Cell Receptor Sequencing Research Articles

ScRNA-seq reveals novel immune-suppressive T cells and investigates CMV-TCR-T cells cytotoxicity against GBM

BackgroundGlioblastoma (GBM) is a fatal primary brain malignancy in adults. Previous studies have shown that cytomegalovirus (CMV) is a risk factor for tumorigenesis and aggressiveness for glioblastoma. However, little is...

Transcriptional signature of durable effector T cells elicited by a replication defective HCMV vaccine.

Human cytomegalovirus (HCMV) is a leading infectious cause of birth defects and the most common opportunistic infection that causes life-threatening diseases post-transplantation; however, an effective vaccine remains elusive. V160 is a live-attenuated replication defective HCMV vaccine that showed a 42.4% efficacy against primary HCMV infection among seronegative women in a phase 2b clinical trial. Here, we integrated the multicolor flow cytometry, longitudinal T cell receptor (TCR) sequencing, and single-cell RNA/TCR sequencing approaches to characterize the magnitude, phenotype, and functional quality of human T cell responses to V160. We demonstrated that V160 de novo induces IE-1 and pp65 specific durable polyfunctional effector CD8 T cells that are comparable to those induced by natural HCMV infection. We identified a variety of V160-responsive T cell clones which exhibit distinctive "transient" and "durable" expansion kinetics, and revealed a transcriptional signature that marks durable CD8 T cells post-vaccination. Our study enhances the understanding of human T-cell immune responses to V160 vaccination.

Characterization of Th17 tissue-resident memory cells in non-inflamed intestinal tissue of Crohn's disease patients

Crohn's disease (CD) is a chronic inflammatory disorder affecting the bowel wall. Tissue-resident memory T (Trm) cells are implicated in CD, yet their characteristics remain unclear. We aimed to investigate the transcriptional profiles and functional characteristics of Trm cells in the small bowel of CD and their interactions with immune cells. Seven patients with CD and four with ulcerative colitis as controls were included. Single-cell RNA sequencing and paired T cell receptor sequencing assessed T cell subsets and transcriptional signatures in lamina propria (LP) and submucosa/muscularis propria-enriched fractions (SM/MP) from small bowel tissue samples. We detected 58,123 T cells grouped into 16 populations, including the CD4+ Trm cells with a Th17 signature and CD8+ Trm clusters. In CD, CD4+ Trm cells with a Th17 signature, termed Th17 Trm, showed significantly increased proportions within both the LP and SM/MP areas. The Th17 Trm cluster demonstrated heightened expression of tissue-residency marker genes (ITGAE, ITGA1, and CXCR6) along with elevated levels of IL17A, IL22, CCR6, and CCL20. The clonal expansion of Th17 Trm cells in CD was accompanied by enhanced transmural dynamic potential, as indicated by significantly higher migration scores. CD-prominent Th17 Trm cells displayed an increased interferon gamma (IFNγ)-related signature possibly linked with STAT1 activation, inducing chemokines (i.e., CXCL10, CXCL8, and CXCL9) in myeloid cells. Our findings underscored the elevated Th17 Trm cells throughout the small bowel in CD, contributing to disease pathogenesis through IFNγ induction and subsequent chemokine production in myeloid cells.

Analysis and Development of Antigen-specific T Cells Derived from Peripheral Blood Mononuclear Cells of Healthy Donors.

Adoptive cell therapy using antigen-specific T cells is a promising treatment modality for cancer patients. Various methods to isolate specific T cells and identify corresponding T cell receptor (TCR) sequences are known. This study aimed to identify antigen-specific TCR from T cells isolated using carboxyfluorescein succinimidyl ester (CFSE), which marks proliferating activated T cells. CFSE stained healthy donor peripheral blood mononuclear cells (PBMCs) were treated with cytomegalovirus (CMV) or Epstein-Barr virus (EBV) peptides for seven days. Then, proliferating T cells with decreased CFSE staining were isolated and single cell VDJ sequencing was performed on isolated T cells to identify antigen-specific TCRs. As antigen-specific TCR candidates, ten TCR clones were selected for the CMV antigen and five for the EBV antigen. The reactivity of ten CMV TCR-transduced T cells and one EBV TCR-transduced T cell toward T2 cells pulsed with CMV or EBV peptide was confirmed via NFAT-luciferase, IFN-γ ELISA, and cytotoxicity assays. Identification of antigen-specific TCRs with CFSE staining is a valid method for the development of effective immunotherapy. The identified CMV- or EBV-specific TCRs can be used for adoptive cell therapy to treat cancer.

Abstract 6406: Clinical and translational results of the academic ARIANES Phase 2 basket study: Longitudinal single-cell analysis of patient tumors identifies biological correlates of response to PARP inhibitors and anti-PD-L1 therapy

