Katherine K. Matthews

Autologous T cell Therapy for Cytomegalovirus as a Consolidative Treatment for Recurrent Glioblastoma

Glioblastoma multiforme (GBM) is one of the most aggressive human brain malignancies. Even with optimal treatment, median survival is less than 6 months for patients with recurrent GBM. Immune-based therapies have the potential to improve patient outcome by supplementing standard treatment. Expression of human cytomegalovirus (CMV) antigens in GBM tissues provides the unique opportunity to target viral antigens for GBM therapy. Here, we report findings of a formal clinical assessment of safety and potential clinical efficacy of autologous CMV-specific T-cell therapy as a consolidative treatment for recurrent GBM. From a total of 19 patients with recurrent GBM, CMV-specific T cells were successfully expanded from 13 patients (68.4%), 11 of whom received up to four T-cell infusions. Combination therapy based on T-cell infusion and chemotherapy was well tolerated, and we detected only minor adverse events. The overall survival of these patients since first recurrence ranged from 133 to 2,428 days, with a median overall survival of 403 days. Most importantly, 4 of 10 patients that completed the treatment remained progression free during the study period. Furthermore, molecular profiling of CMV-specific T-cell therapy from these patients revealed distinct gene expression signatures, which correlated with their clinical response. Our study suggests that a combination therapy with autologous CMV-specific T cells and chemotherapy is a safe novel treatment option and may offer clinical benefit for patients with recurrent GBM.

T-cell Receptor-optimized Peptide Skewing of the T-cell Repertoire Can Enhance Antigen Targeting.

Background: Current peptide vaccines may select suboptimal antigen-specific T-cells from polyclonal populations. Results: A combinatorial peptide library screen was used to generate an optimal ligand that could preferentially activate a known effective T-cell clonotype. Conclusion: Rationally designed altered peptide ligands may enable the preferential selection of high quality, antigen-sensitive T-cell clonotypes. Significance: This proof-of-principle study could facilitate the development of more effective peptide vaccination strategies. Altered peptide antigens that enhance T-cell immunogenicity have been used to improve peptide-based vaccination for a range of diseases. Although this strategy can prime T-cell responses of greater magnitude, the efficacy of constituent T-cell clonotypes within the primed population can be poor. To overcome this limitation, we isolated a CD8+ T-cell clone (MEL5) with an enhanced ability to recognize the HLA A*0201-Melan A27–35 (HLA A*0201-AAGIGILTV) antigen expressed on the surface of malignant melanoma cells. We used combinatorial peptide library screening to design an optimal peptide sequence that enhanced functional activation of the MEL5 clone, but not other CD8+ T-cell clones that recognized HLA A*0201-AAGIGILTV poorly. Structural analysis revealed the potential for new contacts between the MEL5 T-cell receptor and the optimized peptide. Furthermore, the optimized peptide was able to prime CD8+ T-cell populations in peripheral blood mononuclear cell isolates from multiple HLA A*0201+ individuals that were capable of efficient HLA A*0201+ melanoma cell destruction. This proof-of-concept study demonstrates that it is possible to design altered peptide antigens for the selection of superior T-cell clonotypes with enhanced antigen recognition properties.

Naive CD8+ T-cell precursors display structured TCR repertoires and composite antigen-driven selection dynamics

Basic parameters of the naive antigen (Ag)‐specific T‐cell repertoire in humans remain poorly defined. Systematic characterization of this ‘ground state’ immunity in comparison with memory will allow a better understanding of clonal selection during immune challenge. Here, we used high‐definition cell isolation from umbilical cord blood samples to establish the baseline frequency, phenotype and T‐cell antigen receptor (TCR) repertoire of CD8+ T‐cell precursor populations specific for a range of viral and self‐derived Ags. Across the board, these precursor populations were phenotypically naive and occurred with hierarchical frequencies clustered by Ag specificity. The corresponding patterns of TCR architecture were highly ordered and displayed partial overlap with adult memory, indicating biased structuring of the T‐cell repertoire during Ag‐driven selection. Collectively, these results provide new insights into the complex nature and dynamics of the naive T‐cell compartment.

