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Summary: Recent developments in immunotherapy, including immune checkpoint blockade (ICB) and adoptive cell therapy (ACT), have encountered challenges such as immune-related adverse events and resistance, especially in solid tumors. To advance the field, a deeper understanding of the molecular mechanisms behind treatment responses and resistance is essential. However, the lack of functionally characterized immune-related gene sets has limited data-driven immunological research. To address this gap, we adopted non-negative matrix factorization on 83 human bulk RNA sequencing (RNA-seq) datasets and constructed 28 immune-specific gene sets. After rigorous immunologist-led manual annotations and orthogonal validations across immunological contexts and functional omics data, we demonstrated that these gene sets can be applied to refine pan-cancer immune subtypes, improve ICB response prediction and functionally annotate spatial transcriptomic data. These functional gene sets, informing diverse immune states, will advance our understanding of immunology and cancer research.

Abstract Cells often alter metabolic strategies under nutrient-deprived conditions to support their survival and growth. Characterizing metabolic reprogramming in the tumor microenvironment (TME) is of emerging importance in cancer research and patient care. However, recent technologies only measure a subset of metabolites and cannot provide in situ measurements. Computational methods such as flux balance analysis (FBA) have been developed to estimate metabolic flux from bulk RNA-seq data and can potentially be extended to single-cell RNA-seq (scRNA-seq) data. However, it is unclear how reliable current methods are, particularly in TME characterization. Here, we present a computational framework METAFlux (METAbolic Flux balance analysis) to infer metabolic fluxes from bulk or single-cell transcriptomic data. Large-scale experiments using cell-lines, the cancer genome atlas (TCGA), and scRNA-seq data obtained from diverse cancer and immunotherapeutic contexts, including CAR-NK cell therapy, have validated METAFlux’s capability to characterize metabolic heterogeneity and metabolic interaction amongst cell types.

Abstract The discovery and development of novel treatments that harness the patient’s immune system and prevent immune escape has dramatically improved outcomes for patients across cancer types. However, not all patients respond to immunotherapy, acquired resistance remains a challenge, and responses are poor in certain tumors which are considered to be immunologically cold. This has led to the need for new immunotherapy-based approaches, including adoptive cell transfer (ACT), therapeutic vaccines, and novel immune checkpoint inhibitors. These new approaches are focused on patients with an inadequate response to current treatments, with emerging evidence of improved responses in various cancers with new immunotherapy agents, often in combinations with existing agents. The use of cell therapies, drivers of immune response, and trends in immunotherapy were the focus of the Immunotherapy Bridge (November 30th–December 1st, 2022), organized by the Fondazione Melanoma Onlus, Naples, Italy, in collaboration with the Society for Immunotherapy of Cancer.

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Abstract The 2022 Immunotherapy Bridge congress (November 30–December 1, Naples, Italy) featured a Great Debate session which addressed three contemporary topics in the field of immunotherapy. The debates included counterpoint views from leading experts and considered whether adoptive cell therapy (ACT) has a role in the treatment of solid tumors, the use of peripheral/blood biomarkers versus tumor microenvironment biomarkers for cancer immunotherapy and the role of chimeric antigen receptor T cell versus natural killer cell therapy. As is the tradition in the Immunotherapy Bridge Great Debates, speakers are invited by the meeting Chairs to express one side of the assigned debate and the opinions given may not fully reflect their own personal views. Audiences voted in favour of either side of the topic both before and after each debate.

Multiple clinical trials exploring the potential of adoptive natural killer (NK) cell therapy for cancer have employed ex vivo expansion using feeder cells to obtain large numbers of NK cells. We have previously utilized the rhesus macaque model to clonally track the NK cell progeny of barcode-transduced CD34+ stem and progenitor cells after transplant. In this study, NK cells from barcoded rhesus macaques were used to study the changes in NK cell clonal patterns that occurred during ex vivo expansion using culture protocols similar to those employed in clinical preparation of human NK cells including irradiated lymphoblastoid cell line (LCL) feeder cells or K562 cells expressing 4-1BBL and membrane-bound interleukin-21 (IL-21). NK expansion cultures resulted in the proliferation of clonally diverse NK cells, which, at day 14 harvest, contained greater than 50% of the starting barcode repertoire. Diversity as measured by Shannon index was maintained after culture. With both LCL and K562 feeders, proliferation of long-lived putative memory-like NK cell clones was observed, with these clones continuing to constitute a mean of 31% of the total repertoire of expanded cells. These experiments provide insight into the clonal makeup of expanded NK cell clinical products.