Abstract Background: Poly (ADP-ribose) polymerase inhibitors (PARPi) have immunomodulatory properties that may potentiate anti-PD-L1 therapy. To explore this, we developed the academic ARIANES phase 2 basket trial, which evaluated the PARPi rucaparib (R) and the anti-PD-L1 atezolizumab (A) in selected patients (pts). We performed single-cell RNA + T cell receptor sequencing (scRNA+TCR-seq) on 3 sequential tumor biopsies in a pts subset. Methods: ARIANES comprised 4 molecularly-selected DNA damage response deficient (DDRd), 3 platinum-sensitive, and 2 unselected cohorts of pts with non-small cell lung (NSCLC), prostate (CRPC), and other non-breast non-ovarian cancers. R was administered for 3 weeks, followed by R+A. Primary endpoint was overall response rate (ORR) at 12 weeks per cohort. scRNA+TCR-seq was performed on fresh biopsies collected at baseline, on R, and on R + A in the same lesion, with concomitant plasma collection. We tracked the evolution over time of tumor and microenvironment cells, differentially expressed genes and signatures within each cell population, and TCR clonal dynamics. Results: ARIANES enrolled 130 pts, including 27 DDRd CRPC and 3 DDRd NSCLC pts, on which we focus here. Best ORR by RECIST v1.1 was 22% (6/27) in CRPC pts, and mPFS: 7.9 months (95% CI 4 - 11.1) at data cut-off. ORR was 0% in NSCLC pts. We successfully profiled 3 sequential fresh biopsies in 2 BRCA2-mutant CRPC, 1 ATM-mutant, and 1 RAD54L-mutant NSCLC pts. Tumor, T and B lymphoid, myeloid, plasma, dendritic, NK, endothelial, and stromal cells were identified in all samples. Differential expression testing unveiled PARP1 upregulation in tumor cells on R. One CRPC pt with prolonged partial response displayed activation of innate immune sensing pathways (including cGAS-STING and IFN signaling) in tumor and immune cells, as well as JAK/STAT and CCL5, all increasing gradually on R and R + A; scTCR-seq revealed the expansion of specific T cell clonotypes on R + A. One ATM-mutant NSCLC pt with 6-month stable disease displayed increased cGAS/STING, JAK/STAT and CCL5 activation on R in NK cells only, and no TCR expansion. None of the above was observed in the 2 pts who progressed. Complete clinical and translational study results will be presented at the congress. Conclusion: Sequential scRNA+TCR-seq enables the dynamic assessment of tumor and immune cells on therapy. Our data confirms the potential of R to activate innate immune pathways in pt tumors, and R + A to induce T cell activation and clonal expansion. To our knowledge, this is the first study providing a longitudinal single-cell resolution analysis of the clonal evolution of tumor and immune cells in pts on PARPi + anti-PD-L1. We identify potential biological correlates of therapy response, including the activation of innate immune pathways and TCR expansion. Citation Format: Julien Vibert, Clémence Hénon, Lambros Tselikas, Baptiste Bonnet, Arnaud Pagès, Alice Bernard-Tessier, Léo Colmet-Daage, Roman Chabanon, Nicolas Dorvault, Clémence Astier, Anas Gazzah, Aurore Jeanson, Aurélien Parpaleix, Ronan Flippot, Natacha Naoun, Anna Patrikidou, Pernelle Lavaud, Giulia Baciarello, Emeline Colomba, Alina Fuerea, Laurence Albiges, Christophe Massard, Santiago Ponce, Yohann Loriot, Stéphane Champiat, Capucine Baldini, Fanny Bouquet, Nathalie Droin, Karim Fizazi, Damien Vasseur, Patricia Martin-Romano, Etienne Rouleau, Kaïssa Ouali, Sophie Postel-Vinay. Clinical and translational results of the academic ARIANES Phase 2 basket study: Longitudinal single-cell analysis of patient tumors identifies biological correlates of response to PARP inhibitors and anti-PD-L1 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6406.

Abstract 6699: Delineating germline, tumor and extrinsic factors driving mucosal melanoma (MM) risk and response to immune checkpoint inhibitor (ICI) treatment

Abstract Introduction MM is a rare melanoma subtype with distinct biology, low immunogenicity and tumor mutational burden, and subsequently lower response rates to ICIs. The biology of MM is poorly understood. We sought to prospectively, uniformly, and comprehensively profile a cohort of MM patients to determine the interplay of molecular variation, germline predisposition, immunity, gut, mucosal and tumor microbiome and modifiable risk factors on ICI response and resistance in advanced MM. Methods Patients (pts) with MM treated with standard-of-care ICI as any treatment line presenting to MD Anderson are being prospectively enrolled for longitudinal collection for molecular, microbiome, and lifestyle factor profiling. Planned analyses include: whole genome sequencing of normal and tumor tissue, RNA sequencing, and T cell receptor sequencing from fresh tumor samples; germline sequencing and genotype analyses; NanoString Digital Spatial Profiling (DSP) from formalin-fixed paraffin embedded (FFPE) specimens; whole genome shotgun, microbiome profiling and 16S rRNA gene sequencing (16S) of fecal specimens and affected mucosal and tumor sites (swabs); participant lifestyle and patient reported outcomes (PROs) assessments. Fresh tissue is collected and used to develop PDX models and cell lines. Results 98 pts have been enrolled to date; 83 (85%) Caucasians, 8 (8%) Hispanic, 4 (4%) Asians. 67 (68%) females. Median age at MM diagnosis is 64 years (range 32-91 years). MM primary sites include 24 (24%) naso-oral, 29 (30%) urogenital, 26 (27%) anorectal, 7 (7%) conjunctival and 12 (12%) other. Clinical somatic mutation testing was performed in 76 (76%) pts and common mutations were KIT (n = 12, 16%), NRAS (n = 8, 11%) and BRAF V600 or non-V600 (n = 9, 12%). At data cut-off (November 2023), 18 (18%) pts deceased. Median follow-up from first diagnosis to last visit/death was 16 months (range 1-178 months). Sample collections at data cut-off include: blood samples (n = 95; 219 samples); fecal specimens (n = 50; 97 samples); mucosal swabs (tumor/tumor adjacent/oral cavity; n = 38; 101 samples); fresh frozen tumor/normal (n = 38; 55 samples), fresh tumor/normal (n = 28; 36 samples) and FFPE tumor (n = 21; 37 samples) tissue. PROs and dietary assessments have been collected from 47 pts. Fresh tissue for PDX model and cell line development has been collected from 11 pts. Conclusion This is an ongoing prospective study that is expected to drive insights into the tumor/microenvironment/host interactions and factors regulating immunogenicity to predict response and resistance to ICIs in a rare and understudied melanoma subtype. Interrogation of the role of the gut microbiome and its modifiable determinants will lead to the investigation of new therapeutic strategies to modulate the microbiome to improve treatment outcomes in MM. Data will be presented from initial cohort analyses. Citation Format: Florentia Dimitriou, Priyadharsini Nagarajan, Sabitha Prabhakaran, Neus Bota, Mark Knafl, Randy A. Chu, Ashish V. Damania, Pranoti V. Sahasrabhojane, Yasmine Hoballah, Jillian S. Losh, Nadim J. Ajami, Scott E. Woodman, Jennifer A. Wargo, Andrew Futreal, Jennifer L. McQuade. Delineating germline, tumor and extrinsic factors driving mucosal melanoma (MM) risk and response to immune checkpoint inhibitor (ICI) treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6699.

