutic (HDT)" for drug resistant TB infections and HIV/TB co-infections. Imatinib inhibits c-Abl tyrosine kinase (TK), which is dysregulated in CML, as well as related TKs (e.g. c-Kit). Imatinib facilitates clearance of Mycobacterium tuberculosis (Mtb), by disrupting the cellular mechanisms that Mtb uses for entry and survival in host cells. At doses 10-fold lower than those used for CML, imatinib also stimulates "emergency hematopoiesis," a host immune response to infection that mobilizes myeloid cell differentiation in the bone marrow and alters ratios of myeloid to lymphoid cells in the periphery towards protective levels, an effect suppressed by Mtb. Imatinib acts synergistically with antibiotics and is effective against antibiotic-resistant mycobacteria, and may be less likely to engender resistance compared to antibiotics. Preclinical data at low doses indicate efficacy of imatinib in a non-human primate (NHP) model of infection with TB or, alternatively, TB/SIV, which mimics poorly controlled TB or HIV/TB in humans. Study Design, Endpoints, and statistical design: We describe the design of two NIH-sponsored Phase II clinical trials in humans (NCT03891901). The first trial will comprise testing of 4 low doses of imatinib with or without antibiotics in 72 normal individuals in the United States. We will determine safety, immunological responses, and drug-drug interactions with standard of care antibiotics. The primary endpoints are to (i) identify the two best doses that induce myelopoiesis in humans, (ii) maximize bactericidal activity by immune cells ex vivo, and (iii) maximize safety. The trial is powered to detect a 2-fold increase in myelopoiesis across all imatinib doses relative to untreated individuals. The second trial will assess the safety and microbiologic efficacy of two doses of imatinib administered over 3 months in conjunction with optimized background antibiotic regimens versus the optimized background regimen alone. The trial will include 180 individuals with TB or HIV/TB in South Africa (60 per arm). The primary endpoints are (i) the time to sputum culture conversion, (ii) lung function by PET-CT and spirometry, and (iii) immunological parameters associated with myelopoieisis. Secondary endpoints include transcriptomics, proteomics, and measures of pathogen-specific immune responses. The trial is powered to detect a 2-fold increase in myelopoiesis across all imatinib doses relative to untreated individuals. The trial is statistically powered to distinguish at either dose an improvement over baseline treatment in time to sputum conversion or lung function or both. Major Inclusion/Exclusion Criteria: Phase II dosing trial: Normal volunteers, age 18 - 55 years. Phase II efficacy trial: Active antibiotic-sensitive tuberculosis with or without HIV. Pregnant women are excluded from both studies. Trial Status : The dosing trial has FDA and NIAID approval to begin and is currently undergoing registration with DAIDS prior to starting enrollment. Overall Goal: Data from these trials will provide a paradigm with which to further evaluate imatinib or other immunomodulatory HDTs as therapeutics for TB infection and HIV/TB co-infection. If successful, imatinib may shorten the time of treatment and limit development of antibiotic resistance, and may be useful against antibiotic resistant strains. This project is supported a grant from NIH/NIAID. Disclosures Waller: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Other: Travel expenses, Research Funding; Cerus Corporation: Other: Stock, Patents & Royalties; Chimerix: Other: Stock; Cambium Oncology: Patents & Royalties: Patents, royalties or other intellectual property ; Amgen: Consultancy; Kalytera: Consultancy. OffLabel Disclosure: Imatinib is known as a therapeutic for CML. Here, we will discuss our plans to develop imatinib as a host-directed-therapy to improve treatment of multi-drug-resistant tuberculosis

