Evaluation of clinical efficacy and tolerability of intravenous high dose thymopentin in advanced melanoma patients.

Thymopentin (TP5) has been recently evaluated as an immunotherapeutic agent for the treatment of cancer. Melanoma is a highly immunogenic malignancy, and in our previous studies the treatment of metastatic melanoma with TP5 showed encouraging results. In the present study, we evaluated the clinical efficacy and tolerability of high dose intravenous TP5 in 16 patients with melanoma which had metastasized to cutaneous and subcutaneous tissue. All patients were given 1 g intravenous TP5 every second day for 7 weeks and were then evaluated; responders were given a subsequent course of 2 g intravenous TP5 every second day for 5 weeks. Six patients showed a partial response after the first course and were given the second course: one patient achieved a complete response, while the other five remained in partial response at the end of the treatment. The mean duration of response was 7.5 months. No drug side effects were observed. Histopathological and immunohistochemical evaluation of regressing metastatic nodules showed the presence of tumour-infiltrating lymphocytes, necrosis, sclerosis, intratumoral vascular proliferation and microthrombosis. Immunophenotyping of lymphoid infiltrates demonstrated the prevalence of CD4+ and CD45RO+ T-lymphocytes in one patient. We conclude that high dose intravenous TP5 three times a week may induce a clinical response in patients with cutaneous and subcutaneous metastases of melanoma without relevant side effects.