Rituximab

Cancer Treatment

Rituximab is used to treat cancers that affect the blood and immune system. These include:

• Non-Hodgkin's lymphoma: This medication is used for several types of this cancer, either alone or with other drugs.
• Chronic lymphocytic leukemia: It is used to treat this type of blood and bone marrow cancer, usually in combination with chemotherapy.

Autoimmune and Inflammatory Conditions

This medication is also used for conditions where the immune system is overactive and attacks the body's own tissues:

• Rheumatoid arthritis: It is used to reduce symptoms in adults with moderate to severe rheumatoid arthritis, typically when other treatments have not worked well. It is usually given along with methotrexate.
• Blood vessel inflammation: It treats granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), which are rare disorders that cause inflammation of the blood vessels.
• Skin conditions: It is used to treat pemphigus vulgaris, a rare autoimmune disease that causes severe blisters on the skin and the lining of the mouth and throat.

Targeting B-cells

Rituximab is a type of protein called a monoclonal antibody. It is engineered to recognize and bind to a specific marker known as CD20, which is found on the surface of B-lymphocytes (B-cells).

B-cells are white blood cells that play a key role in the immune system. In some conditions, these cells can become cancerous or may begin to attack the body's own healthy tissues. When rituximab attaches to the CD20 marker on these cells, it signals the body's immune system to attack and destroy them.

Effects on Disease

By lowering the number of B-cells, rituximab helps treat different types of illnesses:

• Cancer: In certain blood cancers, it helps the immune system eliminate malignant B-cells to slow or stop the disease.
• Autoimmune Conditions: In diseases like rheumatoid arthritis, it reduces the B-cells that contribute to inflammation and tissue damage.

The medication specifically targets cells expressing the CD20 protein, which allows it to focus on B-cells while leaving other types of immune cells alone.

Common Side Effects

Many people experience mild to moderate side effects during or shortly after treatment. These may include:

• Fever, chills, or shivering
• Nausea, diarrhea, or stomach upset
• Headache or dizziness
• Muscle, joint, or back pain
• Fatigue or weakness
• Cold-like symptoms, such as a runny nose or sore throat
• Flushing or mild skin itching
• Swelling of the hands, ankles, or feet

Serious Side Effects

Seek medical attention immediately if you notice any of the following serious symptoms:

• Infusion reactions: Hives, swelling of the face or throat, shortness of breath, or chest tightness.
• Severe skin reactions: Painful sores, ulcers, or skin that blisters and peels.
• Signs of infection: Persistent fever, chills, cough, or pain when urinating.
• Neurological issues: Confusion, vision changes, loss of balance, or difficulty speaking.
• Heart problems: Chest pain or a fast or irregular heartbeat.
• Bleeding or bruising: Unusual bruising or bleeding that does not stop easily.
• Abdominal issues: Severe stomach pain or black, tarry stools.

Boxed Warnings

Rituximab has several boxed warnings due to the risk of severe and potentially fatal side effects:

• Infusion-Related Reactions: Severe and sometimes fatal reactions can occur, typically during the first infusion. Symptoms may include hives, swelling, difficulty breathing, chest pain, or low blood pressure.
• Hepatitis B Reactivation: The virus can become active again in people who have had hepatitis B in the past, potentially leading to liver failure or death. Screening for hepatitis B is required before starting treatment.
• Progressive Multifocal Leukoencephalopathy (PML): This is a rare but serious brain infection caused by the JC virus. It can lead to severe disability or death.
• Severe Mucocutaneous Reactions: Serious skin and mouth reactions, such as Stevens-Johnson syndrome or toxic epidermal necrolysis, have been reported.

Infection Risk

Rituximab affects the immune system, which may increase the risk of serious bacterial, fungal, or viral infections. Some of these infections can be life-threatening. Patients are monitored for signs of infection, such as fever, cough, or persistent sore throat.

Tumor Lysis Syndrome (TLS)

In patients with certain types of cancer, the rapid breakdown of cancer cells can cause TLS. This condition leads to kidney failure and abnormal electrolyte levels. Preventive measures, such as hydration and specific medications, are often used to reduce this risk.