Sepsis remains a leading cause of death for humans and currently has no pathogenesis-specific therapy. Hampered progress is partly due to a lack of insight into deep mechanistic processes. In the past decade, deciphering the functions of small noncoding miRNAs in sepsis pathogenesis became a dynamic research topic. To screen for new miRNA targets for sepsis therapeutics, we used samples for miRNA array analysis of PBMCs from patients with sepsis and control individuals, blood samples from 2 cohorts of patients with sepsis, and multiple animal models: mouse cecum ligation puncture–induced (CLP-induced) sepsis, mouse viral miRNA challenge, and baboon Gram+ and Gram– sepsis models. miR-93-5p met the criteria for a therapeutic target, as it was overexpressed in baboons that died early after induction of sepsis, was downregulated in patients who survived after sepsis, and correlated with negative clinical prognosticators for sepsis. Therapeutically, inhibition of miR-93-5p prolonged the overall survival of mice with CLP-induced sepsis, with a stronger effect in older mice. Mechanistically, anti–miR-93-5p therapy reduced inflammatory monocytes and increased circulating effector memory T cells, especially the CD4+ subset. AGO2 IP in miR-93–KO T cells identified important regulatory receptors, such as CD28, as direct miR-93-5p target genes. In conclusion, miR-93-5p is a potential therapeutic target in sepsis through the regulation of both innate and adaptive immunity, with possibly a greater benefit for elderly patients than for young patients.

Abstract Integration of single-cell multiomics profiles generated by different single-cell technologies from the same biological sample is still challenging. Previous approaches based on shared features have only provided approximate solutions. Here, we present a novel mathematical solution named bi-order canonical correlation analysis (bi-CCA), which extends the widely used CCA approach to iteratively align the rows and the columns between data matrices. Bi-CCA is generally applicable to combinations of any two single-cell modalities. Validations using co-assayed ground truth data and application to a CAR-NK study and a fetal muscle atlas demonstrate its capability in generating accurate multimodal co-embeddings and discovering cellular identity.

Notch1 is frequently activated promoting T-cell acute lymphoblastic leukaemia (T-ALL). Here, the authors show that Notch1 induces oxidative phosphorylation dependency in T-ALL and synergism when inhibiting both mitochondrial complex I and glutaminolysis in preclinical murine and human xenograft models.

Background B cells play a pivotal role in regulating the immune response. The induction of B cell-mediated immunosuppressive function requires B cell activating signals. However, the mechanisms by which activated B cells mediate T-cell suppression are not fully understood.Methods We investigated the potential contribution of metabolic activity of activated B cells to T-cell suppression by performing in vitro experiments and by analyzing clinical samples using mass cytometry and single-cell RNA sequencing.Results Here we show that following activation, B cells acquire an immunoregulatory phenotype and promote T-cell suppression by metabolic competition. Activated B cells induced hypoxia in T cells in a cell–cell contact dependent manner by consuming more oxygen via an increase in their oxidative phosphorylation (OXPHOS). Moreover, activated B cells deprived T cells of glucose and produced lactic acid through their high glycolytic activity. Activated B cells thus inhibited the mammalian target of rapamycin pathway in T cells, resulting in suppression of T-cell cytokine production and proliferation. Finally, we confirmed the presence of tumor-associated B cells with high glycolytic and OXPHOS activities in patients with melanoma, associated with poor response to immune checkpoint blockade therapy.Conclusions We have revealed for the first time the immunomodulatory effects of the metabolic activity of activated B cells and their possible role in suppressing antitumor T-cell responses. These findings add novel insights into immunometabolism and have important implications for cancer immunotherapy.

