The NLPHL Tumor Microenvironment Is Markedly Enriched in the Tigit and PD-1 Signalling Axes Compared to Classical Hodgkin Lymphoma

Abstract Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) comprises 5% of all Hodgkin lymphomas (HL). Its biology remains poorly characterized. Like classical HL (cHL), it contains minimal malignant cells embedded within a T cell rich intra-tumoral microenvironment (TME). Unlike cHL, it can transform to diffuse large B cell lymphoma (DLBCL). Immune-checkpoint blockade is effective in cHL but has minimal activity in DLBCL. No data is currently available regarding the potential to reactivate host anti-tumoral activity via immune-checkpoint blockade in NLPHL. Diagnostic FFPE samples from 49 NLPHL patients retrospectively collected from 4 Australian centres were interrogated. Inclusion criteria were sample availability and centrally confirmed histological NLPHL. Characteristics were in line with the literature: median age 45 years, range 13-82 years; F:M 1:3.5; stage I/II 55%, III/IV 35% (10% stage unknown) with the majority of cases were of immuno-architectural types A or C. RNA was digitally quantified using the NanoString 770-gene PanCancer Immune panel. Multi-spectral immunofluorescent (mIF) microscopy, plasma soluble PD-1 quantification, cell sorting, T cell receptor (TCR) repertoire analysis and functional immuno-assays were also performed. Results were compared with samples from 38 cHL and 35 DLBCL patients. We initially compared gene expression of NLPHL and cHL, looking for molecular similarities and differences. Ten non-lymphomatous nodes (NLN) were included as controls. Unsupervised clustering showed all but 3 NLPHL cases segregated from the cHL cluster. All NLN congregated in a discrete sub-cluster. As expected, RNA analysis showed significant enrichment for CD20 in NLPHL and CD30 in HL. Volcano plots (Fig. 1a), corrected for false-discovery showed marked variation in gene expression. For NLPHL (vs. cHL) there were 105 upregulated and 337 down regulated genes. Strikingly, the most significantly differentially over-expressed genes in NLPHL were all T cell related (CD247: CD3 zeta chain; CD3D: CD3 delta chain; GZMK: granzyme K; EOMES: marker of CD8 + T cell tolerance; and the immune checkpoints PDCD1: encodes for PD-1; and TIGIT). CD8B expression was increased in NLPHL. For cHL, the most over-expressed genes included macrophage-derived chemokines CCL17 and CCL22. Gene set enrichment analysis revealed activation of the PD-L1 expression and PD-1 checkpoint pathway and 9 of the top 10 Gene Ontology (GO) term enrichment scores involved lymphocyte signalling in NLPHL (Fig. 1b). To better appreciate the impact of the relevant immune checkpoints on their signalling axis, we compared gene ratios for PD-1 and TIGIT receptors with their ligands (PD-L1/L2 and PVR, respectively). NLPHL showed the highest enrichment ratios of these signalling pathways vs. cHL, DLBCL and NLN (Fig. 1c). Although it is known that CD4 +PD-1 +T cells form rosettes around NLPHL cells, the differential cellular localization of immune proteins has not been compared between HL entities. Using mIF, the proportion of intra-tumoral PD-1 + was markedly higher for CD4 + (~7-fold; p<0.0001) and CD8 + (~5-fold; p<0.001) T cells in NLPHL. However, the proportion of T cells expressing LAG3 was similar. Soluble PD-1 was elevated for both NLPHL and cHL, indicating circulating blood is influenced by the TME. For both HL entities over 80% of circulating CD4 + and CD8 + T cells expressed PD-1 alone or in combination with TIGIT. TCR repertoire analysis of sorted T cell subsets showed large intra-tumoral clonal T cell expansions were also detectable in circulating T cells. T cell clones were predominantly PD1 +CD4 + T cells in both HL types. Finally, we developed a functional assay using PD-L1/PD-L2 expressing NLPHL and cHL cell lines. These were co-cultured with genetically engineered PD-1 +CD4 + T cells that express a luciferase reporter. Similar levels of heightened T cell activation were seen with immune-checkpoint blockade for both HL entities, indicating that immune-checkpoint inhibition may also be of benefit in NLPHL. In conclusion, our multi-faceted analysis of the immunobiological features of the TME in NLPHL, provides a compelling rationale for early phase clinical studies that incorporate immune-checkpoint blockade in NLPHL. Figure 1 Figure 1. Disclosures Hawkes: Bristol Myers Squib/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Specialised Therapeutics: Consultancy; Merck KgA: Research Funding; Merck Sharpe Dohme: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Antigene: Membership on an entity's Board of Directors or advisory committees; Regeneron: Speakers Bureau; Janssen: Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel and accommodation expenses, Research Funding, Speakers Bureau. Swain: Janssen: Other: Travel expenses paid; Novartis: Other: Travel expenses paid. Keane: BMS: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Karyopharm: Consultancy; MSD: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Talaulikar: Takeda: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Jansenn: Honoraria, Research Funding; Roche: Honoraria, Research Funding; EUSA Pharma: Honoraria, Research Funding. Gandhi: janssen: Research Funding; novartis: Honoraria.