β-cell-specific CD8 T cell phenotype in type 1 diabetes reflects chronic autoantigen exposure

Autoreactive CD8 T cells play a central role in the destruction of pancreatic islet β-cells that leads to type 1 diabetes, yet the key features of this immune-mediated process remain poorly defined. In this study, we combined high-definition polychromatic flow cytometry with ultrasensitive peptide–human leukocyte antigen class I tetramer staining to quantify and characterize β-cell–specific CD8 T cell populations in patients with recent-onset type 1 diabetes and healthy control subjects. Remarkably, we found that β-cell–specific CD8 T cell frequencies in peripheral blood were similar between subject groups. In contrast to healthy control subjects, however, patients with newly diagnosed type 1 diabetes displayed hallmarks of antigen-driven expansion uniquely within the β-cell–specific CD8 T cell compartment. Molecular analysis of selected β-cell–specific CD8 T cell populations further revealed highly skewed oligoclonal T cell receptor repertoires comprising exclusively private clonotypes. Collectively, these data identify novel and distinctive features of disease-relevant CD8 T cells that inform the immunopathogenesis of type 1 diabetes.

VDJdb: a curated database of T-cell receptor sequences with known antigen specificity.

Abstract The ability to decode antigen specificities encapsulated in the sequences of rearranged T-cell receptor (TCR) genes is critical for our understanding of the adaptive immune system and promises significant advances in the field of translational medicine. Recent developments in high-throughput sequencing methods (immune repertoire sequencing technology, or RepSeq) and single-cell RNA sequencing technology have allowed us to obtain huge numbers of TCR sequences from donor samples and link them to T-cell phenotypes. However, our ability to annotate these TCR sequences still lags behind, owing to the enormous diversity of the TCR repertoire and the scarcity of available data on T-cell specificities. In this paper, we present VDJdb, a database that stores and aggregates the results of published T-cell specificity assays and provides a universal platform that couples antigen specificities with TCR sequences. We demonstrate that VDJdb is a versatile instrument for the annotation of TCR repertoire data, enabling a concatenated view of antigen-specific TCR sequence motifs. VDJdb can be accessed at https://vdjdb.cdr3.net and https://github.com/antigenomics/vdjdb-db.

CD8+ TCR Repertoire Formation Is Guided Primarily by the Peptide Component of the Antigenic Complex

CD8+ T cells recognize infected or dysregulated cells via the clonotypically expressed αβ TCR, which engages Ag in the form of peptide bound to MHC class I (MHC I) on the target cell surface. Previous studies have indicated that a diverse Ag-specific TCR repertoire can be beneficial to the host, yet the determinants of clonotypic diversity are poorly defined. To better understand the factors that govern TCR repertoire formation, we conducted a comprehensive clonotypic analysis of CD8+ T cell populations directed against epitopes derived from EBV and CMV. Neither pathogen source nor the restricting MHC I molecule were linked with TCR diversity; indeed, both HLA-A and HLA-B molecules were observed to interact with an overlapping repertoire of expressed TRBV genes. Peptide specificity, however, markedly impacted TCR diversity. In addition, distinct peptides sharing HLA restriction and viral origin mobilized TCR repertoires with distinct patterns of TRBV gene usage. Notably, no relationship was observed between immunodominance and TCR diversity. These findings provide new insights into the forces that shape the Ag-specific TCR repertoire in vivo and highlight a determinative role for the peptide component of the peptide–MHC I complex on the molecular frontline of CD8+ T cell–mediated immune surveillance.

