T-cell Receptor Repertoire Profiling Research Articles

TIRTL-seq: Deep, quantitative, and affordable paired TCR repertoire sequencing.

ɑ/β T cells are key players in adaptive immunity. The specificity of T cells is determined by the sequences of the hypervariable T cell receptor (TCR) ɑ and β chains. Although bulk TCR sequencing offers a cost-effective approach for in-depth TCR repertoire profiling, it does not provide chain pairings, which are essential for determining T cell specificity. In contrast, single-cell TCR sequencing technologies produce paired chain data, but are limited in throughput to thousands of cells and are cost-prohibitive for cohort-scale studies. Here, we present TIRTL-seq (Throughput-Intensive Rapid TCR Library sequencing), a novel approach that generates ready-to-sequence TCR libraries from live cells in less than 7 hours. The protocol is optimized for use with non-contact liquid handlers in an automation-friendly 384-well plate format. Reaction volume miniaturization reduces library preparation costs to <$0.50 per well. The core principle of TIRTL-seq is the parallel generation of hundreds of libraries providing multiple biological replicates from a single sample that allows precise inference of both frequencies of individual clones and TCR chain pairings from well-occurrence patterns. We demonstrate scalability of our approach up to 1 million unique paired αβTCR clonotypes corresponding to over 30 million T cells per sample at a cost of less than $2000. For a sample of 10 million cells the cost is ~$200. We benchmarked TIRTL-seq against state-of-the-art 5'RACE bulk TCR-seq and 10x Genomics Chromium technologies on longitudinal samples. We show that TIRTL-seq is able to quantitatively identify expanding and contracting clonotypes between timepoints while providing accurate TCR chain pairings, including distinct temporal dynamics of SARS-CoV-2-specific and EBV-specific CD8+ T cell responses after infection. While clonal expansion was followed by sharp contraction for SARS-CoV-2 specific TCRs, EBV-specific TCRs remained stable once established. The sequences of both ɑ and β TCR chains are essential for determining T cell specificity. As the field moves towards greater applications in diagnostics and immunotherapy that rely on TCR specificity, we anticipate that our scalable paired TCR sequencing methodology will be instrumental for collecting large paired-chain datasets and ultimately extracting therapeutically relevant information from the TCR repertoire.

Abstract C156: Examining the role of T cell responses in colorectal cancer sex disparities

Abstract Purpose: Persistent sex disparities in colorectal cancer (CRC) incidence and mortality exist and vary by race and ethnicity. The overarching goal of this proposal is to quantify differences in the CRC tumor immune microenvironment by sex in the Latino Colorectal Cancer Consortium (LC3). Methods: The LC3 is a consortium of pooled individual-level data from Latino participants diagnosed with CRC from California, Florida, and Puerto Rico. Biospecimens, epidemiologic data, and clinical outcomes were collected from each contributing study. DNA was extracted from tumor tissue and paired germline or normal tissue samples. Whole exome sequencing was performed using established protocols. Global genetic ancestry was estimated from whole exome sequence data. High-throughput T cell receptor (TCR) sequencing was used to estimate features of the T cell receptor (TCR) repertoire (e.g. abundance, clonality), and tumor-infiltrating lymphocyte (TIL) counts were obtained through pathology review. We evaluated differences in TCR abundance and TILs by sex using linear models for continuous measurements and generalized linear models for binary or count measurements. Primary analyses were unadjusted, and secondary analyses adjusted for age at diagnosis, stage at diagnosis, tumor location (right colon vs. left colorectum), and microsatellite instability (MSI) status. To examine how genetic ancestry modified the relationship between sex and T cell responses, we fit separate models with an interaction term between each genetic ancestry proportion variable (i.e. African, European, Native American) and sex, and assessed effect modification using a likelihood ratio test. Results: To date, 240 participants had TCR repertoire profiling and whole exome sequencing data generated. 52% were male, with a mean age of 58. 17% of participants had rectal tumors. With respect to Hispanic ethnic heritage or country of origin, 49% of participants were of Mexican descent, followed by 13% of Central or South American descent, and 10% were of Puerto Rican descent. Mean T cell abundance was 0.18 (standard deviation (SD): 0.16) and mean clonality was 0.05 (SD: 0.05). Further analysis is underway. Conclusions: This project leverages within-Latino genetic diversity to disentangle the contributions of sex and genetic ancestry to variability in immune function and to understand how this may further sex disparities in CRC. We anticipate that results from this analysis will provide insight on the relationship between the tumor immune microenvironment and sex disparities in CRC. Citation Format: Nicole C. Loroña, Ya-Yu Tsai, Daniel Sobieski, Eric Cockman, Stephanie L. Schmit, Jane C. Figueiredo. Examining the role of T cell responses in colorectal cancer sex disparities [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C156.