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Intra-Tumoral CD8+ T-Cells in Follicular Lymphoma Contain Large Clonal Expansions That Are Amenable to Dual-Checkpoint Blockade

Blood ◽

10.1182/blood-2019-130050 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 2793-2793 ◽

Cited By ~ 1

Author(s):

Karthik Nath ◽

Soi C. Law ◽

Muhammed B. Sabdia ◽

Lilia Merida De Long ◽

Mohamed Shanavas ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Cd4 T Cells ◽

Research Funding ◽

Checkpoint Blockade ◽

T Cell Subsets ◽

Advisory Committees ◽

Cell Clones ◽

Tcr Repertoire

Introduction. Intra-tumoral T-cell infiltration is associated with R-CHOP responsiveness in aggressive B-cell lymphoma (Keane, Lancet Haem 2015). These patients also have a broad (i.e. diverse) intra-tumoral T-cell receptor (TCR) repertoire with a ~20% superior survival compared to those with a narrow (i.e. clonal) repertoire after R-CHOP therapy. Here, the major contributor to the TCR clonal expansion were CD8+ T cells (Keane, CCR 2017). Paradoxically, our recent results in Follicular Lymphoma (FL) (Tobin, JCO in press) found that clonal T-cell expansions were markedly enriched in those patients that experienced progression of disease within 24 months (POD24). Given that FL is a histological subtype associated with a tumor microenvironment distinct from DLBCL including numerous CD4+ T-follicular helper cells (TFH), we now expand upon these findings by comparing TCR repertoires across histological subtypes. We then established whether the TCR repertoire in FL is related to differential TCR clonal expansions between different T-cell subsets and immune checkpoints. Finally, the overlap between tissue and blood TCR repertoires was investigated. Methods. Firstly, unbiased, high-throughput TCRβ sequencing (ImmunoSEQ, Adaptive Biotechnologies) was compared in 164 FFPE tissues (12 healthy nodes, 40 FL, 88 DLBCL, and as a comparator tumor known to be sensitive to checkpoint blockade and to have a high neoantigen burden, 24 melanoma tissues). Next, to determine the contribution of individual T-cell subsets to overall clonality, a further 21 fresh de-aggregated/cryopreserved FL tumor samples were FACS sorted into four T-cell groupings: CD8+ cytotoxic T-lymphocytes (CTLs), CD4+ TFH, CD4+ regulatory T-cells (TREGs) and 'other' (non-TFH/TREG) CD4+ T-cells. Flow cytometry quantified the expression of the checkpoints LAG3, TIM3 and PD1. Then, 5 FL paired tissue/blood samples were tested for shared TCR clones. Results. FL exhibited strikingly reduced TCR repertoire clonality (higher diversity) compared to DLBCL, melanoma and healthy lymph nodes (Fig 1A). Analysis of de-aggregated sorted nodal T-cells revealed a more complex TCR repertoire. The outcome measure was median clonality index (CIx ranging from '0' or minimal, to '1' or maximal clonality). Large T-cell clones in FL (CIx=0.12) predominantly resided within the CTL subset (34% all T-cells). By contrast, there was marked T-cell diversity in TFH (CIx=0.04; 27% all T-cells), TREG (CIx=0.02; 7% all T-cells) and 'other' CD4+ T-cells (CIx=0.02; 32% all T-cells) (Fig 1B). The CTL population had a bimodal expression for PD1 (+51%/-49%), a marker in FL that has been shown to remain functionally active unless co-expressed with LAG3 and/or TIM3 (Yang, Oncotarget 2017). These dual-checkpoint expressing CTLs have reduced capacity to produce cytokines or lytic granules (i.e. they are 'exhausted'). Notably, 54% of the PD1+ CTLs co-expressed either LAG3 or TIM3. Put together, these results are consistent with expanded CTL clones that are frequently functionally exhausted. In contrast, TFH, TREG and 'other' CD4+ T-cells had a low expression of LAG3 and TIM3, although PD1 was frequently found (as expected, particularly in the TFH cells). Finally, in paired tissue/blood samples, there was weak overlap between the circulating and intra-tumoral TCR repertoire in CTLs and TFH T-cells. Conclusion. Although FL has a markedly less clonal TCR repertoire compared to DLBCL, melanoma and even healthy nodes, this result is misleading. Detailed analysis on sorted intra-tumoral T-cell subsets in FL revealed large clonal expansions in CTLs, with approximately half of these classified as functionally exhausted (dual-positive for PD1 and LAG3 and/or TIM3), a state potentially amenable to reversal by dual-checkpoint blockade. The explanation for TCR repertoire diversity lies in CD4+ T-cells (representing approximately two-thirds of T-cells, including the large TFH subset). T-cells in blood did not reflect FL tissue T-cell clones, further highlighting the need for sorted intra-tumoral nodal tissues to accurately assess TCR repertoires in FL. Further characterization of the neo-antigenic targets that CTL clones potentially recognize is required. These results have implications for therapeutic vaccine design and selective recruitment of patients for immune checkpoint blockade. Disclosures Keane: MSD: Consultancy; Gilead: Consultancy; Celgene: Consultancy; Roche: Consultancy, Other: Travel Grant; BMS: Research Funding. Gandhi:Roche: Honoraria, Other: Travel Support; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Research Funding.

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The Tumor Microenvironment of Nodular Lymphocyte Predominant Hodgkin Lymphoma Is a Unique Immunobiological Entity Distinct from Classical Hodgkin Lymphoma

Blood ◽

10.1182/blood-2018-99-115836 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4123-4123

Author(s):

Jay Gunawardana ◽

Karolina Bednarska ◽

Soi C Law ◽

Justina Lee ◽

Muhammed Bilal Sabdia ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Hodgkin Lymphoma ◽

