1,720,997 research outputs found
Combining CAR-T cells and Oncolytic Viruses for Cancer Immunotherapy
No full textINTRODUCTION: Immunotherapy continues to garner strong support for use in the treatment of cancer. Adoptive transfer therapies offer a promising approach to combating metastatic disease. In addition, viruses can also be exploited to drive antitumor immunity and tumor destruction. While the use of chimeric antigen receptor (CAR)-engineered T cells has shown dramatic clinical benefit for use in blood-based cancers, solid tumors remain a significant hurdle.
METHODS: We have investigated the use of multi-faceted immunotherapies combining CAR-T cells with oncolytic virotherapy. We have also evaluated how these therapies interact with pre-conditioning lymphodepletion regimes.
RESULTS: In chapter 3, we investigated the differences between three similar chimeric receptors targeting NKG2DL. Upon adoptive transfer, we observed dramatic T cell-induced toxicity. In addition, there were stark differences in the severity of toxicity induced between different receptors or across different mouse strains, or if combined with pre-conditioning chemotherapy.
In chapter 4, we tested the ability of oncolytic vaccines to boost engineered T cells through their natural antigen receptor. While CAR-T cells could be boosted via oncolytic vaccines, prolonged T cell engraftment and successful oncolytic vaccine boost required pre-conditioning chemotherapy.
Further analysis revealed a lack of antitumor function of the CAR-T cells in vivo. iii
In chapter 5, we evaluated loading CAR-T cells with oncolytic viruses (OVs). Loading of CAR-T cells with OV did not impair CAR expression or functionality of the T cells. In addition, CAR target recognition did not impact the ability of OV-loaded cells to deposit OVs onto tumor targets. CAR-T cells loaded with OV also displayed enhanced antitumor functions as compared to either treatment alone.
CONCLUSIONS: The research described in this thesis reveals important information into the interactions between CAR-T cells and OVs, and how pre- conditioning regimes may influence responses from either or both therapies. Overall, our research offers novel insight into future CAR-T cell therapeutic developments.ThesisDoctor of Philosophy (PhD
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
T Cell Biology of Recombinant Adenovirus Vaccines
No full text Vaccination is arguably the most effective tool at our disposal to prevent the morbidity and mortality associated with infectious disease. However, there are currently several infectious diseases, notably HIV, malaria and tuberculosis, for which we do not posses effective vaccines. Further complicating matters, traditional methods to construct vaccines for these diseases have been unsuccessful. Advances in our understanding of adaptive immunity have demonstrated that vaccines for these diseases likely rely upon potent T cell immunity to be effective. Recombinant adenovirus (rAd) vectors have shown great promise as vaccination platforms since they are easily constructed, stable, well-tolerated and elicit robust T cell responses. The robust activity of rAd vectors based on the human serotype 5 virus (rHuAd5) in murine and simian models merits futher investigation as a prototypic T cell vaccine. To this end, we have undertaken a comprehensive evaluation of T cell immunity following rAd vaccination. Our previous observations determined that the CD8+ T cell response produced by rHuAd5 vaccines displayed a prolonged effector phase that was associated with long-lived antigen presentation. We have further investigated the mechanisms underlying the maintenance of this memory population. Our results have revealed that the memory phenotype is not due to continual recruitment of naive CD8+ T cells. Rather, the sustained effector phenotype appears to depend upon prolonged expression of the antigen-encoding transgene from the rHuAd5 vector. Interestingly, transgene expression was only required for 60 days after which point the memory population stabilized. Further investigation of the relationship between antigen structure and the CD8+ T cell response revealed that antigens which traffic through the ER produce a CD8+ T cell response that expands more rapidly and displays a more pronounced contraction phase than antigens which are produced within the cytosol. While the exact mechanism underlying this phenomenon is not known, we suspect that pathways related to ER stress may be involved. Despite the more dramatic contraction phase associated with antigens that traffic through the ER, the memory phenotype was unchanged. Interestingly, the CD4+ T cell response was not influenced by antigen structure and displays a sharp contraction phase regardless of whether the antigen traffics through the ER or is produced in the cytosol. We further investigated the relationship between CD4+ T cell help and CD8+ T cell immunity produced by rHuAd5. Based on the partially-exhausted phenotype of the CD8+ T cells produced by rHuAd5 (diminished TNF-a production and little IL-2 production), we suspected that inadequate CD4+ T cell help may have been responsible. However, removal of CD4+ T cells did not further impair the CD8+ T cell response produced by rHuAd5. Rather, a lack of CD4+ T cell help only impacted the magnitude of the primary CD8+ T cell response generated by rHuAd5; the functionality of the CD8+ T cell population, including the ability to proliferate following secondary stimulation, were not affected by the absence of CD4+ T cells. Thus, although CD8+ T cell expansion following immunization with rHuAd5 is dependent upon the availability of CD4+ T cell help, the memory functions of the CD8+ T cell population appears to be independent of CD4+ T cell help. Finally, we compared the magnitude of the CD8+ T cell response produced by rHuAd5 and recombinant vaccinia virus. Our results demonstrated that the functionality of the early T cell response produced by both vectors were identical. However, the primary transgene-specific CD8+ T cell responses produced by rHuAd5 were significantly larger than rVV because the vector specific responses were negligible in the case of rAd but very strong following rVV inoculation. This research has contributed to our understanding of T cell immunity following rAd immunization and will assist in the construction and implementation of future vaccines. ThesisDoctor of Philosophy (PhD