T-cell receptor diversity and allergen sensitivity in childhood asthma and atopic dermatitis.

Childhood allergies of asthma and atopic dermatitis (AD) involve an overactive T-cell immune response triggered by allergens. However, the impact of T-cell receptor (TCR) repertoires on allergen sensitization and their role in mediating different phenotypes of asthma and AD in early childhood remains unclear. A total of 78 children, comprising 26 with asthma alone, 26 with AD alone, and 26 healthy controls (HC), were enrolled. TCR repertoire profiles were determined using a unique molecular identifier system for next-generation sequencing. Integrative analyses of their associations with allergen-specific IgE levels and allergies were performed. The diversity in TCR alpha variable region (TRAV) genes of TCR repertoires and complementarity determining region 3 (CDR3) clonality in TRAV/TRBV (beta) genes were significantly higher in children with AD compared with those with asthma and HC (p < .05). Compared with HC, the expression of TRAV13-1 and TRAV4 genes was significantly higher in both asthma and AD (p < .05), with a significant positive correlation with mite-specific IgE levels (p < .01). In contrast, TRBV7-9 gene expression was significantly lower in both asthma and AD (p < .01), with this gene showing a significant negative correlation with mite-specific IgE levels (p < .01). Furthermore, significantly higher TRAV8-3 gene expression, positively correlated with food-specific IgE levels, was found in children with AD compared with those with asthma (p < .05). Integrated TCR repertoires analysis provides clinical insights into the diverse TCR genes linked to antigen specificity, offering potential for precision immunotherapy in childhood allergies.

The spike-specific TCRβ repertoire shows distinct features in unvaccinated or vaccinated patients with SARS-CoV-2 infection

BackgroundThe evolving variants of SARS-CoV-2 may escape immunity from prior infections or vaccinations. It’s vital to understand how immunity adapts to these changes. Both infection and mRNA vaccination induce T cells that target the Spike protein. These T cells can recognize multiple variants, such as Delta and Omicron, even if neutralizing antibodies are weakened. However, the degree of recognition can vary among people, affecting vaccine efficacy. Previous studies demonstrated the capability of T-cell receptor (TCR) repertoire analysis to identify conserved and immunodominant peptides with cross-reactive potential among variant of concerns. However, there is a need to extend the analysis of the TCR repertoire to different clinical scenarios. The aim of this study was to examine the Spike-specific TCR repertoire profiles in natural infections and those with combined natural and vaccine immunity.MethodsA T-cell enrichment approach and bioinformatic tools were used to investigate the Spike-specific TCRβ repertoire in peripheral blood mononuclear cells of previously vaccinated (n = 8) or unvaccinated (n = 6) COVID-19 patients.ResultsDiversity and clonality of the TCRβ repertoire showed no significant differences between vaccinated and unvaccinated groups. When comparing the TCRβ data to public databases, 692 unique TCRβ sequences linked to S epitopes were found in the vaccinated group and 670 in the unvaccinated group. TCRβ clonotypes related to spike regions S135-177, S264-276, S319-350, and S448-472 appear notably more prevalent in the vaccinated group. In contrast, the S673-699 epitope, believed to have super antigenic properties, is observed more frequently in the unvaccinated group. In-silico analyses suggest that mutations in epitopes, relative to the main SARS-CoV-2 variants of concern, don’t hinder their cross-reactive recognition by associated TCRβ clonotypes.ConclusionsOur findings reveal distinct TCRβ signatures in vaccinated and unvaccinated individuals with COVID-19. These differences might be associated with disease severity and could influence clinical outcomes.Trial registration: FESR/FSE 2014–2020 DDRC n. 585, Action 10.5.12, noCOVID19@UMG.

EP03.03-07 T-Cell Receptor Repertoire Profiling as a Predictive Biomarker for Immunotherapy in Unresectable Stage III Non-small Cell Lung (NSCLC)

EP03.03-07 T-Cell Receptor Repertoire Profiling as a Predictive Biomarker for Immunotherapy in Unresectable Stage III Non-small Cell Lung (NSCLC)

The T cell receptor repertoire reflects the early dynamics of the immune response to vaccination

