Image by Lance Liotta
The US Food and Drug Administration (FDA) has granted orphan designation for the radioimmunoconjugate Iomab-B to be used as a conditioning agent for patients with relapsed or refractory acute myeloid leukemia (AML) who are undergoing hematopoietic stem cell transplant (HSCT).
Iomab-B is a radioimmunoconjugate consisting of BC8, a novel murine monoclonal antibody, and the radioisotope iodine-131.
BC8 targets CD45, a pan-leukocytic antigen widely expressed on white blood cells. This makes BC8 potentially useful in targeting white blood cells in preparation for HSCT.
When labeled with radioactive isotopes, BC8 carries radioactivity directly to the site of cancerous growth and bone marrow, while avoiding the effects of radiation on most healthy tissues, according to Actinium Pharmaceuticals, Inc., the company developing Iomab-B.
Actinium said Iomab-B has been tested as a myeloconditioning/myeloablative agent in more than 250 patients with incurable hematologic malignancies.
The company has released data from a phase 1/2 trial of Iomab-B in patients with relapsed/refractory AML who are older than 50.
The data show that patients who received Iomab-B before HSCT (n=27) had higher rates of survival at 1 and 2 years than patients who underwent HSCT with conventional myeloablative conditioning (n=10) or chemotherapy (n=61).
One-year survival rates were 30% in the Iomab-B arm and 10% each in the conventional conditioning and chemotherapy arms. Two-year survival rates were 19%, 0%, and 0%, respectively.
Now, Actinium is planning a phase 3 trial of Iomab-B in relapsed/refractory AML patients over the age of 55.
About orphan designation
The FDA grants orphan designation to drugs intended to treat diseases or conditions affecting fewer than 200,000 patients in the US.
The designation provides the drug’s sponsor with various development incentives, including opportunities to apply for research-related tax credits and grant funding, assistance in designing clinical trials, and 7 years of US market exclusivity if the drug is approved.