Research Funding ◽

Host Immunity ◽

Immune Checkpoints ◽

Classical Hodgkin Lymphoma ◽

Advisory Committees ◽

Immune Effector

Abstract There is proven pre-clinical and clinical efficacy of mono or combinatorial immune strategies to boost host anti-lymphoma immunity, with classical Hodgkin Lymphoma (cHL) seen as the 'poster child'. Approaches include blockade of immune-checkpoints on exhausted tumor-specific T-cells (via mAb blockade of PD-1, TIM3, LAG3, TIGIT or their ligands), activation of T-cells via mAbs agonistic to CD137, and finally modulation of FOXP3, CTLA-4 and/or LAG3 regulatory T-cells (Tregs) or immunosuppressive tumor-associated macrophages (TAMs). In contrast, studies characterizing the circulating and intra-tumoral microenvironment (TME) of the distinct but rare CD20+ Hodgkin Lymphoma entity (5-8% of HL), Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL), are minimal. Furthermore, to our knowledge no functional profiling studies comparing the host immunity of NLPHL with cHL has been performed. We compared host immunity in 29 NLPHL patients, 30 cHL patients and 10 healthy individuals, with a focus on pertinent and clinically actionable immune parameters. Paraffin-embedded tissue and paired (pre- and post-therapy) peripheral blood mononuclear cells samples were interrogated by digital multiplex hybridization (Nanostring Cancer Immune Profiling Panel) and flow cytometry. Although cytotoxic T-cell gene counts (CD8a, CD8b) were similar, compared to cHL there were higher levels of the immune effector activation marker CD137 (gene counts 439 vs. 287; P<0.01). Consistent with this, CD4 and the Treg markers LAG3, FOXP3 and CTLA-4 were lower in NLPHL (2-4 fold lower, all P<0.05), with no difference in T-helper cell activation markers CD40L and CD30L seen between tumors. TAMs and dendritic cell markers MARCO, CD36, CD68, CD163, COLEC12 and CD11b were all lower in NLPHL than cHL (all P<0.05). In line with the known 'rossette' formed around LP cells by PD-1+ T-lymphocytes, we observed strikingly elevated PD-1 and the other T-cell checkpoints TIM3 and TIGIT in NLPHL (all 2-3 fold, P<0.001). However, in line with the known gene amplification of PD-L1 on HRS cells and its presence on TAMs, gene counts of this checkpoint ligand were 2-fold higher in cHL (P<0.001). Flow cytometry profiling of immune subsets in peripheral blood showed findings consistent with findings in the TME. Specifically, there was elevation of multiple exhaustion markers within CD4, CD8, and NK immune effector cells, with a striking proportion of highly anergic dual-LAG3/PD-1 positive CD8+ T-cells. Also there was elevation of immune-suppressive monocyte/macrophages in cHL relative to NLPHL. Relative to healthy lymph nodes, there was prominent up-regulation of a range of T-cell associated exhaustion markers in both NLPHL and cHL, indicating dysregulated priming of effector immune responses and host immune homeostasis. Comparison between NLPHL and cHL illustrated that NLPHL had a myriad of features that marked its intratumoral TME as a unique immunobiological entity typified by elevated immune checkpoint markers and T-cells with a highly anergic phenotype. Put together, these findings indicate that distinct immune evasion mechanisms are operative within the TME of NLPHL, including markedly higher levels of multiple immune-checkpoints relative to cHL. In contrast, Treg subsets and immune-suppressive monocyte/macrophages were relatively lower than that seen in cHL. T-cells frequently had dual immune-checkpoint expression. The findings from this study provides a compelling pre-clinical rationale for targeting PD-1 or combinatory checkpoint inhibition in NLPHL and sets the basis for future 'chemo-free' rituximab + checkpoint inhibitor clinical trials. Disclosures Tobin: Amgen: Other: Educational Travel; Celgene: Research Funding. Birch:Medadvance: Equity Ownership. Keane:Takeda: Other: Educational Meeting; BMS: Research Funding; Roche: Other: Education Support, Speakers Bureau; Celgene: Consultancy, Research Funding; Merck: Consultancy. Gandhi:BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Takeda: Honoraria; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Synergistic Role of Leukemic and Non-Leukemic Immune Repertoires in CD8+ T-Cell Large Granular Lymphocytic Leukemia As Identified By Single-Cell Transcriptomics

Blood ◽

10.1182/blood-2021-146539 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1318-1318

Author(s):

Dipabarna Bhattacharya ◽

Jani Huuhtanen ◽

Matti Kankainen ◽

Tapio Lönnberg ◽

Cassandra M Kerr ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Lymphocytic Leukemia ◽

