Ibritumomab Tiuxetan

Brand Name: Zevalin

Ibritumomab tiuxetan is used to treat follicular B-cell non-Hodgkin's lymphoma.1

How Does Ibritumomab Tiuxetan Work?

CD20 dimer on the surface of the cell.

CD20 is a dimeric protein found on the surface of B cell, a type of immune cell.2 The precise biological role of CD20 is not fully understood, but it may be required for optimal immune function.3

Non-B cell surface with a single CD20, followed by B cell and lymphoma cell surface with numerous CD20.

In general, non-B cells express little to no CD20 on their surface.2 On the other hand, B cells and some types of lymphoma express large amounts of CD20 on their surface, which provides a target to specifically recognize and kill these cancer cells.4

Ibritumomab tiuxetan binds to CD20 on the surface of the cell. The chelator on the drug catches the radioactive isotope Yttrium-90.

Ibritumomab tiuxetan is a drug based on an antibody that can specifically bind to CD20. Attached to this antibody is a chelator called MX-DTPA, which can chelate or "catch" radioactive isotope Yttrium-90 that is administered alongside ibritumomab tiuxetan.4 Because the radioactive isotope is targeted towards cells expressing the highest amounts of CD20, i.e. the lymphoma cells, these cells are most effectively killed by the radioactivity, while most other cells are spared.

References

1. ZEVALIN. U.S. Food and Drug Administration (2018).

2. Stashenko, P., Nadler, L. M., Hardy, R. & Schlossman, S. F. Characterization of a human B lymphocyte-specific antigen. The Journal of Immunology 125, 1678-1685 (1980).

3. Pavlasova, G. & Mraz, M. The regulation and function of CD20: an “enigma” of B-cell biology and targeted therapy. Haematologica 105, 1494-1506 (2020).

4. Press, O. W. et al. Monoclonal Antibody 1F5 (Anti-CD20) Serotherapy of Human B Cell Lymphomas. Blood 69, 584-591 (1987).

5. Witzig, T. E. et al. Randomized Controlled Trial of Yttrium-90-Labeled Ibritumomab Tiuxetan Radioimmunotherapy Versus Rituximab Immunotherapy for Patients With Relapsed or Refractory Low-Grade, Follicular, or Transformed B-Cell Non-Hodgkin's Lymphoma. Journal of Clinical Oncology 20, 2453-2463 (2002).