Mitoxantrone as a Single Agent in Pretreated Metastatic Breast Cancer: Effects on T Lymphocyte Subsets and Their Relation to Clinical Response

Abstract

Mitoxantrone (DHAD), an anthracenedione with antineoplastic properties similar to doxorubicin, was tested for therapeutic efficacy and for immunomodulating action on lymphocyte subsets in 16 metastatic breast cancer patients, 12 of whom had been previously treated with chemotherapy. DHAD was given intravenously at a dose of 14 mg/m¹ every 21 days. To evaluate total T lymphocytes (CD3), T helper (CD4), and T suppressor/cytotoxic cells (CD8) and the CD4/CD8 ratio, venous blood samples were drawn before and after the first DHAD cycle. Moreover, in 8/16 patients, B lymphocytes (CD20), T suppressor cells (CD8/CD57), T cytotoxic cells (CD8/CD57), NK (CD16) and IL-2 receptor-expressing cells (CD25) were also measured at the same time. An objective tumor response was achieved in 5/16 (31 %) patients and the response rate was significantly higher in patients pretreated with hormone therapy alone than in those pretreated with chemotherapy. No relation was found between clinical response and changes in the CD4/CD8 ratio. Neither the mean number nor the percentage of CD3, CDA and CD8 cells observed after DHAD were significantly different with respect to those seen before. In contrast, the mean number of T suppressor cells, B lymphocytes and CD25-positive cells was significantly lower after than before DHAD administration, whereas no difference was seen in NK cells. These results confirm in humans the immunomodulating properties of DHAD previously described in experimental conditions. However, the DHAD-induced changes in lymphocyte subsets do not seem to be related to the clinical response in breast cancer.