Discovery and Development of Hyperthermia-Enhanced Treatments for Malignant Skin and Uveal Melanomas

Melanomas are among the deadliest cancers, with a high predisposition to metastasis and a bad prognosis in their late stages. The effectiveness of current therapeutic regimens remains suboptimal, and despite initial successes, treatment resistance emerges in cases of cutaneous malignant melanoma. Furthermore, uveal melanoma poses a significant burden due to its pronounced morbidity post-metastasis, prompting the search for novel treatment paradigms. Thermotherapy is a treatment modality for cancer that aims to heat the tumor up to 43°C and shows promising results when combined with small molecular treatments such as chemotherapeutic drugs. The aim of this work was to develop hyperthermia synergistic treatments for cutaneous malignant melanoma and uveal melanoma. To identify ideal compounds for combination studies with hyperthermia, the repurposing chemical library (RCL) comprising 5440 compounds in advanced development stages or FDA-approved, was tested on the skin melanoma cell line A375 and uveal melanoma cell line Mel202 at 42 °C. Combination studies enabled the identification of synergistic drug combinations for both skin and uveal melanomas using the zero-interaction potential method. Mechanistic investigation including apoptosis assay and EdU incorporation assays of the identified synergistic drug combination Idasanutlin- cytarabine for skin melanoma, showed a dose-dependent induction of apoptosis and inhibition of proliferation for single agents and in combination. In vivo studies on C57BL/6J mice inoculated with the B16F10 revealed a significant difference in tumor area between the combination-treated group and the control, as well as between the cytarabine group and control. The discovery of this synergistic drug combination offers promising prospects for overcoming resistance issues and enhancing treatment efficacy for skin melanoma patients.In parallel, the HTS of the RCL enabled the identification of zinc pyrithione, an antifungal compound displaying a heat-dependent anticancer activity on the uveal melanoma cell line Mel202. Combination studies using the zero-interaction potential method, identified the zinc pyrithione – OSI 027 combination as a promising strategy for uveal melanoma treatment when combined with hyperthermia. The evaluation of the effect of this combination was performed on patient-derived uveal melanoma models. These models were characterized using immunohistochemistry and compound testing confirmed the temperature-dependent effect of zinc pyrithione on the primary uveal melanoma spheroids.Moreover, the effect of hyperthermia on protein expression of Retinoblastoma cells (Y79) was also elucidated in this thesis to identify new therapeutic targets and improve the outcome of thermochemotherapy. We report on the identification of 15 upregulated proteins with a 2-fold increase in their expression after the application of hyperthermia for 15 minutes on Y79 cells. Small molecular inhibitors of these potential targets were tested at 37 °C and 42 °C on the retinoblastoma cell line (Y79) and the human retinal pigment epithelial-1 cell line (RPE1) for efficacy and safety testing. Two HSP90 inhibitors (Alvespimycin and Tanespimycin) and one HSP70 inhibitor (VER-155008) exhibited temperature-independent toxicity on the retinoblastoma cells in the micromolar range, showing the potential of these drugs for the treatment of retinoblastoma.