Strategies to enhance immunotherapy efficacy in HPV-related gynecologic (pre-)malignancies

The results of the studies presented in this thesis, indicate that there is room for improvement in terms of immunotherapeutic intervention in vulvar and cervical cancer. It is encouraging that in cervical cancer, TDLN-targeted ICI can be easily and safely applied in the neo-adjuvant setting by local delivery. Future studies will have to prove whether this strategy triggers effective anti-tumor immune responses, and if metastatic spread or recurrent disease is prevented. Only application of anti-PD-(L)1 might not be sufficient, and combinations of ICI may be more effective. Stratification of the histological subtypes AC and SCC in trials investigating ICI should be taken into consideration, as distinct immune microenvironments and immune escape mechanisms have been observed. To predict responses to immunotherapy, PD-L1 expression as assessed by immunohistochemistry is used as selection criterion for pembrolizumab treatment in cervical cancer patients. However, even in this preselected group, many patients do not respond to therapy. We have to improve our understanding of immune-escape mechanisms and resistance to therapy, in order to find markers that are relevant in predicting responses and inform new therapeutic strategies. For the studies presented in this thesis, we used the more conventional immune-monitoring techniques, such as multiplex immunohistochemistry and advanced flow cytometry. However, the developments in immune-profiling techniques and bioinformatic platforms are advancing rapidly. In the future, state of the art high-dimensional techniques such as single-cell RNA-Seq (scRNA-Seq), cytometry by time of flight (CyTOF) and spatially resolved RNA transcriptomics and protein expression patterns should be applied for biomarker discovery. In this way, the depth and dimensionality of immune-profiling in HPV-related vulvar and cervical cancer can be improved greatly, hopefully leading to improved predictors of clinical outcomes for patients receiving immunotherapy as well as novel therapeutic options. Since immune-escape mechanisms at play in the tumor microenvironment are compounded and become more complex with progression of disease, early interventions should be considered. Already in the premalignant setting, overcoming early immune escape could prevent progression to full-blown malignancy. Since prophylactic HPV vaccines have no effect in established HPV-infections, it is important to develop effective therapeutic vaccination strategies. Promising responses were observed with the DNA tattoo vaccination technique in patients presenting with uVIN. Future studies should point out whether this is applicable for premalignancies of other entities related to oncogenic HPV-infection, such as AIN, VAIN and CIN, in order to prevent many future cases of anal, vaginal and cervical cancer as well. Also here combinations with local immune modulation could further increase clinical efficacy, while minimizing side effects which would be unacceptable in these premalignant stages