Leukemic Cells ◽

Healthy Controls ◽

Advisory Committees ◽

Cell Clones ◽

Tcr Repertoire

Abstract Background: T-cell large granular lymphocytic leukemia (T-LGLL), a rare lymphoproliferative disorder of mature T cells, is characterized by the accumulation of activated effector T cells leading to a clonally restricted T-cell receptor (TCR) repertoire. Chronic antigen stimulation together with activating somatic STAT3 mutations have been proposed to lead to clonal expansion of leukemic cells. However, no holistic research has been done to show how leukemic and non-leukemic cells liaise to sustain abnormal immune reactivity in T-LGLL. Methods: We investigated the transcriptome and TCR repertoire in T-LGLL using: 1) single-cell RNA and TCR (scRNA+TCRαβ) sequencing from CD45+ sorted blood cells (T-LGLL n=11, healthy n=6), 2) TCRβ sequencing from blood mononuclear cells (T-LGLL n=48, healthy n=823), 3) bulk RNA sequencing (T-LGLL n=15, healthy n=5), 4) plasma cytokine profiling (T-LGLL n=9, healthy n=9), and 5) flow cytometry validations (T-LGLL n=6, healthy n=6) (Figure) Results: ScRNA+TCRαβ-seq data revealed that in healthy controls, hyperexpanded CD8+ T-cell clones (at least 10 cells with identical TCRs) preferentially had an effector memory phenotype, whereas in T-LGLL, the hyperexpanded clonotypes represented a more cytotoxic (increased expression of GZMB, PRF1, KLRB1) and exhausted (LAG3 and TIGIT) phenotype. Using flow cytometry, we confirmed that upon anti-CD3/CD28/CD49 antibody stimulation, T-LGLL clones (CD8+CD57+) expressed higher levels of cytotoxic proteins (GZMA /GZMB , PRF1) but were deficient in degranulation responses and cytokine secretion as measured by expression of CD107a/b and TNFα/IFNγ, respectively. Focused re-clustering of the extracted T-LGLL clones from the scRNA+TCRαβ-seq data revealed considerable heterogeneity among the T-LGLL clones and partly separated the mutated (mt) STAT3 and wild type (wt) STAT3 clones. STAT3wt clones upregulated T-cell activation and TCR signaling pathways, with a higher cytotoxicity and lower exhaustion score as compared to STAT3mt clones. This was validated with bulk RNA-seq data. To understand the antigen specificities of the T-LGLL clones, we combined previously profiled T-LGLL TCRs with our data to form the largest described dataset of 200 T-LGLL clones from 170 patients. Notably, T-LGLL clones were found to be private to each patient. Furthermore, the analysis by GLIPH2 algorithm grouping TCRs did not reveal detectable structural similarities, suggesting the absence of a unifying antigen in T-LGLL. However, in 67% of T-LGLL patients, the TCRs of leukemic clones shared amino acid level similarities with the rest of the non-leukemic TCR repertoire suggesting that the clonal and non-clonal immune repertoires are connected via common target antigens. To analyze the non-clonal immune repertoire in T-LGLL in detail, we compared our data to other published scRNAseq data from solid tumors (n=4) and hematologic cancers (n=8) and healthy controls (n=6). The analysis revealed that in T-LGLL also the non-leukemic CD8+ and CD4+ T cells were more mature, cytotoxic, and clonally restricted. When compared to healthy controls and other cancer patients, in non-leukemic T-LGLL the most upregulated pathway was IFNγ response. Finally, most of the upregulated cytokines in T-LGLL (e.g., CCL2/3/7, CXCL10/11, IL15RA) were secreted predominantly by monocytes and dendritic cells, which also had upregulated HLA class II expression and enhanced scavenging potential in T-LGLL patients. Ligand-receptor analysis with CellPhoneDB revealed that the number of predicted cell-cell interactions was significantly higher in T-LGLL as compared to reactive T-cell clones in healthy controls. The most co-stimulatory interactions (e.g., CD2-CD58, TNFSF14-TNFRSF14) occurred between the IFNγ secreting T-LGLL clones and the pro-inflammatory cytokine secreting monocytes. Conclusions: Our study shows a synergistic interplay between the leukemic and non-leukemic immune cell repertoires in T-LGLL, where an aberrant antigen-driven immune response including hyperexpanded CD8+ T-LGLL cells, non-leukemic CD8+ cells, CD4+ cells, and monocytes contribute to the persistence of the T-LGLL clones. Our results provide a rationale to prioritize therapies that target the entire immune repertoire and not only the T-LGLL clones in patients with T-LGLL. Figure 1 Figure 1. Disclosures Loughran: Kymera Therapeutics: Membership on an entity's Board of Directors or advisory committees; Bioniz Therapeutics: Membership on an entity's Board of Directors or advisory committees; Keystone Nano: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Maciejewski: Alexion: Consultancy; Novartis: Consultancy; Regeneron: Consultancy; Bristol Myers Squibb/Celgene: Consultancy. Mustjoki: Novartis: Research Funding; BMS: Research Funding; Janpix: Research Funding; Pfizer: Research Funding.

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Rejuvenated BCMA-Specific CD8 + Cytotoxic T Lymphocytes Derived from Antigen-Specific Induced Pluripotent Stem Cells : Immunotherapeutic Application in Multiple Myeloma

Blood ◽

10.1182/blood-2021-153110 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 75-75

Author(s):

