Multi-resolution deep learning characterizes tertiary lymphoid structures and their prognostic relevance in solid tumors

BACKGROUND

Tertiary lymphoid structures (TLSs) are dense accumulations of lymphocytes in inflamed peripheral tissues, including cancer, and are associated with improved survival and response to immunotherapy in various solid tumors. Histological TLS quantification has been proposed as a novel predictive and prognostic biomarker, but lack of standardized methods of TLS characterization hampers assessment of TLS densities across different patients, diseases, and clinical centers.

METHODS

We introduce an approach based on HookNet-TLS, a multi-resolution deep learning model, for automated and unbiased TLS quantification and identification of germinal centers in routine hematoxylin and eosin stained digital pathology slides. We developed HookNet-TLS using n = 1019 manually annotated TCGA slides from clear cell renal cell carcinoma, muscle-invasive bladder cancer, and lung squamous cell carcinoma.

RESULTS

Here we show that HookNet-TLS automates TLS quantification across multiple cancer types achieving human-level performance and demonstrates prognostic associations similar to visual assessment.

CONCLUSIONS

HookNet-TLS has the potential to be used as a tool for objective quantification of TLS in routine H&E digital pathology slides. We make HookNet-TLS publicly available to promote its use in research.

B cell-rich niches support stem-like CD8+ T cells in cancer microenvironment

Cytotoxic T cells are indispensable for the body's fight against most cancers. In the current issue of Cancer Cell, Gaglia et al. reveal how changes in the tumor tissue architecture creating niches of T cell-B cell interactions may support anti-tumor T cell responses.

The roles of tertiary lymphoid structures in chronic diseases

Tertiary lymphoid structures (TLSs) are ectopic lymphoid tissues that drive antigen-specific immune responses at sites of chronic inflammation. Unlike secondary lymphoid organs such as lymph nodes, TLSs lack capsules and have their own unique characteristics and functions. The presumed influence of TLSs on the disease course has led to widespread interest in obtaining a better understanding of their biology and function. Studies using single-cell analyses have suggested heterogeneity in TLS composition and phenotype, and consequently, functional correlates with disease progression are sometimes conflicting. The presence of TLSs correlates with a favourable disease course in cancer and infection. Conversely, in autoimmune diseases and chronic age-related inflammatory diseases including chronic kidney disease, the presence of TLSs is associated with a more severe disease course. However, the detailed mechanisms that underlie these clinical associations are not fully understood. To what extent the mechanisms of TLS development and maturation are shared across organs and diseases is also still obscure. Improved understanding of TLS development and function at the cellular and molecular levels may enable the exploitation of these structures to improve therapies for chronic diseases, including chronic kidney disease.

The Tumor Immune Landscape and Architecture of Tertiary Lymphoid Structures in Urothelial Cancer

Candidate immune biomarkers have been proposed for predicting response to immunotherapy in urothelial cancer (UC). Yet, these biomarkers are imperfect and lack predictive power. A comprehensive overview of the tumor immune contexture, including Tertiary Lymphoid structures (TLS), is needed to better understand the immunotherapy response in UC. We analyzed tumor sections by quantitative multiplex immunofluorescence to characterize immune cell subsets in various tumor compartments in tumors without pretreatment and tumors exposed to preoperative anti-PD1/CTLA-4 checkpoint inhibitors (NABUCCO trial). Pronounced immune cell presence was found in UC invasive margins compared to tumor and stroma regions. CD8⁺PD1⁺ T-cells were present in UC, particularly following immunotherapy. The cellular composition of TLS was assessed by multiplex immunofluorescence (CD3, CD8, FoxP3, CD68, CD20, PanCK, DAPI) to explore specific TLS clusters based on varying immune subset densities. Using a k-means clustering algorithm, we found five distinct cellular composition clusters. Tumors unresponsive to anti-PD-1/CTLA-4 immunotherapy showed enrichment of a FoxP3⁺ T-cell-low TLS cluster after treatment. Additionally, cluster 5 (macrophage low) TLS were significantly higher after pre-operative immunotherapy, compared to untreated tumors. We also compared the immune cell composition and maturation stages between superficial (submucosal) and deeper TLS, revealing that superficial TLS had more pronounced T-helper cells and enrichment of early TLS than TLS located in deeper tissue. Furthermore, superficial TLS displayed a lower fraction of secondary follicle like TLS than deeper TLS. Taken together, our results provide a detailed quantitative overview of the tumor immune landscape in UC, which can provide a basis for further studies.