Description: Introduction: Donor plasmacytoid dendritic cells (pDCs) have important roles in the pathogenesis of graft versus host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Vasoactive intestinal peptide (VIP), a potent anti-inflammatory neuropeptide with pleiotropic effects, has shown promise in managing GvHD through induction of regulatory dendritic cells (Chorny, Blood 2006) and regulatory T cells (Delgado, JLB 2005). Our previous data showed that transplantation of hematopoietic stem cells (HSC) lacking VIP expression in enhanced Th1 polarization and antiviral immunity (Li, JI 2011). Whether VIP produced by pDCs plays a key role in preventing GvHD is the focus of the current study. Method: A reductive allo-HSCT model was established by transplanting purified populations of 5 x 103 hematopoietic stem cells (HSC), 5 x 104 pDCs and 106 T cells from B6 (H-2Kb) to MHC mismatched B10.BR (H-2Kk) recipients. Mice received either VIP knockout pDCs (experimental group) or wild-type pDCs (control). Survival and clinical GvHD scores were monitored for at least 60 days. Serum pro-inflammatory cytokines were measured by luminex on day 3 and day 8. Additional recipients were transplanted for interim analyses of GvHD pathology in histological sections of small intestine and colon on day 8 and day 15. To investigate pDC migration and proliferation status, 5 x 104 luciferase-expressing pDCs, together with 5 x 103 WT B6 HSC, were transplanted to MHC mismatched Balb/c (H2kd) recipients. Bioluminescent imaging was performed on day 14. We used mice carrying an eGFP reporter linked to a VIP promoter to measure VIP production by donor cells in vivo. The construct has the eGFP reporter gene, followed by a polyadenylation sequence, inserted into BAC clone RP23-25A8 at the initiating ATG codon of the first coding exon of the VIP gene, so that eGFP expression is driven by the regulatory sequences of the BAC gene. The BAC is inserted randomly in the genome. We used serial breeding to establish the eGFP-VIP reporter in B6 mice. Bone marrow pDCs were sorted from transgenic eGFP-VIP B6 mice and used in transplant experiments, allowing VIP gene activity from donor-derived pDCs to be detected as GFP expression using confocal microscopy. Results: Compared to recipients of WT pDCs, recipients of VIP-KO pDCs have a significantly lower survival rate with increased GvHD clinical score (Figure 1; *p

Description: Key PointsThe transcriptional networks controlling breakthrough acute GVHD can be mapped, and correlate closely with clinical disease. Breakthrough acute GVHD is transcriptionally controlled by T-cell persistence, inflammation, and Th/Tc17 skewing.

Description: Abstract 1002 Background: Vasoactive intestinal peptide (VIP) is a neuropeptide hormone and type 2 cytokine that inhibits Th1 immunity and induces the generation of regulatory T-cells. We have recently reported that non-transplanted mice “knocked-out” for VIP and syngeneic transplant recipients of VIP-knockout (KO) BM had dramatically improved survival, viral clearance, and increased numbers of specific antiviral CD8+ T-cells following murine cytomegalovirus (mCMV) infection (JI 2011. 187:1057–65). In this study, we used a small molecule VIP antagonist as well as VIP-KO mice to further investigate effects and mechanisms of VIP-signaling on antiviral immune responses in wild type (WT) non-transplanted mice and following allogeneic BMT. Methods: B10BR (CD45.2, H-2Kk) and CB6/J F1 (CD45.2, H-2Kb/d) mice were transplanted with 3 × 103 FACS-sorted hematopoietic stem cells (HSC), 5 × 104 dendritic cells (DC), and 0.3, 1, or 3 × 106 splenic T-cells either from VIP-KO (CD45.2, H-2Kb) or WT donors after myeloablative conditioning (11Gy). WT mice and BMT recipients transplanted with WT grafts were treated with daily subcutaneous injection of VIP antagonist (10 μg/100μL per mouse) or PBS for 7 days (from one day prior to infection to 6 days post-infection). BALB/C mice, B6 VIP-KO and WT littermates, as well as CB6/J F1 BMT recipients, were infected with graded doses (LD10, LD50 and LD90) of mCMV by intraperitoneal injection. Survival, viral load, antigen specific T-cells, and clinical scores of graft versus