Abstract Early ascertainment of the immune response to vaccinations is important. The T cell receptor (TCR) is a promising target to achieve this, with the complete TCR repertoire in PBMCs reflecting the T cells present in an individual. To this end, we developed Tseek, an unbiased and accurate method for profiling the TCR repertoire by sequencing the TCR α and β chains and developing a suite of tools for repertoire analysis. We explored the T cell response to both the COVID-19 mRNA vaccine (n=9) and the seasonal inactivated Influenza vaccine (n=5) at several time points. Neutralizing antibody titers were also measured in the covid vaccine samples. The COVID-19 vaccine elicited a broad T cell response involving multiple expanded clones, whereas the Influenza vaccine elicited a narrower response involving fewer clones. Distinct T cell clones responded at different time points over a month, providing temporal details lacking in the antibody measurements. The physical symptoms following administration of the vaccinations were not indicative of the TCR/antibody responses while the TCR responses broadly presaged the antibody responses. Additionally, the TCR repertoire is akin to a fingerprint: donors of blood samples taken years apart could be identified from the TCR repertoire. TCR repertoire profiling shows great promise as an early and sensitive measure of the adaptive immune response to vaccination, which can help improve immunogen selection and optimize vaccine dosage and spacing between doses.

Abstract 2271: Characteristics of peripheral blood T cell receptor repertoire and correlation with response to chemotherapy in patients with breast cancer

Abstract Purpose: The success of immune checkpoint inhibitors therapy in triple negative breast cancer highlights the potential immunogenic characteristics of breast cancer. Increasing evidence have suggested that conventional chemotherapy can exert anti-cancer activity through various immune-based mechanisms. T cell receptor (TCR) diversity is crucial for immune responses and TCR repertoire has been reported acting as predictive and prognostic markers for cancer outcome. Here, we reported the TCR repertoire profiling in breast cancer and its association with chemotherapy and treatment response in breast cancer patients. Experimental design: This study is part of VGH-TAYLOR study, a comprehensive precision medicine study protocol on the heterogeneity of Taiwanese breast cancer patients (NCT04626440). A total of 856 female patients with luminal A, luminal B1, luminal B2, HER2-enriched, or triple-negative breast cancers were recruited. The enrolled subjects contains patients who receive surgery as the first-line treatment followed by adjuvant therapy and who receive neoadjuvant therapy as the first-line treatment followed by surgery. The blood samples from patients during chemotherapy were collected for TCR sequencing. The Oncomine TCR Beta-LR Assay was applied to determine the dynamic change in TCR repertoire. We examined TCR repertoire in terms of clonality, TCR richness/evenness and convergence. Results: Higher TCR clonality in breast cancer patients was associated with lower clonal richness. TCR clonality was positively correlated with age and stage but not tumor size. Patients with recurrence had higher TCR clonality and lower Shannon diversity. Patients with luminal B2 breast cancer showed lower TCR diversity compared to luminal A and triple-negative breast cancer. However, there were no significant differences in CDR3 length and the usage of variable and joining genes among breast cancer subtypes. Notably, both of adjuvant and neoadjuvant chemotherapies increased convergence and clonality while decreased Shannon diversity of TCR. In neoadjuvant settings, lower post-treatment blood TCR richness was associated with complete pathologic response. Conclusion: These data suggested that TCR repertoire is associated with clinicopathological characteristics including stage and recurrence. TCR clonal richness might provide prognostic value for patients receiving neoadjuvant chemotherapy. Citation Format: Chun-Yu Liu, Chi-Cheng Huang, Ji-Lin Chen, Yi-Fang Tsai, Ta-Chung Chao, Pei-Ju Lien, Yen-Shu Lin, Chin-Jung Feng, Yen-Jen Chen, Jiun-I Lai, Jen-Hwey Chiu, Chih-Yi Hsu, Ling-Ming Tseng. Characteristics of peripheral blood T cell receptor repertoire and correlation with response to chemotherapy in patients with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2271.

T cell receptor gene repertoire profiles in subgroups of patients with chronic lymphocytic leukemia bearing distinct genomic aberrations.

Microenvironmental interactions of the malignant clone with T cells are critical throughout the natural history of chronic lymphocytic leukemia (CLL). Indeed, clonal expansions of T cells and shared clonotypes exist between different CLL patients, strongly implying clonal selection by antigens. Moreover, immunogenic neoepitopes have been isolated from the clonotypic B cell receptor immunoglobulin sequences, offering a rationale for immunotherapeutic approaches. Here, we interrogated the T cell receptor (TR) gene repertoire of CLL patients with different genomic aberration profiles aiming to identify unique signatures that would point towards an additional source of immunogenic neoepitopes for T cells. TR gene repertoire profiling using next generation sequencing in groups of patients with CLL carrying one of the following copy-number aberrations (CNAs): del(11q), del(17p), del(13q), trisomy 12, or gene mutations in TP53 or NOTCH1. Oligoclonal expansions were found in all patients with distinct recurrent genomic aberrations; these were more pronounced in cases bearing CNAs, particularly trisomy 12, rather than gene mutations. Shared clonotypes were found both within and across groups, which appeared to be CLL-biased based on extensive comparisons against TR databases from various entities. Moreover, in silico analysis identified TR clonotypes with high binding affinity to neoepitopes predicted to arise from TP53 and NOTCH1 mutations. Distinct TR repertoire profiles were identified in groups of patients with CLL bearing different genomic aberrations, alluding to distinct selection processes. Abnormal protein expression and gene dosage effects associated with recurrent genomic aberrations likely represent a relevant source of CLL-specific selecting antigens.

