According to a recent article published in the journal Blood, the use of dendritic cell therapy to stimulate a patient’s immune system appears to produce significant anti-cancer activity in follicular lymphoma.
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 two types: B and T-cells. Each of these cells has a very specific function in aiding the body to fight infection. The large majority of NHL cases, including follicular NHL, involve cancer of the B-lymphocytes and are characterized by excessive accumulation of these atypical cells. This causes overcrowding of blood and lymph tissue, 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 body’s ability to fight infection. Follicular lymphoma is a slow-growing NHL whose cells appear clustered when viewed under the microscope. Treatment for follicular lymphoma includes chemotherapy, radiation therapy, stem cell transplantation and/or biologic therapy (treatment used to stimulate the immune system to fight cancer).
Every cell in the body displays specific antigens (small carbohydrates and/or proteins) on their surface. The immune system relies on antigens to recognize “foreign” material, such as bacteria, viruses or cancer cells. Dendritic cells (DC) are specific immune cells that “present” foreign antigens to other cells in the immune system. The immune system then mounts an attack against foreign cells that display the antigen(s) that were presented by the DCs.
Researchers have been evaluating mechanisms to stimulate the immune system to attack cancer cells. Recently, researchers from Stanford University conducted a clinical trial utilizing DCs as part of a treatment regimen for patients with follicular lymphoma. First, the patient’s immune system was stimulated to produce an abundance of DCs that were then collected from peripheral blood. Next, cancer cells were collected from the patient and specific segments from antigens of the cancer cells, referred to as an idiotype (Id), were isolated. Antigens from the keyhole limpet mollusk, called keyhole limpet hemocyanin (KLH), were also used to further stimulate the immune system into recognizing the cancer-specific Id as foreign. DCs were cultured (pulsed) with KLH and Id in the laboratory. Patients received intravenous infusions of DCs pulsed with KLH and Id, followed by injections of KLH and Id without DCs.
In this trial, 25 patients with advanced follicular lymphoma had received initial chemotherapy (remission induction) prior to immunotherapy. Only five patients had achieved a complete remission (disappearance of cancer) following chemotherapy. Two patients whose cancer had continued to progress after chemotherapy and vaccinations discontinued the trial. Approximately 3.5 years following the vaccinations, 70% of patients had no progression of cancer. Among patients who had measurable cancer following chemotherapy, 22% had cancer regression following the vaccinations. One patient whose cancer had recurred 18 months following the vaccinations was treated with “booster” vaccinations consisting of the Id-KLH proteins without DCs. This patient ultimately experienced a complete remission following booster vaccinations. Treatment had very few side effects.
These researchers concluded that Id-pulsed DC therapy with Id-KLH vaccinations produces significant anti-cancer responses in advanced follicular lymphoma. Further evaluation of this type of therapeutic strategy is warranted. Patients with follicular lymphoma may wish to speak with their physician about the risks and benefits of participating in a clinical trial evaluating therapy involving DCs. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. (Timmerman J, Czerwinski D, Davis T, et al. Idiotype-pulsed dendritic cell vaccination for B-cell lymphoma: clinical and immune responses in 35 patients. Blood 2002;99:1517-1526.)
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