BIOLOGICAL-ACTIVITY AND CLINICAL EFFICACY OF INTRAVENOUS HIGH-DOSE THYMOPENTIN IN METASTATIC MELANOMA PATIENTS

Eight patients with cutaneous metastatic melanoma were submitted to hi gh-dose intravenous thymopentin (TP5) treatment for 5 weeks: three pat ients received 1 g three times a week, three received 1 g daily and tw o received 2 g daily. Four out of eight patients presented a partial r esponse of cutaneous lesions lasting for 1-7 months, and six remain al ive with evidence of disease after a follow-up of 2-7 months. A remark able histologic observation is the presence of tumour necrosis, which was seen as both single cells and large confluent areas. The majority of lymphoid cells present in the tumour are CD45RO(+) and CD4(+). The CD4(+) cells might play an important role in the anti-tumour immune lo cal response by secreting cytokines and inducing apoptotic and necroti c cell death. This hypothesis seems to be confirmed by the presence of a high number of CD4(+) cells around intratumoral vessels, while the presence of endovascular micro-thrombosis provides indirect evidence o f cytokine activity. Cellular lysis may be produced by the activity of both CD8(+) and CD4(+) lymphoid cells. The role of TP5 may be an acti vation of CD4(+) and CD8(+) lymphoid cells. Clinical and pathological data indicate that TP5 is able to produce consistent clinical and immu nological effects in melanoma patients with cutaneous metastases.