Chimeric antigen receptor (CAR) T-cell therapy has emerged recently as a standard of care treatment for patients with relapsed or refractory acute lymphoblastic leukemia (ALL) and several subtypes of B-cell non-Hodgkin lymphoma (NHL). However, its use remains limited to highly specialized centers, given the complexity of its administration and its associated toxicities. We previously reported our experience in using a novel Sleeping Beauty (SB) CD19-specific CAR T-cell therapy in the peri-transplant setting, where it exhibited an excellent safety profile with encouraging survival outcomes. We have since modified the SB CD19 CAR construct to improve its efficacy and shorten its manufacturing time. We report here the phase 1 clinical trial safety results. Fourteen heavily treated patients with relapsed/refractory ALL and NHL were infused. Overall, no serious adverse events were directly attributed to the study treatment. Three patients developed grades 1-2 cytokine release syndrome and none of the study patients experienced neurotoxicity. All dose levels were well tolerated and no dose-limiting toxicities were reported. For efficacy, 3 of 8 (38%) patients with ALL achieved CR/CRi (complete remission with incomplete count recovery) and 1 (13%) patient had sustained molecular disease positivity. Of the 4 patients with DLBCL, 2 (50%) achieved CR. The SB-based CAR constructs allow manufacturing of targeted CAR T-cell therapies that are safe, cost-effective and with encouraging antitumor activity.

With the continuous increase in the use of haploidentical donors for transplantation, the selection of donors becomes increasingly important. Haploidentical donors have been selected primarily based on clinical characteristics, while the effects of killer cell immunoglobulin-like receptors (KIRs) on outcomes of haploidentical-hematopoietic stem cell transplantation (haplo-HSCT) with post-transplant cyclophosphamide (PTCy) remain inconclusive. The present study aimed to thoroughly evaluate the effect of KIRs and binding ligands assessed by various models, in addition to other patient/donor variables, on clinical outcomes in haplo-HSCT. In a cohort of 354 patients undergoing their first haplo-HSCT, we found that a higher Count Functional inhibitory KIR score (CF-iKIR) was associated with improved progression-free survival (adjusted hazard ratio [HR], 0.71; P = .029) and overall survival (OS) (HR, 0.66; P = .016), while none of the other models predicted for survival in these patients. Moreover, using exploratory classification and regression tree analysis, we found that donor age 58 years was associated with the worst OS. In the rest of our cohort (80%), cytomegalovirus-reactive recipients with a donor

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for hematologic malignancies. Alloreactivity after HSCT is known to be mediated by adaptive immune cells expressing rearranging receptors. Recent studies demonstrated that the innate immune system could likewise sense the non-self signals and subsequently enhance the alloimmune response. We recently demonstrated that the donor/recipient mismatch of signal regulatory protein α (SIRPα), an immunoglobulin receptor exclusively expressed on innate cells, is associated with a higher risk of cGVHD and relapse protection in a cohort of acute myeloid leukemia patients who underwent allo-HSCT. Whether these effects also occur in other hematologic malignancies remains unclear. In the present study, we compared outcomes by SIRPα match status in a cohort of 310 patients who received allo-HSCT from an HLA matched-related donor for the treatment of lymphoid malignancies. Multivariable analysis showed that SIRPα mismatch was associated with a significantly higher rate of cGVHD (hazard ratio [HR] 1.8, P= .002), cGVHD requiring systemic immunosuppressive therapy (HR 1.9, P= .005), a lower rate of disease progression (HR 0.5, P= .003) and improved progression-free survival (HR 0.5, P= .001). Notably, the effects of SIRPα mismatch were observed only in the patients who achieved >95% of donor T-cell chimerism. The mismatch in SIRPα is associated with favorable relapse protection and concurrently increased risk of cGVHD in patients who undergo allo-HSCT for lymphoid malignancies, and the optimal donor could be selected based on the finding of the study to mitigate the risk of GVHD and relapse.

Abstract: Natural killer (NK) cells are highly heterogeneous, with vast phenotypic and functional diversity at the single-cell level. They are involved in the innate immune response against malignant and virus-infected cells. To understand the effect of NK diversity during immune recovery on the antitumor response after cord blood transplantation (CBT), we used high-dimensional mass cytometry and the metrics of NK cell diversity to study the NK cell repertoire in serial samples from 43 CBT recipients. A higher-diversity index based on single-cell combinatorial phenotypes was significantly associated with a lower risk for relapse after CBT (P = .005). Cytomegalovirus reactivation was a major factor in the development of a more diverse NK repertoire after CBT. Notably, we identified a group of patients whose CB-derived NK cells after transplantation possessed an immature phenotype (CB-NKim), characterized by poor effector function and a low diversity index. Frequencies of CB-NKim of 11.8% or higher during the early post-CBT recovery phase were highly predictive for relapse (area under the curve [AUC], 0.979), a finding that was validated in a second independent cohort of patients (n = 25; AUC, 0.977). Moreover, we showed that the maturation, diversity, and acquisition of effector function by CB-NKim early after CBT were driven by interleukin 15. Our data indicate that the diversity of the NK cell repertoire after CBT contributes importantly to the risk for subsequent relapse. We suggest that the use of diversity metrics and high-dimensional mass cytometry may be useful tools in predicting clinical outcomes and informing the design of therapeutic strategies to prevent relapse after CBT.

