90Y-labeled humanized anti-Tac (90Y-HAT, 90Y-Daclizumab) is a radiolabeled monoclonal antibody developed as a potential iv treatment of adult T-cell leukemia/lymphoma, lymphoid leukemia and non-Hodgkin’s lymphoma. The product is not commercially supported and must be considered as a generic.

90Y-HAT is based on the drug Daclizumab (Zenapax®), a humanized murine monoclonal antibody that binds to CD25 (Interleukin-2). Daclizumab was chemically modified to allow binding with 90Y. Patients with leukemia are treated with doses of about 15–20 mCi and MTD of 90Y-HAT was evaluated at 25 mCi. T

The first Phase I/II trial was performed between 1997 and 2003 in the indication adult T-cell leukemia. Two other trials were performed with NHL and lymphoid leukemia patients. A Phase I/II trial to assess the efficacy of 90Y-HAT in combination with standard treatment in relapsed or refractory Hodgkin’s lymphoma patients was started in October 2011 and should be completed by 2021. In absence of industrial support, this drug must be considered on hold.

Target/Mechanism: CD25 (Interleukin-2)

Leading Emitter: beta electrons (β–)