Abstract 1176: Identification of circulating and spatial dynamics of immune cells response to to immune checkpoint inhibitors in triple-negative breast cancer at single-cell resolution

Abstract Background: Triple-negative breast cancer (TNBC) have had significantly worse survival outcome compared to other BC subtypes even though treatment strategies of TNBC have been advanced. The advent of immune checkpoint inhibitors (ICIs), especially pembrolizumab, a PD-1 inhibitor, has started to revolutionize TNBC treatment, showing encouraging effects in improving survival outcomes regardless of treatment settings. In neoadjuvant setting, pembrolizumab with cytotoxic chemotherapy achieved 13.6 % of pathologic complete response rate improvement and 36% of three-year event reduction. Therefore, pembrolizumab has highlighted new dimensions of TNBC's immunogenic characteristics. However, no immunogenic characteristics to predict the response of pembrolizumab have not been revealed. Methods: This study was designed as prospective, translational research for stage II or III TNBC patients scheduled for neoadjuvant chemotherapy with or without pembrolizumab followed by curative surgery. Tissue and blood samples were collected at baseline, 1 or 3 weeks after the first treatment initiation and curative surgery. We employed various single-cell and bulk RNA techniques for our multiomic analysis, including peripheral blood mononuclear cell (PBMC) single-cell RNA sequencing, T cell receptor sequencing (scTCR), high-resolution single-cell spatial transcriptomics (Xenium) targeting 380 genes, and bulk PBMC and tissue TCR analysis Results: From March 2023 to October 2023, 37 patients were enrolled in this study. Of 37 patients, we collected 36 blood and BC tissue samples at baseline, as well as 35 blood and 14 BC tissues at follow-up. These samples were analyzed and also compared with sex and age-matched healthy controls (n = 65). Of 37 patients, two patients were treated with only cytotoxic chemotherapy without pembrolizumab. We observed substantial increases in both systemic and localized immune responses, primarily marked by an upsurge in activated T cells and a decrease in regulatory T cells. A notable rise in TCR diversity post one week of treatment was followed by clonal expansion of activated T cells after three weeks in both blood and tissue. In addition, we observed a significant enrichment of pathways related to inflammatory response in classical monocytes following treatment. Conclusion: The findings from this study significantly enhance our understanding of the dynamics of circulating and local immune cells in TNBC, analyzed at a single-cell level with spatial information. These insights reveal how pembrolizumab alters the immune landscape and correlates these changes with treatment responses. Importantly, the data provide valuable indicators for predicting which TNBC patients are more likely to respond to neoadjuvant pembrolizumab therapy. Citation Format: Eun Seop Seo, Hae Hyun Jung, Kibyung Kim, Kyunghee Park, Eun Young Ko, Byung Joo Chae, Jeong Eon Lee, Eun Yoon Cho, Ji-Yeon Kim, Woong-Yang Park. Identification of circulating and spatial dynamics of immune cells response to to immune checkpoint inhibitors in triple-negative breast cancer at single-cell resolution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1176.

Abstract 6325: Lineage tracing defines responding CAR T cells in patients with B cell malignancies

