El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Background: Clinical trial completion is critical for new cancer therapies. Premature trial termination or withdrawal is common and impairs progress. We assessed factors of early terminated/withdrawn oncology trials focusing on trials with immune checkpoint inhibitors (ICI), hypothesizing that the latter may be associated with lower rates of premature discontinuation. Materials and Methods: We reviewed all adult, intervention, oncology trials registered in ClinicalTrials.gov (November 16, 2011, to April 16, 2015) to identify all terminated/withdrawn trials and reasons for termination. Logistics regression model was used to identify factors associated with early termination/withdrawal. Discontinuation rate was compared in trials with and without ICI. Results: We identified 12,875 trials (35% industry funded, 12% federal funded), of which 8.5% were prematurely terminated (5%) or withdrawn (3.5%); the main reasons were poor accrual (33%) and logistical (24%). ICI trials (n = 350) had a nonsignificant lower rate of termination or withdrawal compared with all other oncology trials (5.4% vs. 8.5%; p =.9) and were less likely to discontinue due to poor accrual (nonsignificant difference: 21% vs. 33%; p =.4). ICI trials were also less likely to discontinue compared with all other oncology drug trials (e.g., chemotherapy, targeted inhibitors, antiangiogenesis, biologics; 5.4% vs. 7.9%, respectively, nonsignificant difference). The 4-year cumulative incidence of failing to complete for reasons unrelated to toxicity or efficacy was 18% (95% confidence interval 16%–20%). There was no association between annual incidence across different tumor types or accrual goal and rate of trial termination. Conclusion: Poor accrual represents the main cause of early cancer trial termination. Premature termination/withdrawal rate was not significantly lower in ICI compared with other trials. Clinical trial completion remains a high priority and can be influenced by provider and patient factors. Implications for Practice: Clinical trial completion is critical for new cancer therapies. Premature trial termination or withdrawal is common and impairs progress. This study assessed factors of early terminated/withdrawn oncology trials, focusing on trials with immune checkpoint inhibitors (ICI), and found that poor accrual represents the main cause of early cancer trial termination. Premature termination/withdrawal rate was not significantly lower in immune checkpoint inhibitor trials compared to other trials. The discussion herein is focused on measures taken by the National Cancer Institute and other institutions to improve clinical trial accrual and prevent premature clinical trial discontinuation. / Revisión por pares

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Precision medicine has allowed for the development of monoclonal antibodies that unmask the anti-tumor immune response. These agents have provided some patients durable clinical benefit. However, PD-1 and PD-L1 inhibitor therapies are effective in a small group (10-20%) of non-small cell lung cancer (NSCLC) patients when used as single-agent therapy. The approved companion diagnostic is expression of the immune cell surface molecule, programmed death ligand 1 (PD-L1), on tumors measured by immunohistochemistry (IHC). Studies in tumor biology and immune surveillance dictate that PD-1 inhibitor efficacy should depend on the level of PD-L1 expression; however, the literature has not followed with convincing evidence. The limitations of this test include timing of tissue acquisition, tumor heterogeneity, and timing of therapy relative to the expression of PD-L1. In addition, the requirement of analyzing tumor tissue biopsy samples from a patient is cumbersome. Thus, a peripheral blood biomarker that predicts efficacy of PD-1/PD-L1 inhibition would be optimal for precise and cost-effective treatment. A history of chronic inflammatory diseases may be advantageous for a cancer patient who is treated with PD-1/PD-L1 inhibitors and may allow them to then mobilize a swift immune response to tumor cells. Specific biological components of this persistent inflammation may predict PD-1 inhibitor response. We have taken a novel approach to leverage national healthcare claims data that couples patient history with response to therapy. We have identified potential peripheral blood biomarkers of response to PD-1/PD-L1 inhibitors using a combination of healthcare outcomes and molecular markers that correlate with therapeutic efficacy.

