abstract: Osteosarcoma is the most common bone cancer in children and adolescents. Patients with metastatic osteosarcoma are typically refractory to treatment. Numerous lines of evidence suggest that cytotoxic T-lymphocytes (CTL) limit the development of metastatic osteosarcoma. I have investigated the role of Programmed Death Receptor-1 (PD-1) in limiting the efficacy of immune mediated control of metastatic osteosarcoma. I show that human metastatic, but not primary, osteosarcoma tumors express the ligand for PD-1 (PD-L1) and that tumor infiltrating CTL express PD-1, suggesting this pathway may limit CTL control of metastatic osteosarcoma in patients. PD-L1 is also expressed on the K7M2 osteosarcoma tumor cell line that establishes metastases in mice, and PD-1 is expressed on tumor infiltrating CTL during disease progression. Blockade of PD-1/PD-L1 interactions dramatically improves the function of osteosarcoma-reactive CTL in vitro and in vivo, and results in decreased tumor burden and increased survival in the K7M2 mouse model of metastatic osteosarcoma. My results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma should be pursued as a therapeutic strategy. However, PD-1/PD-L1 blockade treated mice still succumb to disease due to selection of PD-L1 mAb resistant tumor cells via up-regulation of other co-inhibitory T cell receptors. Combinational α-CTLA-4 and α-PD-L1 blockade treated mice were able to completely eradicate metastatic osteosarcoma, and generate immunity to disease. These results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma, although improves survival, may lead to tumor resistance, requiring combinational immunotherapies to combat and eradicate disease. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2015

Introduction: Human papillomavirus (HPV) is changing the prevalence, survival and treatment paradigms in oropharyngeal squamous cell carcinoma (OPSCC). Improved survival of patients with HPV positive compared to HPV negative OPSCC has led to trials of treatment de-escalation. Current HPV detection methods are imprecise, therefore standardised assessment of transcriptionally active HPV in OPSCC is required. Furthermore, the differences in immune characteristics and/or the hypoxia response/effects could explain observed differences in prognosis between HPV positive and negative OPSCC. Rigorous HPV detection and subsequent biomarker evaluation should provide additional information required before introduction of treatment de-escalation in broad patient groupings. Methods: The study cohort was 218 patients with OPSCC who received radiotherapy with curative intent. HPV status was determined on pre-treatment, formalin-fixed paraffin-embedded blocks using: 1) polymerase chain reaction (PCR); 2) in-situ hybridisation (ISH) and 3) immuno-histochemistry (IHC). QuantiGene multiplex assay was designed to detect mRNA of reference sequences of the common high-risk HPV types (16, 18, 33, 35, 45, 52 and 58). HPV detection methods were compared with mRNA quantification. Multimarker IHC of immune cell markers using chromogenic and fluorescent staining was performed, analysed and compared with single marker IHC using automated multispectral image analysis. A validated multiplex IHC method was used for a) chromogenic (CD3, CD4, CD8, and FoxP3) and b) fluorescent (CD8, CD68 and PD1/PD-L1) evaluation in tumour and stroma compartments. Single marker IHC was used to investigate tumour hypoxia markers (HIF-1α and CA-IX) in HPV positive and negative OPSCC. Results: p16 IHC and ISH were the most sensitive and specific, respectively, for classifying HPV status. The combination of the three tests had the highest positive/negative predictive values compared with QuantiGene mRNA detection. Multiplex validation showed that, for serial sections up to 6 μm apart, there were highly significant correlations (P<0.0001) between single and multiplex counts for both chromogenic and fluorescent IHC. Overall there was less variation in cell counts with fluorescent staining when compared to chromogenic staining. Multiplex IHC of TILs in HPV positive and negative OPSCC showed higher infiltration in both tumour and stromal areas of CD3+CD4+ and CD3+CD8+ T cells but not CD4+FoxP3 Tregs in HPV positive compared with HPV negative OPSCC. Only CD3+CD8+ stromal and not tumour area infiltration was associated with increased survival (P=0.02). PD-L1 expression was higher in HPV negative OPSCC and this was related to macrophage (CD68) expression of PD-L1. In HPV negative tumours infiltration with CD68+PD-L1 was associated with a good prognosis. HPV negative patients had higher expression of HIF-1α but not CA-IX. High expression of both markers was associated with a poor prognosis irrespective of HPV status. Conclusions: There are other prognostic factors operating in the larger subdivision of HPV positive and negative OPSCC. Precise HPV detection and inclusion of other prognostic factors is required before treatment de-escalation is used. Expression of immune inhibitory factors (PD1/PD-L1) alone without contextualisation with immune cell density is insufficient for patient prognostication and potential selection for therapy using immune checkpoint inhibitors. Hypoxia modification of radiotherapy should be explored in both HPV positive and negative OPSCC.