High-dose chemotherapy and autologous stem-cell transplant (HDC/ASCT) is standard treatment for chemosensitive relapsed classical Hodgkin lymphoma, although outcomes of high-risk relapse (HRR) patients remain suboptimal. We retrospectively analyzed all HRR classical Hodgkin lymphoma patients treated with HDC/ASCT at our institution between 01/01/2005 and 12/31/2019. HRR criteria included primary refractory disease/relapse within 1 year, extranodal extension, B symptoms, requiring more than one salvage line, or positron emission tomography (PET)-positive disease at ASCT. All patients met the same ASCT eligibility criteria. We treated 501 patients with BEAM (n=146), busulphan/melphalan (BuMel) (n=38), gemcitabine( Gem)/BuMel (n=189) and vorinostat/Gem/BuMel (n=128). The Gem/BuMel and vorinostat/Gem/BuMel cohorts had more HRR criteria and more patients with PET-positive disease at ASCT. Treatment with brentuximab vedotin (BV) or anti-PD1 prior to ASCT, PET-negative disease at ASCT, and maintenance BV increased over time. BEAM and BuMel predominated in earlier years (2005-2007), GemBuMel and BEAM in middle years (2008-2015), and vorinostat/GemBuMel and BEAM in later years (2016-2019). The median follow-up is 50 months (range, 6-186). Outcomes improved over time, with 2-year progressionfree survival (PFS)/overall survival (OS) rates of 58%/82% (2005-2007), 59%/83% (2008-2011), 71%/94% (2012-2015) and 86%/99% (2016- 2019) (P

Acute graft-vs.-host (GVHD) disease remains a common complication of allogeneic stem cell transplantation with very poor outcomes once the disease becomes steroid refractory. Mesenchymal stem cells (MSCs) represent a promising therapeutic approach for the treatment of GVHD, but so far this strategy has had equivocal clinical efficacy. Therapies using MSCs require optimization taking advantage of the plasticity of these cells in response to different microenvironments. In this study, we aimed to optimize cord blood tissue derived MSCs (CBti MSCs) by priming them using a regimen of inflammatory cytokines. This approach led to their metabolic reprogramming with enhancement of their glycolytic capacity. Metabolically reprogrammed CBti MSCs displayed a boosted immunosuppressive potential, with superior immunomodulatory and homing properties, even after cryopreservation and thawing. Mechanistically, primed CBti MSCs significantly interfered with glycolytic switching and mTOR signaling in T cells, suppressing T cell proliferation and ensuing polarizing toward T regulatory cells. Based on these data, we generated a Good Manufacturing Process (GMP) Laboratory protocol for the production and cryopreservation of primed CBti MSCs for clinical use. Following thawing, these cryopreserved GMP-compliant primed CBti MSCs significantly improved outcomes in a xenogenic mouse model of GVHD. Our data support the concept that metabolic profiling of MSCs can be used as a surrogate for their suppressive potential in conjunction with conventional functional methods to support their therapeutic use in GVHD or other autoimmune disorders.

BackgroundCOVID-19 Convalescent plasma (CCP) is safe and effective, particularly if given at an early stage of the disease. Our study aimed to identify an association between survival and specific antibodies found in CCP.Patients and MethodsPatients ≥18 years of age who were hospitalized with moderate to severe COVID-19 infection and received CCP at the MD Anderson Cancer Center between 4/30/2020 and 8/20/2020 were included in the study. We quantified the levels of anti-SARS-CoV-2 antibodies, as well as antibodies against antigens of other coronavirus strains, in the CCP units and compared antibody levels with patient outcomes. For each antibody, a Bayesian exponential survival time regression model including prognostic variables was fit, and the posterior probability of a beneficial effect (PBE) of higher antibody level on survival time was computed.ResultsCCP was administered to 44 cancer patients. The median age was 60 years (range 37-84) and 19 (43%) were female. Twelve patients (27%) died of COVID-19-related complications. Higher levels of two non-SARS-CoV-2-specific antibodies, anti-HCoV-OC43 spike IgG and anti-HCoV-HKU1 spike IgG, had PBE = 1.00, and 4 SARS-CoV-2-specific antibodies had PBEs between 0.90 and 0.95. Other factors associated with better survival were shorter time to CCP administration, younger age, and female sex.ConclusionsCommon cold coronavirus spike IgG antibodies anti-HCoV-OC43 and anti-HCoV-HKU1 may target a common domain for SARS-CoV-2 and other coronaviruses. They provide a promising therapeutic target for monoclonal antibody production.