Peripheral blood T-cell receptor repertoire profiling of advanced non-small cell lung cancer patients receiving PD-1/PD-L1 treatment.

e21004 Background: Whether peripheral blood T cell receptor (TCR) repertoire profiling can serve as a biomarker to predict clinical benefit from anti-PD-1/PD-L1 checkpoint immunotherapy is not well understood. Moreover, it is not known which methods for TCR repertoire analysis are most clinically meaningful. To address this, we have performed TCR repertoire analysis of patients with advanced/metastatic non-small cell lung cancer (NSCLC) receiving PD-1/PD-L1 treatment. Methods: We analyzed 29 patients receiving PD-1/PD-L1 monotherapy or combination therapy in any line of treatment, excluding patients with EGFR mutations or Alk alterations. Genomic DNA was extracted from peripheral blood examples, and CDR3 regions of the rearranged TCR beta genes were amplified and sequenced using the immunoSEQ platform (Adaptive Biotechnologies, Seattle, WA). Libraries were sequenced using Illumina HiSeq 2500. TCR clonality, diversity, evenness, and the percentage of high-frequency clones (&gt; 0.1% of the repertoire) were calculated at pre-treatment and post-treatment (1 – 3 months) timepoints. Morisita’s overlap index was calculated for 25 paired pre- and post-treatment samples. Metrics were compared in patients with and without durable clinical response at 6 months using the Mann-Whitney test. Results: There were no statistically significant differences in TCR repertoire clonality, diversity, evenness, or high-frequency clones between patients with and without durable clinical benefit, either at pre-treatment or post-treatment time points (p &gt; 0.05). Conclusions: TCR repertoire metrics including clonality, diversity, evenness, percentage of high-frequency clones, and Morisita’s overlap index do not predict immunotherapy responses in this cohort of advanced/metastatic NSCLC patients receiving PD-1/PD-L1 monotherapy or combination therapy. Limitations of this study include sample size and heterogeneity of the patient cohort. This highlights the need for advanced TCR repertoire metrics, for example, considering shared TCR specificities and clonal identity. In ongoing work, we are defining TCR specificity groups and TCR clones in NSCLC as biomarkers of immunotherapy responsiveness.

A novel unconventional T cell population enriched in Crohn’s disease

ObjectiveOne of the current hypotheses to explain the proinflammatory immune response in IBD is a dysregulated T cell reaction to yet unknown intestinal antigens. As such, it may be possible...

A Nextflow pipeline for T-cell receptor repertoire reconstruction and analysis from RNA sequencing data

T-cell receptor (TCR) analysis is relevant for the study of immune system diseases. The expression of TCRs is usually measured with targeted sequencing approaches where TCR genes are selectively amplified. However, many non-targeted RNA-seq experiments also contain reads of TCR genes, which could be leveraged for TCR expression analysis while reducing sample requirements and costs. Moreover, a step-by-step pipeline for the processing of transcriptome RNA-seq reads to deliver immune repertoire data is missing, and these types of analyses are usually not included in RNA-seq studies of immunological conditions. This represents a missed opportunity for complementing them with the analysis of the immune repertoire.We present a Nextflow pipeline for T-cell receptor repertoire reconstruction and analysis from RNA sequencing data. We used a case study where TCR repertoire profiles were recovered from bulk RNA-seq of isolated CD4 T cells from control patients, cirrhotic patients without and with Minimal Hepatic Encephalopathy (MHE). MHE is a neuropsychiatric syndrome, mediated by peripheral inflammation, that may affect cirrhotic patients. After the recovery of 498-1,114 distinct TCR beta chains per patient, repertoire analysis of patients resulted in few public clones, high diversity and elevated within-repertoire sequence similarity, independently of immune status. Additionally, TCRs associated with celiac disease and inflammatory bowel disease were significantly overrepresented in MHE patient repertoires. The provided computational pipeline functions as a resource to facilitate TCR profiling from RNA-seq data boosting immunophenotype analyses of immunological diseases.

T cell receptor dynamic and transcriptional determinants of T cell expansion in glioma-infiltrating T cells.

