This is the fifth part of our series about the condition based on our patient booklet “Fast Facts for Patients: Thrombotic Thrombocytopenic Purpura”. This article addresses medications that suppress the immune system in immune thrombotic thrombocytopenic purpura (iTTP) treatment, including possible side effects.

Steroids

Steroids (given intravenously or as tablets) are usually given in the first few days or weeks after acute iTTP is diagnosed. They suppress the immune system quickly, which is useful in the short-term because other therapies can take time to work.

Possible Side Effects

• Changes in mood, indigestion and stomach pains: these are the most common side effects.
• Other side effects can be thinning of the bones (osteoporosis), weight gain, a “round face” and easy bruising, but these are normally seen in patients who are on steroids longer term (many months or years).
• Your blood sugar can be affected, so this will be monitored; if you are diabetic, your medication/insulin dosage may need to be altered while you are on steroids.

Practical Tips

• Where possible you should take steroids in the morning, and you will be given another tablet to protect your stomach while you are taking them.

Rituximab/Anti-CD20 Therapy

Rituximab is given during an acute iTTP episode, but you can also have it electively as an outpatient (where you come to hospital for a short appointment rather than being “admitted”) to prevent another acute TTP episode occurring (known as an acute relapse).

Rituximab is an antibody medication that binds to a type of lymphocyte (a type of white blood cell) called a B cell at a receptor called CD20. B cells can produce antibodies, including the antibody that causes TTP. When rituximab binds to the CD20 receptor, it causes the B cells to break down and clears the TTP-causing antibodies from the body. Other so-called anti-CD20 therapies are sometimes used instead of rituximab.

Rituximab is given as a drip (infusion) through a cannula inserted into a vein. Normally, 4–8 weekly infusions are given after an acute TTP episode, depending on how long it takes to get a response. It is quite common to get a mild reaction during the rituximab infusion, so the first infusion is usually given slowly over 8–12 hours, during which time you will be closely monitored by the TTP team. You will be given an antihistamine (such as piriton) and paracetamol beforehand to help reduce the risk of a reaction.

Possible Side Effects

• Flu-like symptoms, including a high temperature, chills, weakness, muscle aches, tiredness, dizziness and headaches, can occur during the infusion, but do not usually last long.
• You may have low blood pressure (hypotension) during the infusion, so your blood pressure will be checked regularly.
• If you feel sick and/or have occasional vomiting, you will be given antisickness tablets.
• You may have a slight allergic reaction.
• Rituximab can reduce your body’s production of antibodies, making you more likely to get an infection.
• Sometimes the number of neutrophils (a type of white blood cell) can drop after treatment, making you more likely to get a bacterial infection.
• You may experience warmth in your face (flushing) as well as some redness or darkening for a short time during the infusion.
• Very rarely, patients can complain of joint pains, especially in the knees.
• Progressive multifocal leukoencephalopathy is a very rare complication of rituximab. It is usually seen in patients receiving combination chemotherapy. If you have more questions, please discuss these with your doctor.

Practical Tips

• If you still feel sick after taking antisickness tablets, tell the nurses, who will get a stronger antisickness medication prescribed for you.
• Let the nurses know if you have any of the following allergic reaction symptoms: skin rashes or itching, a feeling of swelling in the tongue, irritation of the nasal passages, wheezing, cough or breathlessness.

Mycophenolate Mofetil (MMF)

MMF is taken as a tablet; it is usually started when ADAMTS13 levels stay low despite administration of rituximab. MMF works by inhibiting lymphocytes (a type of white blood cell) called B cells and T cells. It can take up to 4–6 weeks for MMF to start working, so there will not be an immediate response. The dose may be increased depending on the response. Side effects are generally mild and usually only occur in the first few weeks of treatment.

Possible Side Effects

• Headache is common, but not experienced by all patients.
• Abdominal distension (swelling) can happen in some patients; others may experience abdominal pain.
• Feeling sick and occasional vomiting can occur.
• Some patients experience changes in their sense of taste.
• You may be more likely to get an infection, so you will be closely monitored in the clinic by the TTP team.

Practical Tip

• If you do feel sick, let your doctor/nurse know and antisickness tablets can be prescribed if needed.

Velcade^® (bortezomib)

Velcade^® (bortezomib) is sometimes given together with other treatments for TTP. It works by reducing the number of B cells. Velcade^® can be given either as a subcutaneous injection (given under the skin) or intravenously. Most people do not experience any side effects, and any experienced are normally mild. This is because the doses of Velcade^® used to treat TTP are quite low.

Possible Side Effects

• Low blood pressure (hypotension) can occur, which may make you feel dizzy or faint. If this happens, it is important to make sure you drink more fluids and stay hydrated.
• Nerve problems (peripheral neuropathy) cause a tingling sensation in the fingers and toes. Patients with TTP do not usually get this because only a few injections of low-dose Velcade^® are given.
• Abdominal problems like diarrhea or constipation.
• There is an increased risk of infection. You will be closely monitored by the TTP team in the clinic.

Other Treatments

Although not common, TTP is sometimes associated with an infection, including with the human immunodeficiency virus (HIV). This is rare, but if it is identified you will be started on antiviral medications after discussion with a specialist.

Please check out the other posts of our series here:

• What Is Thrombotic Thrombocytopenic Purpura (TTP)?
• Types and Symptoms of Thrombotic Thrombocytopenic Purpura (TTP)
• How Is Thrombotic Thrombocytopenic Purpura (TTP) Treated?
• Immune Thrombotic Thrombocytopenic Purpura (iTTP) Treatment: Plasma Exchange
• Medications for Immune Thrombotic Thrombocytopenic Purpura (iTTP) and the Role of Clinical Trials
• Thrombotic Thrombocytopenic Purpura (TTP): The UK TTP Registry
• Thrombotic Thrombocytopenic Purpura (TTP): 10 Frequently Asked Questions

Information based on Fast Facts for Patients: Thrombotic Thrombocytopenic Purpura (Karger, 2022).