Frequent HLA class I alterations in human prostate cancer: molecular mechanisms and clinical relevance.

Reduced expression of HLA class I is an important immune escape mechanism from cytotoxic T cells described in various types of malignancy. It often correlates with poor prognosis and resistance to therapy. However, current knowledge about the frequency, underlying molecular mechanisms, and prognostic value of HLA class I and II alterations in prostate cancer (PC) is limited.

Immune escape of cancer cells with beta2-microglobulin loss over the course of metastatic melanoma.

Cancer cells escape T-cell-mediated destruction by losing human leukocyte antigen (HLA) class I expression via various mechanisms, including loss of beta2-microglobulin (β2m). Our study illustrates the immune escape of HLA class I-negative tumor cells and chronological sequence of appearance of tumor β2m gene mutation in successive lesions obtained from a patient with metastatic melanoma. We observed a gradual decrease in HLA expression in consecutive lesions with few HLA-negative nodules in the primary tumor and the emergence of a totally negative lesion at later stages of the disease.