This thesis aims to improve the treatment of patients with stage III melanoma. The first part describes different aspects of treatment with Talimogene Laherparepvec (T-VEC), a genetically modified... Show moreThis thesis aims to improve the treatment of patients with stage III melanoma. The first part describes different aspects of treatment with Talimogene Laherparepvec (T-VEC), a genetically modified herpes virus, which is used as oncolytic immunotherapy for skin and lymph node metastases in melanoma patients. We show that patients with a low tumor burden have the best outcomes, suggesting T-VEC should be used earlier on in the course of the disease. We present a prediction model, allowing a more accurate selection of patients for T-VEC monotherapy. Two studies focused on the use of T-VEC in clinical practice and the results allowed us to make recommendations on the use of PET/CT and dermoscopy during T-VEC treatment. Part two focuses on the value of surveillance and screening imaging in high-risk melanoma patients. We show that FDG-PET/CT is a valuable imaging tool to detect recurrence after complete resection of stage III disease, even shortly after surgery (before starting adjuvant therapy). Finally, we conclude that nodal staging with US as adjunct to SLNB is useful in the work- up of stage IIB/C melanoma, as it can lead to alterations in treatment and prevent unnecessary surgery. Show less
Oncolytic reovirus has the natural preference to kill transformed cells while sparing normal cells. Its administration has been shown to be safe in clinical trials, but the anti-cancer efficacy... Show moreOncolytic reovirus has the natural preference to kill transformed cells while sparing normal cells. Its administration has been shown to be safe in clinical trials, but the anti-cancer efficacy remains to be improved. In this thesis, we discuss several aspects that are important for the design of a potent anti-cancer therapeutic strategy using reovirus. We explored which cellular factors and pathways are important for efficient reovirus replication. Furthermore, we genetically modified the reovirus genome to encode potentially therapeutic transgenes. We tested the potency of these recombinant reoviruses, and describe what we believe is the most promising strategy to move forward. Moreover, we discuss the stability issues that we encountered during the generation of recombinant reoviruses. Finally, we discuss the various challenges and opportunities in how to proceed. Show less
The Reoviridae are a family of viruses with a non-enveloped icosahedral capsid and a segmented double-stranded RNA genome. Prototypes of the mammalian Orthoreoviruses have been isolated from human... Show moreThe Reoviridae are a family of viruses with a non-enveloped icosahedral capsid and a segmented double-stranded RNA genome. Prototypes of the mammalian Orthoreoviruses have been isolated from human respiratory and enteric tracts and are not associated with human disease. One of these, human reovirus type 3 Dearing (T3D), usually serves as a model for the family. In the last decade the mammalian Orthoreoviruses, especially T3D, have been evaluated as oncolytic agents in experimental cancer therapy. This is based on the observation that reoviruses induce cell death in tumor cells, but not in healthy non-transformed cells. Cancer cells have developed all kinds of strategies to escape control of normal regulators in tissue. If the strategy involves evading cell death pathways on which the reovirus relies on for replication or if the expression of the canonical receptor is diminished, the effect of the therapy is severely reduced. To boost the oncolytic potency of reoviruses in tumor cells that resist reovirus infection and replication, we used two strategies; 1) a bioselection procedure to select for reoviurses that can replicate in cells lacking the receptor and 2) genetic modification to insert small transgenes in one of the reovirus dsRNA segments (S1). Show less
Recombinant viral vectors hold great promise in the field of cancer gene therapy. While a plethora of viruses is being evaluated as oncolytic agents, human adenoviruses of serotype 5 (HAdV-5) are... Show moreRecombinant viral vectors hold great promise in the field of cancer gene therapy. While a plethora of viruses is being evaluated as oncolytic agents, human adenoviruses of serotype 5 (HAdV-5) are among the most popular of viruses to be developed. Although clinical studies have demonstrated safety of cancer gene therapy with HAdV-5-derived vectors, the efficacy still needs further enhancement. Several factors have been identified that limit the anti-tumor efficacy. One major bottleneck is the inadequate penetration and spread of the virus within the tumor. This is attributable, at least in part, to the low or heterogeneous expression of the coxsackie and adenovirus receptor (CAR) on the tumor cells. This thesis describes the development and preclinical evaluation of novel tumor-targeted HAdV-5 vectors, through implementing the genetic fusion of capsid proteins (protein IX and fiber) with a variety of tumor-targetin g polypeptides. Show less