Molecular, Immunological, and Clinical Features Associated With Lymphoid Neogenesis in Muscle Invasive Bladder Cancer

Lymphoid neogenesis gives rise to tertiary lymphoid structures (TLS) in the periphery of multiple cancer types including muscle invasive bladder cancer (MIBC) where it has positive prognostic and predictive associations. Here, we explored molecular, clinical, and histological data of The Cancer Genome Atlas, as well as the IMvigor210 dataset to study factors associated with TLS development and function in the tumor microenvironment (TME) of MIBC. We also analyzed tumor immune composition including TLS in an independent, retrospective MIBC cohort. We found that the combination of TLS density and tumor mutational burden provides a novel independent prognostic biomarker in MIBC. Gene expression profiles obtained from intratumoral regions that rarely contain TLS in MIBC showed poor correlation with the prognostic TLS density measured in tumor periphery. Tumors with high TLS density showed increased gene signatures as well as infiltration of activated lymphocytes. Intratumoral B-cell and CD8⁺ T-cell co-infiltration was frequent in TLS-high samples, and such regions harbored the highest proportion of PD-1⁺TCF1⁺ progenitor-like T cells, naïve T cells, and activated B cells when compared to regions predominantly infiltrated by either B cells or CD8⁺ T cells alone. We found four TLS maturation subtypes; however, differences in TLS composition appeared to be dictated by the TME and not by the TLS maturation status. Finally, we identified one downregulated and three upregulated non-immune cell-related genes in TME with high TLS density, which may represent candidates for tumor-intrinsic regulation of lymphoid neogenesis. Our study provides novel insights into TLS-associated gene expression and immune contexture of MIBC and indicates towards the relevance of B-cell and CD8⁺ T-cell interactions in anti-tumor immunity within and outside TLS.

CD39+PD-1+CD8+ T cells mediate metastatic dormancy in breast cancer

Some breast tumors metastasize aggressively whereas others remain dormant for years. The mechanism governing metastatic dormancy remains largely unknown. Through high-parametric single-cell mapping in mice, we identify a discrete population of CD39+PD-1+CD8+ T cells in primary tumors and in dormant metastasis, which is hardly found in aggressively metastasizing tumors. Using blocking antibodies, we find that dormancy depends on TNFα and IFNγ. Immunotherapy reduces the number of dormant cancer cells in the lungs. Adoptive transfer of purified CD39+PD-1+CD8+ T cells prevents metastatic outgrowth. In human breast cancer, the frequency of CD39+PD-1+CD8+ but not total CD8+ T cells correlates with delayed metastatic relapse after resection (disease-free survival), thus underlining the biological relevance of CD39+PD-1+CD8+ T cells for controlling experimental and human breast cancer. Thus, we suggest that a primary breast tumor could prime a systemic, CD39+PD-1+CD8+ T cell response that favors metastatic dormancy in the lungs.

Abstract PO019: CD39+PD-1+CD8+ T cells mediate metastatic dormancy in breast cancer

Some breast tumors metastasize aggressively whereas others remain in a state of metastatic dormancy for months or even years. The mechanism governing such metastatic dormancy remains largely unknown. Through high-parametric single-cell mapping, we identified a discrete population of CD39+PD-1+CD8+ T cells present both in primary tumors and in dormant metastasis, which was hardly found in aggressively metastasizing tumors. Of note, the adoptive transfer of purified CD39+PD-1+CD8+ T cells prevented metastatic outgrowth. Stimulation of CD39+PD-1+CD8+ T cells with PD-1 blockade reduced the number of disseminated dormant cells. In human breast cancer, the frequency of CD39+PD-1+CD8+ but not of total CD8+ T cells correlated with delayed metastatic relapse after resection (disease-free survival), thus underlining the biological relevance of CD39+PD-1+CD8+ T cells for controlling experimental and human breast cancer. Furthermore, density of CD39+PD-1+CD8+ T cells may serve as a novel biomarker and may serve as a potential immunotherapy target. Here, we discovered that a primary breast tumor primes a systemic, CD39+PD-1+CD8+ T cell response that is essential for metastatic dormancy in the lungs.

Citation Format: Paulino Tallón de Lara, Héctor Castañón Cuadrado, Marijne Vermeer, Nicolás Núñez, Karina Silina, Bettina Sobottka, Joaquín Urdínez, Virginia Cecconi, Farkhondeh Movahedian Attar, Stefanie Hiltbrunner, Isabelle Glarner, Holger Moch, Sònia Tugues, Burkhard Becher, Maries van den Broek. CD39+PD-1+CD8+ T cells mediate metastatic dormancy in breast cancer [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO019.

