Therapy of chronic lymphocytic leukemia and cutaneous T-cell lymphoma with T101 monoclonal antibody.

The findings accompanying the administration of 50 intravenous courses of monoclonal antibody to human T-cell (T101) in eight patients, four with chronic lymphocytic leukemia and four with cutaneous T-cell lymphoma are reported. Infusion rates of 0.7 to 1 mg/min were associated with unacceptable toxicity in the presence of circulating target cells, but slower rates were well-tolerated. Immunofluorescence techniques confirmed that circulating cells did bind the antibody in vivo and were subsequently removed from the circulation. Modulation of the antigen on target cells in the bone marrow and skin has important implications for the schedule of administration of such antibodies, and points out the possible limitation of effector cell-mediated cytotoxicity at the tissue level. Production of anti-mouse antibodies resulted in neutralization of therapy in two patients with cutaneous T-cell lymphoma, and suggests that whether such an anti-mouse response is produced may be secondary to the underlying immune status of the patient or the amount of mouse protein to which immunocompetent cells are exposed. The relative specificity and efficacy of monoclonal antibody therapy is encouraging, but the limited clinical benefit and problems of modulation and anti-mouse antibody production underscore the need for continued research into passive therapy and suggest that cytotoxic conjugates may be of more clinical value.