Rituxan (Rituximab) for Non-Hodgkin Lymphoma, CLL, and More

Rituxan is a genetically engineered mouse-human combination antibody. It is used to treat several conditions including non-Hodgkin lymphoma.

How It Works

Knowing how our immune systems can target and then eliminate bacteria and viruses in our environment, scientists thought it might be possible to mimic that mechanism to attack cancer cells.

Our immune system is able to recognize markers on the surface of bacteria and viruses that indicate they don't belong in the body. When we are exposed to these microorganisms we manufacture antibodies to attach to these surface markers, letting the rest of our immune system know to attack. It's been found that some non-Hodgkin lymphoma cells also have markers that can set them apart. This marker is called the CD20 antigen and is on the surface of some of our immune cells known as B-lymphocytes, or B cells. These are the cells that become cancerous in some forms of non-Hodgkin lymphoma and chronic lymphocytic leukemia.

The next step was to find a drug that could act like the antibodies our body's make—antibodies that would likewise recognize surface markers, but on cancer cells. Rituxan (rituximab) is the "artificial antibody" found to stick to the CD20 antigen on cancerous young pre-B cells and mature B-lymphocytes. Once Rituxan binds to the CD20 on the cancerous cells, there are likely a few mechanisms by which the cancer cells are then destroyed.

Scientists categorize antibodies into different groups, based on their structure and function, and Rituxan is categorized as an immunoglobulin G or IgG. Rituxan is classified as a monoclonal antibody— a type of immunotherapy which uses "man-made" antibodies to attack cancer.

Uses

Rituxan is used for both cancerous and noncancerous diseases. How is this possible? Well, it all relates to the white blood cells known as B-cells or B-lymphocytes, which are part of the immune system. B-cells—the same cells that become cancerous in a variety of lymphomas—may also play a role in the development of rheumatoid arthritis and other inflammatory illnesses. It may be used for cancers and noncancerous diseases.

Cancers:

• People with some types of non-Hodgkin's lymphomas including follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL).
• People with chronic lymphocytic leukemia (CLL) which is CD20 positive.

Noncancerous Diseases:

• Some people with rheumatoid arthritis.
• Some people with rare blood vessel diseases such as granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
• It is being studied in clinical trials for possible use in multiple sclerosis and systemic lupus erythematosus.

Targeting B-Cells in Non-Hodgkin Lymphoma and Chronic Lymphocytic Leukemia

The addition of Rituxan to our repertoire of drugs to treat NHL has made a significant difference. Prior to its introduction at the beginning of this century, the death rate from lymphoma had been steadily rising. Since that time it has been declining, likely due to improved survival from Rituxan. Some of the lymphomas for which Rituxan makes a difference include the following.

Follicular lymphoma - Follicular lymphoma is the most common type of indolent— meaning slow-growing—NHL, usually appearing in lymph nodes throughout the body. As a slow-growing type of NHL, FL does not always require immediate treatment. If your healthcare provider decides to use Rituxan for FL, it is used in 2 different ways:

• Initial treatment: to get to remission
  Rituxan is used in combination with chemotherapy. If treatment results in partial or complete remission, Rituxan may be used as maintenance therapy.
• Maintenance therapy: to stay in remission
  The goal of maintenance therapy is to help keep the disease in remission for a longer period of time. Rituxan is used alone, without chemotherapy, during maintenance therapy.

Diffuse large B-cell lymphoma (DLBCL) - Diffuse large B-cell lymphoma makes up more than 30 percent of newly diagnosed cases of NHL. Rituxan is considered a standard part of initial treatment when used with chemotherapy combinations like CHOP. Three large studies have demonstrated that not only does adding Rituxan delay disease relapse or progression, it may also result in improved survival. Rituxan is therefore given with each cycle of chemotherapy and may be continued for a period beyond completion of chemotherapy cycles. For those who have been treated earlier with chemotherapy alone and have now relapsed or progressed, Rituxan may be administered as a salvage treatment. (Salvage treatment refers to a treatment which decreases symptoms and/or extends survival, but cannot cure the disease.)

How Rituxan Is Given

Rituxan is administered as an infusion in your veins. Rituximab is given over a few hours. The infusion is started slowly, and if the patient does not show any reactions to the medicine, the rate of infusion is increased every hour until the infusion is over.

Rituxan is administered on a weekly basis for 4 to 8 weeks when it is administered alone. When administered along with chemotherapy, it is usually given on the first day of each cycle of chemotherapy for each of the 6 to 8 cycles.

Side effects with Rituxan:

• The main side effects of Rituxan are related to infusion allergic reactions. The majority of patients have some kind of a reaction, more so during the first infusion. The most common symptoms are fever and chills, with some patients feeling itchy or lightheaded. These are easily controlled by trained staff and are rarely worrisome.
• Rituxan may result in a fall in blood counts, like chemotherapy. This may occasionally result in fever and may require growth factor injections for control.
• A small number of patients may have some cough and nasal discharge following Rituxan. Serious lung complications are very rare.

Gazyva

As opposed to Rituxan, Gazyva is a fully humanized monoclonal antibody. Gazyva as a newer drug that targets the same "tag" as Rituxan, namely the CD20 antigen. Rituxan and Gazyva both target the CD20 antigen that’s present on the surface of certain cells, including the white blood cells known as B-lymphocytes, or B cells.

Like Rituxan, Gazyva is a monoclonal antibody. That is, it's a special kind of antibody engineered by scientists and produced by manufacturers. The final product is hung in a bag as a liquid and given via intravenous infusion.

According to a press release by the drug makers, Gazyva is thought to have an increased ability to induce direct cell death, inducing greater activity in recruiting the body’s immune system to attack B-cells.