Non-Hodgkin's lymphoma
Description
An in-depth report on the causes, diagnosis, and treatment of non-Hodgkin's lymphoma.
Alternative Names
Lymphoma - non-Hodgkin's; NHL; B-cell lymphomas
Biologic Therapy (Immunotherapy)
Biological response modifier therapy, also called immunotherapy, uses the body's own immune system to fight cancer using natural or laboratory-developed factors. These drugs are often combined with other treatments.
Monoclonal Antibodies
Monoclonal antibodies (MAbs) are designed in the laboratory to produce the same effects as natural antibodies and are exciting new weapons in the anti-cancer armament. They bind to specific proteins called antigens and make them vulnerable to attack by other factors in the immune system. Lymphomas carry antigens that provoke strong immune responses and so are believed to be particularly good candidates for MAb therapy.
MAbs are called either
unconjugated
or
conjugated
, depending on how they are designed to destroy the cancer cell.
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Unconjugated monoclonal antibodies rely on a strong natural immune system. The antibody builds up at the tumor site until it is able to trigger an immune response against the cancer. A possible downside to this form is the potential development of tolerance to the antibody so that it loses its effectiveness. Rituximab is an unconjugated form and the first MAb to be approved for any cancer.
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Conjugated monoclonal antibodies are linked to a plant or bacterial toxin or radioisotope. The antibody specifically attacks the antigen on the lymphoma cell and the toxin or radioactive material from the isotope kills it.
Unconjugated MAbs (Rituximab).
Rituximab (Rituxan) was the first monoclonal antibody approved for cancer. This drug targets the CD-20 antigen, which is found on most B-cell lymphomas.
First approved in 1997 for treatment of relapsed or refractory NHL, rituximab has received several expanded indications since that time. As of 2006, rituximab is approved for:
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Relapsed or refractory, low-grade or follicular, CD20-positive, B-cell, NHL
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First-line treatment of diffuse large B-cell (DLBC), CD20-positive, NHL in combination with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) or other anthracycline-based chemotherapy regimens
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First-line treatment of follicular, CD20-positive, B-cell NHL in combination with CVP (cyclophosphamide, vincristine and prednisolone) chemotherapy
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Low-grade, CD20-positive, B-cell NHL in patients with stable disease or patients who have been partially or completely helped by first-line treatment with CVP chemotherapy
Rituximab in combination with CHOP (a regimen called R-CHOP or CHOP-R) is used for first-line treatment for aggressive lymphomas, with studies reporting 3-year event-free survival of 53% compared to 35% with CHOP alone. A 2006 study also indicated that rituximab provides benefits when used as maintenance treatment after CHOP or R-CHOP induction therapy. Rituximab plus CHOP is also showing promise as a first-line treatment for mantle cell lymphoma.
Rituximab is given by infusion. The treatment has mild-to-moderate short-term side effects, including nausea, fever, chills, hives, dizziness, and headache. Uncommon and more serious side effects are severe allergic reactions, very low blood pressure, blood abnormalities, wheezing, infections, and sudden heart events.
Rituximab has also been associated with cases of progressive multifocal leukoencephalopathy (PML), a rare and potentially deadly brain infection. Patients who experience any of the following symptoms should immediately contact their doctors:
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Vision problems or unusual eye movements
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Confusion
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Dizziness or loss of balance
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Difficulty talking or walking
Patients who have previously had hepatitis B, or who are at high-risk for this viral infection, should be tested before taking rituximab because the drug has been linked to reactivation of the hepatitis B virus. Patients who are HIV-positive may experience more adverse effects from rituximab than with CHOP.
Conjugated Monoclonal Antibodies with Radioimmunotherapy.
Conjugated MAbs with radioimmunotherapy contain tiny amounts of radioactive materials. When the drug is injected, the monoclonal antibody targets an antigen (protein) on the surface of the tumor. The radioisotope is then delivered directly into the tumor where it kills the cancer. Ibritumomab and tositumomab both target the CD-20 antigen. Treatment with these drugs takes about 7 - 9 days to complete, compared to several months for traditional chemotherapy treatments.