Cancer-Cell-Intrinsic cGAS Expression Mediates Tumor Immunogenicity

Sensing of cytoplasmic DNA by cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS) results in production of the dinucleotide cGAMP and consecutive activation of stimulator of interferon genes (STING) followed by production of type I interferon (IFN). Although cancer cells contain supra-normal concentrations of cytoplasmic DNA, they rarely produce type I IFN spontaneously. This suggests that defects in the DNA-sensing pathway may serve as an immune escape mechanism. We find that cancer cells produce cGAMP that is transferred via gap junctions to tumor-associated dendritic cells (DCs) and macrophages, which respond by producing type I IFN in situ. Cancer-cell-intrinsic expression of cGAS, but not STING, promotes infiltration by effector CD8⁺ T cells and consequently results in prolonged survival. Furthermore, cGAS-expressing cancers respond better to genotoxic treatments and immunotherapy. Thus, cancer-cell-derived cGAMP is crucial to protective anti-tumor CD8⁺ T cell immunity. Consequently, cancer-cell-intrinsic expression of cGAS determines tumor immunogenicity and makes tumors hot. These findings are relevant for genotoxic and immune therapies for cancer.

Biomarker analysis and updated clinical follow-up of preoperative ipilimumab (ipi) plus nivolumab (nivo) in stage III urothelial cancer (NABUCCO)

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Background: Encouraging pathological complete response (pCR) rates were observed in trials testing neoadjuvant pembrolizumab or atezolizumab in urothelial cancer (UC). In cT3-4N0 tumors, pCR to atezolizumab was only 17% and restricted to tumors showing characteristics of preexisting T cell immunity. In NABUCCO, we aimed to increase response to pre-operative checkpoint blockade, particularly in high risk patients (pts), by combining ipi plus nivo in stage III UC. We previously reported pCR in 46% and downstaging to no remaining invasive disease in 58% (ESMO2019). Here, we present biomarker analyses and updated clinical follow-up (FU) data. Methods: Twenty four stage III (cT3-4aN0 or cT2-4aN1-3) UC pts who were unfit to receive cisplatin-based chemotherapy or refused, were treated with ipi 3 mg/kg (day 1), ipi 3 mg/kg + nivo 1 mg/kg (day 22), and nivo 3 mg/kg (day 43), followed by resection. The primary endpoint was feasibility (resection < 12 weeks). Efficacy (pCR), safety and biomarker analysis were secondary endpoints. Whole-exome sequencing (WES) was done on baseline tumor samples and local lymph node (LN) metastases showing no response. RNA-seq and multiplex immunofluorescence (mIF) for immune cell markers were done pre- and post-therapy. Results: After a median FU of 15.6 months, 2 pts relapsed (both non-pCR); 1 of these 2 pts died of metastatic disease. Tumors showing complete response (CR, for biomarker analysis defined as pCR, CIS or pTa) had a significantly higher tumor mutational burden than non-CR tumors. CR to ipi+nivo was independent of baseline CD8 T-cell presence. There was no difference between CR and non-CR tumors in baseline immune gene signatures, such as interferon gamma and T-effector signatures. Surprisingly, exploratory gene expression analysis revealed that non-CR was associated with a baseline B cell immune signature, particularly immunoglobulins and genes involved in B cell receptor signaling. CD20 positive cells (by mIF) and presence of tertiary lymphoid structures (TLS) at baseline were also associated with non-CR. Upon treatment with ipi+nivo, early and mature TLS increased significantly in responding tumors. A subset of pts showed CR in the bladder, but non-CR in a local LN tumor focus. WES revealed that these LN metastases were genetically different from the primary tumor bulk. Conclusions: At 15.6 months follow-up, recurrence after pre-operative ipi+nivo was low. Pathological complete response was not restricted to tumors exhibiting preexisting T cell immunity. Clinical trial information: NCT03387761 .