Jooeun Bae ◽

Shuichi Kitayama ◽

Laurence Daheron ◽

Zach Herbert ◽

Nikhil C. Munshi ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

T Cell Differentiation ◽

Immune Checkpoints ◽

Publicly Traded ◽

Advisory Committees ◽

Induced Pluripotent

Abstract T cell regenerative medicine represents an emerging immunotherapeutic approach using antigen-specific Induced Pluripotent Stem Cells (iPSC) to rejuvenate CD8 + cytotoxic T lymphocytes (CTL). Here we report on an iPSC-derived therapeutic strategy targeting B-Cell Maturation Antigen (BCMA) against multiple myeloma (MM) via establishment of antigen-specific iPSC, followed by differentiation into highly functional BCMA-specific CD8 + CTL. The reprogrammed BCMA-specific iPSC displayed normal karyotypes and pluripotency potential as evidenced by expression of stem cell markers (SSEA-4, TRA1-60) and alkaline phosphatase, along with differentiation into three germ layers (Ectoderm, Mesoderm, Endoderm). During embryoid body formation, BCMA-specific iPSC further polarized into the mesoderm germ layer, evidenced by the activation of SNAI2, TBX3, PLVAP, HAND1 and CDX2 transcriptional regulators. Next, the BCMA-specific iPSC clones committed to CD8 + T cell differentiation were characterized by analyzing their hematopoietic progenitor cells (HPC; CD34 + CD43 +/CD14 - CD235a -) for specific transcriptional regulation. RNAseq analyses indicated a low variability and similar profiles of gene transcription within the iPSC clones committed to CD8 + CTL compared to increased transcriptional variability within iPSC clones committed to different cell types. The unique transcriptional profiles of the iPSC committed to CD8 + T cells included upregulation of transcriptional regulators controlling CD4/CD8 T cell differentiation ratio, memory CTL formation, NF-kappa-B/JNK pathway activation, and cytokine transporter/cytotoxic mediator development, as well as downregulation of regulators controlling B and T cell interactions, CD4 + Th cells, and inhibitory receptor development. Specifically, a major regulatory shift, indicated by upregulation of specific genes involved in immune function, was detected in HPC from the iPSC committed to CD8 + T cells. BCMA-specific T cells differentiated from the iPSC were characterized as displaying mature CTL phenotypes including high expression of CD3, CD8a, CD8b, TCRab, CD7 along with no CD4 expression (Fig. 1). In addition, the final BCMA iPSC-T cells were predominantly CD45RO + memory cells (central memory and effector memory cells) expressing high level of T cell activation (CD38, CD69) and costimulatory (CD28) molecules. Importantly, these BCMA iPSC-T cells lacked immune checkpoints (CTLA4, PD1, LAG3, Tim3) expression and regulatory T cells induction, distinct from other antigen-stimulated T cells. The rejuvenated BCMA iPSC-T cells demonstrated a high proliferative (1,000 folds increase) during the differentiation process as well as poly-functional anti-tumor activities and Th1 cytokine (IFN-g, IL-2, TNF-a) production triggered in response to MM patients' cells in HLA-A2-restricted manner (Fig. 2). Furthermore, the immune responses induced by these BCMA iPSC-T cells were specific to the parent heteroclitic BCMA 72-80 (YLMFLLRKI) peptide used to reprogram and establish the antigen-specific iPSC. Evaluation of 88 single cell Tetramer + CTL from the BCMA iPSC-T cells revealed a clonotype of unique T cell receptor (TCRa, TCRb) sequence. The BCMA-specific iPSC clones maintained their specific differentiation potential into the antigen-specific CD8 + memory T cells, following multiple subcloning in long-term cultures under feeder-free conditions or post-thaw after long-term (18 months) cryopreservation at -140 oC, which provides additional benefits to treat patients in a continuous manner. Taken together, rejuvenated CD8 + CTL differentiated from BCMA-specific iPSC were highly functional with significant (*p < 0.05) levels of anti-MM activities including proliferation, cytotoxic activity and Th-1 cytokine production. Therefore, the antigen-specific iPSC reprogramming and T cells rejuvenation process can provide an effective and long-term source of antigen-specific memory CTL lacking immune checkpoints and suppressors for clinical application in adoptive immunotherapy to improve patient outcome in MM. Figure 1 Figure 1. Disclosures Munshi: Amgen: Consultancy; Karyopharm: Consultancy; Takeda: Consultancy; Adaptive Biotechnology: Consultancy; Bristol-Myers Squibb: Consultancy; Celgene: Consultancy; Abbvie: Consultancy; Janssen: Consultancy; Legend: Consultancy; Oncopep: Consultancy, Current equity holder in publicly-traded company, Other: scientific founder, Patents & Royalties; Novartis: Consultancy; Pfizer: Consultancy. Ritz: Amgen: Research Funding; Equillium: Research Funding; Kite/Gilead: Research Funding; Avrobio: Membership on an entity's Board of Directors or advisory committees; Akron: Consultancy; Biotech: Consultancy; Blackstone Life Sciences Advisor: Consultancy; Clade Therapeutics, Garuda Therapeutics: Consultancy; Immunitas Therapeutic: Consultancy; LifeVault Bio: Consultancy; Novartis: Consultancy; Rheos Medicines: Consultancy; Talaris Therapeutics: Consultancy; TScan Therapeutics: Consultancy. Anderson: Sanofi-Aventis: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Millenium-Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Scientific Founder of Oncopep and C4 Therapeutics: Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Membership on an entity's Board of Directors or advisory committees.

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Combined PD-L1 and TIM-3 blockade improves the expansion of fit human CD8+ antigen-specific T cells for adoptive immunotherapy

10.1101/2021.08.30.21262835 ◽

2021 ◽

Author(s):

Shirin Lak ◽

Valérie Janelle ◽

Anissa Djedid ◽

Gabrielle Boudreau ◽

Ann Brasey ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Checkpoint ◽

Cell Expansion ◽

Ex Vivo ◽

Immune Checkpoint Blockade ◽

Checkpoint Blockade ◽

Immune Checkpoints ◽

T Cell Expansion ◽

And Function

AbstractBackgroundThe stimulation and expansion of antigen-specific T cells ex vivo enables the targeting of a multitude of cancer antigens. However, clinical scale T-cell expansion from rare precursors requires repeated stimulations ex vivo leading to T-cell terminal effector differentiation and exhaustion that adversely impact therapeutic potential. We leveraged immune checkpoint blockade relevant to antigen-specific CD8+ human T cells to improve the expansion and function of T cells targeting clinically relevant antigens.MethodsA clinically-compliant protocol relying on peptide-pulsed monocyte-derived dendritic cells and cytokines was used to expand antigen-specific CD8+ targeting the oncogenic Epstein-Barr virus (EBV) and the tumor associated antigen (TAA) Wilms Tumor 1 (WT1) protein. The effects of antibody-mediated blockade of immune checkpoints applied to the cultures (T-cell expansion, phenotypes and function) were assessed at various time points. Genomic studies including single cell RNA (scRNA) sequencing and T-cell receptor sequencing were performed on EBV-specific T cells to inform about the impact of immune checkpoint blockade on the clonal distribution and gene expression of the expanded T cells.ResultsSeveral immune checkpoints were expressed early by ex vivo expanded antigen-specific CD8+ T cells, including PD-1 and TIM-3 with co-expression matching evidence of T-cell dysfunction as the cultures progressed. The introduction of anti-PD-L1 (expressed by the dendritic cells) and anti-TIM-3 antibodies in combination (but not individually) to the culture led to markedly improved antigen-specific T-cell expansion based on cell counts, fluorescent multimer staining and functional tests. This was not associated with evidence of T-cell dysfunction when compared to T cells expanded without immune checkpoint blockade. Genomics studies largely confirmed these results, showing that double blockade does not impart specific transcriptional programs or patterns on TCR repertoires. However, our data indicate that combined blockade may nonetheless alter gene expression in a minority of clonotypes and have donor-specific impacts.ConclusionsThe manufacturing of antigen-specific CD8+ T cells can be improved in terms of yield and functionality using blockade of TIM-3 and the PD-L1/PD-1 axis in combination. Overcoming the deleterious effects of multiple antigenic stimulations through PD-L1/TIM-3 blockade is a readily applicable approach for several adoptive-immunotherapy strategies.

