On the biological relevance of MHC class II and B7 expression by tumour cells in melanoma metastases.

A large number of studies have indicated that specific immune reactivity plays a crucial role in the control of malignant melanoma. In this context, expression of MHC I, MHC II and B7 molecules by melanoma cells is seen as relevant for the immune response against the tumour. For a better understanding of the biological relevance of MHC II and B7 expression by tumour cells in metastatic melanoma, we studied the expression of these molecules in melanoma metastases in relation to the inflammatory response, regression of the tumour and survival from 27 patients treated with biochemotherapy (30 mg m(-2) Cisplatin and 250 mg m(-2) decarbazine (dimethyl-triazene-imidazole-carboxamide, DTIC) on days 1-3 i.v., and 10(7) IU IFN-alpha 2b 3 days a week s.c., q. 28d). In 19 out of 27 lesions studied, we found expression of MHC II by the tumour cells, while only in one out of 11 tumour biopsies obtained from untreated metastatic melanoma patients, MHC II expression was detected. Expression of B7.1 and B7.2 by tumour cells was found in nine out of 24 and 19 out of 24 lesions, respectively. In all cases where B7.1 expression was found, expression of B7.2 by the tumour cells was also seen. In general, no or only few inflammatory cells positive for B7 were found. Expression of MHC II by tumour cells was positively correlated with the presence of tumour-infiltrating lymphocytes, regression of the lesion, and with time to progression (TTP) and overall survival (OS) of the patient. However, no significant correlation between B7.1 or B7.2 expression and regression of the tumour, TTP or OS was found. In light of other recent findings, these data altogether do support a role as biomarker for MHC II expression by tumour cells; however, its exact immunological pathomechanism(s) remain to be established.

Biochemotherapy of metastatic malignant melanoma. Predictive value of tumour-infiltrating lymphocytes.

The therapeutic efficacy of biochemotherapy in metastatic malignant melanoma still carries a low remission rate, but with some durable responses. It would therefore be of considerable importance if patients with a high probability of responding could be identified using predictive tests. The response to interferon-alpha (IFN-alpha) correlates with the occurrence of CD4(+) lymphocytes identified by fine-needle aspirates from melanoma metastases (Håkansson et al, 1996). The present investigation studies a possible correlation between tumour-infiltrating CD4(+) lymphocytes in malignant melanoma metastases and the therapeutic effect of biochemotherapy. A total of 25 patients with systemic and 16 with regional metastatic melanoma were analysed before initiation of biochemotherapy (cis-platinum 30 mg/m(2) d.1-3, DTIC 250 mg/m(2) d.1-3 i.v. and IFN-alpha 2 b 10 million IU s.c. 3 days a week, q. 28d.). A monoclonal antibody, anti-CD4, was used to identify tumour-infiltrating lymphocytes in fine-needle aspirates before start of treatment. The presence of these lymphocytes was correlated to response, time to progression and overall survival. A statistically significant correlation (P = 0.01) was found between the occurrence of CD4(+) lymphocytes and tumour regression during biochemotherapy in patients with systemic disease. Out of 14 patients with moderate to high numbers of infiltrating CD4(+) lymphocytes, 12 achieved tumour regression. In contrast, among patients with low numbers of these cells in metastatic lesions, 8 out of 11 had progressive disease. We also found a significantly longer time to progression (P < 0.003) and overall survival (P < 0.01) among patients with moderate to high numbers of these cells compared to patients with low numbers of these cells before initiation of biochemotherapy. Furthermore, in patients with regional disease, we found a significantly longer time to progression (P = 0.01) and a trend toward a longer overall survival time (P = 0.09). Based on these results and as previously shown with IFN-alpha therapy alone, there seems to be a need for CD4(+) lymphocytes infiltrating the tumours before the start of biochemotherapy to make the treatment successful. Determination of these cells in fine-needle aspirates seems to be a method to predict responders to biochemotherapy, thus increasing the cost-benefit of this treatment strategy considerably, both in terms of patient adverse reactions and health care costs.

