Cancer immunotherapy has experienced remarkable advances in the last decades. Striking clinical responses have been achieved for several solid cancers, particularly cancer types with a high... Show moreCancer immunotherapy has experienced remarkable advances in the last decades. Striking clinical responses have been achieved for several solid cancers, particularly cancer types with a high mutation burden, which placed tumour-mutated antigens (neoantigens) centre stage as targets of tumour immunity and cancer immunotherapy. Neoantigens can be presented in complex with HLA molecules on the tumour cell surface, where T cells with the correct specificity can recognize the neoantigen as ‘non-self’ which will trigger killing of the tumour cell by the T cell. In theory, cancers with a low/moderate mutation burden that present neoantigens in complex with HLA class molecules could still be eligible for T cell-mediated immunotherapy. This thesis, describes the finding that neoantigen-specific T cells are present in mismatch-repair proficient (MMR-p) colorectal cancer patients, a low mutation burden cancer type. Moreover, CD39 and CD103 were found as cell surface markers that pinpoint the T cell population that contains the neoantigen-specific T cells. In addition, subsequent metastasis of a melanoma patient cohort were studied and revealed that also at advanced, late-stage disease, neoantigen-directed T cell therapy is, in theory, still applicable. Taken together, the studies reveal potential for the development of neoantigen-directed cancer immunotherapy for a broader patient population. Show less
To generate a successful novel therapy, a deep understanding of oncogenesis in combination with mechanistic understanding of anti-cancer compounds are needed. The work described in this thesis aims... Show moreTo generate a successful novel therapy, a deep understanding of oncogenesis in combination with mechanistic understanding of anti-cancer compounds are needed. The work described in this thesis aims to contribute to the knowledge on SUMO regulated oncogenesis, understanding the consequences of abolishment of SUMO signaling and exploiting the potential of SUMO E1 inhibitors. To this end, we describe SUMO as a potential biomarker for cancer aggressiveness and increase our understanding on SUMO’s role in cell cycle progression. We exploited the potential of SUMO E1 inhibition by combining with hypomethylating compound 5-Aza-2’ deoxycytidine, leading to increased cytostatic efficacy. Furthermore, we repurposed the SUMO E1 inhibitor TAK981 and hypomethylating drug 5-Aza-2’ deoxycytidine to improve engineered TCR (eTCR) T cell therapy and broaden our understanding of its immunomodulatory potential. Show less
T cell exhaustion is a state of T cell hypofunction arising during persistent viral infections and cancer. Recent advances in the field of immunology uncover the roles of cytokines in regulating T... Show moreT cell exhaustion is a state of T cell hypofunction arising during persistent viral infections and cancer. Recent advances in the field of immunology uncover the roles of cytokines in regulating T cell responses. Using LCMV Clone-13 as a model of persistent viral infection, this thesis investigates the roles of IL-27 and IFN-I in regulating T cells during infection. In addition, the thesis explores the potential of JAK inhibitor in rescuing T cell exhaustion during persistent viral infection and cancer. Show less
Immunotherapies for cancer are an emerging class of therapeutic strategies which aim to treat cancer via augmentation of the immune system. Despite significant success of immunotherapies in the... Show moreImmunotherapies for cancer are an emerging class of therapeutic strategies which aim to treat cancer via augmentation of the immune system. Despite significant success of immunotherapies in the past decade, not all patients will respond to these treatments and the reasons why immunotherapies are successful in some patients, but not others, remain incompletely understood. The immune response to cancer is a complex, multistage process, and mathematical and computational models are a useful tool for understanding such complex systems. In this thesis, I develop mathematical and computational models of cytotoxic T lymphocytes (CTLs), who are key players in the immune system due to their ability to recognise, destroy, and provide long lasting protection against malignant or virally infected cells. Show less
Immunotherapy approach to cancer is only benefiting to a minority of patients. In this study, we approach cancer solutions by studying the microenvironment and its immunological signature... Show moreImmunotherapy approach to cancer is only benefiting to a minority of patients. In this study, we approach cancer solutions by studying the microenvironment and its immunological signature throughout the body by focusing on the systemic immunity with new technology like mass cytometry. By highlighting specific immunological patterns in cancer, we were able to associate responsive immune cells and positive outcome, therefore paving the way to improve immunotherapy in cancer. Show less
MHC class I antigen-presentation plays a pivotal role in anti-tumor immunity. High surface expression of MHC-I molecules is generally correlated with high CD8 T cell infiltrate and improved overall... Show moreMHC class I antigen-presentation plays a pivotal role in anti-tumor immunity. High surface expression of MHC-I molecules is generally correlated with high CD8 T cell infiltrate and improved overall survival in many cancers. In contrast, partial or complete loss of MHC-I surface expression is associated with reduced survival and primary-resistance to immunotherapy in cancers. Expression of additional molecules in the tumor microenvironment (TME), such as PD-L1 and HLA-E, further shape immune responses. The presence of immune cells and the expression of immune-related genes together determine the ‘immune landscape’ of cancers, while the local production of interferons strongly impacts this environment. Although MHC-I and PD-L1 are both regulated by the IFN pathway, an in-depth study on immune escape of NSCLC showed that the expression of co-inhibitory markers and the loss of MHC-I expression are two independent mechanisms of immune evasion. This classifies tumors into different “types” depending on their MHC-I and PD-L1 expression. The differential expression of MHC-I and PD-L1 suggests that immune-escape of cancer cells occurs through a multitude of distinct “hard-wired” and “soft-wired” modifications and knowing which of the mechanisms underlie immune escape determines which immunotherapeutic strategy has the most potential for clinical success. Show less