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Strong Expression of the Immune Checkpoint Regulators LAG3 and Tim3 in Hodgkin Lymphoma

Blood ◽

10.1182/blood.v128.22.2952.2952 ◽

2016 ◽

Vol 128 (22) ◽

pp. 2952-2952 ◽

Cited By ~ 5

Author(s):

Layal el Halabi ◽

Julien Adam ◽

Virginie Marty ◽

Jacques Bosq ◽

Julien Lazarovici ◽

...

Keyword(s):

T Cells ◽

Tumor Microenvironment ◽

Board Of Directors ◽

Hodgkin Lymphoma ◽

Immune Checkpoint ◽

Single Case ◽

Immune Checkpoint Blockade ◽

Immune Checkpoints ◽

Advisory Committees ◽

Secondary Resistance

Abstract Background: Recent results of immune checkpoint blockade trials have provided a proof of concept for immunotherapy in classical Hodgkin lymphoma (cHL) with more than two third of relapsed/refractory patients responding to blockade of the PD1/PDL1 axis. Unfortunately, there is still a proportion of patients who will present primary or secondary resistance to immunotherapy. Besides the PD1/PDL1 axis, several other molecules are critical regulators of the immune response and may be the target of therapeutic intervention. Combined immune checkpoint targeting has shown interesting results in preclinical and clinical trials in several types of tumors. Methods: Patients with initially diagnosed or relapsed cHL for whom formalin fixed paraffin embedded (FFPE) tissue was available at our institution were identified. Fifty-seven cases were selected depending solely on the availability and the quality of the FFPE blocks. Expression of the following immune checkpoints PD1, PDL1, LAG3, TIM3 was assessed using immunohistochemical methods with a threshold of 5% set for positivity. Results: Complete results for 25 cases were available at the time the abstract was written. Hodgkin and Reed Sternberg cells (HRS) were identified morphologically upon microscopic examination. Consistently with data published in the literature, HRS stained positively and intensely for PDL1 in 100% of the cases (25/25). HRS were positive for Tim3 in 36% (9/25) of cases but with more varying intensities. No PD1 or LAG3 expression was found on HRS cells except for a single case where 5% of HRS stained weakly for LAG3. In the tumor microenvironment, PD1 expression was detected in 65% of cases (15/23) and PDL1 in 60% of cases (15/25). Impressively, LAG3 and TIM3 stained positively in 96% (23/24) and 92% (24/25) of cases respectively. Lymphocyte-rosetting was present in 9/25 cases. These CD4+ FoxP3- T cells surrounding HRS were positive for PD1 in 5 cases, for LAG3 in 2 cases and for both PD1 and LAG3 in 2 cases, suggesting they represented exhausted T-cells. Concomitant expression of PD1 and PDL1 in the tumor microenvironment was present in 43% of cases (10/23). Conclusion: LAG3 and TIM3 are nearly universally expressed in the tumor microenvironment of cHL. These findings provide a strong rationale for their blockade alone or in combination in relapsed/refractory patients with cHL. The role of TIM3 expression by HRS remains unclear. Correlation of these findings with clinical data and survival outcome of the patients will be done for the whole sample. Disclosures Ribrag: NanoString: Membership on an entity's Board of Directors or advisory committees; Esai: Membership on an entity's Board of Directors or advisory committees; ArgenX: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees.

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Transcriptomic Features of Immune Exhaustion and Senescence Predict Outcomes and Define Checkpoint Blockade-Unresponsive Microenvironments in Acute Myeloid Leukemia

Blood ◽

10.1182/blood-2021-145854 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 223-223

Author(s):

Sergio Rutella ◽

Jayakumar Vadakekolathu ◽

Francesco Mazziotta ◽

Stephen Reeder ◽

Tung On Yau ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Myeloid Leukemia ◽