host disease (GvHD) were assessed at distinct time-points post-BMT or after mCMV infection. The expression of co-stimulatory or co-inhibitory markers (CD25, CD62L, CD69, PD-1, FoxP3, PD-L1, CD80, CD86, and MHC-II) and intracellular expression of cytokines (IL-10, IFN-γ, TNF-α, and IL-12) on T-cells and DC from the mice were measured by flow cytometry. Results: Improved survival was seen in mCMV-infected allogeneic B6→CB6/J F1 transplant recipients of VIP-KO grafts (100%) compared with recipients of WT grafts treated with PBS (40%). Allogeneic recipients of VIP-KO grafts and allogeneic recipients of WT grafts treated with VIP antagonist had increased viral clearance and enhanced in vivo killing of viral-peptide-pulsed targets compared with PBS-treated recipients of WT grafts. No difference in the incidence or severity of acute GvHD was seen in allogeneic BMT recipients of graded doses of VIP-KO versus WT splenic T-cells (0.3, 1, and 3 × 106) in murine MHC mis-matched BMT models. Allogeneic transplant recipients of VIP-KO grafts and WT grafts treated with VIP antagonist, infected with low dose mCMV, had lower levels of PD-L1 and PD-1 expression on DC and T-cells, respectively, and higher levels of CD80, CD86 and MHC-II expression on conventional DC (cDC) and plasmacytoid DC (pDC) compared with recipients of WT allografts treated with PBS. Recipients of VIP-KO grafts and recipients treated with VIP antagonist had higher-levels of IL-12+ cDC, activated CD25+/CD69+ CD4 and CD8 T-cells, and more mCMV-M45-peptide MHC-I tetramer+ CD8+ T-cells compared with recipients of WT grafts treated with PBS. Absence of VIP-signaling led to enhanced intracellular expression of IFN-γ and less IL-10 expression in T-cells from mCMV-infected recipients of VIP-KO B6→CB6/J F1 allogeneic transplants, and mCMV-infected, VIP antagonist-treated recipients of WT allogeneic transplants. In the absence of mCMV infection, the numbers of regulatory T cells (Treg) were similar among VIP-KO mice, WT mice treated with VIP antagonist, and PBS-treated WT controls. In contrast, mCMV-infected VIP-KO mice had significantly fewer Treg compared with mCMV- infected WT mice, non-infected WT mice and non-infected VIP-KO mice. Conclusion: Genetic or pharmacological blockade of VIP-signaling enhanced both innate and adaptive antiviral immune responses in allogeneic BMT recipients without significantly elevating GvHD. Selective targeting of VIP-signaling represents a novel therapeutic approach to enhance antiviral immunity in the setting of immunodeficiency and allogeneic BMT. Disclosures: No relevant conflicts of interest to declare.

Description: Allogeneic hematopoietic stem cell transplantation (HSCT) can eradicate chemorefractory leukemia through the graft-versus-leukemia (GVL) activity of donor T cells. However, the clinical success of allo-HSCT is limited by the graft-versus-host disease (GVHD) activity of donor T cells. We have reported previously that donor bone marrow precursors of plasmacytoid dendritic cells (pre-pDCs) can activate donor T cells toward T-helper 1 immune polarization in murine allogeneic HSCT. To optimize the GVL activity of these activated donor T cells and limit their graft versus host activity, we engineered the cellular constituents of an allogeneic hematopoietic stem cell graft with highly purified hematopoietic stem cells, T cells, and pre-pDCs and studied their GVL and GVHD activities in a murine model of allogeneic HSCT. Transplanted donor pre-pDCs expanded in vivo for 2 weeks after transplant, and they markedly augmented the activation and GVL activity of donor T cells while attenuating their GVHD activity, leading to an improved therapeutic index. Bidirectional signaling between donor T cells and donor pDCs with IFN-γ synthesis by donor T cells inducing indoleamine 2,3-dioxygenase synthesis by donor pDCs limited GVHD by altering the balance between donor T-reg and inflammatory T cells. Manipulating the content of donor DC precursors in allogeneic HSCT is a novel method to optimize the balance between GVL and GVHD.