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Ibritumomab (Zevalin) is approved for patients with relapsed or refractory low-grade, follicular or transformed B-cell NHL. It is also approved for patients with follicular NHL who have not responded to rituximab (Rituxan). Research indicates it may also be safe for patients with advanced NHL who have had stem cell transplantation. Zevalin uses an yttrium-90 (90-Y) radioactive isotope.
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Tositumomab and Iodine I-131 (Bexxar) combines the monoclonal antibody tositumomab with the radioisotope I-131. The Bexxar treatment is approved for treatment of relapsed or refractory low-grade, follicular, or transformed B-cell NHL. Overall response rates of 56% have been reported with Bexxar, with up to 30% being complete responses (no evidence of cancer). Recent studies suggest that when Bexxar is used as a first treatment, it may produce long-term complete remission in patients with advanced stage follicular lymphoma. In a 2005
New England Journal of Medicine
study, 95% of previously untreated patients with advanced follicular lymphoma responded to Bexxar, and 75% had complete responses. Seventy percent who had complete responses from Bexxar treatment were still disease-free 4 - 7 years later.
In general, these drugs cause fewer side effects than traditional chemotherapy. However, serious complications may include skin infections, severe allergic reactions, and temporary lowering of blood counts.
Other Monoclonal Antibodies.
Other MAbs are being developed that target other antigens on lymphomas. For example, epratuzumab targets CD-22 and is showing promise in early studies. Some are being studied in both conjugated and unconjugated forms and also in combination with MAbs that target different antigens.
Interferon Alpha
Interferon alpha (Intron A) is used as an antiviral drug that also has properties that are effective against some common forms of NHL, particularly low-grade, follicular NHL in advanced stages. It is usually combined with chemotherapy regimens such as CHOP that contain an anthracycline drug (usually doxorubicin). The combination is toxic, however, and outcomes are very variable. Interferon is also being studied for lymphomas in the central nervous system. It may be useful after autologous stem cell transplantation.
Side Effects.
Side effects of interferon include flu-like symptoms, severe depression, irritability, weight loss, vomiting, general weakness and loss of strength, and fever. About a third of patients have a severe drop in white blood cells. About 10% of patients cannot tolerate the drug's side effects.
Other Biologic Drugs
Cytotoxic Deoxyguanosine Analogue Prodrugs
. Nelarabine (Arranon) is approved for treating T-cell lymphoblastic lymphoma (T-LBL). T-LBL is a rare form of lymphoma that accounts for less than 2% of all cases of NHL.
Proteasome Inhibitors.
In 2006, bortezomib (Velcade) was approved for treatment of mantle cell lymphoma in patients who have received at least one prior therapy.
Investigational Biologic Therapies
Antisense Oligonucleotide.
Oblimersen (G3139) is called an antisense oligonucleotide. It blocks BCL-2, a protein that is genetically overexpressed in some lymphomas and prevents apoptosis (a natural process by which all cells, including cancer cells, self-destruct). Studies suggest it may have some activity against mantle-cell lymphoma.
Cyclin-Dependent Kinase Inhibitors.
Flavopiridol, a drug known as a cyclin-dependent kinase inhibitor, is showing some effect in patients with mantle-cell lymphoma. This drug is designed to block enzymes that regulate cell cycles and so help block their growth.
Vaccines
. Lymphoma vaccines, which are still experimental, are therapeutic vaccines -- they are used to treat, not prevent, cancer. They are part of an immunotherapy approach called personalized medicine; each vaccine is individually tailored to the genetic composition of the patient’s tumor. The vaccine is usually given a few months after a patient receives chemotherapy.
Several different vaccines are showing promise in late-stage clinical trials. The MyVax vaccine uses a protein from the patient’s own tumor and combines it with a second protein that helps activate the immune system. It is currently being tested in a Phase III trial for follicular B-cell NHL. Another vaccine, BioVaxID, has also shown good results in clinical trials. In a Phase II trial for follicular B-cell NHL, the BioVaxID vaccine produced long-term clinical remission and an overall survival rate of more than 95 percent. In a Phase II trial for mantle cell lymphoma, the vaccine yielded an 89% survival rate. The vaccine is currently in Phase III trials for slow-growing follicular NHL.
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Review Date: 1/17/2007
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Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.
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