Research Funding ◽

Checkpoint Blockade ◽

Newly Diagnosed ◽

Advisory Committees ◽

Immune Exhaustion

Abstract Acute myeloid leukemia (AML) is a molecularly and clinically heterogeneous disease. Reinstating immunological control of AML is highly desirable to eradicate chemotherapy-resistant clones and provide long-term disease control. We recently identified bone marrow (BM) microenvironmental transcriptomic profiles that stratify patients with newly diagnosed AML into an immune-infiltrated and an immune-depleted subtype and that refine the accuracy of survival prediction beyond that afforded by current prognosticators (Vadakekolathu J et al., 2020). We have also shown that CD8 + T cells from patients with AML exhibit features of immune exhaustion and senescence (IES), including heightened expression of killer cell lectin-like receptor subfamily G member 1 (KLRG1) and B3GAT1 (encoding CD57) (Knaus H et al., 2018). Whether deranged T-cell functions affect the likelihood of responding to antitumor therapy, including immune checkpoint blockade (ICB), is an outstanding question in AML. In the current study, we analyzed 183 BM samples collected longitudinally at time of AML onset, response assessment and disease relapse from multiple cohorts of patients with AML treated with standard-of-care induction chemotherapy, and from 33 elderly AML patients with newly diagnosed or chemotherapy-refractory/relapsed AML treated with azacitidine, and the PD-1 checkpoint inhibitor pembrolizumab (NCT02845297). Primary patient specimens and associated clinical data were obtained via informed consent in accordance with the Declaration of Helsinki on research protocols approved by the Institutional Review Boards of the participating Institutions. RNA (150-200 ng) was extracted from BM aspirates and was processed on the nCounter FLEX analysis system (NanoString Technologies, Seattle, WA) using the PanCancer Immune profiling panel, as previously published (Vadakekolathu J et al., 2020). The correlation between transcriptomic features of IES, clinical characteristics, therapeutic response and patient outcome was validated using publicly available RNA-sequencing and NanoString data from 1,698 patients with AML, including samples from the TCGA-AML (n=147 cases), Beat-AML Master Trial (n=264 cases, of which 240 with survival data and 195 with chemotherapy response data) and Children's Oncology Group (COG)-TARGET AML series (n=145 cases). We initially showed that, compared with their non-senescent CD8 +CD57 -KLRG1 - counterpart, senescent CD8 +CD57 +KLRG1 + T cells are functionally impaired in terms of their ability to effect AML-blast killing mediated by an anti-CD33/CD3 bi-specific T-cell engager antibody construct (kindly provided by Amgen, USA; effector/target [E/T] ratio = 1:5). We then used gene set enrichment analysis (GSEA) to derive a transcriptomic signature of IES encompassing natural killer (NK)-cell and stem-like CD8 + T-cell markers, and showed that IES states correlate with lymphoid infiltration, adverse-risk molecular lesions (TP53 and RUNX1 mutations), experimental gene signatures of leukemia stemness (LSC17 score; Ng et al., 2016) and poor outcome in response to standard induction chemotherapy (Fig. 1A). In independent validation cohorts of children and adults with AML, the IES score was higher at baseline in patients with primary induction failure (following a standard 2 cycles of chemotherapy) compared with complete remission, increased in post-chemotherapy BM specimens, and predicted survival with greater accuracy than the ELN cytogenetic risk classifier (Fig. 1B). In the immunotherapy setting, high IES scores at baseline defined a checkpoint blockade-unresponsive AML tumor microenvironment and correlated with significantly shorter overall survival (9.1 versus 15.56 months in patients with high and low IES scores, respectively; HR = 3.32 (95% CI = 1.19-9.25); log-rank P = 0.021; Fig. 1C). Finally, the IES-related gene set also predicted for long-term outcomes and objective responses, based on RECIST criteria, to single-agent nivolumab or pembrolizumab, or combination anti-PD-1 + anti-CTLA-4, in 106 patients with melanoma (PRJEB23709 and GSE93157 series), a tumor type known to derive durable clinical benefit from ICB (Fig. 1D). Our findings encourage the pursuit of immune senescence reversal as a strategy to functionally reinvigorate T cells and could inform the delivery of ICB and other T cell-targeting immunotherapies to patients who are likely to benefit. Figure 1 Figure 1. Disclosures Radojcic: Syndax Pharmaceuticals: Research Funding; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Allakos: Membership on an entity's Board of Directors or advisory committees. Minden: Astellas: Consultancy. Tasian: Aleta Biotherapeutics: Consultancy; Gilead Sciences: Research Funding; Kura Oncology: Consultancy; Incyte Corporation: Research Funding.

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Identification of Novel Immune-Checkpoint Molecules on Multiple Myeloma Cells Using a High-Throughput Discovery Platform

Blood ◽

10.1182/blood.v128.22.380.380 ◽

2016 ◽

Vol 128 (22) ◽

pp. 380-380

Author(s):

Valentina Volpin ◽

Till Michels ◽

Antonio Sorrentino ◽

Dirk Hose ◽

Anthony D. Ho ◽

...

Keyword(s):

Multiple Myeloma ◽

T Cell ◽

Board Of Directors ◽

High Throughput ◽

Immune Checkpoint ◽

Research Funding ◽

Immune Checkpoints ◽

Advisory Committees ◽

Myeloma Cells ◽

Immune Checkpoint Molecules

Abstract Introduction: Multiple myeloma (MM) is a B-cell malignancy, characterized by accumulation of plasma cell clones in the bone marrow. While novel therapeutic agents like immunomodulatory drugs and proteasome inhibitors have improved overall survival of MM patients, the disease remains incurable in most patients. Several studies showed that immune-checkpoint molecules are expressed by myeloma cells and induce tumor-related immune suppression. Despite the promising results achieved by blocking CTLA4 and the PD-1/PD-L1 axis in the treatment of various solid tumors and Hodgkin's lymphoma, targeting these checkpoints did not induce objective responses in Phase I/II trials in MM patients. Therefore, identification of novel immune-checkpoints and defining the subsequent molecular mechanisms of inhibition are essential for further improvement. Methods: Our main goal is to identify novel MM-related immune-checkpoint molecules by taking advantage of a high-throughput (HT) RNAi screen and sequentially validate the role of candidate molecules, whose blockade could potentially induce anti-tumor immunity in MM patients. Methods: High-throughput RNAi screens offer a possibility to systemically search for immune-checkpoint molecules. Therefore, we established a high-throughput screening system to discern candidate molecules and evaluate their use as potential targets for multiple myeloma immunotherapy. We established a luciferase based read-out system by generating a stable luciferase expressing MM cell line (KMM-1-luc). To test the effect of immune-checkpoint molecules, KMM-1-luc cells were transfected with a siRNAs library targeting 2514 genes encoding for cell surface proteins, kinases and GPCRs. Transfected tumor cells were subsequently co-cultured with patient-derived HLA-matched Myeloma Infiltrating T Lymphocytes (MILs) and the effect of gene knock-down on T-cell mediated tumor lysis was measured. Results: Based on our primary HT-screening, we have identified 132 candidate molecules (hits) whose knockdown increased T-cell mediated killing more efficiently than the established checkpoint genes CCR9. To confirm the hits and the robustness of the screening, we re-tested the identified candidates in a secondary screening. Among these potential immune-checkpoints we selected 10 hits for further validation. So far, we were able to confirm expression of the hits at mRNA level and to validate siRNAs on-target effect by qPCR and luciferase-based cytotoxicity assay. Detailed results will be presented at the meeting. Conclusion: Altogether we optimized a high-throughput RNAi screen to discover novel immune-checkpoints that are potential immunotherapeutic targets for the treatment of multiple myeloma. We are currently investigating the mode of action of the candidate hits in vitro. Further in vivo validation of these immune-checkpoint molecules is still required for clinical studies. Disclosures Goldschmidt: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Chugai: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Witzens-Harig:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Vaccine Increases the Diversity and Activation of Intratumoral T Cells in the Context of Combination Immunotherapy

