Efficacy of astatine-211-labeled monoclonal antibody in treatment of murine T-cell lymphoma.

The short-lived isotope 211At (half-life, 7.2 hr), an alpha particle-emitting halogen, has been attached to a monoclonal antibody (anti-thy 1.1, IgG1, OX7) and used in mice in the treatment of a thy 1.1 T-cell lymphoma (A120). Forty-eight hours after receiving an iv injection of 10(3) or 10(5) A120 cells, mice were treated with phosphate-buffered saline, 211At-, antibody alone, or 211At conjugated to OX7. Treatment with the 211At-labeled OX7 conjugate increased the median survival time of mice and probably "cured" (survival at 200 days) 6 of the 15 mice given 10(5) cells and 21 of the 27 mice given 10(3) cells.