Cardiovascular and Renal Concerns

Rituximab may cause heart rhythm problems or chest pain, particularly in individuals with a history of heart disease. It can also cause kidney damage, especially when used in combination with certain chemotherapy drugs or in cases of TLS.

Vaccinations

The use of live vaccines is generally avoided shortly before or during treatment with rituximab, as the medication may reduce the vaccine's effectiveness or increase the risk of infection from the vaccine.

Pregnancy

Rituximab can cross the placenta and may affect the immune system of a developing fetus. Specifically, it may lead to a decrease in B-cells, which are a type of white blood cell, in the newborn. It is important to notify a healthcare provider immediately if you are pregnant or planning to become pregnant before starting this medication.

Contraception

Because of the potential risks to a fetus, healthcare providers typically recommend using effective birth control during treatment. This contraception should be continued for at least 12 months after the final dose of rituximab.

Breastfeeding

It is currently unknown if rituximab passes into human breast milk. Due to the risk of serious side effects in a nursing infant, breastfeeding is generally not recommended while receiving rituximab and for at least 6 months after the last dose. Patients should discuss the risks and benefits of breastfeeding with their medical team.

Administration Methods

Rituximab is supplied as a liquid solution for use by medical professionals. It is available in two primary forms:

• Intravenous Infusion: This form is injected directly into a vein. The first dose is usually given slowly over several hours to monitor for reactions.
• Subcutaneous Injection: This form is injected into the tissue under the skin, typically in the abdominal area. It is often used after a patient has already received at least one dose through a vein.

The medication is provided in single-dose vials of varying concentrations. Your healthcare provider will determine the appropriate dose based on your body size and the specific condition being treated.

FDA Approval and Indications

Rituximab is approved by the U.S. Food and Drug Administration (FDA) for the treatment of several conditions, including:

• Non-Hodgkin's lymphoma (NHL)
• Chronic lymphocytic leukemia (CLL)
• Rheumatoid arthritis (in combination with methotrexate)
• Granulomatosis with polyangiitis (GPA) and Microscopic polyangiitis (MPA)
• Moderate to severe pemphigus vulgaris

The medication is available as the original reference product and as several FDA-approved biosimilars. It is administered via intravenous infusion, though some formulations combined with hyaluronidase are approved for subcutaneous injection for specific indications.

Boxed Warnings

The FDA requires a boxed warning for rituximab because of the risk of severe and potentially fatal adverse reactions. These include:

• Infusion-related reactions: Severe and fatal reactions have occurred, typically during the first infusion.
• Severe mucocutaneous reactions: These include Stevens-Johnson syndrome and toxic epidermal necrolysis, which can be fatal.
• Hepatitis B virus (HBV) reactivation: The FDA has issued safety communications requiring healthcare providers to screen all patients for HBV infection before starting treatment. Reactivation can lead to fulminant hepatitis, hepatic failure, and death.
• Progressive multifocal leukoencephalopathy (PML): This is a rare, serious, and often fatal viral infection of the brain caused by the JC virus.

Administration Process

Rituximab is administered by a healthcare professional in a medical setting, such as a hospital or infusion center. It is typically given as an intravenous (IV) infusion into a vein. Some versions of the medication may be given as a subcutaneous injection under the skin, usually in the abdominal area.

The first infusion is usually given slowly to monitor for any adverse reactions. If the patient tolerates the initial treatment well, future infusions may be administered at a faster rate.

Premedication

To help prevent or lessen the severity of infusion reactions, healthcare providers usually give other medications approximately 30 to 60 minutes before the rituximab treatment begins. These premedications often include:

• Acetaminophen to reduce the risk of fever.
• Antihistamines to help prevent allergic reactions.
• Steroids to decrease inflammation.

Monitoring During and After Infusion

Medical staff will monitor vital signs, including blood pressure and heart rate, throughout the procedure. Monitoring typically continues for at least 15 to 30 minutes after the infusion is complete. Patients should notify their healthcare provider immediately if they experience any of the following during or after the treatment:

• Fever, chills, or shivering
• Itching, hives, or skin rash
• Difficulty breathing, wheezing, or shortness of breath
• Dizziness, lightheadedness, or fainting
• Chest pain or a racing heartbeat
• Swelling of the face, lips, tongue, or throat