Acquired TTP - Overview of acute treatment
The treatment of aTTP often includes PEX and immunosuppression. The first type of treatment is plasma exchange therapy.1,2 With plasma exchange, the goal is to remove the antibodies that block the ADAMTS13 enzyme and replace the ADAMTS13 enzymes in the blood.1 The second type of treatment is a medicine called an immunosuppressant.1,2 This type of treatment aims to stop the immune system from producing new antibodies against ADAMTS13.
Treatment for TTP differs
depending on the type of TTP
- For aTTP, there are two types of treatment that are used together: plasma exchange therapy and immunosuppression
- These treatments aim to remove antibodies from the blood, replace ADAMTS13 and stop the formation of new antibodies
- For inherited TTP, treatment involves plasma infusion which aims to replace the ADAMTS13 in the plasma
- For all TTP patients, regular follow-up and monitoring may be required
Plasma exchange therapy
Plasma exchange therapy (sometimes also called plasmapheresis) is an important treatment for patients with acquired TTP. To understand how plasma exchange works, it is important to know a little about the different components that make up your blood.
Blood has four main components:
- Red blood cells, which help carry oxygen around the body
- White blood cells, which help fight infections
- Platelets, which help form blood clots if bleeding occurs
- Plasma, the liquid part of the blood, which helps transport blood cells, platelets and other substances (antibodies and nutrients) throughout the body
In patients with aTTP, a critical part of treatment is to remove the antibodies in the blood that block the ADAMTS13 enzyme. These antibodies are contained in the blood plasma.
What to expect from plasma exchange
During plasma exchange, blood is taken out of a vein and goes into a machine that separates the plasma from the blood cells and platelets.1 The blood cells and platelets are combined with donated plasma and returned into your body.1 Only a small portion of your blood is removed at any time so the whole process will take several hours.1
Plasma exchange is normally repeated every day until the antibodies are no longer present in your blood and your platelet count is back to normal.1 The length of time for this to happen varies widely from patient to patient – for some it may be days of treatment, for others it may be up to several weeks.1
Immunosuppressants are a type of medicine used to treat many different conditions and diseases. Immunosuppressants affect the way that the immune system works, and are commonly used in autoimmune conditions – conditions where the immune system attacks healthy cells. As the name suggests, immunosuppressants suppress or dampen the strength of the immune response, stopping the attack on healthy cells.
In aTTP, the immune system produces antibodies against the ADAMTS13 enzyme, stopping ADAMTS13 from working properly. This production of antibodies is the underlying cause of aTTP.
Immunosuppressants are used to directly address this cause, by stopping the production of these antibodies by the immune system.1,2 In this way, immunosuppression supports plasma exchange therapy: plasma exchange removes existing antibodies while immunosuppressants stop the production of new antibodies.
What to expect from immunosuppression
There are several different types of immunosuppressants that may be used to treat TTP.2 They may be drugs that are taken orally or they may be given intravenously.2 Some immunosuppressants are taken every day during treatment while others are given less frequently.2 In all cases, immunosuppressants are used in combination with plasma exchange therapy.2
Immunosuppressants are generally started at the same time as plasma exchange therapy and it may take several days before there is an effect on stopping the production of antibodies to ADAMTS13. Immunosuppressants may also be continued for a period of time after plasma exchange therapy has been stopped, as patients are most at risk of relapse shortly after the initial episode.
Follow-up monitoring and treatment
Once a patient has recovered from an acute episode of TTP, they may be monitored on an ongoing basis in an attempt to prevent relapses. The monitoring consists of regular tests to determine patients’ ADAMTS13 activity levels. During an episode of TTP, patients’ ADAMTS13 activity levels are much lower than normal and after initial treatment, most patients’ ADAMTS13 activity returns to normal levels.
In follow-up, if a patient’s ADAMTS13 activity levels are low or if antibodies to ADAMTS13 are discovered, then the patient may be at risk of a relapse.2 In this situation, a patient may receive immunosuppressant therapy to stop the production of new antibodies and allow the body to recover.2
Inherited TTP – overview of acute treatment
The main treatment for patients with inherited TTP is an infusion of donor plasma, also called fresh frozen plasma.1,2 The aim of the treatment is simple: to replace the ADAMTS13 enzyme in the patient’s plasma.1 Fresh frozen plasma contains the normal levels of ADAMTS13 enzyme so when it is infused into a patient with inherited TTP, it replaces the patients’ missing or damaged ADAMTS13 enzymes and allows the patients’ blood levels return to normal. Because patients with inherited TTP do not have antibodies to ADAMTS13, plasma exchange and immunosuppression are not necessary.
What to expect with plasma infusion
Fresh frozen plasma is given through an intravenous (IV) line inserted into a vein.1 Treatment is given daily and, as with treatment for aTTP, is continued until platelet counts return to normal.2 The length of time that it takes for this to happen may vary.
Follow-up and ongoing treatment
Inherited TTP is a lifelong condition and patients may require ongoing monitoring and treatment, depending on the severity of their condition.2 Patients with a more severe condition may require ongoing treatment to keep their platelet count normal and avoid relapses.2 This ongoing treatment will involve regular infusions of frozen fresh plasma.2 The frequency of these infusions will vary from patient to patient but may be in the region of every few weeks.2
- National Institute of Health. How Is Thrombotic Thrombocytopenic Pur- pura Treated? [online]. 2014. Available at: https://www.nhlbi.nih.gov/health/ health-topics/topics/ttp/treatment;
- MScully et al. Br J Haematol 2012;158:323– 35;
- National Institute of Health. Living With Thrombotic Thrombocytopenic Purpura. [online]. 2016. Available at: https://www. nhlbi.nih.gov/health/health-topics/topics/ ttp/livingwith.