Activation‐induced KIR3DL2 binding to HLA‐B27 licenses pathogenic T cell differentiation in Spondyloarthritis

In the spondyloarthritides (SpA), increased numbers of CD4+ T cells express killer cell immunoglobulin‐like receptor 3DL2 (KIR‐3DL2). The aim of this study was to determine the factors that induce KIR‐3DL2 expression, and to characterize the relationship between HLA–B27 and the phenotype and function of KIR‐3DL2–expressing CD4+ T cells in SpA.

Activation‐Induced Killer Cell Immunoglobulin‐like Receptor 3DL2 Binding to HLA–B27 Licenses Pathogenic T Cell Differentiation in Spondyloarthritis

In the spondyloarthritides (SpA), increased numbers of CD4+ T cells express killer cell immunoglobulin‐like receptor 3DL2 (KIR‐3DL2). The aim of this study was to determine the factors that induce KIR‐3DL2 expression, and to characterize the relationship between HLA–B27 and the phenotype and function of KIR‐3DL2–expressing CD4+ T cells in SpA.

Pre-emptive and therapeutic adoptive immunotherapy for nasopharyngeal carcinoma: Phenotype and effector function of T cells impact on clinical response

ABSTRACT Adoptive T cell therapy has emerged as a powerful strategy to treat human cancers especially haematological malignancies. Extension of these therapies to solid cancers remains a significant challenge especially in the context of defining immunological correlates of clinical responses. Here we describe results from a clinical study investigating autologous Epstein-Barr virus (EBV)-specific T cells generated using a novel AdE1-LMPpoly vector to treat patients with nasopharyngeal carcinoma (NPC) either pre-emptively in at-risk patients with no or minimal residual disease (N/MRD) or therapeutically in patients with active recurrent/metastatic disease (ARMD). Tolerability, safety and efficacy, including progression-free survival (PFS) and overall survival (OS), were evaluated following adoptive T-cell immunotherapy. Twenty-nine patients, including 20 with ARMD and nine with N/MRD, successfully completed T-cell therapy. After a median follow-up of 18.5 months, the median PFS was 5.5 months (95% CI 2.1 to 9.0 months) and the median OS was 38.1 months (95% CI 17.2 months to not reached). Post-immunotherapy analyses revealed that disease stabilization in ARMD patients was significantly associated with the functional and phenotypic composition of in vitro-expanded T cell immunotherapy. These included a higher proportion of effector CD8+ T-cells and an increased number of EBV-specific T-cells with broader antigen specificity. These observations indicate that adoptive immunotherapy with AdE1-LMPpoly-expanded T cells stabilizes relapsed, refractory NPC without significant toxicity. Promising clinical outcomes in N/MRD patients further suggest a potential role for this approach as a consolidation treatment following first-line chemotherapy.

Progression of carcinogen‐induced fibrosarcomas is associated with the accumulation of naïve CD4+ T cells via blood vessels and lymphatics

The tumor microenvironment comprises newly formed blood and lymphatic vessels which shape the influx, retention and departure of lymphocytes within the tumor mass. Thus, by influencing the intratumoral composition of lymphocytes, these vessels affect the manner in which the adaptive immune system responds to the tumor, either promoting or impairing effective antitumor immunity. In our study, we utilized a mouse model of carcinogen‐induced fibrosarcoma to examine the composition of tumor‐infiltrating lymphocytes during tumor progression. In particular, we sought to determine whether CD4+Foxp3+ regulatory T cells (Tregs) became enriched during tumor progression thereby contributing to tumor‐driven immunosuppression. This was not the case as the proportion of Tregs and effector CD4+ T cells actually declined within the tumor owing to the unexpected accumulation of naïve T cells. However, we found no evidence for antigen‐driven migration of these T cells or for their participation in an antitumor immune response. Our data support the notion that lymphocytes can enter tumors via aberrantly formed blood and lymphatic vessels. Such findings suggest that targeting both the tumor vasculature and lymphatics will alter the balance of lymphocyte subpopulations that enter the tumor mass. A consideration of this aspect of tumor immunology may be critical to the success of solid cancer immunotherapies.