213Bi-Lintuzumab (213Bi-Bismab-A™, 213Bi-CHX-A’’-DTPA-huM195) is an anti-CD33 humanized antibody huM195 labeled with 213Bi that was under development for the treatment of patients with acute myeloid leukemia (AML). Lintuzumab is the name of the chimeric monoclonal antibody M195 targeting CD33. CD33 is a myeloid-specific transmembrane receptor expressed on cells of myeloid lineage. In some rare cases it can also be found on some lymphoid cells.

The first clinical trial with 213Bi-CHX-A”-DTPA-huM195 was also the first trial ever in humans with a conjugated Alpha emitter. These trials were conducted at Memorial Sloan Kettering Cancer Center (MSKCC), New York NY, and were started as early as 1996. Recruitment included patients with AML over the age of 60 and ineligible for other treatments, as well as patients with relapsed or refractory AML. Further trials against AML demonstrated complete responses in patients whose tumor burden had been previously reduced by cytarabine. The responses in this very high-risk population lasted up to 12 months.

213Bi-Bismab-A™ has been administered to almost 50 patients to date. Therapeutic dose has been established at about 1–1.25 mCi/kg (about 70–90 mCi/patient) and results show that the product has maintained a low side-effect profile and clear indications of efficacy.

This product is on hold and has been replaced by the analogue compound labeled with 225Ac, 225Ac-Lintuzumab (Actimab-A).

Target/Mechanism: CD33

Leading Emitter: Alpha particle (α)