A Single-Cell Atlas of the Tumor and Immune Ecosystem of Human Breast Cancer

Breast cancer is a heterogeneous disease. Tumor cells and associated healthy cells form ecosystems that determine disease progression and response to therapy. To characterize features of breast cancer ecosystems and their associations with clinical data, we analyzed 144 human breast tumor and 50 non-tumor tissue samples using mass cytometry. The expression of 73 proteins in 26 million cells was evaluated using tumor and immune cell-centric antibody panels. Tumors displayed individuality in tumor cell composition, including phenotypic abnormalities and phenotype dominance. Relationship analyses between tumor and immune cells revealed characteristics of ecosystems related to immunosuppression and poor prognosis. High frequencies of PD-L1⁺ tumor-associated macrophages and exhausted T cells were found in high-grade ER⁺ and ER^- tumors. This large-scale, single-cell atlas deepens our understanding of breast tumor ecosystems and suggests that ecosystem-based patient classification will facilitate identification of individuals for precision medicine approaches targeting the tumor and its immunoenvironment.

Abstract A113: Harnessing lymphoid organ neogenesis as a novel prognostic biomarker and therapeutic target

Lymphoid organ neogenesis takes place in chronically inflamed tissues including cancer and yields the development of tertiary lymphoid structures (TLS). TLS are ectopic lymphoid organs that activate antigen specific T-cells and B cells in infection and autoimmunity and correlate with prolonged survival in various cancer types. This suggests that TLS contribute to protective anti-tumor immunity. Therefore, promoting the development of tumor-associated TLS could be a novel immunotherapeutic approach. However, the molecular and cellular mechanisms of TLS development in human cancer or how TLS contribute to survival are largely not understood. Here we used multiparameter immunofluorescence and digital pathology to quantify TLS and to characterize their cellular composition and tissue context in cohorts of lung squamous cell carcinoma (LSCC, n=138), colorectal cancer (CRC, n=111), clear cell renal cell carcinoma (ccRCC, n=50) and bladder cancer (BC, n=33) patients. Furthermore, we established an experimental model to characterize TLS development and its impact on tumor-specific immunity. We discovered that TLS development and maturation followed the same steps in all analyzed tumor types as well as in the lungs of mice in our experimental model. First, B and T lymphocytes accumulated around blood vessels. Second, a network of follicular dendritic cells developed within the lymphocytic aggregate, and third, a germinal center (GC) reaction was activated. Additionally, we identified a niche of CXCL13+ perivascular stroma and CXCL12+LTB+ and PD-L1+ epithelial cells that were associated with TLS in LSCC. We found that the number of tumor-associated TLS was an independent prognostic factor for prolonged survival in untreated LSCC, CRC and BC, but not in ccRCC patients or in LSCC and BC patients who were treated with neoadjuvant chemotherapy. By comparing the chemotherapy-treated and untreated cohorts we observed that the number of TLS was not changed but TLS maturation (i.e. GC formation) was significantly impaired after chemotherapy. This difference was at least partially dictated by corticosteroids, which are commonly used to treat the side effects of chemotherapy of LSCC patients. We further studied the mechanisms underlying TLS development using the experimental model. We identified a combination of stimuli that induces the development of mature TLS in the lungs of mice. Besides inflammatory stimuli, a foreign antigen was necessary to achieve a significant increase in TLS numbers and maturation stage, suggesting that cognate interactions are crucial for lymphoid organ neogenesis. This is further supported by our observation that CRC patients with microsatellite instability, which presumably results in more neoantigens, had an increased proportion of mature TLS. The negative impact of corticosteroids on TLS development was confirmed in this model. In summary, we propose that GC+ TLS represent the relevant TLS phenotype contributing to survival in different tumor types. Lymphoid organ neogenesis is negatively affected by corticosteroids, which might impair the spontaneous as well as therapy-induced anti-tumor immunity. The established experimental model will allow investigation of the mechanisms of TLS development and function in cancer and assessment of their therapeutic potential.

Citation Format: Karina Silina, Alex Soltermann, Chiara Burkhardt, Farkhondeh Movahedian Attar, Ruben Casanova, Alessandra Curioni-Fontecedro, Holger Moch, Florian Posch, Thomas Winder, Nick van Dijk, Charlotte Voskuilen, Michiel van der Heijden, Maries van den Broek. Harnessing lymphoid organ neogenesis as a novel prognostic biomarker and therapeutic target [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A113.

