According to results recently presented at the 43rd annual meeting of the American Society of Hematology, subcutaneous alemtuzumab therapy appears to induce high anti-cancer responses and is well tolerated by patients with previously untreated CLL.
Chronic lymphocytic leukemia (CLL) is a cancer involving the lymph (immune) system, which includes lymph nodes, blood and blood vessels found throughout the body, as well as the spleen, thymus and tonsils. This cancer is found in high quantities throughout circulating blood and in bone marrow (spongy material inside large bones that produces blood forming cells). CLL is characterized by the production of atypical lymphocytes. Lymphocytes are specialized immune cells, of which there are two types: B and T-cells. These cells are produced in the bone marrow and each has a very specific function in aiding the body to fight infection. The large majority of CLL cases involve mature B-lymphocytes that tend to live much longer than normal, accumulating in the blood, bone marrow, lymph nodes and spleen. This results in overcrowding of these areas, suppressing the formation and function of blood and immune cells that are normally present. Additionally, the cancerous lymphocytes themselves do not function normally, leading to a further decrease in the ability of the body to fight infection. CLL is considered a slow-growing or low-grade cancer.
Alemtuzumab is a monoclonal antibody, which is a specific type of biological agent. Monoclonal antibodies are proteins that can be made in the laboratory and are designed to recognize and bind to very specific cells. Alemtuzumab recognizes the CD52 antigen (a specific protein located on a cell’s surface), which is expressed on normal B and T cells as well as on abnormal B cells characteristic of CLL. In previous studies, alemtuzumab produced anti-cancer effects in 33% of patients resistant to Fludara®.
Researchers are also exploring whether alemtuzumab can be safely and effectively administered subcutaneously (beneath the skin) rather than intravenously (through a vein). Most chemotherapy or biological agents are delivered intravenously, but intravenous (I.V.) infusion requires patients to receive treatment at a hospital or clinical setting staffed with trained healthcare professionals. In addition, patients treated with I.V. therapy may develop infections, pain, vein irritation and incur increased medical costs. In contrast, subcutaneous injections can be self-administered at home.
Researchers in Sweden and England recently conducted a clinical trial evaluating subcutaneous alemtuzumab in 38 patients with previously untreated CLL. Patients received alemtuzumab via subcutaneous injection for a maximum of 18 weeks. The overall anti-cancer response was 87%. Of these responding patients, 95% had complete disappearances of cancer (remission) in the blood and 79% achieved partial or complete disappearances of cancer in the bone marrow. For most patients, complete remission of CLL in the bone marrow required 18 weeks of alemtuzumab therapy. Lymphadenopathy (inflammation of lymph glands) also responded to treatment in 87% of the patients. Treatment effects appear to be durable, with the average time to cancer progression not yet reached at over 18 months following treatment. At the start of treatment, most patients experienced mild fevers and a mild reaction at the injection site. The only severe side effect was transient neutropenia (abnormally low number of specific white blood cells), which was experienced by 24% of patients.
Results from this trial indicate that subcutaneous alemtuzumab produces significant anti-cancer responses in untreated CLL, particularly in patients able to undergo 18 weeks of treatment. Most patients are able to tolerate subcutaneous alemtuzumab and this method of delivery may also be viable for other monoclonal antibodies. Individuals may wish to speak with their physician regarding the risks and benefits of alemtuzumab or about participating in a clinical trial. Two sources of information regarding ongoing clinical trials include comprehensive, easy-to-use listing services provided by the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients.
(Proceedings from the 43rdAmerican Society of Hematology, abstract #3215, Orlando, Florida, December 2001)
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