abstract: Immunotherapy has received great attention recently, as it has become a powerful tool in fighting certain types of cancer. Immunotherapeutic drugs strengthen the immune system's natural ability to identify and eradicate cancer cells. This work focuses on immune checkpoint inhibitor and oncolytic virus therapies. Immune checkpoint inhibitors act as blocking mechanisms against the binding partner proteins, enabling T-cell activation and stimulation of the immune response. Oncolytic virus therapy utilizes genetically engineered viruses that kill cancer cells upon lysing. To elucidate the interactions between a growing tumor and the employed drugs, mathematical modeling has proven instrumental. This dissertation introduces and analyzes three different ordinary differential equation models to investigate tumor immunotherapy dynamics. The first model considers a monotherapy employing the immune checkpoint inhibitor anti-PD-1. The dynamics both with and without anti-PD-1 are studied, and mathematical analysis is performed in the case when no anti-PD-1 is administrated. Simulations are carried out to explore the effects of continuous treatment versus intermittent treatment. The outcome of the simulations does not demonstrate elimination of the tumor, suggesting the need for a combination type of treatment. An extension of the aforementioned model is deployed to investigate the pairing of an immune checkpoint inhibitor anti-PD-L1 with an immunostimulant NHS-muIL12. Additionally, a generic drug-free model is developed to explore the dynamics of both exponential and logistic tumor growth functions. Experimental data are used for model fitting and parameter estimation in the monotherapy cases. The model is utilized to predict the outcome of combination therapy, and reveals a synergistic effect: Compared to the monotherapy case, only one-third of the dosage can successfully control the tumor in the combination case. Finally, the treatment impact of oncolytic virus therapy in a previously developed and fit model is explored. To determine if one can trust the predictive abilities of the model, a practical identifiability analysis is performed. Particularly, the profile likelihood curves demonstrate practical unidentifiability, when all parameters are simultaneously fit. This observation poses concerns about the predictive abilities of the model. Further investigation showed that if half of the model parameters can be measured through biological experimentation, practical identifiability is achieved. / Dissertation/Thesis / Doctoral Dissertation Applied Mathematics 2020

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal cancer, accounting for 3.2% of new cancer cases yearly but nearly 8% of all yearly cancer mortalities. Over the past twenty years, our understanding of cancer biology has greatly improved which has resulted in vastly improved prognoses for many cancers. However, the prognosis of pancreatic ductal adenocarcinoma has not improved despite the advance in cancer treatments. This is especially apparent with cancer immunotherapies, a newer therapeutic strategy that utilizes the innate defense mechanism of the body to target malignancies. Immune checkpoint inhibitors are a type of cancer immunotherapy that act by inhibiting the PD-1/PD-L1 and CTLA-4 immune checkpoint pathways and allowing T lymphocytes to proliferate and generate an antitumor response. They have greatly improved the prognosis for many types of malignancies, but clinical studies show that immune checkpoint inhibition has had a limited effect on the prognosis of PDAC. Recent studies have demonstrated that the immune microenvironment of PDAC is highly immunosuppressive, which is a probable factor in limiting the therapeutic efficacy of immune checkpoint inhibitors. Myeloid derived suppressor cells (MDSCs) are a main component of the immune microenvironment in PDAC. They are immature cells of myeloid origin that express CD11b+Gr-1+ on their surface, making them phenotypically distinct from mature dendritic cells. Their infiltration of the PDAC microenvironment early on in the course of the disease is promoted in a large part by the cytokine GM-CSF. MDSCs are believed to contribute to the limited efficacy of immune checkpoint inhibitor therapy both directly and indirectly. Indirect mechanisms are mediated by promoting the activity of other immunosuppressive cells in the PDAC microenvironment such as tumor associated macrophages and regulatory T lymphocytes. MDSCs induce the transformation of naïve CD4+ T lymphocytes into protumorigenic regulatory T lymphocytes. They also promote the polarization of macrophages to the tumor associated macrophage phenotype (IL-10high IL-12low) by secreting IL-10, which decreases IL-12 synthesis by macrophages present in the tumor microenvironment. On top of mediating immunosuppression through other cell types, MDSCs directly mediate immunosuppression by decreasing the amounts of amino acids necessary for anti-tumor immunity in the tumor microenvironment and disrupting the activity of antigen presenting cells and the signaling needed to initiate a cytotoxic T lymphocyte response. The decreased amount of arginine limits the ability of T cells to proliferate, resulting in a weaker cytotoxic response. These mechanisms limit the antitumor response against pancreatic ductal adenocarcinoma, resulting in the decreased response to immune checkpoint inhibitor therapy observed in clinical trials. Future attempts to strengthen the anti-tumor immune response must be combinatorial therapies that incorporate therapeutic strategies that seek to alleviate MDSC-mediated immunosuppression of T lymphocytes from the tumor microenvironment in addition to the more widely available immune checkpoint inhibitor therapy. Such therapeutics are currently being studied in murine models and have shown promising preliminary results but have yet to have been examined in clinical trials. These therapies are an ideal avenue to explore in a search for more effective therapy for this highly lethal disease.