BackgroundGlioblastoma (GBM) is characterized by low numbers of glioma-infiltrating lymphocytes (GIL) with a dysfunctional phenotype. Whether this dysfunctional phenotype is fixed or can be reversed upon ex vivo culturing is poorly understood. The aim of this study was to assess T cell receptor (TCR)-dynamics and -specificities as well as determinants of in vitro GIL expansion by sequencing-based technologies and functional assays to explore the use of GIL for cell therapy.MethodsBy means of flow cytometry, T cell functionality in GIL cultures was assessed from 9 GBM patients. TCR beta sequencing (TCRB-seq) was used for TCR repertoire profiling before and after in vitro expansion. Microarrays or RNA sequencing (RNA-seq) were performed from 6 micro-dissected GBM tissues and healthy brain RNA to assess the individual expression of GBM-associated antigens (GAA). GIL reactivity against in silico predicted tumor-associated antigens (TAA) and patient-individual GAA was assessed by ELISpot assay. Combined ex vivo single cell (sc)TCR-/RNA-seq and post-expansion TCRB-seq were used to evaluate transcriptional signatures that determine GIL expansion.ResultsHuman GIL regains cellular fitness upon in vitro expansion. Profound TCR dynamics were observed during in vitro expansion and only in one of six GIL cultures, reactivity against GAA was observed. Paired ex vivo scTCR/RNA-seq and TCRB-seq revealed predictive transcriptional signatures that determine GIL expansion.ConclusionsProfound TCR repertoire dynamics occur during GIL expansion. Ex vivo transcriptional T cell states determine expansion capacity in gliomas. Our observation has important implications for the use of GIL for cell therapy including genetic manipulation to maintain both antigen specificity and expansion capacity.

Selective Cell State in the Clonally Expanded T-Cell Compartment of Vκ*MYC Mice Responding to Treatment with Checkpoint Inhibitors

Introduction: Immune checkpoint receptor (ICR) blockade has emerged as an effective anti-tumour modality, but only in a subset of cancer patients. Moreover, in Multiple myeloma (MM), single-agent activity has not been observed, highlighting the need to better understand the mechanism of action of this class of drugs. We recently showed that combinatorial ICR blockade using αLAG3 and αPD-1 delays disease progression and improves survival in the transplantable Vκ*MYC model of MM (Croucher et al. ASH 2018). However, despite this being a controlled study with genetically-homogeneous tumours, anti-tumour immune responses were heterogeneous, with only a subset of mice demonstrating a delay in tumour progression (17/29 mice, response rate = 58.6%). Thus, using this model, we set out to define mechanisms underlying variability in response to ICR blockade.Methods: We established a cohort of mice by engrafting 5-week-old C57BL/6 mice with Vκ12598 cells via tail vein injection. Treatment with αLAG3/αPD-1 or Ig-control was initiated 1-week post-engraftment and bone marrow (BM) samples were collected 3 weeks after the start of treatment. Following FACS-enrichment of T cells and plasma cells (PCs), single cell suspensions were subjected to matched single-cell gene expression (5' scRNA-seq) and T cell receptor (TCR)/B cell receptor (BCR) profiling (10x Genomics).Results: Samples were selected for profiling based on response to treatment, with responders (n=4) defined by significantly lower disease burden compared to non-responders (n=3) and control-treated mice (n=5), as measured by serum M-protein and %PCs in BM/spleen at sacrifice. Unsupervised clustering of scRNA-seq data from PCs (n=3,318 cells) identified no gene expression or BCR repertoire differences between control and treated, or between responder and non-responder samples, supporting that variability in response was not related to malignant Vκ12598 cells themselves. Across all samples, a statistically significant difference was not detected between the total number of unique TCR sequences (clonotypes) comparing control-treated (351-2369), non-responders (1185-2327) and responders (1378-1698), with no overlapping TCR sequences between top clonotypes. Evaluation of TCR repertoire diversity revealed that αLAG3/αPD-1 treatment induces clonal T cell expansion in control versus treated mice, but this was not significantly different between responders and non-responders. Analysis of paired scRNA-seq data (n=21,520 cells) revealed that expanded T cells from αLAG3/αPD-1-treated mice occupy a different cell state in responder vs. non-responder mice. We speculate that underlying differences in the TCR repertoire may dictate the downstream phenotype of expanded, anti-tumour T cells in mice treated with combinatorial αLAG3/αPD-1. Tumour control following treatment was associated with clonal expansion of T cells expressing genes related to cytoxicity and activation (Ccl5, Ifng, Fasl, Gzmb), whereas tumour progression was associated with clonal expansion of proliferative T cells (Cdkn3, Birc5, Ccna2, Aurka, Mki67). Although T cell proliferation is typically a phenotype ascribed to effector T cells, recent studies have similarly observed this proliferative cell state in dysfunctional T cells within melanoma tumours. Moreover, emerging evidence supports suppression of T cell proliferation by CDK4/6 inhibitors as a means to augment anti-tumour activity of ICR-based therapy. Thus, studies exploring whether reversal of the observed proliferative T cell state can restore response to αLAG3/αPD-1 treatment in non-responding Vκ12598 mice are ongoing and will be reported.Conclusions: ICR inhibitors demonstrate significant activity in some cancers, however many patients fail to respond and a similarly promising level of efficacy has not been achieved in MM. Studies aimed at unraveling the mechanisms of response and resistance to ICR inhibitors are therefore needed to improve the utility of this class of drugs for all patients. Our approach of using paired single-cell gene expression and TCR repertoire profiling has enabled identification of molecular cell states specifically in expanded T cells of responder vs. non-responder mice. In turn, our work nominates novel mechanisms that may be used as potential biomarkers for anti-tumour immune responses as well as potential targets to augment responses to ICR blockade therapy. DisclosuresChesi: Abcuro: Patents & Royalties: Genetically engineered mouse model of myeloma; Novartis: Consultancy, Patents & Royalties: human CRBN transgenic mouse; Pfizer: Consultancy; Pi Therapeutics: Patents & Royalties: Genetically engineered mouse model of myeloma; Palleon Pharmaceuticals: Patents & Royalties: Genetically engineered mouse model of myeloma. Bergsagel: GSK: Consultancy, Honoraria; Genetech: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Oncopeptides: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties: human CRBN mouse; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Sebag: Janssen: Research Funding; Bristol Myers-Squibb: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Karyopharm Therapeutics: Consultancy, Honoraria. Trudel: BMS/Celgene: Consultancy, Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Research Funding; Roche: Consultancy; Sanofi: Honoraria; Pfizer: Honoraria, Research Funding; Genentech: Research Funding.