Abstract Autologous T cells engineered to express a chimeric antigen receptor (CAR) have transformed the standard of care for patients with B cell malignancies, but >50% of patients progress following therapy. Here, we sought to understand key T cell intrinsic factors impacting efficacy: CAR T cell expansion, persistence, and homing to the tumor. Using an endogenous T cell receptor (TCR) sequence as a ‘barcode’, we followed individual T cell clonotypes at the single-cell level from pre-manufacture apheresis and infusion products to tumor-involved lymph nodes and blood at peak and late expansion in 22 adult patients with relapsed or refractory large B cell lymphoma (LBCL) or acute lymphoblastic leukemia (ALL) treated with axicabtagene ciloleucel, an FDA-approved CD19-CAR T cell therapy, or bispecific CD19/CD22-CAR T cells on an investigator-initiated trial (NCT03233854). The resulting CAR T cell atlas comprises matched transcriptome (scRNA-seq) and surface protein expression (CITE-seq) for 846,344 cells from 97 samples, with 251,175 unique TCR clonotypes identified, including 17,479 clonotypes that could be traced across ≥2 timepoints in CAR+ cells, enabling lineage tracing at scale for the first time. We found that T cells present in apheresis that preferentially expand during manufacturing primarily comprise T central memory (Tcm) cells and are enriched for predicted specificity to common viruses, including influenza, but also include a subset of T regulatory (Treg) cells. In infusion products, CAR T conventional (non-Treg) cells with superior abilities to home to the tumor, expand, and persist post-infusion share features of activated T effector memory (Tem) phenotype enriched for expression of BATF3 and high TCF4 transcription factor activity. Baseline apheresis and infusion products were enriched for cells classified as Tregs in patients with poor response. This observation aligned with our recent work linking post-infusion CAR Tregs to progression following CD19-CAR T cell therapy. We therefore performed lineage tracing and methylation analysis of the Treg-specific demethylated region (TSDR) in the FOXP3 gene and found that post-infusion CAR Tregs are primarily derived from pre-existing Tregs. Of interest, flow cytometry analysis of baseline blood from a cohort of 53 patients treated with CD19-CAR for LBCL showed that Tregs are elevated in baseline blood relative to healthy donors. Removing Tregs from healthy donor T cells prior to manufacturing enhanced CAR T cell expansion and anti-tumor activity against JeKo-1 human lymphoma cell line, whereas adding 5% Tregs to mimic patient T cells rendered the resulting CAR T cells less active. These analyses pinpoint the identities of apheresis T cells and infusion CAR T cells with properties impacting efficacy, and also identify pre-existing Tregs as limiting efficacy of CAR T cell immunotherapies. Citation Format: Zinaida Good, Mark P. Hamilton, Jay Y. Spiegel, Moksha H. Desai, Zachary J. Ehlinger, Patrick J. Quinn, Yiyun Chen, Snehit Prabhu, Shin-Heng Chiou, Sreevidya Kurra, Eric Yang, Michael G. Ozawa, Matthew J. Frank, Lori Muffly, Gursharan K. Claire, Sushma Bharadwaj, Saurabh Dahiya, Katherine A. Kong, Mark M. Davis, Sylvia K. Plevritis, Elena Sotillo, Bita Sahaf, David B. Miklos, Crystal L. Mackall. Lineage tracing defines responding CAR T cells in patients with B cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6325.

Abstract 1184: Combination pembrolizumab and radiotherapy induces anti-tumor immune responses in immunologically-cold non-small cell lung cancer

Abstract Introduction: Primary resistance to immune checkpoint inhibition (ICI) is in part driven by a “cold” tumor microenvironment in the context of low PD-L1 expression, low tumor mutation burden or oncogenic mutations that drive tumor immune exclusion. Radiation has the potential to sensitize tumors to ICI through extra-tumoral T cell activation in response to tumor antigens released from irradiated cancer cells (abscopal effect). Here, we investigate tumor microenvironment and T cell repertoire reshaping leveraging serial biospecimens from a phase 2 randomized clinical trial of stereotactic body radiation therapy followed by pembrolizumab (SBRT arm) vs. pembrolizumab alone (control arm) in non-small cell lung cancer (NSCLC; NCT02492568). Methods: We employed whole exome sequencing, RNA sequencing and T cell receptor (TCR) sequencing to analyze 293 serial tumor and peripheral blood samples collected at baseline and after 8 weeks of treatment from 72 patients in the control (n=35) and SBRT (n=37) arms. Immunologically-cold tumors were defined as low TMB (<300 mutations per exome, n=43), PD-L1 null (0% expression on immunohistochemistry, n=41), or WNT-activated (presence of mutations affecting genes in the WNT pathway, n=10). TCR clonotypic differential abundance analyses and RNA sequencing deconvolution and gene set enrichment analyses were performed on baseline and on-therapy blood and tumor samples from the control and SBRT arms. Results: Patients with immunologically-cold tumors in the SBRT arm had significantly longer progression free survival compared to the pembrolizumab monotherapy arm (log rank p=0.029 for TMB-low, p=0.022 for PD-L1-null, p=0.037 for the WNT-activated subsets). Induction of interferon-gamma, interferon-alpha, antigen processing and presentation, and inflammatory response gene sets was significantly enriched on-therapy in the SBRT arm (FDR adjusted p<0.01 for TMB-low, PD-L1-null, and WNT-activated tumors). We observed greater enrichment in newly expanded TCR clones on-therapy intratumorally and in peripheral blood in the SBRT arm compared to the control arm (mean 16.17 vs 7.54 clonotypes, p=0.022 in tumor; mean 4.56 vs 1.00, p=0.039 in blood; Mann-Whitney U test). Similarly, we noted greater expansion of pre-existing TCR clones in the SBRT arm than within the control arm (mean 34.83 vs 18.69, p=0.021 in tumor; mean 21.61 vs 8.15, p=0.009 in blood; Mann-Whitney U test). Within the SBRT arm, there was no significant difference in T cell expansion between TMB-stratified (<300 mutations vs >=300 mutations) or PD-L1-stratified (0% vs >= 1% expression) groups. Conclusions: SBRT followed by pembrolizumab was associated with priming and augmenting anti-tumor immune responses in immunologically-cold NSCLC, which opens a therapeutic window of opportunity for radiotherapy to overcome primary resistance to immune checkpoint inhibition. Citation Format: Justin Huang, Willemijn S. Theelen, Zineb Belcaid, Mimi Najjar, Christopher Cherry, Archana Balan, James R. White, Noushin Niknafs, Jaime Wehr, M.M. van den Heuvel, Rachel Karchin, Paul Baas, Victor E. Velculescu, Valsamo Anagnostou. Combination pembrolizumab and radiotherapy induces anti-tumor immune responses in immunologically-cold non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1184.

