Antibody drug conjugates (ADCs) are emerging as powerful anti-cancer treatments. They are designed to combine the tumor specificity, pharmacokinetics and biodistribution properties of antibodies... Show moreAntibody drug conjugates (ADCs) are emerging as powerful anti-cancer treatments. They are designed to combine the tumor specificity, pharmacokinetics and biodistribution properties of antibodies with the potent cell-killing activity of small molecules. The approval of brentuximab vedotin (Adcetris) for the treatment of Hodgkin lymphoma and trastuzumab emtansine (Kadcyla) for the treatment of metastatic breast cancer has spurred clinical development of ADCs. As the field of ADCs is rapidly emerging, a better understanding of the requirements needed for optimal intracellular delivery of ADCs seems mandatory. The aim of this thesis was to better understand the antibody and antigen requirements that are needed for effective ADC treatment. Different tumor antigens and targeting antibodies were compared for their capacity to deliver a cytotoxic payload to tumor cells, uncovering general mechanisms. In the course of this work, TF was identified as an excellent ADC target because of its rapid internalization and lysosomal targeting characteristics. Furthermore we have explored a novel Ab platform that improves the intracellular delivery of cytotoxic payloads. These findings provide a better insight in the Ab and antigen requirements needed for optimal payload delivery and support the development of novel and further improved ADCs for the treatment of cancer. Show less
Tissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled... Show moreTissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled receptor family, PARs, thus play a role in breast cancer growth and angiogenesis. The switch between signaling and coagulant TF regulated by the oxidation/reduction of an allosteric disulfide bond which resides in TF antigen. A decade ago, it was discovered that TF RNA can be alternatively spliced to form a soluble protein called Alternatively Spliced Tissue Factor (asTF). This protein is non-coagulant. However, it plays a major role in breast cancer growth via inducing cancer cell proliferation. The mechanism lying behind behind this phenomenon is asTF's capability to ligate integrins thus it can initiate integrin signaling. Moreover, both TF and asTF can synergize with estrogen pathway thus providing a complex regulation of breast cancer progression. Show less
Microparticles (MPs) have important physiological and pathological roles in blood coagulation, inflammation and tumor progression. In recent years MPs also have been recognized to participate in... Show moreMicroparticles (MPs) have important physiological and pathological roles in blood coagulation, inflammation and tumor progression. In recent years MPs also have been recognized to participate in important biological processes, such as in signaling and in the horizontal transfer of their specific proteins and mRNAs. However, studies of MPs have been hampered by the lack of methods for the sensitive detection and accurate quantification of MPs. Thus, we have developed a new methodology by using atomic force microscopy (AFM) and cryo-electron microscopy (cryo-EM) to detect, quantify and characterize MPs in plasma. We have shown that AFM detects 1000-fold more platelet derived-MPs than a conventional flow cytometry does. These MPs have diameters ranging from 10-475 nm with a peak at 67.5 nm, which is clearly far below the detection limit of flow cytometry. By using cryo-EM we found that the number of lipoprotein particles exceeds that of MPs or exosomes in plasma. We also demonstrated that by using immuno-magnetic beads selected subset of MPs could directly be captured/depleted from plasma and assessed for MP-associated tissue factor activity. In the future the measurement of MPs will perhaps serve as a diagnostic tool to identify and predict diseases, like cancer. Show less
This thesis elaborates the occurrence of venous thrombosis in cancer patients. Cancer is known to be associated with venous thrombosis with a spectrum of clinical manifestations varying from deep... Show moreThis thesis elaborates the occurrence of venous thrombosis in cancer patients. Cancer is known to be associated with venous thrombosis with a spectrum of clinical manifestations varying from deep vein thrombosis of the leg and pulmonary embolism, recurrent thrombophlebitits saltans et migrans (also called Trousseau__s syndrome) to disseminated intravascular coagulation and arterial embolism. The causes of venous thrombosis can be divided in environmental risk factors such as bed rest, surgery, plaster cast, trauma, long-distance travel, oral contraceptives or pregnancy and puerperium and genetic risk factors such as factor V Leiden and prothrombin 20210A mutation. Various factors may contribute to the development of venous thrombosis in cancer patients, and circulating mucins as well as circulating microparticles which express active TF on their surface may provide a missing link between cancer and thrombosis in (adeno) carcinoma patients. Treatment options include vitamin K antagonists and low-molecular-weight heparins, and the long-term use of these heparins in prevention of venous thrombosis may improve the outcome in comparison with oral anticoagulants. Further research is needed to better understand the morbidity and mortality associated with thrombosis in cancer patients and to optimize strategies of prevention and treatment Show less