Antigen Specificity and Clinical Significance of IgG and IgA Autoantibodies Produced in situ by Tumor-Infiltrating B Cells in Breast Cancer

An important role for tumor infiltrating B lymphocytes (TIL-B) in the immune response to cancer is emerging; however, very little is known about the antigen specificity of antibodies produced in situ. The presence of IgA antibodies in the tumor microenvironment has been noted although their biological functions and clinical significance are unknown. This study used a 91-antigen microarray to examine the IgG and IgA autoantibody repertoires in breast cancer (BC). Tumor and adjacent breast tissue supernatants and plasma from BC patients together with normal breast tissue supernatants and plasma from healthy controls (patients undergoing mammary reduction and healthy blood donors) were analyzed to investigate relationships between autoantibodies and the clinical, histological and immunological features of tumors. Our data show that >84% of the BC samples tested contain autoantibodies to one or more antigens on the array, with ANKRD30BL, COPS4, and CTAG1B being most frequently reactive. Ex vivo TIL-B responses were uncoupled from systemic humoral responses in the majority of cases. A comparison of autoantibody frequencies in supernatants and plasma from patients and controls identified eight antigens that elicit BC-associated autoantibody responses. The overall prevalence of IgG and IgA autoantibodies was similar and while IgG and IgA responses were not linked they did correlate with distinct clinical, pathological and immunological features. Higher levels of ex vivo IgG responses to BC-associated antigens were associated with shorter recurrence-free survival (RFS), HER2 overexpression and lower tumor-infiltrating CD8⁺ T cell counts. Higher IgA levels were associated with estrogen and progesterone receptor-negative cancers but were not significantly associated with RFS. Furthermore, ex vivo IgA but not IgG autoantibodies reactive to BC-associated antigens were linked with germinal center and early memory B cell maturation and the presence of tertiary lymphoid structures suggesting that these TIL-B are activated in the tumor microenvironment. Overall, our results extend the current understanding of the antigen specificity, the biological and the clinical significance of IgG and IgA autoantibodies produced by BC TIL-B in situ.

Maturation of tertiary lymphoid structures and recurrence of stage II and III colorectal cancer

Tertiary lymphoid structures (TLS) are associated with favorable outcome in non-metastatic colorectal carcinoma (nmCRC), but the dynamics of TLS maturation and its association with effective anti-tumor immune surveillance in nmCRC are unclear. Here, we hypothesized that not only the number of TLS but also their composition harbors information on recurrence risk in nmCRC. In a comprehensive molecular, tissue, laboratory, and clinical analysis of 109 patients with stage II/III nmCRC, we assessed TLS numbers and degree of maturation in surgical specimens by multi-parameter immunofluorescence of follicular dendritic cell (FDC) and germinal center (GC) markers. TLS formed in most tumors and were significantly more prevalent in highly-microsatellite-instable (MSI-H) and/or BRAF-mutant nmCRC. We could distinguish three sequential TLS maturation stages which were characterized by increasing prevalence of FDCs and mature B-cells: [1] Early TLS, composed of dense lymphocytic aggregates without FDCs, [2] Primary follicle-like TLS, having FDCs but no GC reaction, and [3] Secondary follicle-like TLS, having an active GC reaction. A simple integrated TLS immunoscore reflecting these parameters identified a large subgroup of nmCRC patients with a very low risk of recurrence independently of clinical co-variables such as ECOG performance status, age, stage, and adjuvant chemotherapy. We conclude that (1) mismatch repair and BRAF mutation status are associated with the formation of TLS in nmCRC, (2) TLS formation in nmCRC follows sequential maturation steps, culminating in germinal center formation, and (3) this maturation process harbors important prognostic information on the risk of disease recurrence.

The maturation stage of tumoral tertiary lymphoid structures to predict recurrence risk in localized colorectal cancer

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Background: The tumor immune infiltrate and organized lymphocytic aggregates within the tumor microenvironment, known as tertiary lymphoid structures (TLS), play a critical role in cancer. We hypothesize that the maturation stage of TLS harbors prognostic information on recurrence risk in patients (pts) with non-metastatic colorectal cancer (nmCRC). Methods: In a comprehensive immunofluorescence and clinical analysis of 111 pts with UICC stage II & III nmCRC (median age: 65 yrs; female: n = 53 (48%); stage III: n = 69 (62%)), we quantified the number and maturation status of tumor-associated TLS in baseline surgical specimens:[1] Early TLS (E-TLS, composed of dense lymphocytic aggregates without follicular dendritic cells (FDCs), [2] Primary follicle-like TLS (PFL-TLS, having FDCs but no germinal center (GC) reaction), and [3] Secondary follicle-like TLS (SFL-TLS, having an active GC reaction). The 3-year incidence of recurrence was the primary endpoint of this study, which occurred in 19 pts (3-year recurrence risk = 18.3%). Results: Most TLS formed in tissue adjacent to the tumor. The median number of TLS/mm of tumor perimeter was 1.0 [25th-75th percentile: 0.5-1.7]. The average proportions of different TLS maturation stages were 56% of E-TLS [40-78], 20% of PFL-TLS [6-37], and 16% of SFL-TLS [0-32]. A structural equation model was fitted to summarize the TLS counts and maturation stages into a TLS maturation immunoscore for predicting recurrence. 3-year recurrence risks were 31.7% (95%CI: 17.2-47.3), 15.9% (5.7-30.5), and 9.4% (2.4-22.4) in pts in the 1st, 2nd, and 3rd tertile of the score (Gray’s test p = 0.05). A higher score was significantly associated with a lower recurrence risk (Hazard ratio (HR) for 10 units increase = 0.76, 95%CI: 0.59-0.97, p = 0.03), and this association prevailed in multivariable analysis adjusting for age, ECOG performance status, stage, and adjuvant chemotherapy (Adjusted HR = 0.73, 0.54-0.99, p = 0.05). Conclusions: Tumors of nmCRC pts with a very low risk of recurrence are characterized by an increased fraction of mature TLS comprising FDCs and GCs. If confirmed prospectively, adjuvant chemotherapy may be avoided in nmCRC pts with a high TLS maturation score.