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Engineered T cells for multiple myeloma
Full text linkMultiple myeloma is a plasma cell cancer that progressively evolves to an aggressive, multi-drug resistant disease, which presents an unmet clinical need. In clinical trials, myeloma shows susceptibility to novel immunotherapeutic agents, particularly those targeting B-cell maturation antigen (BCMA). Among different classes of immunotherapies, T cell-based approaches have progressed the most due to their ability to induce durable responses in patients with advanced drug-resistant blood cancers. Most T cell engineering strategies rely on the use of chimeric antigen receptors (CARs), which although effective, can cause serious life-threatening toxicities. We created a new synthetic receptor, T cell antigen coupler (TAC), which recruits the endogenous T cell receptor and allows T cells to autoregulate their activity. Our experience in solid tumor models has shown that TAC-T cells are similarly efficacious and significantly less toxic than CAR-T cells. This thesis describes our optimization of BCMA-specific TAC-T cells and analysis of different anti-BCMA antigen-binding domains.
TAC receptor functions by engaging endogenous TCR-CD3 complex and redirecting it to the target of interest. In Chapter 3, we characterize optimization and humanization of the CD3-recruitment domain in the TAC scaffold and provide evidence that TAC-T cells are effective against multiple myeloma, irrespective of receptor surface levels. In Chapter 4, we describe selection of the human BCMA-binding domain and the creation of a fully humanized TAC receptor against BCMA. Chapters 5 and 6 describe how a BCMA-targeting antigen-binding domain that cross-reacts with an unknown antigen in mice augments in vivo efficacy of TAC- and CAR-T cells, respectively.
The work described in Chapters 3 and 4 presents an optimized, fully human BCMA-TAC that is being moved into clinical testing. The work in Chapters 5 and 6 improves our understanding of how antigen-targeting domains in synthetic receptors influence the functionality of engineered T cells.ThesisDoctor of Science (PhD)Multiple myeloma is an incurable blood cancer that has a remarkable ability to develop resistance to different types of chemotherapy. In recent years, treatments redirecting immune cells against tumors have shown impressive clinical responses against different types of chemotherapy-resistant blood cancers, including multiple myeloma. Our lab has developed a new technology for redirecting T cells against tumors, called T cell antigen coupler (TAC) receptor. This thesis describes optimization of a fully human TAC receptor specific for a target on the surface of myeloma cells, known as BCMA. Durable remissions induced by TAC-engineered T cells in a preclinical mouse model of myeloma in the absence of toxicity warrant further testing of this therapeutic in a clinical trial
TAC-engineered T cells as carriers of oncolytic virus
Full text linkThe field of immuno-oncology has made tremendous advances in the treatment of cancer. Adoptive cellular transfer (ACT) of tumor-specific T cells and oncolytic viruses (OVs) are powerful anti-tumor agents, but each modality faces significant challenges. Despite the promise of ACT against hematological malignancies, success has been limited in solid tumors. OVs preferentially lyse tumor cells, but have difficulty overcoming antiviral host factors when delivered systemically – therapeutic doses must therefore be quite high to achieve tumor delivery. One means of overcoming viral neutralization is by loading OV onto cellular carriers prior to treatment. Since engineered T cells and OVs both possess anticancer activity, and since viruses naturally associate with nearby circulating immune cells, employing T cells engineered with a T cell antigen coupler (TAC) receptor as viral carriers may offer an ideal combination. Our studies indicated that loading oncolytic maraba virus (MRB) onto T cells – engineered with a TAC receptor targeting HER2 – had no impact on the functionality or receptor expression of these T cells. OV loaded on the surface of these TAC-T cells enabled killing of a variety of tumor targets that may be otherwise resistant to TAC-T cell therapy. Efficacy remains to be elucidated in vivo using xenograft murine models due to the lack of a protective antiviral immune response, which ultimately resulted in encephalopathy. These observed toxicities were likely model-specific, as MRB has shown to be highly attenuated in healthy tissues of wild type models. While conceptually attractive, using TAC-T cells as viral carriers to deliver a multi-pronged, one-pot antitumor therapy directly to the site of the tumor requires further evaluation before considering human studies.ThesisMaster of Science (MSc
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
PRE-CLINICAL DEVELOPMENT OF SYNTHETIC RECEPTOR-ENGINEERED T LYMPHOCYTES FOR THE TREATMENT OF CANCER: NOVEL RECEPTORS AND UNDERSTANDING TOXICITY
Full text linkAdvances in our understanding of the molecular events leading to cancer have facilitated the development of next-generation targeted therapies. Among the most promising new approaches is immuno-oncology, where therapeutic agents engage the immune system to fight cancer. One exciting strategy therein is the adoptive transfer of ex vivo cultivated tumor-specific T lymphocytes into a cancer patient. Tumor-specific T cells can be produced by engineering a patient’s own T cells with synthetic receptors (e.g. chimeric antigen receptors (CARs)) designed to redirect T cell cytotoxicity against a tumor target. CAR-engineered T cells (CAR-T cells) were expected to be a non-toxic cellular therapy which would seek out and specifically eliminate disseminated tumors. The clinical experience supports the promise of CAR-T cell therapy (striking efficacy has been observed in the treatment of hematological malignancies), while highlighting areas for improvement; CAR-T cell use has been associated with a host of toxicities and robust clinical efficacy has yet to be replicated in solid tumors.