Abstract 6090: Integration of innate and adaptive immune signatures for early detection of cancer

Abstract Up to 50% of cancer patients are diagnosed at a late stage with tumors that are often unresectable, leading to intensive treatments and a preventable loss of life. Whilst multiple assays have been developed to tackle the issue of disease mortality, these approaches have serious limitations. For example, circulating tumor DNA (ctDNA) preferentially detects hard-to-treat tumors and micrometastatic disease, with limited sensitivity and specificity for early-stage malignancy, underscoring an urgent need for novel early detection strategies. Substantial evidence exists to demonstrate that signals related to innate (e.g. pro-inflammatory cytokines) and adaptive (e.g. antibodies and T cell receptors [TCRs]) immune engagement arise early in the development of cancer. The immune system therefore offers potential as an exquisitely sensitive and highly specific intrinsic early detection system for cancer. Here we propose the development of a pan-cancer novel early detection assay, using peripheral blood to measure three key cancer-specific components of the anti-tumor immune response: i) T cell receptor (TCR) sequences, ii) antibody signatures, iii) cytokine markers. Our preliminary data demonstrates that an age and smoking-matched cohort of lung cancer patients can be distinguished from healthy donors using TCR sequencing data processed through a published machine learning approach (p<0.01). In support of this, a pilot study on a custom peptide microarray comprised of lung cancer associated antigens and recurrent neoantigens demonstrated that lung cancer patient samples show significantly higher antibody intensities than healthy donors. Thirdly, using data from a prospective cohort study, we have demonstrated that inflammatory markers can be leveraged to predict future cancer diagnosis, and identified key protein markers for future work. These data provide proof-of-principle for the use of these analytes as a tool for early detection. We are actively curating a unique cohort of samples for this work from a prospective study, Nodule Immunophenotyping Biomarker for Lung Cancer Early Diagnosis (NIMBLE) (NCT05432739), which recruits patients with indeterminate lung nodules that may represent early cancers (>280 patients to date). This malignancy has high mortality rates and a significant need for early detection strategies. Through this, we aim to understand the early immunobiological response to cancer and leverage this information to design a novel multi-parametric immunopredictor assay for early detection of cancer. Citation Format: Evelyn Fitzsimons, Alexander Coulton, Hongchang Fu, Marcellus Augustine, Richard Lee, James Reading, Kevin Litchfield. Integration of innate and adaptive immune signatures for early detection of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6090.

Abstract 4093: Modeling tumor immunoediting under immune selective pressure to inform neoantigen landscape dynamics for effective cancer vaccines

Abstract Tumor specific neoantigens, encoded by somatic mutations, are recognized by T cells, inducing anti-tumor immune responses. This renders neoantigens viable targets for personalized cancer vaccines. However, the identification of immunogenic neoantigens remains suboptimal. Understanding how immune selective pressure-mediated tumor evolution and neoantigen editing contribute to emergence of immunogenic neoantigens may improve prediction accuracy. In this study, we aimed to model tumor evolution and heterogeneity under immune pressure using three preclinical models of lung cancer with common driver mutations, Kras G12D/+ and p53 -/-, namely KPA, KPC, and HKP1, subcutaneously implanted in immunocompetent C57BL/6 (B6) and immune-deficient Rag1-/- mice. Our data suggest that despite shared driver mutations identified by whole exome and RNA-seq, tumor growth in vivo varied between tumor models. KPA tumors were immunogenic, as they were controlled in B6 mice but rapidly progressed in Rag1-/- mice, suggesting immunoediting of KPA-specific neoantigens. In contrast, HKP1 was non-immunogenic, with tumors progressing regardless of immune competency. KPC showed moderate tumor control in B6 mice, which was lost in Rag1-/- mice. We then estimated the cancer cell fraction on every mutation based on phylogenetic reconstruction. Immunogenic KPA tumors had significantly lower mutation burden in B6 than in Rag1-/- mice and the fraction of cell line mutations edited in vivo was significantly higher, suggesting active immunoediting in the former. Non-immunogenic HKP1 tumors did not show significant differences in mutation burden nor fraction of mutations edited between B6 and Rag1-/- mice. The immunogenicity was reflected in the immune infiltrate levels within tumors, with KPA being highly infiltrated by activated CD4 and CD8 T cells compared to KPC. HKP1 tumors showed increased infiltration of suppressive regulatory T cells. T cell receptor (TCR) sequencing on lung tumors showed that clonal expansion is strongly associated with immunogenicity. KPA tumors showed significantly higher TCR clustering with less diversity compared to KPC and more than HKP1. Following a simple approach to study the immunogenicity of shared neoantigens to elicit cross-protective anti-tumor responses, mice were immunized with whole irradiated (IR) tumor cell lines and implanted with live tumor cells (matched and unmatched). While immunization with IR-KPA protected against corresponding tumor implant and moderately against KPC, it did not protect against HKP1, indicating lack of immunogenicity of mutations shared between KPA and HKP1. Further studies testing the anti-tumor responses and characteristics of neoantigens shared between these three related tumor cell lines will inform the conditions under which tumors may escape or regress and help improve neoantigen identifying algorithms. Citation Format: Mariam Mathew George, Jayon Lihm, Hyejin Choi, Yuval Elhanati, Stephen Martis, Marta Luksza, Benjamin Greenbaum, Jedd D. Wolchok, Taha Merghoub. Modeling tumor immunoediting under immune selective pressure to inform neoantigen landscape dynamics for effective cancer vaccines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4093.