Abstract B85: Tertiary lymphoid structures in chemotherapy-treated and untreated lung squamous cell carcinoma patients

Tertiary lymphoid structures (TLS) form in chronically inflamed tissues and contain organized compartments of T cells, B cells and follicular dendritic cells (FDCs). TLS were first noticed in autoimmune diseases where they support ectopic germinal center (GC) reactions and facilitate the activation and infiltration of immune cells. In cancer B cell and mature DC markers have been used for TLS detection because of their frequent localisation in TLS, and show a significant association with improved survival in several tumor types. Together these studies have driven the interest in TLS as a potential site of anti-tumor immune response activation and/or facilitation of lymphocyte infiltration. Here we aimed to characterise TLS as a microanatomical structure excluding non-organised lymphocytic infiltrates and to determine their prognostic value and association with clinico-pathologic parameters in non-small cell lung cancer patients.

We characterised TLS density and presence of GCs in tumor center and periphery using H&E stained whole sections from 4 different tumor regions of 127 surgically resected lung squamous cell carcinoma (SCC) patients with an annotated 5-year follow-up. Intratumoral TLS where observed in 30% of patients, while &gt;95% of cases showed TLS in the tumor periphery. Patients with TLS-rich (n=65) and TLS-poor (n=62) tumour microenvironments could be distinguished. High density and GC positivity of TLS correlated with increased lymphocyte infiltration (Pearson correlation 0.34, p&lt;0.001), but not other clinical parameters.

In neo-adjuvant chemotherapy-naïve patients, high density of GC-containing TLS was a significant positive prognosticator for disease free survival independent of pTNM, tumor grade, vascular and pleural invasion, age, gender, or pack years (n=87, multivariate Cox regression p=0.006, hazard ratio=0.365, 95% CI 0.18-0.75). In contrast, prognostic significance was abrogated in patients treated by neo-adjuvant chemotherapy using a doublet of platinum-containing drug with either gemcitabine, taxanes or vinorelbine. We observed that the density of TLS in tumor periphery was not altered in this cohort compared to untreated patients, but the proportion of TLS with active GCs was decreased (Pearson correlation -0.32, p&lt;0.001). Further, when we stratified the neo-adjuvant chemotherapy-naïve patients along adjuvant chemotherapy post-surgery, the prognostic significance was retained only in the adjuvant untreated group (n=55, multivariate Cox regression p=0.001, hazard ratio=0.17, 95% CI 0.06-0.5). This suggests that chemotherapy might affect the quality rather than formation of TLS and disturb their immunostimulatory function.

We further investigated, which factors might affect the density of TLS in tumors. Because the chemokines CXCL13, CXCL12 and CCL21 have been shown to induce TLS formation in the lung under inflammatory conditions, we analyzed their expression in tumor samples by immunohistochemistry. Positive pixel algorithm (ImageJ software) was used for the quantification of immunostained tissue sections in central and peripheral tumor areas. We saw that the overexpression of CXCL13 in both, stromal and cancer cells, was associated with increased density of TLS (Student's T test p&lt;0.05), while the expression of CXCL12 and CCL21 did not differ between the TLS-rich and TLS-poor tumor microenvironments.

In conclusion, we propose that the deliberate induction of TLS in lung cancer, possibly by CXCL13, may represent a novel immunotherapeutic approach. Thereto, the identification of molecular changes that chemotherapy exerts on the functionality of TLS, and whether this can be reversed, will provide novel ideas for the combination of immunotherapy with chemotherapy and thereby increasing the efficiency of standard treatments.