The final publication is available at http://dx.doi.org/10.1073/pnas.1315828110. Yuxiang Rui, Tasuku Honjo, and Shunsuke Chikuma. Programmed cell death 1 inhibits inflammatory helper T-cell development through controlling the innate immune response. PNAS 2013 110 (40) 16073-16078; published ahead of print September 16, 2013. / 京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第17954号 / 医科博第47号 / 新制||医科||4(附属図書館) / 30784 / 京都大学大学院医学研究科医科学専攻 / (主査)教授 竹内 理, 教授 生田 宏一, 教授 篠原 隆司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21303号 / 医博第4392号 / 新制||医||1030(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 小川 誠司, 教授 生田 宏一, 教授 濵﨑 洋子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13557号 / 論医博第2286号 / 新制||医||1067(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 生田 宏一, 教授 伊藤 能永, 教授 森信 暁雄 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24487号 / 医博第4929号 / 新制||医||1063(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 竹内 理, 教授 上野 英樹, 教授 髙折 晃史 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Melanoma is a highly malignant neoplasia with high rates of metastasis in humans and dogs. Regardless of being considered a highly immunogenic neoplasm, the function of the immune system is hampered by the expression of immune checkpoint molecules by the cancer cells. In contrast, soft tissue sarcomas are poorly immunogenic, as Tumor infiltrating Lymphocytes are lacking, or when present they are usually at the periphery of the tumor. Still, soft tissue sarcomas are considered immunosuppressed. Checkpoint molecules from the PD-axis are overexpressed in numerous human malignant neoplasia and have recently gained attention with a few reports in canine tumors. Immunotherapies against these checkpoint molecules have shown great efficacy in humans, but in order to determine translational approaches into canine patients, more research is needed. Here we determined the gene expression of Programed Death receptor-1, and its ligands PD-L1 and PD-L2 in canine tumors with two distinct immune profiles. Our results show that regardless of their immune profiles, melanoma versus soft tissue sarcoma, checkpoint molecules expression was higher in malignant tumors with a higher grade. Additionally, we evaluated the expression of these molecules in a set of patients that received histotripsy, which is a non-invasive and non-thermal ultrasound focused therapy that induces mechanical stress to the cells, leading to liquefactive necrosis. Here we reported a focal decrease of the expression of these checkpoint molecules in tissue sections obtain at the treatment interface, compared to those taken from untreated areas of the tumor. In addition, a positive relationship was noticed between the infiltration of CD3+ T lymphocytes and the expression of these checkpoint molecules in both canine melanoma, and soft tissue sarcoma. Our findings demonstrate that immunotherapies targeting these checkpoint molecules have a great potential for efficacy in canine neoplasia, along or combined with tumor ablation therapies that increased immune cell infiltration in poorly immunogenic neoplasia. / Doctor of Philosophy / Melanoma is a highly malignant tumor and very resistant to therapy for humans and dogs. At the same time, this neoplasia is usually highly infiltrated by cells from the immune system. However, this immune infiltration is often inhibited by molecules expressed by the melanoma cells. In contrast, soft tissue sarcoma is considered poorly immunogenic, as they often contain low levels of immune cell infiltrates but are still considered immune suppressed. In this study, we determined the expression of molecules that inhibit the effect of T lymphocytes, specifically Programed cell death receptor-1, PD-Ligand 1, and PD-Ligand 2 for these neoplasms with distinct immune profiles. We encounter that despite their immune profiles, the expression of these molecules is higher in malignant tumors. Additionally, we evaluated the expression of these molecules in a set of patients that received histotripsy, which is a non-invasive and non-thermal focused ultrasound therapy that induces mechanical stress to the cancerigenous cells, leading to its death (necrosis). Here we reported a focal decrease of the expression of these checkpoint molecules in tissue sections obtain at the treatment interface, compared to those taken from untreated areas of the tumor. In addition, a positive relationship was noticed between the infiltration of T lymphocytes and the expression of these checkpoint molecules in both canine melanoma, and soft tissue sarcoma. Our findings demonstrate that immunotherapies targeting these checkpoint molecules have a great potential for efficacy in canine neoplasms, along or combined with tumor ablation therapies that increased immune cell infiltration in poorly immunogenic neoplasia.