Single cell T cell landscape and T cell receptor repertoire profiling of AML in context of PD-1 blockade therapy

In contrast to the curative effect of allogenic stem cell transplantation in acute myeloid leukemia via T cell activity, only modest responses are achieved with checkpoint-blockade therapy, which might be explained by T cell phenotypes and T cell receptor (TCR) repertoires. Here, we show by paired single-cell RNA analysis and TCR repertoire profiling of bone marrow cells in relapsed/refractory acute myeloid leukemia patients pre/post azacytidine+nivolumab treatment that the disease-related T cell subsets are highly heterogeneous, and their abundance changes following PD-1 blockade-based treatment. TCR repertoires expand and primarily emerge from CD8+ cells in patients responding to treatment or having a stable disease, while TCR repertoires contract in therapy-resistant patients. Trajectory analysis reveals a continuum of CD8+ T cell phenotypes, characterized by differential expression of granzyme B and a bone marrow-residing memory CD8+ T cell subset, in which a population with stem-like properties expressing granzyme K is enriched in responders. Chromosome 7/7q loss, on the other hand, is a cancer-intrinsic genomic marker of PD-1 blockade resistance in AML. In summary, our study reveals that adaptive T cell plasticity and genomic alterations determine responses to PD-1 blockade in acute myeloid leukemia.

Longitudinal high-throughput TCR repertoire profiling reveals the dynamics of T-cell memory formation after mild COVID-19 infection.

COVID-19 is a global pandemic caused by the SARS-CoV-2 coronavirus. T cells play a key role in the adaptive antiviral immune response by killing infected cells and facilitating the selection of virus-specific antibodies. However, neither the dynamics and cross-reactivity of the SARS-CoV-2-specific T-cell response nor the diversity of resulting immune memory is well understood. In this study, we use longitudinal high-throughput T-cell receptor (TCR) sequencing to track changes in the T-cell repertoire following two mild cases of COVID-19. In both donors, we identified CD4+ and CD8+ T-cell clones with transient clonal expansion after infection. We describe characteristic motifs in TCR sequences of COVID-19-reactive clones and show preferential occurrence of these motifs in publicly available large dataset of repertoires from COVID-19 patients. We show that in both donors, the majority of infection-reactive clonotypes acquire memory phenotypes. Certain T-cell clones were detected in the memory fraction at the pre-infection time point, suggesting participation of pre-existing cross-reactive memory T cells in the immune response to SARS-CoV-2.

T-cell tracking, safety, and effect of low-dose donor memory T-cell infusions after αβ T cell-depleted hematopoietic stem cell transplantation.