The development and design of immune-based strategies have become an increasingly important topic during the last few years in acute myeloid leukemia (AML), based on successful immunotherapies in solid cancer. The spectrum ranges from antibody drug conjugates, immune checkpoint inhibitors blocking programmed cell death protein 1 (PD1), cytotoxic T lymphocyte antigen 4 (CTLA4) or T cell immunoglobulin and mucin domain containing-3 (TIM3), to T-cell based monoclonal and bispecific T-cell engager antibodies, chimeric antigen receptor-T-cell (CAR-T) approaches and leukemia vaccines. Currently, there are many substances in development and multiple phase I/II studies are ongoing. These trials will help us to deepen our understanding of the pathogenesis of AML and facilitate the best immunotherapeutic strategy in AML. We discuss here the mode of action of immune-based therapies and provide an overview of the available data.

Head and neck squamous cell carcinoma encompasses a complex and heterogeneous group of malignant diseases. Originally, this tumor type was associated with tobacco and alcohol consumption. However, a significantly expanding subset of tumors associated with oncogenic human papillomavirus infection arising in deep tonsillar crypts was identified within the last decades. Due to the essential role of the immune system in antiviral and anticancer immune response, the prognosis of patients is significantly influenced by the volume, composition and functional capacity of the immune infiltrate. The immunosuppressive landscape of head and neck cancer leads to unfavorable outcome of patients and decreased efficacy of immunotherapy. The response rate to standard treatment is high, however, standard therapy is accompanied by considerable toxicity influencing the quality of life. In 2016, the first immunotherapeutics for the treatment of patients with recurrent squamous cell carcinoma of the head and neck were approved - the anti-PD-1 immune checkpoint inhibitors nivolumab and pembrolizumab. This type of therapy, based on mitigation of immunosuppression, shows strong efficacy and less toxicity in combination with other therapies. Therefore, anti-PD-1 immunotherapy was recently approved in the first-line...

Many studies show the ability of gut microbes to modulate the anti-tumour immune response by direct triggering the immune cells or by bacterial metabolites. Interestingly bacteria may even migrate to the tumour tissue and orchestrate the immune response on site. These anti-tumour effects can be improved by the administration of immune checkpoint inhibitors (ICI). Notably, some microbial effects occur only in the presence of ICI. On the contrary, microbiota may also promote tumour growth and negatively impact the effects of ICI therapy. We have disrupted the gut microbiota homeostasis by antibiotics (ATB) to study the effects of gut microbiota on the ICI. This disturbance led surprisingly to reduced tumour growth and enhanced pro-inflammatory immune response not only in the gut but also within the tumour tissue, where especially IFN-γ orchestrated the anti-tumour immune response. Importantly the anti-tumour immune response could be transferred through colonisation of germ-free mice by ATB-changed gut microbiota if concomitantly anti- programmed cell death protein 1 (αPD-1) monoclonal antibody was administrated. These mice had elevated levels of segmented filamentous bacteria (SFB), which induced systemic immune response with increased expression of IL-17 and elevated amounts of Th 17 cells,...