La transplantation de sang de cordon ombilical (TSCO) est utilisée pour traiter les enfants atteints de maladies hématologiques en l’absence de donneurs apparentés compatibles. Elle est associée avec des risques plus élevés d’échec de greffe et d’infections opportunistes dans les premiers mois qui suivent la transplantation en comparaison avec une greffe de moelle osseuse. Par contre, la TSCO comporte un risque plus faible de maladie du greffon contre l’hôte et une incidence comparable de rechute de leucémie. Ces quatre complications impliquent directement les lymphocytes T. Dans le but de mieux comprendre le schéma particulier des évènements qui suivent la TSCO et d’améliorer le pronostic des patients, nous avons étudié le potentiel fonctionnel, la persistance et la reconstitution antivirale des lymphocytes T au sein d’un groupe d’enfants transplantés de sang de cordon ombilical (SCO). Étant donné que le SCO contient une majorité de lymphocytes T naïfs, nous avons étudié les lymphocytes T spécifiques au HLA-A2:Melan-A26-35 A27L; seul répertoire naïf et abondant caractérisé chez l’homme. Nous avons observé que les lymphocytes T du SCO se différencient en populations effectrices, s’oligoclonalisent, produisent de l’IFN-γ et lysent spécifiquement leur cible suite à la stimulation. Néanmoins, ces cellules produisent moins d’IFN-γ et sont moins bifonctionnelles que leurs homologues issus du sang périphérique d’adultes. Chez les patients, les lymphocytes T du SCO s’épuisent après la TSCO : ils s’oligoclonalisent dramatiquement, sont principalement en différenciation terminale, et une importante fréquence exprime PD-1 (« programmed death-1 ») dans les 3 à 6 premiers mois post-greffe. Très peu de patients sont capables de développer des réponses antivirales durant cette période et la fréquence de lymphocytes T qui expriment PD-1 semble aussi avoir un impact sur le risque subséquent de faire une rechute de leucémie. La deuxième vague de lymphocytes T émergeant à 6 mois post-TSCO mène à une population fonctionnelle et diversifiée. En conclusion, la fonctionnalité des lymphocytes T présents dans les 3 à 6 premiers mois post-TSCO doit être rétablie pour améliorer les risques d’infections opportunistes et de rechute de leucémie. / Umbilical cord blood (UCB) is increasingly used as a source of hematopoietic progenitor cells to treat a variety of disorders in children. UCB transplantation (UCBT) is associated with a reduced incidence of graft-versus-host disease, a robust graft-versus-leukemia effect, more frequent graft failures and a higher incidence of opportunistic infections (OI) compared to bone marrow transplantation; four processes in which donor-derived T lymphocytes are known to be predominantly involved. UCB T cells are mostly naïve. To examine the differential functionality of UCB T cells, CD8+ T cells specific for the melanoma-associated HLA-A2-restricted Melan-A26-35 A27L peptide were isolated from UCB and UCBT recipients, as it represents an abundant preimmune repertoire in human. Following in vitro stimulation, UCB T cells proliferated, oligoclonalized, acquired cell surface markers reflective of effector/memory differentiation, expressed cytolytic activity and produced IFN-γ. While functional properties of UCB T cells resembled their counterparts in adult peripheral blood, they were more likely to reach terminal differentiation following stimulation, produced less IFN-γ and were less frequently bifunctional (IFN-γ and cytolysis). Following UCBT, T cells became exhausted: they oligoclonalized dramatically, exhibited a terminal differentiation phenotype and a