The delayed recovery of adaptive immunity underlies transplant-related mortality (TRM) after αβ T cell-depleted hematopoietic stem cell transplantation (HSCT). We tested the use of low-dose memory donor lymphocyte infusions (mDLIs) after engraftment of αβ T cell-depleted grafts.A cohort of 131 pediatric patients (median age 9 years) were grafted with αβ T cell-depleted products from either haplo (n = 79) or unrelated donors (n = 52). After engraftment, patients received mDLIs prepared by CD45RA depletion. Cell dose was escalated monthly from 25 × 103 to 100 × 103/kg (haplo) and from 100 × 103 to 300 × 103 /kg (MUD). In a subcohort of 16 patients, T-cell receptor (TCR) repertoire profiling with deep sequencing was used to track T-cell clones and to evaluate the contribution of mDLI to the immune repertoire.In total, 343 mDLIs were administered. The cumulative incidence (CI) of grades II and III de novo acute graft-versus-host disease (aGVHD) was 5% and 2%, respectively, and the CI of chronic graft-versus-host disease was 7%. Half of the patients with undetectable CMV-specific T cells before mDLI recovered CMV-specific T cells. TCR repertoire profiling confirmed that mDLI-derived T cells significantly contribute to the TCR repertoire up to 1 year after HSCT and include persistent, CMV-specific T-cell clones.

Distinct T-cell receptor profiles associated with hepatitis B e antigen seroconversion during entecavir treatment.

T-cell receptor (TCR) repertoire is ambiguously changed in chronic hepatitis B (CHB) patients during antivirus therapy. We tried to assess TCR repertoire dynamics and its clinical significance upon HBeAg seroconversion in CHB patients. Twenty CHB patients undergoing 1-year entecavir (ETV) treatment were enrolled, including 10 complete response (CR) vs 10 non-complete response (NCR) patients based on HBeAg seroconversion at week 48. The TCRβ complementarity-determining region 3 (CDR3) of peripheral CD4+ and CD8+ T cells at weeks 0, 12 and 48 was analyzed by unbiased high-throughput sequencing. The TCR repertoire profiles and their correlations with serological parameters were analyzed. The diversity of TCRβ repertoires was decreasing in CR patients but increasing in NCR patients. The distribution pattern of TCR repertoires stratified according to clonotype frequencies changed in the opposite direction between CR and NCR patients. Narrow amounts of newly appearing clonotypes in CR patients experienced a more intensive and robust expansion and this phenomenon could occur as early as week 12 for the CD4+ subset but later at week 48 for the CD8+ subset. There existed some CR-exclusive clonotypes with a relatively low but increasing frequency at week 48. The number of unique TCRβ clonotypes was positively correlated with the ALT or HBV DNA level in CR patients but showed no or negative correlation in NCR patients. Distinct TCR profiles contribute to predicting HBeAg seroconversion in CHB patients during ETV treatment and certain TCRβ CDR3 motif may be utilized for CHB immunotherapy in the future.

Gene expression profiling and TCR diversity of ATA188, a Pre-manufactured, Allogeneic Epstein-Barr Virus-targeted T-cell Immunotherapy for Patients with Multiple Sclerosis

Background & Aim There is increasing evidence that infection with the Epstein-Barr virus (EBV) plays a role in the development and pathogenesis of multiple sclerosis (MS). We have developed a novel allogeneic T cell therapy targeting EBV-encoded antigens, ATA188, that has shown safety and initial efficacy in Progressive MS patients (NCT03283826). The goal of this study is to characterize ATA188 allogeneic EBV-T specific cells to delineate activated gene sets, molecular signatures, T-cell receptor (TCR) repertoire and underlying functional pathways associated with effector cell function and therapeutic potential. Here we provide a novel report on a comprehensive multi-parametric gene expression and TCR characterization for a clinical stage off-the-shelf allogeneic cell therapy derived from multiple donors. Methods, Results & Conclusion ATA188 T cells were profile with a curated 326-gene panel using the NanoString nCounter® platform. Total RNA from control and antigen-activated EBV-specific CD8+ T cells were sorted following EBV stimulation, sequenced, and analyzed. Individual genes differentially expressed were identified and further subjected to enrichment analyses. Furthermore, deep TCRβchain sequencing (TCR-seq) was conducted to define TCR clonal diversity and identity in ATA188 cells. Despite being derived from unrelated healthy donors, the ATA188 T cells showed considerable concordance in expression profiles (Spearman>0.80; p 1.5, p Transcriptional and TCR repertoire profiling of ATA188 revealed T-cell-intrinsic signatures and clonotypes associated with defined EBV-specific TCR repertoire, EBV-specific T-cell activation, and functional signaling pathways. These data are consistent with the proposed mechanism of action of ATA188 targeting EBV infected B cells by recognizing EBV antigens presented by defined TCRs.

