According to an article recently published in the journal Cancer, standard radiation therapy provides high anticancer response rates among patients with non-Hodgkin’s lymphoma that has recurred or progressed following treatment with Zevalin®.
Non-Hodgkin’s lymphoma (NHL) is a form of cancer that begins in the cells of the lymph system (the spleen, thymus, tonsils, bone marrow, lymph nodes, and circulating immune cells). Lymphocytes are the main cells in the lymph system and exist in two forms: B and T-cells. Each of these cells serves a specific function in helping the body fight infection.
In NHL an excessive amount of atypical (cancerous) lymphocytes accumulates in the lymph system. These lymphocytes can crowd and suppress the formation and function of other immune and blood cells.
Non-Hodgkin’s lymphoma is categorized by the type of lymphocyte it involves and further defined by the rate at which the cancer grows. The appearance of the cells under a microscope indicates the growth rate. High-grade or aggressive NHL is the fastest growing, whereas low-grade or indolent lymphoma develops slowest. Advanced mantle cell lymphoma is often considered difficult to effectively treat. Follicular NHL is a slow-growing cancer.
Zevalin is a biologic agent that is used for treatment of patients with low-grade NHL who have received prior therapy.
- Zevalin is comprised of ibritumomab, a monoclonal antibody that is attached to a radioactive substance called Yttrium 90 (90Y). The monoclonal antibody portion of Zevalin binds to proteins (CD 20 antigens) found only on the surface of B-cells. When Zevalin binds to the cancer cells, the immune system is stimulated to attack the cancer cells while the attached 90Y destroys these cells by spontaneous radiation emission.
- Researchers speculate that Zevalin may also produce anticancer effects through additional mechanisms not fully understood at present.
- This type of treatment not only provides anticancer treatment through separate strategies, but also delivers greater amounts of radiation to the cancer cells than external radiation therapy. Additionally, radiation exposure to normal cells is minimized.
Differing schedules of Zevalin within treatment regimens for several cancers of the immune system are currently being studied in various clinical trials.
Researchers from the Mayo Clinic in Minnesota conducted a clinical trial to evaluate the effectiveness of standard, external-beam radiation therapy for the treatment of NHL in 16 patients whose cancer has recurred following treatment with Zevalin. External beam radiation therapy involves the use of a machine outside the body that aims radiation to specific cancerous sites in the body.
- Overall anticancer responses were achieved a 90% of the cancer sites that were treated with external beam radiation.
- Side effects from radiation therapy were generally reversible; side effects occurred at the specific sites where radiation was aimed.
The researchers concluded that external beam radiation therapy provides high rates of anticancer responses among patients with NHL whose cancer has recurred following treatment with Zevalin. Patients with recurrent NHL may wish to speak with their physician regarding their individual risks and benefits of treatment with external beam radiation therapy.
Reference: Justice T, Martenson J, Wiseman G, et al. Safety and Efficacy of External Beam Radiation Therapy for Non-Hodgkin Lymphoma in Patients with Prior 90Y-Ibritumomab Tiuxetan Radioimmunotherapy. Cancer. 2006; 107: 433 – 438.
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