high frequency also expressed PD-1 (“ programmed death 1 ”) in the first 3-6 months post-UCBT. Moreover, very few patients developed an antiviral response during this period. Finally, the frequency of PD-1+ CD8+ T cells was significantly higher in subjects who subsequently experienced leukemic relapse. A second wave of T cells emerging at 6 months post-UCBT was observed and characterized by an increase in the repertoire diversity till 1 year, the development of a naïve population with polyfunctional potential and the progressive reconstitution of antiviral responses. This study reports to the biological properties of UCB-derived CD8+ T cells and provides a rationale for the characteristics of UCBT in terms of immune reconstitution and OI. These results also suggest that the first wave of CD8+ T cells in the first 3-6 months post-UCBT should be targeted in priority to improve both OI and leukemic relapse risks.

Les cellules T CD8+ jouent un rôle primordial dans le contrôle des infections virales en limitant la dissémination des cellules infectées. Lors de l’infection chronique par le virus HIV, les cellules T CD8+ HIV-spécifiques ne se différencient pas en cellules effectrices fonctionnelles capables de tuer les cellules infectées par le virus ; ces cellules ne sont plus capables de proliférer ou de produire l’ IL-2. Ces cellules expriment PD-1 et l’engagement de PD-1, par son ligand, aboutit a plusieurs de ces déficits fonctionnels des cellules T . Le rôle de PD-1 dans la régulation d'évènements transcriptionnels contrôlant la différentiation et l'obtention des fonction effectrices des cellules T CD8+ reste à démontrer. Id2 joue un rôle central dans la différenciation des cellules T CD8+ effectrices. Nous avons émis l’hypothèse que le défaut de maturation observé chez les cellules T CD8+ PD-1 high HIV-spécifiques (CD8+PD-1hi) au cours de l’infection chronique par le virus HIV pouvait être lié à la diminution d’expression du régulateur Id2. Nous avons ainsi démontré que l'engagement de PD-1 contribuait à une diminution d'expression de Id2 et de ses cibles transcriptionnelles. La surexpression de Id2 de ces cellules a permis de restaurer l'expression de marqueurs tels que Granzyme B et Bcl-2 et diminuir l’expression du marqueur de maturation de CD27. La famille des cytokines à chaine gamma joue un rôle clef dans la survie et l’homéostasie des cellules T. Dans ce travail, nous avons démontré que l’IL-15 était unique grâce à ses capacités de stimulation de l’expression d’Id2 et ses propriétés favorisant la survie ainsi que la différenciation des cellules T CD8+ effectrices. l’IL-15 induit la prolifération de toutes les populations de cellules T mémoires provenant de donneurs sains. L’addition de cette cytokine aux sous-populations cellulaires Ttm et Tem a permis leur différenciation en cellules effectrices capables de produire Granzyme B alors que la stimulation par l’IL-15 des cellules Tcm ne favorise pas leur différenciation. Un test de cytotoxicitié par cytométrie en flux nous a permis de confirmer que la stimulation de cellules T CD8+ HIV spécifiques par l’IL-15 favorisait l’expression de Id2 et restaurait les fonctions cytotoxiques des cellules T CD8+ HIV spécifiques. En conclusion, nous avons pour la première fois dans cette thèse défini les mécanismes moléculaires impliqués dans la modulation de l’expression du régulateur transcriptionnel Id2 par l’IL-15. Nous avons également révélé comment l’engagement de PD-1 conduisait a une altération de l’expression et de la fonction d’Id2 et favorisait la diminution des fonctions effectrices des cellules T CD8-HIV