Abstract 3862: Identification, profiling and clonotypic tracking of tumor-reactive T cells derived from bronchoalveolar lavage in lung cancer patients

Abstract Immunotherapeutic strategies for disinhibiting T cell responses have revolutionized lung cancer treatment. However, the identification of tumor-reactive T cells and the acquisition of adequate tissue for molecular and immune profiling remains a challenge that hinders our ability to adequately characterize the mechanisms of immunotherapy response versus resistance. To address this gap, we are investigating the use of bronchoalveolar lavage (BAL) as an alternative to blood or tumor biopsy samples to identify tumor reactive T cells. We collected cells from a prospective bronchoscopic biorepository of patients undergoing lung cancer evaluation that were subjected to bilateral BAL, phlebotomy, and tissue sampling. We then employed flow cytometry and single-cell multi-omic analyses to identify, characterize and clonotypically track tumor-reactive T cells obtained from BAL, blood and tumor samples from lung cancer patients. Analysis of BAL samples revealed a significant enrichment of terminally exhausted CD8+CD39+CD103+ T cells in BAL from tumor-bearing lungs compared to non-tumor bearing lung BAL and blood PBMCs in 14 patients. We then used single-cell sequencing-based multi-omics to deeply profile bilateral BAL cells, blood PBMCs and tumor tissues from 5 of these patients. By tracking T cell receptor (TCR) sequences across patient-matched samples, we found BAL derived T cell clonotypes that expressed markers of terminal exhaustion, such as CD39 and CXCL13 in the tumor, which strongly implicates them as being tumor reactive and relatively abundant in BAL. Further validation through functional assays is being used to confirm the tumor reactivity of these clones. These data demonstrate the feasibility of capturing tumor-specific T cells during bronchoscopy, providing promising opportunities for patient outcome characterization and exploration of novel therapies. This relatively non-invasive and practical test during routine bronchoscopy offers a cost-effective and safe alternative to identifying tumor-reactive T cells from surgical specimens or biopsies. Citation Format: Heeju Ryu, Wei Sun, Michelle A. Wurscher, Viswam S. Nair, Evan W. Newell. Identification, profiling and clonotypic tracking of tumor-reactive T cells derived from bronchoalveolar lavage in lung cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3862.

Abstract 2661: Identification of a novel morphology of tertiary lymphoid structure in patients with hepatocellular carcinoma treated with neoadjuvant immune checkpoint blockade

Abstract Background: Tertiary lymphoid structures (TLS) are ectopic lymphoid follicles that arise in non-lymphoid tissue. TLS may contribute to response to immune checkpoint blockade (ICB) in solid tumors, but understanding of the life cycle of these structures, particularly the circumstances of their resolution and the functional contribution of this stage to the adaptive immune response, remains incomplete. Methods: We employed a multi-omics approach to evaluate TLS in the tumors of patients with hepatocellular carcinoma (HCC) treated with neoadjuvant ICB (n = 19) and untreated controls (n = 14). TLS density was assessed by immunohistochemistry and correlated with pathologic response, relapse free survival, and overall survival. Imaging mass cytometry was used to characterize distinct TLS morphologies in areas of tumor regression bed and viable tumor. Individual TLS from treated tumors were microdissected and characterized by T cell receptor (TCR) and immunoglobulin heavy chain (IGH) sequencing, and TCR clonotypes identified in TLS were further characterized by comparison against matched single cell RNA and TCR sequencing of peripheral blood and TIL. Results: Intratumoral TLS density was significantly increased in HCC tumors treated with neoadjuvant ICB compared to untreated controls (p = 0.05). Tumors with major or complete pathologic response to treatment had significantly higher intratumoral TLS density compared to tumors with partial pathologic response (p = 0.000246) and non-response (p = 0.0129). In the treatment group, patients with tumors in the top tertile of intratumoral TLS density had significantly longer relapse free survival (p = 0.021 by log-rank test). In the regression bed of treated tumors, an involuted TLS morphology was identified which was notable for dispersion of the B cell germinal center, retention of a T cell zone enriched for T-DC interactions, and increased expression of markers of T cell memory. In a subset of patients, immune repertoire sequencing demonstrated increased TCRβ clonality and BCR somatic hypermutation at involuted TLS. Highly expanded T cell clonotypes identified in TLS were found in the GZMK+ and GZMB+ CD8 T effector memory clusters in matched single cell data. Conclusions: These data suggest that in HCC tumors treated with neoadjuvant ICB, treatment may induce formation of intratumoral TLS, which are associated with superior pathologic response and relapse free survival. An involuted TLS morphology is identified in tumor regression bed with features consistent with dissolution of the B cell germinal center, persistent antigen presentation to T cells, and increased T cell memory formation. Taken together, these findings suggest a potential role for late-stage TLS in supporting consolidation of the intratumoral T cell repertoire after elimination of viable tumor. Citation Format: Daniel H. Shu, Won Jin Ho, Luciane T. Kagohara, Alexander Girgis, Sarah M. Shin, Ludmila Danilova, Jae W. Lee, Dimitrios N. N. Sidiropoulos, Sarah Mitchell, Kabeer Munjal, Kathryn Howe, Kayla J. Bendinelli, Hanfei Qi, Guanglan Mo, Janelle Montagne, Tamara Y. Lopez-Vidal, Qingfeng Zhu, Amanda L. Huff, Xuan Yuan, Alexei Hernandez, Erin M. Coyne, Neeha Zaidi, Daniel J. Zabransky, Logan L. Engle, Aleksandra Ogurtsova, Marina Baretti, Daniel Laheru, Jennifer N. Durham, Hao Wang, Robert Anders, Elizabeth M. Jaffee, Elana J. Fertig, Mark Yarchoan. Identification of a novel morphology of tertiary lymphoid structure in patients with hepatocellular carcinoma treated with neoadjuvant immune checkpoint blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2661.

