Rituxan®, a monoclonal antibody, has demonstrated moderate anti-cancer activity in mantle cell lymphoma. Monoclonal antibodies are proteins that can be made in the laboratory and are designed to recognize and bind to very specific cells. Rituxan® is a monoclonal antibody that binds to proteins on the surface of B-lymphocytes. This binding action stimulates the immune system to attack and kill the cancerous B-cells. A significant benefit of this approach is that Rituxan® only targets cancer cells (B-cells), thus sparing healthy cells from destruction. This is in contrast to chemotherapy or radiation, which do not differentiate between cancer cells and healthy cells in the body, a characteristic leading to potentially destructive side effects.
Recently, researchers have been linking radioisotopes to monoclonal antibodies in an attempt to augment anti-cancer effects. This type of treatment uses two separate strategies to target and kill cancer cells.
High-Dose Radioactive Labeled Rituxan® Effective for Refractory Mantle Cell Lymphoma
According to results recently published in the journal Cancer, treatment with high dose Rituxan® linked to iodine-131 followed by an autologous stem cell transplant appears to produce significant anti-cancer activity in patients with mantle cell lymphoma that has stopped responding to standard therapies.
Mantle cell lymphoma is an especially aggressive type of non-Hodgkin’s lymphoma with an unfavorable prognosis. Patients with mantle cell lymphoma have a 5 year survival rate of less than 20%. Non-Hodgkin’s lymphoma (NHL) is a cancer of the lymph tissue, which is part of the body’s immune system. Lymph tissue is present in lymph nodes, lymph vessels and bone marrow, which exist throughout the body. It is also present in organs such as the thymus, tonsils and spleen. The main cells in the lymph system are called lymphocytes, of which there are 2 types: B and T-cells. Each of these cells has a specific function in aiding the body to fight infection. The large majority of NHL cases involve cancer of the B-lymphocytes, characterized by the excessive accumulation of these atypical cells. These cancerous cells can crowd the lymph tissue, thereby causing suppression of normal formation and function of other cells necessary for normal immune functions. While NHL is categorized by the type of lymphocyte it involves, it is also further defined by the specific appearance of the affected cells, as well the grade of the disease (how fast it is likely to grow). These determinations are based on how the cells look under a microscope. In terms of NHL grade, high-grade or aggressive NHL is the fastest growing.
Although mantle cell lymphoma may respond to initial therapy, the majority of patients ultimately experience a recurrence of their cancer. Once the cancer has stopped responding to standard therapies (refractory disease), patients are left with limited treatment options. This has prompted researchers to evaluate novel therapeutic approaches in patients with refractory NHL in order to improve survival.
Rituxan®, a monoclonal antibody, has demonstrated moderate anti-cancer activity in mantle cell lymphoma. Monoclonal antibodies are proteins that can be made in the laboratory and are designed to recognize and bind to very specific cells. Rituxan® is a monoclonal antibody that binds to proteins on the surface of B-lymphocytes. This binding action stimulates the immune system to attack and kill the cancerous B-cells. A significant benefit of this approach is that Rituxan® only targets cancer cells (B-cells), thus sparing healthy cells from destruction. This is in contrast to chemotherapy or radiation, which do not differentiate between cancer cells and healthy cells in the body, a characteristic leading to potentially destructive side effects.
Recently, researchers have been linking radioisotopes to monoclonal antibodies in an attempt to augment anti-cancer effects. This type of treatment uses two separate strategies to target and kill cancer cells. Radioactive isotopes are unstable molecules that spontaneously emit forms of radiation. Thus, when the monoclonal antibody binds to the cancer cells, the attached radioisotope destroys the cells by emission of its radiation. This type of treatment not only provides two separate treatment strategies, but also allows the delivery of greater amounts of radiation to the cancer cells while minimizing radiation exposure to normal cells.
Researchers from Germany recently conducted a small clinical trial evaluating high-dose therapy consisting of Rituxan® linked to the radioisotope iodine-131 followed by an autologous stem cell transplant in seven patients with refractory mantle cell lymphoma. All patients had a cancer recurrence following previous treatment with high-dose chemotherapy and an autologous stem cell transplant, and were no longer responding to chemotherapy. Following therapy with Rituxan®/iodine-131, six patients experienced a complete disappearance of cancer (complete remission) and one patient experienced significant anti-cancer activity (partial remission). Five patients are still in complete remission and six are alive at over three years following therapy.
Cancer, treatment with high dose Rituxan® linked to iodine-131 followed by an autologous stem cell transplant appears to produce significant anti-cancer activity in patients with mantle cell lymphoma that has stopped responding to standard therapies.
Although mantle cell lymphoma may respond to initial therapy, the majority of patients ultimately experience a recurrence of their cancer. Once the cancer has stopped responding to standard therapies (refractory disease), patients are left with limited treatment options. This has prompted researchers to evaluate novel therapeutic approaches in patients with refractory NHL in order to improve survival.
Rituxan®, a monoclonal antibody, has demonstrated moderate anti-cancer activity in mantle cell lymphoma. Monoclonal antibodies are proteins that can be made in the laboratory and are designed to recognize and bind to very specific cells. Rituxan® is a monoclonal antibody that binds to proteins on the surface of B-lymphocytes. This binding action stimulates the immune system to attack and kill the cancerous B-cells. A significant benefit of this approach is that Rituxan® only targets cancer cells (B-cells), thus sparing healthy cells from destruction. This is in contrast to chemotherapy or radiation, which do not differentiate between cancer cells and healthy cells in the body, a characteristic leading to potentially destructive side effects.
Recently, researchers have been linking radioisotopes to monoclonal antibodies in an attempt to augment anti-cancer effects. This type of treatment uses two separate strategies to target and kill cancer cells. Radioactive isotopes are unstable molecules that spontaneously emit forms of radiation. Thus, when the monoclonal antibody binds to the cancer cells, the attached radioisotope destroys the cells by emission of its radiation. This type of treatment not only provides two separate treatment strategies, but also allows the delivery of greater amounts of radiation to the cancer cells while minimizing radiation exposure to normal cells.
Researchers from Germany recently conducted a small clinical trial evaluating high-dose therapy consisting of Rituxan® linked to the radioisotope iodine-131 followed by an autologous stem cell transplant in seven patients with refractory mantle cell lymphoma. All patients had a cancer recurrence following previous treatment with high-dose chemotherapy and an autologous stem cell transplant, and were no longer responding to chemotherapy. Following therapy with Rituxan®/iodine-131, six patients experienced a complete disappearance of cancer (complete remission) and one patient experienced significant anti-cancer activity (partial remission). Five patients are still in complete remission and six are alive at over three years following therapy. Two patients have had a cancer recurrence; one at three months following therapy and one at 26 months following therapy. Side effects were mild to moderate.
The researchers conducting this trial concluded that high-dose Rituxan® plus iodine-131 followed by an autologous stem cell transplant appears to produce high anti-cancer response rates with moderate side effects in patients with refractory mantle cell lymphoma. Although this trial was small, these results warrant further clinical trials to evaluate this therapeutic approach in patients with refractory mantle cell lymphoma, as few effective treatment options exist for this group of patients. Patients with mantle cell lymphoma may wish to speak with their physicians about the risks and benefits of participating in a clinical trial further evaluating high-dose Rituxan® plus iodine-131 or other therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute.
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