On down-regulation of the immune response to metastatic malignant melanoma.

Treatment of metastatic malignant melanoma with interferon alpha (IFNalpha) results in objective remission in approximately 15% of patients. In a previous investigation, we found that about 50% of the patients achieved at least minor or short-lived remissions. In some tumours extensive areas of regressive tumour change occurred. However, even in these areas remnants of tumour cells were generally found. The short duration of the immune response in some patients and the incomplete eradication of the tumour can be due either to selection of non-immunogenic tumour cells or to down-regulation of the immune reactivity to the tumour. In the present paper, the expression of the zeta chain of the T cell receptor in CD3+ lymphocytes and the expression of CD28 in CD3+, CD4+ and CD8+ lymphocytes was studied in resectable melanoma metastases from 20 treated (IFNalpha or IFNalpha in combination with cisplatinum and dacarbazine) and 16 untreated patients. A double-staining technique was used, and the occurrence and distribution of lymphocytes showing down-regulation of the zeta chain or CD28 were separately registered in different areas of the metastases: close to the tumour cells in areas of unaffected tumour growth, in areas with regressive tumour changes, in areas with marked fibrosis and in stromal areas with densely packed lymphocytes. CD3+ zeta lymphocytes were found in all metastases, but their number and distribution varied considerably. Down-regulation of the zeta chain was most often found in areas of regressive changes. In contrast, T lymphocytes infiltrating close to the tumour cells had a stronger expression of the zeta chain (P = 0.016). Down-regulation was also found in stromal areas of densely packed lymphocytes and in areas of fibrosis. The pattern of down-regulation of CD28 in various subsets of lymphocytes was similar to that of zeta chain. The same pattern of down-regulation of CD28 and the zeta chain was found in both untreated and treated patients, indicating that the down-regulation is not due to treatment but to the release of immunosuppressor factors from areas with high tumour cell density or extensive destruction of tumour cells. These results concur well with the view that IFNalpha treatment can result in immune-mediated tumour cell destruction early in the treatment period and that this immune response to the tumour can be followed by immunosuppression within a few weeks.

Expression of ICAM-1 during IFN-alpha-based treatment of metastatic malignant melanoma: relation to tumor-infiltrating mononuclear cells and regressive tumor changes.

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in cell to cell interactions. In malignant melanoma, ICAM-1 expression correlates with malignant behavior. We used monoclonal antibodies, anti-ICAM-1, anti-CD4+, anti-CD8+, and anti-CD11c+ to study the effect of interferon-alpha (IFN-alpha) on the expression of ICAM-1 by melanoma cells in regional metastases and its correlation to the occurrence of CD4+, CD8+, and CD11c+ cells close to tumor cells and in the tumor stroma. We also estimated the expression of ICAM-1 and regressive changes in malignant melanoma metastases, correlating the duration of treatment to these effects of IFN-alpha. Twenty-three IFN-alpha-treated and 10 untreated patients with regional metastatic malignant melanoma were studied. The duration of IFN-alpha treatment influenced the expression of ICAM-1. In metastases from patients treated for 1 week only, 1 of 5 showed high expression of ICAM-1 compared with 6 of 11 of those treated for 3 weeks (p = 0.01, chi-square test for trend comparing untreated patients and patients with various durations of IFN-alpha treatment). In IFN-alpha-treated patients with low expression of ICAM-1, none of 7 metastases showed CD4+ cells infiltrating close to tumor cells, in contrast to 6 of 10 metastases expressing high amounts of ICAM-1 (p = 0.03). Similarly, the expression of ICAM-1 was found to correlate with the occurrence of CD8+ cells close to the tumor cells (p = 0.04). We also showed a correlation between ICAM-1 expression and histologic evidence of tumor regression (p = 0.02).