ScRNA+TCR+BCR-seq revealed the proportions and gene expression patterns of dual receptor T and B lymphocytes in NPC and NLH

While the relationship between single receptor lymphocytes and cancer has been deeply researched, the origin and biological roles of dual receptor lymphocytes in tumor microenvironment (TME) remain largely unknown. And since nasopharyngeal carcinoma (NPC) is a type of cancer closely associated with immune infiltration, studying the TME of NPC holds particular significance. Utilizing single-cell RNA sequencing combined with T cell receptor (TCR) and B cell receptor (BCR) sequencing (scRNA + TCR + BCR-seq), we analyzed data from 7 patients with NPC and 3 patients with nasopharyngeal lymphatic hyperplasia (NLH). In our research, it was firstly found that the presence of dual receptor lymphocytes in both the TME of NPC and the inflammatory environment of NLH. We also confirmed their clonal expansion, suggesting their potential involvement in the immune response. Subsequently, we further discovered the lineage and the pairing characteristics. It was found that the dual receptor lymphocytes in NPC and NLH mainly originate from memory cells, and the predominant pairing type for dual TCR was β+α1+α2 and dual BCR was heavy+κ+λ. By further analyzing their gene expression, we compared the function of dual receptor cells with single receptor cells in the context of both NPC and NLH. This groundbreaking research has enhanced our comprehension of the features of dual-receptor cells and has contributed to a better understanding of the TME in NPC. By comparing with NLH, it illuminates part of the alterations in the process of malignant transformation in NPC. These findings present the potential to acquire improved diagnostic markers and treatment modalities.

Abstract 4034: Lag3 blockade enhances the anti-tumor effect of dual GITR agonism and PD-1 blockade in a preclinical melanoma model

Abstract Immune checkpoint blockade (ICB) therapies, specifically anti PD-1 and anti CTLA-4, have resulted in tremendous success in the clinic. However, a substantial number of patients still relapse due to either inherent or acquired resistance to ICB therapies. In this scenario, activation of T cell co-stimulation pathways along with ICB emerges as a promising strategy to improve anti-tumor responses. Engagement of Glucocorticoid induced TNFR Related protein (GITR) costimulatory molecule, leads to enhanced activation of cytotoxic T cells while destabilizing suppressive T regulatory cells in the tumor microenvironment. Additionally, combining GITR agonism with PD-1 blockade improves the anti-tumor response in a murine model of advanced melanoma resistant to ICB, positioning GITR as an attractive immunotherapeutic target. In this study, we evaluated the therapeutic efficacy of combining blockade of the immune checkpoint LAG3 with GITR agonism for treating ICB-resistant advanced melanoma, using the B16 model. The combination of LAG3 blockade with GITR agonism was well tolerated, leading to better tumor control and improved survival. Our data revealed increased B cell infiltration and activation within tumors and draining lymph nodes (LNs) of treated mice. B cell depletion diminished the anti-tumor effect of the combination therapy, suggesting that B cells play an active role in controlling tumor growth. Spleens from treated mice exhibited increased lymphocytic hyperplasia, along with more and larger germinal centers. B cell receptor sequencing revealed an increased clonality and reduced entropy. Treating B cells with GITR agonism and LAG3 blockade in vitro led to increased activation and proliferation, suggesting a direct effect of these therapies on B cells. Furthermore, adding LAG3 blockade to the dual combination of GITR agonism and PD-1 blockade resulted in superior tumor control and increased B cell activity in the draining LNs. Collectively, our findings suggest that the humoral response significantly contributes to the anti-tumor responses elicited by ICB when combined with GITR agonism. This triple combination therapy (LAG3 blockade + PD1 blockade + GITR agonism) holds promise as a safe and potent therapeutic strategy to overcome ICB resistance. Further investigation into the mechanism of action by which GITR agonism leads to enhanced B cell responses when combined with ICB is warranted in order to design more effective therapies for cancer treatment. Citation Format: Rachana R. Maniyar, Yuval Elhanati, Levi Mangarin, Yacine Marouf, Ashley Ahmed, Benjamin Greenbaum, Jedd Wolchok, Taha Merghoub. Lag3 blockade enhances the anti-tumor effect of dual GITR agonism and PD-1 blockade in a preclinical melanoma model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4034.

Machine learning predictions of T cell antigen specificity from intracellular calcium dynamics.

Adoptive T cell therapies rely on the production of T cells with an antigen receptor that directs their specificity toward tumor-specific antigens. Methods for identifying relevant T cell receptor (TCR) sequences, predominantly achieved through the enrichment of antigen-specific T cells, represent a major bottleneck in the production of TCR-engineered cell therapies. Fluctuation of intracellular calcium is a proximal readout of TCR signaling and candidate marker for antigen-specific T cell identification that does not require T cell expansion; however, calcium fluctuations downstream of TCR engagement are highly variable. We propose that machine learning algorithms may allow for T cell classification from complex datasets such as polyclonal T cell signaling events. Using deep learning tools, we demonstrate accurate prediction of TCR-transgenic CD8+ T cell activation based on calcium fluctuations and test the algorithm against T cells bearing a distinct TCR as well as polyclonal T cells. This provides the foundation for an antigen-specific TCR sequence identification pipeline for adoptive T cell therapies.

