Adoptive T Cell Therapy for Treatment of Metastatic Melanoma

Malignant melanoma is a common type of solid tumor that causes high cancer-related mortality in young adults of Northern Europe. The incidence of melanoma increases rapidly which renders us a special responsibility to investigate this disease in depth. One recent promising approach to treat malignant melanoma is adoptive cell therapy with tumor-directed autologous T cells. This thesis aims to improve this therapy in four different studies. We first sought to establish a protocol for the assessment of melanoma-specific T-cell cultures in order to screen for optimal specificity and reactivity in a robust, reliable and simple manner. The conclusion was that reactive cells could be found in a majority of patients and could be screened for specificity by stimulation with melanoma cell lines. In the next study, 28 melanoma patients with advanced disease were treated with autologous tumor-infiltrating T cells. Objective responses (18%) including one sustained complete response were observed. This is the first study in cancer patients with autologous T cell transfer combined with low-dose s.c. IL-2 as supportive cytokine. In the following two studies we wanted to improve management and culture conditions of the T cells. When investigating methods for improved handling and preservation of large numbers of T cells, we observed that freeze-thawing of T cells could impair the metabolic activity of the T cells. Another conclusion was that rapid expansion of T cells could lead to loss of antigenic specificity and apoptosis. These adverse effects could be prevented with short time recovery. In order to improve expansion methods, mass expansion of T cells in an automated bioreactor was evaluated. We concluded that the bioreactor is suitable for this task and allows for higher cell densities and absolute cell numbers compared to traditional culturing conditions without influencing cell phenotype or reactivity. Taken together, my current studies present guiding principles and encouragement for the further development of immunotherapies for treatment of patients with malignant melanoma.