Pediatric, adolescent and young adult (AYA) patients receiving novel cancer immunotherapies may develop associated toxicities with overlapping signs and symptoms that are not always easily distinguished from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection/clinical sequelae. We describe 2 diagnostically challenging cases of SARS-CoV-2 and Multi-Inflammatory Syndrome-Adult (MIS-A), in patients with a history of acute lymphoblastic leukemia following cellular therapy administration and review evolving characterization of both the natural course of SARS-CoV-2 infection and toxicities experienced in younger cancer immunotherapy patients. Vigilant monitoring for unique presentations and epidemiologic surveillance to promptly detect changes in incidence of either condition may be warranted.

Natural killer (NK) cells are innate lymphocytes recognized for their important role against tumor cells. NK cells expressing chimeric antigen receptors (CARs) have enhanced effector function against various type of cancer and are attractive contenders for the next generation of cancer immunotherapies. However, a number of factors have hindered the application of NK cells for cellular therapy, including their poor in vitro growth kinetics and relatively low starting percentages within the mononuclear cell fraction of peripheral blood or cord blood (CB). To overcome these limitations, we genetically-engineered human leukocyte antigen (HLA)-A− and HLA-B− K562 cells to enforce the expression of CD48, 4-1BBL, and membrane-bound IL-21 (mbIL21), creating a universal antigen presenting cell (uAPC) capable of stimulating their cognate receptors on NK cells. We have shown that uAPC can drive the expansion of both non-transduced (NT) and CAR-transduced CB derived NK cells by >900-fold in 2 weeks of co-culture with excellent purity (>99.9%) and without indications of senescence/exhaustion. We confirmed that uAPC-expanded research- and clinical-grade NT and CAR-transduced NK cells have higher metabolic fitness and display enhanced effector function against tumor targets compared to the corresponding cell fractions cultured without uAPCs. This novel approach allowed the expansion of highly pure GMP-grade CAR NK cells at optimal cell numbers to be used for adoptive CAR NK cell-based cancer immunotherapy.

Abstract T cells engineered to express chimeric antigen receptors (CARs) have revolutionised the field of cellular therapy for cancer. Despite its success, this strategy has some recognised limitations and toxicities. Hence, there is growing interest in developing novel cellular therapies based on non‐αβ T‐cell immune effector cells, including NK cells that offer clear advantages in cancer immunotherapy. As a result, NK cells are being explored as an alternative platform for CAR engineering and are becoming recognised as important players in the next generation of cellular therapies targeting cancer. In this review, we highlight preclinical and clinical studies of CAR‐NK cells derived from different sources and discuss strategies under investigation to enhance the antitumor activity of these engineered innate immune cells.

Cytomegalovirus (CMV) remains a major cause of morbidity following allogeneic hematopoietic stem cell transplant. Natural killer cells expressing NKG2C have been shown to play a role in the immune surveillance of human CMV. We studied NKG2C copy number in the donor graft and the risk of CMV reactivation after double umbilical cord blood transplantation (DUCBT) in 100 CMV seropositive DUCBT recipients and their corresponding cord blood (CB) grafts (n = 200). In the setting of DUCBT, the combined graft may contain 0–4 functional copies of NKG2C gene. Sixteen patients received a combined graft with 1 or 2 NKG2C copies and 84 patients were recipients of a combined graft with 3 or 4 NKG2C copies. The 6-month cumulative incidence of CMV reactivation for the two groups was 93.7 and 58.4%, respectively (p = 0.0003). In multivariate analysis, low NKG2C copies in the graft was an independent predictor of CMV reactivation (HR = 2.72, CI = 1.59–4.64; p < 0.0001). Our study points to an important role for donor NKG2C for protection against CMV reactivation after DUCBT. These novel findings may help identify patients at a higher risk of CMV reactivation after DUCBT. Donor NKG2C genotype may be used as a potential criterion in the algorithm for graft selection for DUCBT.