spécifiques. Une perspective de traitement avec des agents tels que l’IL-15 ou le bloquage de PD-1, en combinaison avec les traitements conventionnels, pourrait contribuer à une meilleure stimulation des réponses immunes favorisant ainsi la réactivation des cellules T CD8+ et permettant la destruction de cellules T CD4+ infectées de manière latente. / CD8+ T cells play a fundamental role in controlling viral replication and dissemination by killing virus-infected cells. However during chronic HIV infection HIV-specific CD8+ T cells fail to differentiate to functional cytotoxic effector cells and develop functional defects such as loss of IL-2 secretion, decreased proliferation and express high levels of PD-1. Persistent expression of PD-1 and triggering by its ligand results in immune dysfunction; it is not known how PD-1 signaling influences transcriptional events involved in T cell differentiation and effector function. We found that the transcriptional regulator Id2 was downregulated in PD-1hi HIV-specific CD8+ T cells when compared to PD-1low CMV-specific CD8+ T cells from the same HIV-infected donors. Since Id2 has been shown to play a central role during differentiation of effector CD8+T cells, we hypothesized that skewed maturation of the PD-1hi HIV-specific CD8+ T during chronic HIV infection could result from decreased levels of Id2. We found that signals transduction pathways downstream of PD-1 ligation inhibited the expression of Id2; transfection of PD-1hi effector cells from HIV infected individuals with a Tat-Id2 construct could reverse an apoptotic fate associated with the exhausted phenotype. Finally, overexpression of Id2 restored expression of Granzyme-B and Bcl-2 and led to a decreased expression of the T cell maturation marker CD27. Although the extrinsic signals and costimulation needed to activate cell proliferation and effector function are well known, signal-transduction pathways that regulate differentiation of memory cells to effector cells are beginning to be understood. Thechain family of cytokines is essential for the survival and homeostasis of T cells; they have pleiotropic effects on the differentiation of effector and memory virus-specific CD8+ T cells. IL-15 was unique among gamma-chain cytokines in upregulating the expression of Id2 and promoting the survival and differentiation of effector memory CD8+ T cells. IL-15 induced proliferation of all memory subsets from healthy subjects but only induced differentiation, Granzyme-B production, and cytotoxic effector function in CD8+ Ttm and Tem cells. Stimulation of Tcm with IL-15 failed to induce their differentiation; this was associated with their decreased ex vivo levels of IL-15R when compared to Tem and Ttm subsets. Finally, we developed a single cell flow-cytometry cytotoxicity assay, and found that stimulation of CD8+T cells from HIV chronically infected subjects with peptide plus IL-15 induced the differentiation of tetramer+ CD8+ Ttm cells and restored Id2 expression and their cytotoxic activity . Overall, we illustrate in this thesis, for the first time, the molecular mechanisms of effector T cell differentiation mediated by IL-15 and its downstream transcriptional regulator Id2; we reveal how PD-1 engagement leads to alteration of the Id2 pathway leading to decreased effector function of the HIV-specific CD8+ T cells. Immunotherapy with agents such as IL-15 or PD-1 blocking antibody that increase levels of Id2 expression , in combination with HAART, should trigger the functional re-activation of HIV-specific CD8+ T cells and the killing of latently HIV-infected CD4+ T cells.

