Treating ITP

ITP treatment and management^1,2

Many ITP patients without severe bleeding could be managed by observation and may only require pharmacological interventions when their platelet count falls below 20-30 (x10⁹/L).^1,2

More information on how healthcare providers can create an individualised ITP treatment plan can be found in the ITP diagnosis and treatment guidelines.

Treating ITP with pharmacological interventions^3-10

Current ITP therapies aim to address thrombocytopenia only, by preventing bleeding and increasing low platelet counts. Whilst ITP-related bleeding is common, only in rare cases is it life-threatening. 

There remains an unmet need for therapies that address multiple targets contributing to the underlying immune dysregulation driving ITP instead of just the primary symptoms.

Corticosteroids for ITP^1,2,11

For many patients, corticosteroids are the recommended first-line treatment for ITP. The therapy may be initiated in newly diagnosed adult patients without severe bleeding when their platelet count falls below a threshold between 30 (x10⁹/L) to 20 (x10⁹/L).

Corticosteroids may ameliorate platelet counts by broadly suppressing the activity of the autoreactive immune system, thereby reducing the generation of autoantibodies against platelets. 

The medication starts to exert its function within 2-14 days and has a response rate of 60-80%. However, only 30-50% of patients show a durable response when the medication is discontinued, and permanent remissions are uncommon. 

Corticosteroids may cause side effects in most patients, including negative impact on mental health, hypertension, muscular atrophy, and glaucoma.

Thrombopoietin receptor agonists (TPO-RA) for ITP

TPO-RA are usually indicated for second-line treatment in treatment-resistant patients with new, persistent, and chronic ITP. They can also be used as an emergency treatment.^1,2,11,12 

TPO-RA stimulate thrombocytopoiesis in megakaryocytes. Effects are seen after 3-14 days depending on the specific drug used, with response rates varying between 65-80% and only 8-32% of patients experiencing a durable response after stopping the medication.^2,11,12

TPO-RA cause various side effects such as thrombosis, transaminitis skin reactions, and gastrointestinal problems.^2,11,12

Targeted immunotherapy for ITP^1,2,11,12

Targeted immunotherapy is used as a second- or third-line treatment. These drugs might be a suitable option for patients who want to avoid long-term medication and surgery. 

Targeted immunotherapy uses antibodies to target the autoantibody-producing B cells leading to the destruction of the cells. 

This therapy starts to exert its function after 7-56 days. 60% of patients initially respond to the treatment, with the effect sustained in 10-40% after the drug is discontinued. 

Side effects are usually mild; however, treatment could make patients more susceptible to infections. 

Intravenous immunoglobulin (IVIg) for ITP^1,2,13,14

IVIg quickly elevates platelet levels and could therefore be used as an emergency treatment for ITP. As a first-line treatment, IVIg could also be combined with corticosteroids. However, IVIg treatment for ITP alone has not been reported to provide a durable response. 

The detailed mechanism of action of IVIg is currently unknown. They are thought to inhibit phagocytosis of platelets. 

Clinically relevant side effects of IVIg can include low blood pressure, arrhythmia, skin reactions, and flu-like symptoms.

Anti-D immunoglobulin (anti-D) for ITP^1,2

Anti-D immunoglobulin is only available in some countries for the treatment of ITP. It could be used as a first-line treatment. However, the potential side effects could render it unsuitable for most patients without severe bleeding. 

Anti-D is an antibody that attaches selectively to rhesus-positive erythrocytes. The interaction leads to the degradation of the erythrocytes by the spleen. The process is thought to interfere with the destruction of platelets and consequently cause an increased platelet count in patients with immune thrombocytopenia. 

Serious side effects of anti-D treatment for ITP include intravascular haemolysis. 

Non-pharmacological treatments of ITP

In addition to medications, non-drug-based interventions are available.

Splenectomy for ITP^1-3,11,12,15

Splenectomy can be a useful second-line treatment for chronic patients who prefer to avoid long-term medication and aim for a durable response—the success rate of splenectomy for ITP is approximately 80%. A splenectomy should be avoided in the first 12 months of the initial diagnosis since ITP can go spontaneously into remission during the first year. Furthermore, ITP relapse or refractory ITP after a splenectomy affects 30-50% of patients. 

A splenectomy can also be used as an emergency treatment. 

The spleen plays a dual role in ITP. Splenic macrophages clear platelets covered in autoantibodies while splenic plasma cells are the main producers of autoantibodies against platelets. Therefore, removing the spleen interrupts these processes.

Side effects for ITP patients post-splenectomy include an increased risk of infection with encapsulated bacteria and require repeated vaccinations. A large registry-based study showed a higher risk of both early and late sepsis among patients with ITP who had undergone splenectomy than among those who did not. A higher incidence of other vascular complications, such as coronary artery disease, stroke, and chronic thromboembolic pulmonary hypertension, has also been reported among patients who have undergone splenectomy.

Platelet transfusion for ITP^{2,11,12,16,17}

Platelet transfusion in combination with IVIg and corticosteroids can be used as an emergency treatment. 

The effect of platelet transfusions wanes quickly. In addition, the treatment appears to fail in reducing mortality, and there are only limited studies on the benefits of platelet transfusions in ITP. 

It’s important to note that platelet transfusions can induce severe immune responses such as anaphylactic and febrile non-haemolytic transfusion reactions. 

Medication induced ITP^18,19

Some drugs can trigger ITP. Medications that can induce ITP include quinine, penicillin, heparin, gold salts, sulfonamide antibiotics, and non-steroidal anti-inflammatory drugs. In these cases, stopping the medication should be considered for the management of ITP.

Lifestyle²

Some ITP patients may have to adopt lifestyle changes to prevent bleeding. This could include avoiding activities that are associated with an increased risk of bleeding, such as combat and contact sports.

Emerging treatments for ITP

Bleeding is only one consequence of ITP, but there is a wide range of ITP symptoms that impact the health-related quality of life (HRQoL) of patients.^3,20-23

Treatment goals in ITP have shifted from targeting only platelet counts to comprehensive disease control.²

An improved understanding of ITP disease pathophysiology is enabling researchers to develop innovative treatments that target the underlying mechanisms of ITP. Among these are Bruton’s tyrosine kinase (BTK) inhibitors, neonatal Fc receptor (FcRn) blockers, recombinant immunoglobulin multimers, complement inhibitors, plasma-cell–depleting therapies, and B cell activating factor (BAFF) inhibitors.^7,11

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