Immunotherapy for Uveal Melanoma - Current Knowledge and Perspectives

Uveal melanoma is the most prevalent primary intraocular tumour in adults with the incidence between five and six cases per million people in the United States and Europe. The prognosis of patients with uveal melanoma is unfavourable with a 5-year survival rate of 50-70% despite significant advances in local tumour treatment using radiotherapy or surgical resection. Approximately 50% of the patients develop metastases within 15 years from initial diagnosis, mostly in the liver. The median survival rate after the onset of metastases is 6 months. Potential treatment options for metastatic uveal melanoma are chemotherapy, targeted therapy, and immunotherapy but no method showed satisfactory results. Immunotherapy with checkpoint inhibition showed promising results in the treatment of cutaneous melanoma; however, it did not appear to be equally effective with uveal melanoma. This may be due to differences in mutational burden, expression of neoantigens between these two types of tumour, immunosuppressive tumour microenvironment, and low immunogenicity and immune privilege of uveal melanoma. Considering the disappointing results of treatment with anti-CTLA-4 and PD-1/PD-L1 blockade in patients with advanced uveal melanoma several new forms of therapies are being developed. This may include immunotherapy with IMCgp100, glembatumumab vedotin and the infusion of autologous TILs, targeted therapy with selective MEK inhibitors, epigenetic therapy, and nanotherapy. Better insight into the molecular and genetic profile of uveal melanoma will facilitate detection of new prognostic biomarkers and thus enable a better modification of the existing immunotherapy methods and development of new forms of treatment specifically designed for uveal melanoma patients.