Citation Format: Karina Silina, Alex Soltermann, Holger Moch, Aija Line, Maries van den Broek. Tertiary lymphoid structures in chemotherapy-treated and untreated lung squamous cell carcinoma patients. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B85.

Rational Combination of Immunotherapies with Clinical Efficacy in Mice with Advanced Cancer

In the context of cancer, naïve T cells are insufficiently primed and become progressively dysfunctional. Boosting antitumor responses by blocking PD-1 or CTLA-4 results in durable clinical responses only in a limited proportion of cancer patients, suggesting that other pathways must be targeted to improve clinical efficacy. Our preclinical study in TRAMP mice comparing 14 different immune interventions identified anti-CD40 + IL2/anti-IL2 complexes + IL12Fc as a uniquely efficacious treatment that prevents tolerance induction, promotes priming of sustained, protective tumor-specific CD8(+) T cells, and cures late-stage cancer when given together with adoptively transferred tumor-specific T cells. We propose that improving signals 2 (costimulation) and 3 (cytokines) together with fresh tumor-specific, rather than boosting of dysfunctional preexisting memory, T cells represents a potent therapy for advanced cancer.

ELISPOT assays provide reproducible results among different laboratories for T-cell immune monitoring--even in hands of ELISPOT-inexperienced investigators

Measurements of antibodies in bodily fluids (e.g., by ELISA) have provided robust and reproducible results for decades and such assays have been validated for monitoring of B-cell immunity. In contrast, measuring T-cell immunity has proven to be a challenge due to the need to test live cells in functional assays ex vivo. Several previous efforts looking into the reproducibility of ex vivo T-cell assays between different laboratories, or even within the same laboratory, have provided rather discouraging results. The hypothesis we tested in this study is that those poor results are due to the lack of assay and data analysis standardization, rather than the inherent complexity of T-cell assays. In this study, 11 laboratories across Europe and the United States were provided identical reagents and were asked to follow the same protocol while testing aliquots of the same three cryopreserved peripheral blood mononuclear cells (PBMC) in an interferon-gamma (IFNgamma) ELISPOT assay measuring the antigen-specific T-cell response to a CMV peptide. All individuals performing the assays were ELISPOT novices. At their first attempt, while three of these individuals failed with the basic logistics of the trial, eight detected the peptide-specific CD8+ T-cells in frequencies approximating the values established by the Reference Laboratory. The data show that ELISPOT assays provide reproducible results among different laboratories when the assay procedure and data analysis is standardized. Since ELISPOT assays have been qualified and validated for regulated studies, they are ideal candidates for robust and reproducible monitoring of T-cell activity in vivo.

Effects of kaempferol and myricetin on inducible nitric oxide synthase expression and nitric oxide production in rats

When administered as drugs or consumed as food components, polyphenolic compounds synthesized in plants interfere with intracellular signal transduction pathways, including pathways of nitric oxide synthase expression. However, effects of these compounds in vivo do not always correlate with nitric oxide synthase-inhibiting activities revealed in experiments with cultured cells. The initial goal of this work was to compare effects of flavonoids kaempferol and myricetin on inducible nitric oxide synthase mRNA and protein expression monitored by real-time RT-PCR and immunohistochemistry and to evaluate the impact of these effects on nitric oxide production in rat organs measured by means of electron paramagnetic resonance spectroscopy. Kaempferol and myricetin attenuated the lipopolysaccharide-induced outburst of inducible nitric oxide synthase gene expression; kaempferol also significantly decreased the lipopolysaccharide-induced outburst of inducible nitric oxide synthase protein expression in the liver. Myricetin decreased nitric oxide production in intact rat liver. Kaempferol did not decrease nitric oxide production neither in intact rats nor in the lipopolysaccharide-treated animals. Kaempferol even enhanced the lipopolysaccharide-induced increase of nitric oxide production in blood. Myricetin did not interfere with lipopolysaccharide effects. As both kaempferol and myricetin are known as inhibitors of inducible nitric oxide synthase expression, our results suggest that modifications of nitric oxide level in tissues by these compounds cannot be predicted from data about its effects on nitric oxide synthase expression or activity.