Abstract 3377: T-cell receptor repertoire profiling using an augmented transcriptome

Abstract Immunotherapy is growing as one of the most promising therapeutic approaches in clinical oncology practice. This brings with it an increasing need for comprehensive immuno-genomic profiling of tumors to better understand the interaction with the immune system. This includes profiling of the T and B-cell receptor repertoires (TCR/BCR), which has traditionally not been feasible with an exome/transcriptome platform. To address these challenges, we developed ImmunoID NeXT, an augmented, immuno-oncology optimized exome/transcriptome platform designed to provide comprehensive information regarding the tumor and tumor microenvironment (TME) from limited FFPE tumor biopsies, including the TCR alpha, beta, gamma and delta chains and BCR heavy and light chains. We show how this platform accurately profiles abundant clones, and can be applied to understand the diversity and activity of the adaptive immune system. We characterize the performance of ImmunoID NeXT at profiling TCR beta from RNA. We analyze the reproducibility of clones identified using replicates of PBMC and FFPE samples, and assess the concordance of top clones from a standalone TCR sequencing approaches to ours. Then, we test LOD by diluting well-characterized clonal T-cell line samples into PBMCs. We also analyze patient-derived FFPE tumors to understand the profiles of tumor-infiltrating immune repertoires. First, we compare TCR beta profiling with IHC quantification of CD3+ cells in both tumor and adjacent normal tissues. Finally, to better understand both B and T cell infiltration, we profile the intra-sample heterogeneity of BCR and TCR in a set of tumors. Between replicates of PBMC samples, abundances for shared clones have high concordance (R2&amp;gt;0.98). We observe strong concordance of the abundances for shared clones between adjacent curls of a tumor FFPE sample (R2&amp;gt;0.87), showing that our approach is robust to degraded FFPE samples. Compared to a standalone approach, we identify over 93% of the top 1000 clones, with highly concordant abundances (R2&amp;gt;0.94). Assessing LOD in dilutions of T cell lines into a PBMC sample, we are able to identify clones present at over 0.00032% RNA by mass. In our analysis of T-cell infiltration, we find a significant T-cell population in normal tissues. We also compare TCR read counts detected by ImmunoID NeXT in tumor and normal tissues with IHC results. Finally, we find substantial inter-sample variations in the number of TCR and BCR clones in tumors. ImmunoID NeXT has been designed to enable sensitive detection of abundant TCR and BCR clones in addition to comprehensive biomarkers from exome/transcriptome data. We demonstrate that our platform is reproducible, sensitive, and concordant with the top-abundance clones derived from targeted TCR methods, as well as feasible with FFPE samples. Finally, we highlight how immune repertoire results from ImmunoID NeXT can be used to gain understanding about the immunological composition of the TME. Citation Format: Eric Levy, Pamela Milani, Sean M. Boyle, Shujun Luo, Gabor Bartha, Charles Abbott, Rena McClory, Robin Li, John West, Richard Chen. T-cell receptor repertoire profiling using an augmented transcriptome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3377.

Comprehensive Analysis of TCR-\u03b2 Repertoire in Patients with Neurological Immune-mediated Disorders

In this study we characterized the TCR repertoire profiles in patients with chronic progressive inflammatory neurological disorders including HAM/TSP, associated with human T-cell lymphotropic virus type I (HTLV-I) infection, and multiple sclerosis (MS), an inflammatory, demyelinating disease of the CNS of unknown etiology. We hypothesized that a T-cell receptor (TCR) clonal repertoire ‘signature’ could distinguish HAM/TSP patients from healthy controls, as well as from patients with a more heterogeneous CNS-reactive inflammatory disease such as MS. In this study, we applied an unbiased molecular technique – unique molecular identifier (UMI) library-based strategy to investigate with high accuracy the TCR clonal repertoire by high throughput sequencing (HTS) technology. cDNA-TCR β-chain libraries were sequenced from 2 million peripheral mononuclear cells (PBMCs) in 14 HAM/TSP patients, 34 MS patients and 20 healthy controls (HC). While HAM/TSP patients showed a higher clonal T-cell expansion compared to MS and HC, increase of the TCR clonal expansion was inversely correlated with the diversity of TCR repertoire in all subjects. In addition, longitudinal analysis of TCR repertoires from HAM/TSP patients demonstrated a correlation of the TCR clonal expansion with HTLV-I proviral load. Surprisingly, MS patients showed a higher diversity of TCR repertoires than other groups. Despite higher TCR clonal expansions in HAM/TSP patients, no disease-specific TCRs were shared among patients. Only non-shared or “private” TCR repertoires was observed. While no clones that shared the same CDR3 amino acid sequences were seen in either HC or MS patients, there was a cluster of related CDR3 amino acid sequences observed for 18 out of 34 MS patients when evaluated by phylogenetic tree analysis. This suggests that a TCR-repertoire signature may be identified in a subset of patients with MS.