Human leukocyte antigen (HLA) matched allogeneic stem cell transplantation (SCT) is an established curative treatment for hematopoietic malignancies and an investigative immunotherapeutic approach... Show moreHuman leukocyte antigen (HLA) matched allogeneic stem cell transplantation (SCT) is an established curative treatment for hematopoietic malignancies and an investigative immunotherapeutic approach for solid tumors. The curative effect of allogeneic SCT is based on so called graft versus-tumor (GvT) responses. The GvT effect in the HLA-matched setting is mainly driven by donor immune responses against so called minor histocompatibility antigens (mHags). Emerging data suggest that immunotherapy targeting mHags may eradicate cancer without severe side effects. This thesis investigated 1) the proof of concept for the efficacy of mHag specific immunotherapy in vitro and in vivo, 2) the optimal circumstances under which mHag specific cytotoxic T-cells (CTLs) are most effective against established leukemia and solid tumors, 3) new immune escape mechanisms in cancer that need to be considered when targeting mHags, 4) the optimal protocols for the in vitro expansion of mHags CTLs, 5) the optimal design of mHag peptide vaccines and 6) the optimal parameters for the clinical guidance of mHags specific immunotherapy of cancer. The data acquired in this thesis have provided relevant knowledge that is already partially implemented in the design of new HA-1 vaccination studies aiming at curing leukemia and solid tumors. Show less
Steenwijk, P.J.D. van; Ramwadhdoebe, T.H.; Lowik, M.J.G.; Minne, C.E. van der; Berends-van der Meer, D.M.A.; Fathers, L.M.; ... ; Burg, S.H. van der 2012
In this thesis, we report on various aspects of tumor - host (immune) interactions in Ewing sarcoma patients with the aim to obtain leads for immunotherapeutic or targeted treatment strategies. We... Show moreIn this thesis, we report on various aspects of tumor - host (immune) interactions in Ewing sarcoma patients with the aim to obtain leads for immunotherapeutic or targeted treatment strategies. We demonstrate a key role for interferon gamma (IFNg) in enhancing both Ewing sarcoma immunogenicity and susceptibility to cytotoxicity. An (endogenous) pro-inflammatory tumor microenvironment consisting of cytotoxic T-lymphocytes and IFNg-inducible chemokines provides prognostic benefit. Moreover, despite evidence for immunologic pressure in selection of HLA class I loss variants, intact IFNg-inducibility of the HLA class I antigen processing machinery emphasizes the significance of a pro-inflammatory microenvironment for initiation/ execution of adaptive anti-tumor immunity. Pre-clinical support for the potential of adoptive cell transfer therapies, in particular combinatorial natural killer cell-based therapy, is provide d. Sensitization of Ewing sarcoma by conventional or targeted therapies, including histone deacetylase inhibitors, combined with cytokine activation of natural killer cells enhances anti-tumor responses and overcomes both intrinsic functional natural killer cell defects as well as cross-resistance of chemotherapy-resistant Ewing sarcoma to natural killer cells. Finally, due to a crucial role of the CXCR4-CXCL12 axis in Ewing sarcoma progression, disruption of this axis by a CXCR4-specific antagonist may represent a promising treatment option for patients with Ewing sarcoma. Show less
The immune system plays an important role in the balance between viral clearance and viral persistence in HPV related (pre)malignant lesions. In this thesis, we analyzed HPV clade A9-specific T... Show moreThe immune system plays an important role in the balance between viral clearance and viral persistence in HPV related (pre)malignant lesions. In this thesis, we analyzed HPV clade A9-specific T-cell responses in relation to virological and clinical outcome to gain further insight into HPV-specific cellular immunity in relation to the natural course of disease. In depth analysis of cellular immune responses against the E6 antigen of HPV16 and the closely related members of clade A9 (HPV31, 33, 35, 52 and 58) showed us that HPV-specific cross-reactive CD4+ T cells are rare and unlikely to mediate cross protection (chapter 2). The clinical course of cervical HPV infection and HPV-specific immune responses in prospective studies are described in chapter 4 and 5. In those chapters, a strong correlation is observed between a persistent HPV infection or progressive disease and the lack or failure of a type-specific immune response (>90% of the cases). No correlation is detected between HPV type-specific cellular immune responses and virological clearance of the infection and HPV type-specific immunity may be associated with clearance of a cervical HPV induced lesion (chapter 4 and 5). Interestingly, a statistically significant trend could be detected between the presence of a type-specific immunity (HPV16E2) and regression of a low-grade lesion (chapter 5). A similar, but - due to small number of patients __ not statistically significant trend was observed in chapter 4. Together, this suggests that the local innate immune system might play a role in the clearance of transient infections, whereas the cellular immune response can play a role in regression of histologically proven HPV induced lesions. Detection of HPV16 type-specific cellular immune responses in vivo, by the use of a DTH skin test, confirmed that cellular immune responses in healthy subjects consist of both HPV-specific CD4+ Th1/Th2 and CD8+ T cells (chapter 3). 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