La transplantation de sang de cordon ombilical (TSCO) est utilisée pour traiter les enfants atteints de maladies hématologiques en l’absence de donneurs apparentés compatibles. Elle est associée avec des risques plus élevés d’échec de greffe et d’infections opportunistes dans les premiers mois qui suivent la transplantation en comparaison avec une greffe de moelle osseuse. Par contre, la TSCO comporte un risque plus faible de maladie du greffon contre l’hôte et une incidence comparable de rechute de leucémie. Ces quatre complications impliquent directement les lymphocytes T. Dans le but de mieux comprendre le schéma particulier des évènements qui suivent la TSCO et d’améliorer le pronostic des patients, nous avons étudié le potentiel fonctionnel, la persistance et la reconstitution antivirale des lymphocytes T au sein d’un groupe d’enfants transplantés de sang de cordon ombilical (SCO). Étant donné que le SCO contient une majorité de lymphocytes T naïfs, nous avons étudié les lymphocytes T spécifiques au HLA-A2:Melan-A26-35 A27L; seul répertoire naïf et abondant caractérisé chez l’homme. Nous avons observé que les lymphocytes T du SCO se différencient en populations effectrices, s’oligoclonalisent, produisent de l’IFN-γ et lysent spécifiquement leur cible suite à la stimulation. Néanmoins, ces cellules produisent moins d’IFN-γ et sont moins bifonctionnelles que leurs homologues issus du sang périphérique d’adultes. Chez les patients, les lymphocytes T du SCO s’épuisent après la TSCO : ils s’oligoclonalisent dramatiquement, sont principalement en différenciation terminale, et une importante fréquence exprime PD-1 (« programmed death-1 ») dans les 3 à 6 premiers mois post-greffe. Très peu de patients sont capables de développer des réponses antivirales durant cette période et la fréquence de lymphocytes T qui expriment PD-1 semble aussi avoir un impact sur le risque subséquent de faire une rechute de leucémie. La deuxième vague de lymphocytes T émergeant à 6 mois post-TSCO mène à une population fonctionnelle et diversifiée. En conclusion, la fonctionnalité des lymphocytes T présents dans les 3 à 6 premiers mois post-TSCO doit être rétablie pour améliorer les risques d’infections opportunistes et de rechute de leucémie. / Umbilical cord blood (UCB) is increasingly used as a source of hematopoietic progenitor cells to treat a variety of disorders in children. UCB transplantation (UCBT) is associated with a reduced incidence of graft-versus-host disease, a robust graft-versus-leukemia effect, more frequent graft failures and a higher incidence of opportunistic infections (OI) compared to bone marrow transplantation; four processes in which donor-derived T lymphocytes are known to be predominantly involved. UCB T cells are mostly naïve. To examine the differential functionality of UCB T cells, CD8+ T cells specific for the melanoma-associated HLA-A2-restricted Melan-A26-35 A27L peptide were isolated from UCB and UCBT recipients, as it represents an abundant preimmune repertoire in human. Following in vitro stimulation, UCB T cells proliferated, oligoclonalized, acquired cell surface markers reflective of effector/memory differentiation, expressed cytolytic activity and produced IFN-γ. While functional properties of UCB T cells resembled their counterparts in adult peripheral blood, they were more likely to reach terminal differentiation following stimulation, produced less IFN-γ and were less frequently bifunctional (IFN-γ and cytolysis). Following UCBT, T cells became exhausted: they oligoclonalized dramatically, exhibited a terminal differentiation phenotype and a high frequency also expressed PD-1 (“ programmed death 1 ”) in the first 3-6 months post-UCBT. Moreover, very few patients developed an antiviral response during this period. Finally, the frequency of PD-1+ CD8+ T cells was significantly higher in subjects who subsequently experienced leukemic relapse. A second wave of T cells emerging at 6 months post-UCBT was observed and characterized by an increase in the repertoire diversity till 1 year, the development of a naïve population with polyfunctional potential and the progressive reconstitution of antiviral responses. This study reports to the biological properties of UCB-derived CD8+ T cells and provides a rationale for the characteristics of UCBT in terms of immune reconstitution and OI. These results also suggest that the first wave of CD8+ T cells in the first 3-6 months post-UCBT should be targeted in priority to improve both OI and leukemic relapse risks.