Pulmonary aspergillosis is an opportunistic fungal infection affecting immunocompromised individuals. Increasing understanding of natural killer (NK) cell immunobiology has aroused considerable interest around the role of NK cells in pulmonary aspergillosis in the immunocompromised host. Murine studies indicate that NK cells play a critical role in pulmonary clearance of A. fumigatus. We show that the in vitro interaction between NK cells and A. fumigatus induces partial activation of NK cell immune response, characterised by low-level production of IFN-γ, TNF-α, MIP-1α, MIP-1β, and RANTES, polarisation of lytic granules and release of fungal DNA. We observed a contact-dependent down-regulation of activatory receptors NKG2D and NKp46 on the NK cell surface, and a failure of full granule release. Furthermore, the NK cell cytokine-mediated response to leukaemic cells was impaired in the presence of A. fumigatus. These observations suggest that A. fumigatus-mediated NK cell immunoparesis may represent an important mechanism of immune evasion during pulmonary aspergillosis.

Adoptive cell therapy has emerged as a powerful treatment for advanced cancers resistant to conventional agents. Most notable are the remarkable responses seen in patients receiving autologous CD19-redirected chimeric antigen receptor (CAR) T cells for the treatment of B lymphoid malignancies; however, the generation of autologous products for each patient is logistically cumbersome and has restricted widespread clinical use. A banked allogeneic product has the potential to overcome these limitations, yet allogeneic T-cells (even if human leukocyte antigen-matched) carry a major risk of graft-versus-host disease (GVHD). Natural killer (NK) cells are bone marrow-derived innate lymphocytes that can eliminate tumors directly, with their activity governed by the integration of signals from activating and inhibitory receptors and from cytokines including IL-15, IL-12, and IL-18. NK cells do not cause GVHD or other alloimmune or autoimmune toxicities and thus, can provide a potential source of allogeneic “off-the-shelf” cellular therapy, mediating major anti-tumor effects without inducing potentially lethal alloreactivity such as GVHD. Given the multiple unique advantages of NK cells, researchers are now exploring the use of CAR-engineered NK cells for the treatment of various hematological and non-hematological malignancies. Herein, we review preclinical data on the development of CAR-NK cells, advantages, disadvantages, and current obstacles to their clinical use.

Chronic graft-versus-host disease (cGvHD) remains a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). A number of studies support a role for B cells in the pathogenesis of cGvHD. In this study, we report the presence of an expanded population of CD19+CD21− B cells with features of exhaustion in the peripheral blood of patients with cGvHD. CD21− B cells were significantly increased in patients with active cGvHD compared to patients without cGvHD and healthy controls (median 12.2 versus 2.12 versus 3%, respectively; p

Chronic lymphocytic leukemia (CLL) cells possess regulatory functions comparable to those of normal B10 cells, a regulatory B cell subset that suppresses effector T-cell function through STAT3-mediated IL-10 production. However, the mechanisms governing IL-10 production by CLL cells are not fully understood. Here, we show that the CXC chemokine ligand 12 (CXCL12)–CXCR4–STAT3 axis regulates IL-10 production by CLL cells and their ability to suppress T-cell effector function through an IL-10 mediated mechanism. Knockdown of STAT3 significantly impaired the ability of CLL cells to produce IL-10. Furthermore, experiments to assess the role of lenalidomide, an immunomodulatory agent with direct antitumor effect as well as pleiotropic activity on the immune system, showed that this agent prevents a CXCL12-induced increase in p-S727-STAT3 and the IL-10 response by CLL cells. Lenalidomide also suppressed IL-10-induced Y705-STAT3 phosphorylation in healthy T cells, thus reversing CLL-induced T-cell dysfunction. We conclude that the capacity of CLL cells to produce IL-10 is mediated by the CXCL12–CXCR4–STAT3 pathway and likely contributes to immunodeficiency in patients. Lenalidomide appears to be able to reverse CLL-induced immunosuppression through including abrogation of the CXCL12–CXCR4–S727–STAT3-mediated IL-10 response by CLL cells and prevention of IL-10-induced phosphorylation of Y705-STAT3 in T cells.