In the clinic, several forms of immunotherapy are combined with the standard treatments, including chemotherapy. Translational studies trying to understand the different outcomes in patients have... Show moreIn the clinic, several forms of immunotherapy are combined with the standard treatments, including chemotherapy. Translational studies trying to understand the different outcomes in patients have led to new questions and hypotheses. The studies described in this thesis are to answer some of these questions. We revealed the immunostimulatory effect of the chemotherapy agent; cisplatin. Next, we studied the mechanism of relapse following immunotherapy with HPV16 SLP vaccination in mice. We demonstrated that unsuccessful immunotherapy results in immune editing and secondary resistance. To overcome this, the combination therapies are required. Moreover, we showed the importance of IL-6 producing by tumors in dampening anti-tumor response. To induce a long-term sustained effector T cell response, we examined the potency of mouse cytomegalovirus as a viral vector-based vaccine. We demonstrated that the demarcated thresholds of vaccine-specific T cells correlate to tumor protection. Recognizing the fact that at each phase of the antitumor immune response a different type of help might have to be provided to obtain maximal therapeutic efficacy, the correct timing of various types of chemotherapeutic agents or immune modulators when used in combination is discussed. Finally, we discussed the general aspects and relevance of the studies mentioned in this thesis. Show less
The breakthrough of immunotherapy for cancer has introduced promising new options, but nonetheless only a minority of cancer patients show significant clinical benefit. This situation has inspired... Show moreThe breakthrough of immunotherapy for cancer has introduced promising new options, but nonetheless only a minority of cancer patients show significant clinical benefit. This situation has inspired two avenues of research to find solutions to this problem: mechanistic studies to decipher the working mechanisms of immunotherapies and to investigate why many patients do not respond, and studies developing combination treatments to achieve clinical benefit in situations where immunotherapy alone is not sufficient. This thesis explores both these avenues by investigating applications of visible light in immunotherapy of cancer in pre-clinical models. We developed optical imaging platforms for visualization of immune cells and immunotherapies, which can shed light on the immunological events after administration of immunotherapy. In addition, we investigated novel therapies based on the combination of tumor ablation by Photodynamic Therapy and different types of immunotherapy. Our findings may prove useful in understanding success and failure of immunotherapy, and provide new combination treatment options when the efficacy of monotherapy is insufficient. Show less
This dissertation deals with the role of local immune stimulation in the lymph node and tumor microenvironment and its effect on systemic CD8+ T cell responses, in particular the anti-tumor CD8+ T... Show moreThis dissertation deals with the role of local immune stimulation in the lymph node and tumor microenvironment and its effect on systemic CD8+ T cell responses, in particular the anti-tumor CD8+ T cell responses. In chapter 2 the use of a slow-release system is described to deliver the immune-activating agonistic CD40 antibody to the tumor-draining area, and the advantages of this method over systemic administration of the antibody. The local, slow-release administration was very effective in activating a systemic anti-tumor effector CD8+ T cell response, to such an extent that a tenfold lower dose of antibody could be used without loss of efficacy. Adverse side-effects, analyzed by organ histology and liver enzymes in the blood, were much lower upon local anti-CD40 antibody delivery compared to systemic administration. The local delivery of anti-CD40 antibody resulted in a systemic anti-tumor CD8+ T cell response, capable of clearing distant tumors expressing identical tumor antigens. Chapter 3 shows that slow-release local administration of CTLA-4 blocking antibody can also activate a tumor-specific CD8+ T cell response and cause tumor regression, while lowering systemic adverse side-effect as compared to systemic administration. CTLA-4 blocking antibody is being widely used in clinical trials, and its use has been complicated by induction of auto-immune disease. Here we show that using a local low dose injection of CTLA-4 blocking antibody in a slow-release formulation is equally effective in activating a tumor-specific CD8+ T cell response, capable of eradicating tumor cells as systemic high dose treatment. The influence of local lymph node activation on systemic T cell responses is further analyzed in chapter 4. CD8+ T cell priming generally occurs in a locally inflamed lymph node, called a reactive LN, due to the presence of pathogens. The role of the inflammatory milieu on the priming and fate of CD8+ T cells was studied by separating the TCR-MHC interaction from the inflammatory cues, by priming briefly in vitro followed by transfer to mice with or without a CpG-induced reactive lymph node. The primary CD8+ T cell response was not influenced by the presence of a reactive lymph node, however, after a boost vaccination in the memory phase, CD8+ T cells primed in the presence of a reactive LN displayed a strong quantitative advantage over control CD8+ T cells. The reactive LN, which remained swollen with enhanced cellularity for a pronounced period of time, was envisaged to act as a shelter for CD8+ T cells while undergoing contraction after the primary response. In chapter 5, the advantages and disadvantages of the use of dextran-based microparticles as slow-release system for the delivery of immune-activating antibodies such as agonistic CD40 in the tumor-draining area are described. Dextran-based microparticles can be tailored to release antibodies in desired pharmacokinetics, leading to an even further decrease of adverse side-effects, as compared to previously described Montanide-ISA 51. However, dextran-based particles were unexpectedly found to have a stimulating effect on tumor-outgrowth. This effect coincided with the appearance of large, ulcerated swellings at the site of injection. In chapter 6, the issues presented in this thesis are discussed. The knowledge gained in the work shown here, compared with and strengthened by related published work, is used to state the opinion that targeting the tumor-draining lymph node and/or tumor microenvironment for immune-activating therapy against tumors must be seriously considered. Show less
