Changes of the blood lymphocyte population in cancer patients treated with bestatin, a new immunomodulator. A phase I study.

Twenty one patients with advanced metastatic cancer of various types received 30 mg of Bestatin daily per os as a single treatment for several weeks. It was observed that the blood lymphocyte counts remained unchanged but the frequency of SRBC rosette forming cells increased and the frequency of lymphocytes possessing receptors for the Fc-part of IgG became normalized after two weeks of treatment. The frequency of lymphocytes possessing receptors for C'3 was not changed. The natural killer activity of peripheral lymphocytes for K562 and Chang cells increased but the PPD stimulation of the lymphocytes was not altered. A slight, but significant increase of the PHA stimulation of lymphocytes was observed after 4-7 weeks of Bestatin treatment. It is concluded that Bestatin is a nontoxic drug which changes the cellular composition as well as certain immunological functions of human lymphocytes.