Melanoma: Saleh FH

Saleh FH, Crotty KA, Hersey P, Menzies SW. · Sydney Melanoma Unit, Melanoma and Skin Cancer Research Institute, Department of Surgery, University of Sydney at Royal Prince Alfred Hospital, Camperdown, Australia. · Int J Cancer. · Pubmed #11745443 No free full text.

Abstract: A prediction of the theory of immunologic surveillance is that tumour antigens can be recognised by cell-mediated immunity during early development of the primary tumour by formation of tumour antigen-specific cytotoxic lymphocytes (CTLs) and that such recognition leads to destruction of those tumour cells (tumour regression) with subsequent appearance of tumour antigen-loss variants. However, this has never been shown in nonviral-induced experimental animal models of primary malignancy or in human primary cancer. We examined 2 groups of human melanoma patients where primary tumour regression was observed. Twenty-three patients with multiple (>/=3) primary melanoma showed significant histologic regression of their last tumour (median tumour regression 33%) compared to matched tumours from patients with a single primary melanoma (median 0%) (p = 0.008) or compared to their first primary tumour (median 0%) (p = 0.001). This increased regression is consistent with an "immunisation effect" seen in murine tumour transplantation studies where innoculation with >/=3 asynchronous tumours induces transplantation rejection on subsequent challenge. A significant decrease in MART-1-positive stained tumour area in the last primary tumour from multiple melanoma subjects (median 8%) vs. matched single melanoma patients (median 79%) (p = 0.004) and in the last vs. first tumour (median 76%) in multiple primary subjects was found (p = 0.008). Metastatic tumours from 17 patients whose primary skin melanomas had completely regressed (occult primary melanoma) also showed significant MART-1 tumour-loss variants (median 0% MART-1-positive tumour) compared to matched metastatic tumours from patients with nonregressing primary tumours (median 51%) (p = 0.001). A correlation with the presence of peripheral blood MART-1-specific CTLs (MHC class I-restricted IFN-gamma producing T lymphocytes) and MART-1 tumour antigen-loss variants was found (p = 0.001). Thus, in 2 groups of human melanoma subjects, we provide evidence of tumour regression associated with Melan A/MART-1 tumour antigen-loss variants correlating with formation of specific Melan A/MART-1 CTLs.

Saleh FH, Crotty KA, Hersey P, Menzies SW, Rahman W. · Department of Human Morphology, Faculty of Medicine, The American University of Beirut, PO Box 11-0236, Beirut, Lebanon. FaridS l · J Pathol. · Pubmed #12845635 No free full text.

Abstract: Spontaneous histopathological regression of cancer has been reported. The involvement of the immune system in such regression has been advocated, leading to the theory of immunological surveillance against cancer. A prediction of this theory is that common tumour antigens can be recognized upon repeated exposure by cell-mediated immunity, which leads to tumour regression and the subsequent appearance of tumour antigen-loss variants. However, no direct evidence has been provided in non-viral-induced experimental animal models of primary malignancy or in human primary cancer. This study examined two groups of melanoma patients where histopathological regression of the primary tumour was observed. Many of the 23 patients with multiple (> or =3) primary melanomas showed significant regression of their last melanoma (median 33%, mean 40) compared with matched melanomas from patients with a single primary melanoma (median 0%, mean 12) (p=0.0080), or compared with their first primary melanoma (p=0.0013). Regression was consistent with an 'immunization effect' seen in murine tumour transplantation studies, where inoculation with > or =3 asynchronous tumours induces transplantation rejection on subsequent challenge. A significant decrease in the expression of the melanoma common tumour antigen MART-1 in the last primary tumour from multiple melanoma patients (median 8%, mean 24) versus matched single melanoma patients (median 79%, mean 68) (p=0.0041) and in the last versus first tumour in multiple primary patients was found (p=0.0083). Metastases from 17 patients whose primary skin melanomas had completely regressed (occult primary melanoma) also showed significant MART-1 loss (median 0%, mean 11) compared with matched metastases from patients with non-regressing primary melanoma (median 51%, mean 50) (p=0.0013). MART-1 antigen-loss variants observed in the multiple primary and occult primary patients correlated with the presence of peripheral blood MART-1-specific cytotoxic T lymphocytes (CTLs) (p=0.03). No similar effects were observed with two other melanoma antigens, gp100 and CD63. Thus, in two groups of human melanoma patients, evidence is provided for histopathological tumour regression associated with cancer immune surveillance.