Mesenchymal stromal cells (MSCs) support the growth and differentiation of normal hematopoietic stem cells (HSCs). Here we studied the ability of MSCs to support the growth and survival of leukemic stem cells (LSCs) in vitro. Primary leukemic blasts isolated from the peripheral blood of 8 patients with acute myeloid leukemia (AML) were co-cultured with equal numbers of irradiated MSCs derived from unrelated donor bone marrow, with or without cytokines for up to 6 weeks. Four samples showed CD34+CD38− predominance, and four were predominantly CD34+CD38+. CD34+ CD38− predominant leukemia cells maintained the CD34+ CD38− phenotype and were viable for 6 weeks when co-cultured with MSCs compared to co-cultures with cytokines or medium only, which showed rapid differentiation and loss of the LSC phenotype. In contrast, CD34+ CD38+ predominant leukemic cells maintained the CD34+CD38+ phenotype when co-cultured with MSCs alone, but no culture conditions supported survival beyond 4 weeks. Cell cycle analysis showed that MSCs maintained a higher proportion of CD34+ blasts in G0 than leukemic cells cultured with cytokines. AML blasts maintained in culture with MSCs for up to 6 weeks engrafted NSG mice with the same efficiency as their non-cultured counterparts, and the original karyotype persisted after co-culture. Chemosensitivity and transwell assays suggest that MSCs provide pro-survival benefits to leukemic blasts through cell–cell contact. We conclude that MSCs support long-term maintenance of LSCs in vitro. This simple and inexpensive approach will facilitate basic investigation of LSCs and enable screening of novel therapeutic agents targeting LSCs.

Cord blood transplant requires less stringent human leukocyte antigen matching than unrelated donors. In 133 patients with hematologic malignancies who engrafted after double cord blood transplantation with a dominant unit, we studied the effect of high resolution testing at 4 loci (-A, -B, -C, -DRB1) for its impact on 2-year transplant-related mortality. Ten percent of the dominant cord blood units were matched at 7–8/8 alleles using HLA-A, -B, -C, and -DRB1; 25% were matched at 6/8, 40% at 5/8, and 25% at 4/8 or less allele. High resolution typing at 4 loci showed that there was no 2-year transplant-related mortality in 7–8/8 matched patients. Patients with 5–6/8 matched dominant cord blood units had 2-year transplant-related mortality of 39% while patients with 4/8 or less matched units had 60%. Multivariate regression analyses confirmed the independent effect of high resolution typing on the outcome when adjusted for age, diagnosis, CD34+ cell dose infused, graft manipulation and cord to cord matching. The worst prognostic group included patients aged over 32 years with 4/8 or less matched cord blood units compared with patients who were either younger than 32 years old independent of allele-level matching, or aged over 32 years but with 5–6/8 matched cord blood units (Hazard Ratio 2.2; 95% confidence interval: 1.3–3.7; P

Disease can be conceptualized as the result of interactions between infecting microbe and holobiont, the combination of a host and its microbial communities. It is likely that genomic variation in the host, infecting microbe, and commensal microbiota are key determinants of infectious disease clinical outcomes. However, until recently, simultaneous, multiomic investigation of infecting microbe and holobiont components has rarely been explored. Herein, we characterized the infecting microbe, host, micro- and mycobiomes leading up to infection onset in a leukemia patient that developed invasive mucormycosis. We discovered that the patient was infected with a strain of the recently described Mucor velutinosus species which we determined was hypervirulent in a Drosophila challenge model and has a predisposition for skin dissemination. After completing the infecting M. velutinosus genome and genomes from four other Mucor species, comparative pathogenomics was performed and assisted in identifying 66 M. velutinosus-specific putatively secreted proteins, including multiple novel secreted aspartyl proteinases which may contribute to the unique clinical presentation of skin dissemination. Whole exome sequencing of the patient revealed multiple non-synonymous polymorphisms in genes critical to control of fungal proliferation, such as TLR6 and PTX3. Moreover, the patient had a non-synonymous polymorphism in the NOD2 gene and a missense mutation in FUT2, which have been linked to microbial dysbiosis and microbiome diversity maintenance during physiologic stress, respectively. In concert with host genetic polymorphism data, the micro- and mycobiome analyses revealed that the infection developed amid a dysbiotic microbiome with low α-diversity, dominated by staphylococci. Additionally, longitudinal mycobiome data showed that M. velutinosus DNA was detectable in oral samples preceding disease onset. Our genome-level study of the host-infecting microbe-commensal triad extends the concept of personalized genomic medicine to the holobiont-infecting microbe interface thereby offering novel opportunities for using synergistic genetic methods to increase understanding of infectious diseases pathogenesis and clinical outcomes.