Similarity Network Analysis of the Adaptive Immune Response in the Proximal Airway.

Recent immunologic study of the adaptive immune repertoire in the subglottic airway demonstrated high-frequency T cell clones that do not overlap between individuals. However, the anatomic distribution and antigenic target of the T cell repertoire in the proximal airway mucosa remain unresolved. Single-cell RNA sequencing of matched scar and unaffected mucosa from idiopathic subglottic stenosis patients (iSGS, n = 32) was performed and compared with airway mucosa from healthy controls (n = 10). T cell receptor (TCR) sequences were interrogated via similarity network analysis to explore antigenic targets using the published algorithm: Grouping of Lymphocyte Interactions by Paratope Hotspots (GLIPH2). The mucosal T cell repertoire in healthy control airways consisted of highly expressed T cell clones conserved across anatomic subsites (trachea, bronchi, bronchioles, and lung). In iSGS, high-frequency clones were equally represented in both scar and adjacent non-scar tissue. Significant differences in repertoire structure between iSGS scar and unaffected mucosa was observed, driven by unique low-frequency clones. GLIPH2 results suggest low-frequency clones share targets between multiple iSGS patients. Healthy airway mucosa has a highly conserved T cell repertoire across multiple anatomic subsites. Similarly, iSGS patients have highly expressed T cell clones present in both scar and unaffected mucosa. iSGS airway scar possesses an abundance of less highly expanded clones with predicted antigen targets shared between patients. Interrogation of these shared motifs suggests abundant adaptive immunity to viral targets in iSGS airway scar. These results provide insight into disease pathogenesis and illuminate new treatment strategies in iSGS. NA Laryngoscope, 134:3245-3252, 2024.

A self-assembled, genetically engineered, irradiated tumor cell debris vaccine.

Vaccine-based therapeutics for cancers face several challenges including lack of immunogenicity and tumor escape pathways for single antigen targets. It has been reported that radiotherapy has an in situ vaccine effect that provides tumor antigens following irradiation, helping to activate antigen-presenting cells (APCs). Herein, a new vaccine approach is developed by combining genetically engineered irradiated tumor cell debris (RTD) and hyaluronic acid (HA), termed HA@RTD. A cancer cell line is developed that overexpresses granulocyte-macrophage colony-stimulating factor (GM-CSF). A hydrogel was developed by covalent conjugation of HA with RTD proteins that acted as a potent vaccine system, the effects which were probed with T cell receptor sequencing. The engineered vaccine activated antitumor immunity responses and prevented tumor growth in mice even with a single immunization. HA@RTD vaccine efficacy was also assessed in therapeutic settings with established tumors and in combination with immune checkpoint blockade.

Reversing immunosuppression in the tumor microenvironment of fibrolamellar carcinoma via PD-1 and IL-10 blockade

Fibrolamellar carcinoma (FLC) is a rare liver tumor driven by the DNAJ-PKAc fusion protein that affects healthy young patients. Little is known about the immune response to FLC, limiting rational design of immunotherapy. Multiplex immunohistochemistry and gene expression profiling were performed to characterize the FLC tumor immune microenvironment and adjacent non-tumor liver (NTL). Flow cytometry and T cell receptor (TCR) sequencing were performed to determine the phenotype of tumor-infiltrating immune cells and the extent of T cell clonal expansion. Fresh human FLC tumor slice cultures (TSCs) were treated with antibodies blocking programmed cell death protein-1 (PD-1) and interleukin-10 (IL-10), with results measured by cleaved caspase-3 immunohistochemistry. Immune cells were concentrated in fibrous stromal bands, rather than in the carcinoma cell compartment. In FLC, T cells demonstrated decreased activation and regulatory T cells in FLC had more frequent expression of PD-1 and CTLA-4 than in NTL. Furthermore, T cells had relatively low levels of clonal expansion despite high TCR conservation across individuals. Combination PD-1 and IL-10 blockade signficantly increased cell death in human FLC TSCs. Immunosuppresion in the FLC tumor microenvironment is characterized by T cell exclusion and exhaustion, which may be reversible with combination immunotherapy.

Multimodal and spatially resolved profiling identifies distinct patterns of T cell infiltration in nodal B cell lymphoma entities

The redirection of T cells has emerged as an attractive therapeutic principle in B cell non-Hodgkin lymphoma (B-NHL). However, a detailed characterization of lymphoma-infiltrating T cells across B-NHL entities is missing. Here we present an in-depth T cell reference map of nodal B-NHL, based on cellular indexing of transcriptomes and epitopes, T cell receptor sequencing, flow cytometry and multiplexed immunofluorescence applied to 101 lymph nodes from patients with diffuse large B cell, mantle cell, follicular or marginal zone lymphoma, and from healthy controls. This multimodal resource revealed quantitative and spatial aberrations of the T cell microenvironment across and within B-NHL entities. Quantitative differences in PD1+TCF7− cytotoxic T cells, T follicular helper cells or IKZF3+ regulatory T cells were linked to their clonal expansion. The abundance of PD1+TCF7− cytotoxic T cells was associated with poor survival. Our study portrays lymphoma-infiltrating T cells with unprecedented comprehensiveness and provides a unique resource for the investigation of lymphoma biology and prognosis.