Molecular characterisation and expression analysis of SEREX-defined antigen NUCB2 in gastric epithelium, gastritis and gastric cancer

NUCB2 is an EF-hand Ca2+ binding protein that has been implicated in various physiological processes like calcium homeostasis, hypothalamic regulation of feeding and TNF receptor shedding. In our previous study we identified NUCB2 as a potential tumour antigen eliciting autoantibody responses in 5.4% of gastric cancer patients but not in the healthy individuals.The current study aimed to elucidate the molecular mechanism underlying NUCB2 immunogenicity and to gain an insight into the physiological functions of NUCB2 in the stomach. mRNA expression analysis demonstrated that NUCB2 is ubiquitously expressed in normal tissues, including lymphoid tissues, and downregulated in gastric tumours when compared with the adjacent relatively normal stomach tissues.The search for molecular alterations resulted in the identification of novel mRNA variants transcribed from an alternative promoter and expressed predominantly in gastric cancers. Western blot analysis demonstrated that the protein levels correspond to mRNA levels and revealed that NUCB2 is phosphorylated in gastric mucosa. Furthermore, a 55 kDa isoform,generated presumably by yet an unidentified post-translational modification was detected in gastric tumours and AGS gastric cancer cells but was absent in the relatively normal gastric mucosa and thereby might have served as a trigger for the immune response against NUCB2. Staining of stomach tissue microarray with anti-NUCB2 antibody revealed that it is expressed in the secretory granules of chief cells and in the cytoplasm of parietal cells in the functioning gastric glands which are lost in atrophic glands and tumour cells. Hence we propose that NUCB2 may be implicated in gastric secretion by establishing an agonist-releasable Ca2+ store in ER or Golgi apparatus, signalling via heterotrimeric Galpha proteins and/or mediating the exocytosis of the secretory granules.

Molecular characterisation and expression analysis of SEREX-defined antigen NUCB2 in gastric epithelium, gastritis and gastric cancer

NUCB2 is an EF-hand Ca²⁺ binding protein that has been implicated in various physiological processes like calcium homeostasis, hypothalamic regulation of feeding and TNF receptor shedding. In our previous study we identified NUCB2 as a potential tumour antigen eliciting autoantibody responses in 5.4% of gastric cancer patients but not in the healthy individuals. The current study aimed to elucidate the molecular mechanism underlying NUCB2 immunogenicity and to gain an insight into the physiological functions of NUCB2 in the stomach. mRNA expression analysis demonstrated that NUCB2 is ubiquitously expressed in normal tissues, including lymphoid tissues, and downregulated in gastric tumours when compared with the adjacent relatively normal stomach tissues. The search for molecular alterations resulted in the identification of novel mRNA variants transcribed from an alternative promoter and expressed predominantly in gastric cancers. Western blot analysis demonstrated that the protein levels correspond to mRNA levels and revealed that NUCB2 is phosphorylated in gastric mucosa. Furthermore, a 55 kDa isoform, generated presumably by yet an unidentified post-translational modification was detected in gastric tumours and AGS gastric cancer cells but was absent in the relatively normal gastric mucosa and thereby might have served as a trigger for the immune response against NUCB2. Staining of stomach tissue microarray with anti-NUCB2 antibody revealed that it is expressed in the secretory granules of chief cells and in the cytoplasm of parietal cells in the functioning gastric glands which are lost in atrophic glands and tumour cells. Hence we propose that NUCB2 may be implicated in gastric secretion by establishing an agonist-releasable Ca²⁺ store in ER or Golgi apparatus, signalling via heterotrimeric G_α proteins and/or mediating the exocytosis of the secretory granules.

Characterisation of tumour-associated antigens in colon cancer

In order to search for clinically relevant cancer-associated genes and to define further the spectrum of immunogenic proteins, we applied SEREX (serological identification of antigens by recombinant expression cloning) to analyse genes expressed in colon adenocarcinoma. Eight different serum-reactive cDNA clones were isolated by immunoscreening from a colon cancer-derived cDNA expression library. mRNA expression studies showed that 2 of them, RHAMM and AD034, have a differential tissue distribution, and that 3 genes, NAP1L1, RHAMM and AD034, are overexpressed in tumours in comparison with the adjacent non-cancerous tissues. 5' RLM-RACE analysis of AD034, a sequence with a tyrosine kinase motif, revealed a frameshifting insertion of 32 bp, most likely generated by use of cryptic splice site in tumour-derived cDNA. Analysis of full-length RHAMM cDNA sequence revealed the presence of two splice variants, which are known to have a different sub-cellular localisation; expression of these splice variants is altered in colon cancer tissues. Serological responses to three antigens (C21ORF2, EPRS and NAP1L1) were found mainly in cancer patients' sera.