Description: Bortezomib, a proteasome inhibitor with efficacy in multiple myeloma, is associated with thrombocytopenia, the cause and kinetics of which are different from those of standard cytotoxic agents. We assessed the frequency, kinetics, and mechanism of thrombocytopenia following treatment with bortezomib 1.3 mg/m2 in 228 patients with relapsed and/or refractory myeloma in 2 phase 2 trials. The mean platelet count decreased by approximately 60% during treatment but recovered rapidly between treatments in a cyclic fashion. Among responders, the pretreatment platelet count increased significantly during subsequent cycles of therapy. The mean percent reduction in platelets was independent of baseline platelet count, M-protein concentration, and marrow plasmacytosis. Plasma thrombopoietin levels inversely correlated with platelet count. Murine studies demonstrated a reduction in peripheral platelet count following a single bortezomib dose without negative effects on megakaryocytic cellularity, ploidy, or morphology. These data suggest that bortezomib-induced thrombocytopenia is due to a reversible effect on megakaryocytic function rather than a direct cytotoxic effect on megakaryocytes or their progenitors. The exact mechanism underlying bortezomib-induced thrombocytopenia remains unknown but it is unlikely to be related to marrow injury or decreased thrombopoietin production.

Description: Graft versus host disease (GvHD) is the most common complication of hematopoietic stem cell transplant (HCT). However, our understanding of the molecular pathways that cause this disease remains incomplete, leading to inadequate targeted strategies for prevention and treatment. To address this, we determined the gene expression profile of non-human primate (NHP) T cells during active and partially controlled acute GvHD (aGvHD), in order to accomplish two goals: 1) uncover important genetic drivers of aGvHD and 2) identify novel, targetable pathways for optimal aGvHD prevention. Utilizing microarray technology, we measured the gene expression profiles of flow cytometrically purified CD3+ T cells from NHP recipients of MHC partially-matched HCT in three treatment cohorts resulting in increasing degrees of survival: 1) no immunoprophylaxis (No Rx, MST = 7.5); 2) sirolimus monotherapy (MST = 17) tacrolimus-methotrexate (Tac-Mtx) dual prophylaxis (MST = 49). Arrays were performed on T cells purified on Day +14 post-transplant (unless terminal analysis occurred earlier due to severe disease). This comparison allowed us to determine the impact of both mTOR and calcineurin inhibition on the molecular pathways dysregulated during GvHD, and to determine which genes and pathways remained dysregulated despite prophylaxis. Pathways identified by this strategy may contain new therapeutic targets unaffected by current immunoprophylactic approaches. We found that the transcriptional profile of donor T cells from HCT recipients with unprophylaxed GvHD was characterized by significant perturbation of pathways regulating T cell proliferation, effector function and cytokine synthesis (Figure 1a). By identifying pathways unaffected by sirolimus or tac-mtx therapy (Figure 1b), we discovered multiple potentially druggable targets not previously implicated in the pathophysiology of aGvHD. These targets prominently included the hedgehog and the aurora kinase A pathways. Utilizing a murine aGvHD model, we demonstrated that pharmacologic inhibition of these pathways could mitigate disease and improve survival (Figure 2a,b). These data provide the first identification of the T cell transcriptome of primate acute GvHD and the hedgehog and aurora kinase A pathways as novel potential targets for prevention of this disease. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 2960 Background: Donor cell engraftment following allogeneic bone marrow transplantation (BMT) is affected by several factors, including immunological major histocompatibility complex (MHC) barriers, the intensity of the conditioning regimen, and the content of T-cells in the graft. The current model for engraftment in allogeneic BMT is that host dendritic cells (DCs) activate donor T-cells which promote engraftment by eliminating radio-resistant cytotoxic host immune cells, especially natural killer (NK) cells and T-cells. To explore the interaction between donor T-cell and host antigen-presenting cells (APC) in engraftment in allogeneic BMT, we focused on the role of interleukin-12 (IL-12), a key cytokine produced mainly by DCs that drives the development of donor type 1 helper T cells (Th1) and type 1 cytotoxic T lymphocytes (Tc1). Methods: Radiation chimeras with 〉95% donor chimerism were created by transplanting 5 × 106 bone marrow (BM) cells from IL-12 knock out (IL-12 KO) or wild type (WT) B6 (H-2Kb, CD45.2) donors into congenic BL6 Pepboy (B6.SJL-PtprcaPep3b/BoyJ, H-2Kb, CD45.1) mice following lethal 11 Gy irradiation. A second allogeneic BMT was conducted 2 months later using MHC mismatched FVB (H-2q, CD45.1), BA.B10 (H-2Kk, CD45.2, CD90.1) or B10.BR (H-2Kk, CD45.2, CD90.2) donor cells. In vivo bioluminescent imaging (BLI) was performed to analyze the number and in vivo distribution of luciferase+ donor T-cells. The whole-body bioluminescent signal was used as a marker of the donor T cell expansion. Engraftment of donor myeloid cells was determined by flow cytometry using mAbs for specific leukocyte markers expressed on donors and recipients (CD45.1, CD45.2, H-2Kb). Intracellular cytokine expression (IL-4, IL-10, IFN-g) by donor CD4+ and CD8+ T cells was analyzed by flow cytometry. Results: WT BL6→BL6 radiation chimeras recipients showed greater expansion of luciferase+ donor T-cells compared with IL-12 KO BL6→BL6 radiation chimeras recipients and FVB→FVB syngeneic recipients at early time point (2 wks) following 9 Gy re-irradiation and transplantation of 3 × 105 luciferase+ FVB-L2G85 T-cells in combination with 5 × 106 T cell depleted (TCD) BM cells from FVB mice following (Fig 1). At 4 weeks post transplant, more WT BL6→BL6 radiation chimeras achieved myeloid engraftment than IL-12 KO BL6→BL6 radiation chimera recipients(75.0% versus 33.3% respectively, p = 0.086), and the former group had better erythroid engraftment than the latter group (RBC 8.65 ± 1.88 × 1012/L versus 5.67 ± 2.22 × 1012/L respectively, p = 0.011). However, when FVB, WT BL6→BL6 or IL-12 KO BL6→BL6 radiation chimeras recipients were conditioned with a larger dose of irradiation prior to the second transplantation (10 Gy) and received a larger dose of donor T-cells (5 × 105), both the WT BL6→BL6 and IL-12 KO BL6→BL6 radiation chimeras recipients achieved full donor engraftments (85.7% versus 87.5% respectively, p = NS). Donor T cells in allogeneic BMT recipients were Th1/Tc1 polarized, there were no differences in frequencies and total numbers of Th1/Tc1 donor CD4+ and CD8+ T cells comparing recipients of WT BL6→BL6 and IL-12 KO BL6→BL6 radiation chimeras. In spite of an increased irradiation dose and larger number of donor T-cells in the second transplant regimen, no increase in graft versus host disease (GVHD) clinical scores and GVHD-mortality were observed in the recipients of WT BL6→BL6 radiation chimeras compared with recipients of IL-12 KO BL6→BL6 radiation chimeras. Conclusion: These data support a role for host BM-derived IL-12 in facilitating engraftment in allogeneic BMT following a reduced dose (9 Gy) radiation. The lack of host BM-derived IL-12 expression led to allograft rejection. Rejection could be overcome by increasing the dose of pre-transplant irradiation and the content of donor T-cells without causing lethal GVHD. As the main source of host BM-derived IL-12, recipient APC thus play an important role in donor T-cell activation. As has been previously demonstrated in a murine BMT model, the addition of IL-12 in the peri-transplant period helped to separate graft versus leukemia effects from the GVHD-promoting activity of donor T-cells (Yang, 1997). Patients predicted to be high risk of graft failure may benefit from treatment strategies that contribute to production of IL-12 during the early phases of hematopoietic engraftment. Disclosures: No relevant conflicts of interest to declare.