This thesis uses pre-clinical models to describe previously unappreciated aspects of CAR-T cell-associated toxicity and novel synthetic receptor strategies, including:
i. The capacity of NKG2D-based CAR-T cells to mediate toxicity.
ii. The utility of designed ankyrin repeat proteins as CAR antigen-binding domains.
iii. The discovery that variables intrinsic to human CAR-T cell products contribute to toxicity.
iv. A novel synthetic receptor capable of redirecting T cell specificity against a tumor target – the T cell antigen coupler (TAC). Unlike equivalent CAR-T cells, TAC-T cells are capable of mediating efficacy against a solid tumor in the absence of toxicity.
We anticipate that these results will contribute towards the development of next-generation synthetic receptor-engineered T cell products that can deliver upon the promise of safe, systemic cancer therapeutics.ThesisDoctor of Philosophy (PhD)The human immune system has the unique capacity to “seek and destroy” tumor cells throughout the body. A novel class of drugs, immuno-oncology agents, harness this ability to fight cancer. Within this class is a new cellular drug where genetic engineering is used to create killer immune cells (called T cells) capable of recognizing and eliminating tumors. Two of these cellular drugs have recently received FDA approval, supporting the feasibility of this approach. However, further research is needed to improve the safety of engineered-T cells and increase the number of patients whom can benefit from their use. This thesis uses laboratory investigations to better understand the side-effects associated with anti-cancer engineered-T cells and evaluate new engineering strategies. We anticipate that these results will contribute towards the development of next-generation engineered-T cell drugs which retain the ability to function systemically against cancer but offer an enhanced safety profile
ADAPTIVE EVENTS IN THE TUMOR LIMIT THE SUCCESS OF CANCER IMMUNOTHERAPY
No full textPre-clinical and clinical data strongly support the use of immunotherapies for cancer treatment. Cancer vaccines offer a promising approach, however, the outcomes of clinical vaccine trials have been largely disappointing, prompting a need for further investigation. Using the B16F10 murine melanoma, we have investigated the local events within growing tumors following recombinant adenovirus immunization. In chapter 2, we investigated the ability of a pre-clinical vaccine to elicit only transient tumor growth suppression. We observed that tumors were initially infiltrated by a small number of highly functional tumor-specific CD8+ T cells following vaccination that instigated a rapid adaptive response in the tumor that suppressed local immune activity. In chapter 3, we questioned whether increasing the rate and magnitude of early immune attack would result in more robust tumor attack prior to tumor adaptation. Increasing the rate of tumor-specific CD8+ T cell expansion following vaccination resulted in tumor regression and durable cures in approximately 65% of treated mice. Further analysis revealed that tumor regression correlated with an early burst in immune attack that outpaced tumor adaptation. In chapter 4, we explored whether the same vaccine could be improved when combined with immunomodulatory antibodies. Vaccination combined with anti 4-1BB and anti PD-1 resulted in complete tumor regression and durable cure of >70% of treated animals and was associated with increased local immune activity. Gene expression profiling revealed a unique gene signature associated with the curative treatment, which was also associated with positive outcome in human melanoma patients. The described research sheds new light on mechanisms that limit the efficacy of therapeutic cancer vaccines. Namely, rapid tumor adaptation, triggered by early vaccine-induced CD8+ T cells, acts to suppress the local immune response prior to maximal immune attack. Strategies to overcome these adaptive processes should therefore be considered in future vaccine design.Doctor of Philosophy (Medical Science
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