Cancers ◽

10.3390/cancers13050968 ◽

2021 ◽

Vol 13 (5) ◽

pp. 968

Author(s):

Lucas A. Horn ◽

Kristen Fousek ◽

Duane H. Hamilton ◽

James W. Hodge ◽

John A. Zebala ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Checkpoint ◽

Recombinant Adenovirus ◽

Cytotoxic T Cells ◽

Cell Receptor ◽

Immune Checkpoint Blockade ◽

Checkpoint Blockade ◽

T Cell Infiltration ◽

Tcr Repertoire

Resistance to immune checkpoint blockade therapy has spurred the development of novel combinations of drugs tailored to specific cancer types, including non-inflamed tumors with low T-cell infiltration. Cancer vaccines can potentially be utilized as part of these combination immunotherapies to enhance antitumor efficacy through the expansion of tumor-reactive T cells. Utilizing murine models of colon and mammary carcinoma, here we investigated the effect of adding a recombinant adenovirus-based vaccine targeting tumor-associated antigens with an IL-15 super agonist adjuvant to a multimodal regimen consisting of a bifunctional anti-PD-L1/TGF-βRII agent along with a CXCR1/2 inhibitor. We demonstrate that the addition of vaccine induced a greater tumor infiltration with T cells highly positive for markers of proliferation and cytotoxicity. In addition to this enhancement of cytotoxic T cells, combination therapy showed a restructured tumor microenvironment with reduced Tregs and CD11b+Ly6G+ myeloid cells. Tumor-infiltrating immune cells exhibited an upregulation of gene signatures characteristic of a Th1 response and presented with a more diverse T-cell receptor (TCR) repertoire. These results provide the rationale for the addition of vaccine-to-immune checkpoint blockade-based therapies being tested in the clinic.

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Immune Reconstitution and Thymic Function After Reduced Intensity Allogeneic Hematopoietic Cell Transplantation

Blood ◽

10.1182/blood.v116.21.1254.1254 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1254-1254

Author(s):

Benedetto Bruno ◽

Paola Omedè ◽

Silvia Cena ◽

Maddalena Noviello ◽

Milena Gilestro ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Cd8 T Cells ◽

Research Funding ◽

Chronic Gvhd ◽

Advisory Committees ◽

Thymic Function ◽

Post Transplant ◽

Tcr Repertoire

Abstract Abstract 1254 Background: The thymus is fundamental for the generation of T-cell diversity following allografting even though its function declines with age. Non-myeloablative conditionings have extended the eligible age for allografting to 65–70 yrs for patients with hematological cancers. The thymic generation of the TCR diversity occurs through the recombination of gene segments coding for the TCR alpha and beta chains generating by-products defined as signal joint TCR excision circles (sjTRECs). sjTRECs are extrachromosomal DNA fragments, most frequently found in naive T cell, that do not replicate with subsequent cell divisions. Methods: sjTRECs evaluation by quantitative PCR and the kinetics of naive and memory T cells by flow-cytometry were used to asses the thymic function. Moreover, TCR repertoire analysis of V-beta families was evaluated, in a subset of patients, by spectratyping up to 1 year post-transplant. Finally, TRECs values were compared with 67 paediatric patients (median age 9, r 1–19 years). Subpopulations studied included peripheral mononuclear cells (PMC), sorted CD4- and CD8 – T cells. Results: Overall, 55 patients, median age 51 (r 34–64) years, conditioned with low dose TBI (200 cGy), with/without fludarabine, followed by G-CSF mobilised donor peripheral blood stem cell infusion from HLA identical siblings or unrelated donors, were evaluated at different time points: baseline, at 28, 56, 84, 100, 180 days, and at 1, 2, 3, 4, 5 years post-transplant. Naive CD4+CD62L+CD45RA+bright T cells and memory CD4+CD62L+CD45R0+bright T cells showed a gradual increase up to 3 years post-transplant with median values of 882/ul and of 532/ul respectively. Median values of sjTREC copies/100ng DNA in PMC increased 5 fold at 1 yr, 20 fold at 3 yrs and 75 fold at 5 yrs from 0.7 (pre-transplant), whereas median sjTREC copies/100ng DNA from sorted CD4+ cells (purity>95%) increased 7 fold at 1 yr and 15 fold at 5 yrs from 5 at 3 months post-transplant. A significant correlation was demonstrated between TREC values and CD4+CD62L+CD45RA+bright T cells (p<0.001). Importantly, a 60 y/o patient thymectomised 10 years before transplant showed no thymic output and a very poor recovery of the TCR repertoire. However, in the subset of studied patients, though slow, TCR repertoire of V-beta families required at least 1 year to clearly become polyclonal. sjTRECs levels in both sorted CD4- and CD8- T cells at 1 year were significantly higher in patients without chronic GVHD (p=0.0135 and 0.007). At 2 years post-transplant, sjTRECs levels were significantly higher in paediatric patients versus adults (median values 240 vs 56.9, p=0.001). Conclusions: Detectable thymic function persisted post-transplant in all patients except one who had previously been thymectomised. T cell reconstitution was somewhat slow especially during the first year post-transplant. The thymus may be an important target of chronic GVHD. Age played an important role in thymic output. Disclosures: Boccadoro: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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