Cure of xenografted human tumors by bispecific monoclonal antibodies and human T cells.

Tumor immunotherapy should increase both the number of T cells that kill the tumor and the likelihood that those cells are activated at the tumor site. Bispecific monoclonal antibodies (Bi-mAbs) were designed that bound to a Hodgkin's tumor-associated antigen (CD30) on the tumor and to either CD3 or CD28 on the T cell. Immunodeficient mice were cured of established human tumors when mice were treated with both the CD3-CD30 and the CD28-CD30 Bi-mAbs and then given human peripheral blood lymphocytes that had been incubated with the CD3-CD30 Bi-mAb and cells that expressed CD30. The enrichment of human T cells within the tumor and the fact that established tumors can be cured may indicate in situ activation of both the T cell receptor and the costimulatory pathway.