The majority of patients with acute myeloid leukemia will relapse, and older patients often fail to achieve remission with induction chemotherapy. We explored the possibility that leukemic suppression of innate immunity might contribute to treatment failure. Natural killer cell phenotype and function was measured in 32 consecutive acute myeloid leukemia patients at presentation, including 12 achieving complete remission. Compared to 15 healthy age-matched controls, natural killer cells from acute myeloid leukemia patients were abnormal at presentation, with downregulation of the activating receptor NKp46 (P=0.007) and upregulation of the inhibitory receptor NKG2A (P=0.04). Natural killer cells from acute myeloid leukemia patients had impaired effector function against autologous blasts and K562 targets, with significantly reduced CD107a degranulation, TNF-α and IFN-γ production. Failure to achieve remission was associated with NKG2A overexpression and reduced TNF-α production. These phenotypic and functional abnormalities were partially restored in the 12 patients achieving remission. In vitro co-incubation of acute myeloid leukemia blasts with natural killer cells from healthy donors induced significant impairment in natural killer cell TNF-α and IFN-γ production (P=0.02 and P=0.01, respectively) against K562 targets and a trend to reduced CD107a degranulation (P=0.07). Under transwell conditions, the inhibitory effect of AML blasts on NK cytotoxicity and effector function was still present, and this inhibitory effect was primarily mediated by IL-10. These results suggest that acute myeloid leukemia blasts induce long-lasting changes in natural killer cells, impairing their effector function and reducing the competence of the innate immune system, favoring leukemia survival.

Background We previously showed that vaccination with one dose of PR1 and WT1 peptides induces transient anti-leukemia immunity. We hypothesized that maintenance of a sustained anti-leukemia response may require frequent boost injections.Design and Methods Eight patients with myeloid malignancies were enrolled in this phase II study, and 6 completed 6 injections of PR1 and WT1 peptides in Montanide-adjuvant with GM-CSF, every two weeks.Results Both high- and low-avidity PR1 or WT1-specific CD8+ T cells were detected in all evaluable patients after the first vaccine dose. Repeated vaccination led to selective deletion of high avidity PR1- and WT1-specific CD8+ T cells and was not associated with significant reduction in WT1-expression. Additional boosting failed to increase vaccine-induced CD8+ T-cell frequencies further and in all patients the response was lost before the 6th dose. PR1- or WT1-specific CD8+ T cells were not detected in bone marrow samples, excluding their preferential localization to this site. Following a booster injection three months after the 6th vaccine dose, no high-avidity PR1 or WT1-specific CD8+ T cells could be detected, whereas low-avidity T cells were readily expanded.Conclusions These data support the immunogenicity of PR1 and WT1 peptide vaccines. However, repeated delivery of peptides with Montanide-adjuvant and GM-CSF leads to rapid loss of high-avidity peptide-specific CD8+ T cells. These results may offer an explanation for the lack of correlation between immune and clinical responses observed in a number of clinical trials of peptide vaccination. New approaches are needed to induce long-term high-avidity memory responses against leukemia antigens. (ClinicalTrials.gov Identifier: NCT00499772)

Background In 2009 the declaration by the World Health Organization of a global pandemic of influenza-H1N1 virus led to a vaccination campaign to ensure protection for immunocompromised patients. The goal of this study was to determine the efficacy of the 2009 H1N1 vaccine in patients with hematologic malignancies.Design and Methods We evaluated humoral and cellular immune responses to 2009 H1N1 vaccine in 97 adults with hematologic malignancies and compared these responses with those in 25 adult controls. Patients received two injections of vaccine 21 days apart and the controls received one dose. Antibody titers were measured using a hemagglutination-inhibition assay on days 0, 21 and 49 after injection of the first dose. Cellular immune responses to H1N1 were determined on days 0 and 49.Results By day 21 post-vaccination, protective antibody titers of 1:32 or more were seen in 100% of controls compared to 39% of patients with B-cell malignancies (P