[Therapy of malignant melanoma at the stage of distant metastasis]

Systemic therapy of non-resectable metastatic melanoma

In advanced metastatic melanoma (non-resectable stage III/IV), the prognosis still remains poor, with median survival times between six and twelve months. Systemic therapeutic approaches for metastatic melanoma include chemotherapy, immunotherapy, immunochemotherapy, small molecules and targeted therapy. In this review, we will focus on the various treatment modalities as well as new agents used for targeted therapy.

[Experimental treatment of malignant melanoma and its rationale]

To treat malignant melanoma successfully currently means to recognize the tumor at an early stage and to remove it immediately. Aside from individual cases, available treatment modalities are not able to increase survival, especially in the palliative situation. Thus innovative experimental approaches are urgently needed to strongly improve the palliative and adjuvant treatment of melanoma. Anti-tumor effects are expected from targeted therapies, which are directed against defined molecules decisive for tumor pathogenesis. Crucial points of attack are signaling pathways, angiogenesis and apoptosis resistance. New diagnostic and therapeutic developments have enhanced the efficacy of chemotherapies. Increasing insights into tumor immunology provide new treatment approaches of vaccination, cell transfer and especially of blocking immune tolerance mechanisms. It will be challenging for the future to identify and characterize more precisely those patients who might most benefit from a certain treatment approach.

Low expression of CD161 and NKG2D activating NK receptor is associated with impaired NK cell cytotoxicity in metastatic melanoma patients

Natural killer (NK) cells play a role in the innate and adaptive antitumor immune responses. The activity of NK cells is regulated by functionally opposing, activating and inhibitory receptors whose balance ultimately determines whether target cells will be susceptible to NK cell mediated lysis. As melanoma is an immunogenic tumor, the effect of immunomodulating agents is consistently investigated. In this study in 79 metastatic melanoma (MM) patients and 52 controls NK activity, expression of activating NKG2D and CD161 receptors and KIR receptors, CD158a and CD158b, on freshly isolated PBL and NK cells were evaluated. Native NK cell activity of melanoma patients in clinical stage I-III and MM patients was determined against NK sensitive K562, NK resistant Daudi, human melanoma FemX, HeLa and HL 60 target tumor cell lines. In addition, predictive pretherapy immunomodulating effect after 18 h in vitro treatments of PBL of MM patients with rh IL-2, IFN-alpha (IFN), 13-cis retinoic acid (RA) and combination IFN-alpha and RA was evaluated with respect to NK cell lyses against K562 and FemX cell lines. In this study we show for the first time that low expression of CD161 and activating NKG2D receptors, without increased expression of KIR receptors CD158a and CD158b, as well as a decrease in the cytotoxic, CD16(bright) NK cell subset, is associated with a significant impairment in NK cell activity in MM patients. Furthermore, the predictive pretherapy finding that IL-2, IFN, IFN and RA, unlike RA alone, can enhance NK cell activity of MM patients against FemX melanoma tumor cell line can be of help in the design and development of therapeutic regimens, considering that it has recently been shown that low-dose combination of different immunomodulators represents the most promising approach in the therapy of MM.

Therapie des metastasierten Melanoms

The incidence of malignant melanoma is steadily increasing worldwide. The most crucial requirement to cure the disease is early detection of thin primary tumors. At the stage of distant metastases, the treatment options are predominantly palliative. Resection of localized metastases is currently the most effective approach. Dacarbazine is considered as standard chemotherapy for inoperable metastatic disease showing remission rates of 5-20% without any noteworthy effect on overall survival. Quite recently, a large spectrum of innovative treatment approaches have been developed from an increasing insight into tumor biology. Along with improved vaccination strategies, targeted therapies have attracted the most attention in the treatment of advanced melanoma. Those anti-proliferative, anti-angiogenic and proapoptotic agents are directed against pathogenetically important pathways of the tumor cell. First clinical experiences are encouraging, but results from controlled trials have to be awaited.

[Role of MHC class I molecules in anti-tumoral mechanisms in human malignant melanoma]

Malignant melanoma is still the most frequent cause of death due to skin cancer with a rising incidence and mortality. Despite continued progress in understanding the pathophysiology of tumor progression and metastasis, curative therapeutic options are still missing for metastatic melanoma. The ability of a malignant melanoma to metastasize is partially derived from the capacity to avoid destruction by an intact immune system. Thus, a better understanding of the immunological processes that lead to the escape of melanoma cells from immune recognition could help to develop preventive strategies or effective new therapies. Therefore, an analysis of the MHC class I pathway and molecules involved in peptide loading of the MHC class I molecules could provide an important clue to future immune-based melanoma therapies, and might also help to select patients who could be expected to profit from T-cell-based immunotherapy. In this review article, we report on current data and concepts about the generation of MHC class I peptide complexes in human malignant melanoma.