Immune Thrombocytopenia (ITP)


Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet count, purpura, and hemorrhagic events that occur due to antiplatelet autoantibodies. The diagnosis is typically reached by ruling out any known causes of thrombocytopenia.1 

Symptomatic cases of ITP require treatment. Even though this differs from person to person, the objective is to reach a hemostatic platelet count, which is usually between 20 and 30×109/L.2

The 1996 evidence-based practice guidelines for managing ITP published by the American Society of Hematology (ASH) recommend starting treatment for any individuals with a new diagnosis when platelets are less than 30×109/L. According to the 2011 recommendations, this objective cutoff is still valuable, but a treatment decision ultimately depends on the patient’s preferences, the severity of their symptoms, and any potential for bleeding.2

Treatment for ITP is complex and should be tackled in a stepwise manner. Immune suppression has proven to be the most effective first-line treatment for ITP. Switching to or supplementing corticosteroids with intravenous immunoglobulin (IVIG) or anti-RhD antibodies show comparable high response rates in patients with steroid-refractory ITP. These first-line treatments result in complete remission in up to 70% to 90% of cases. Second-line treatments include splenectomy, rituximab, and thrombopoietin receptor agonists. Although many patients respond to the conventional first- and second-line medications, new and better treatment alternatives are still needed for chronic and refractory cases of ITP.2,3 

First-Line Treatments

Steroids 

Corticosteroids are the main treatment for ITP in adults. Prednisone and dexamethasone have been demonstrated to alter B-cell and dendritic cell activation, resulting in a reduction in the immune system’s ability to destroy platelets. Close to 80% of patients benefit from steroid treatment, however, many of them relapse after the medication is tapered off.2 

Prednisone, at a dose of 1 mg/kg/d for 2 to 4 weeks, has been considered to be the cornerstone of therapy, but many recent studies have demonstrated that high-dose dexamethasone is even more efficacious.2 It is crucial to gradually decrease the dosage and cease the medication when bleeding stops or when the platelet count reaches 20×109/L or above. In actuality, irrespective of the outcome, most doctors end treatment after 2 to 3 weeks.4

The response and side effects influence the course of treatment and dosage. Avascular necrosis, diabetes, gastritis, ulcers, growth retardation, hypertension, sleeplessness, osteoporosis (in adults), changes in personality, and opportunistic infections are frequent side effects linked to corticosteroid therapy.4 For pregnant patients with ITP who need treatment, corticosteroids are considered safe.2

Read more about ITP guidelines

Intravenous Immunoglobulin 

Intravenous immunoglobulin has immunomodulatory actions, including the anti-idiotypic neutralization of antiplatelet antibodies, stimulation of Fc gamma receptor IIB expression, and inhibition of Fc gamma receptor-mediated platelet destruction.5 Treatment with IVIG is more expensive than intravenous Rh anti-D antibodies. However, IVIG is more effective than intravenous Rh anti-D antibodies in achieving platelet counts around 20×109/L. And the use of IVIG is safe and may reduce the length of hospital stay due to the medication’s quick action, which typically occurs within 24 to 48 hours. This action is temporary and lasts for several days to around 2 weeks.4,6 

Some common infusion-related side effects include headache, fever, chills, and nausea. Aseptic meningitis, renal impairment or failure, and thromboembolic events are concerning but uncommon adverse effects.4,6 

Read more about ITP complications

Rh Immune Globulin

Intravenous anti-D antibodies increase platelet counts in patients with ITP who are RhD positive. Anti-D antibodies coat red blood cells that are positive for the D antigen, and these opsonized red blood cells then fight with opsonized platelets for sequestration in the spleen.4 

Despite the fact that adverse effects are more frequent with a larger dose, reports indicate that a dose of 75 μg/kg given over 3 to 5 minutes is more effective than a dose of 50 μg/kg.4 When used with corticosteroids, anti-RhD antibodies can be helpful for patients who are RhD positive. While some studies have demonstrated a patient efficacy of 37%, others report an efficacy of 50% to 70%. Nevertheless, care should be exercised as some patients may experience side effects such as acute hemolysis, nausea, fever, and headache.2 

Read more about ITP prognosis

Second-Line Treatments

Patients with chronic refractory ITP continue to have symptoms that do not respond to first- line therapies. Only when there is a serious bleeding problem are these individuals treated. Many new drugs have been introduced for chronic refractory ITP in recent years. These medications may be appropriate for cases in which splenectomy is contraindicated or has a higher risk, such as in children and pregnant patients. There is evidence of platelet response following treatment with azathioprine, cyclophosphamide, cyclosporin A, danazol, dapsone, mycophenolate mofetil, vinblastine, vincristine, and the thrombopoietin receptor agonist (TPO-RA) medications eltrombopag and romiplostim, though studies are still ongoing. Side effects from these treatments are generally manageable.2,7

Splenectomy 

Splenectomy, which is performed to reduce splenic sequestration of platelets, has typically been the second-line treatment for adult patients who fail initial therapy. It is recommended to avoid splenectomy for the first 12 months following initial diagnosis to allow spontaneous or treatment-induced remission. This surgery is rarely advised for pediatric patients as the majority of children recover spontaneously. Surgery is still an option, however, in cases that are severe and symptomatic and have persisted for more than a year. Children’s response rates are comparable to those of adults, with complete remission occurring in 70% to 80% of cases.2

Splenectomy procedures can be open or laparoscopic, as their response rates are identical. Even in individuals with extremely low platelet counts, splenectomy has been demonstrated to be safe, and prophylactic platelet infusion is typically not recommended. Splenectomy hazards include infection, bleeding, thrombosis, recurrence, and risks related to surgery.2

Read more about ITP surgical management

Rituxan®

Rituxan (rituximab) is a monoclonal antibody against the CD20 antigen for chronic and persistent ITP. The standard dose is 375 mg/m2/week given intravenously for 4 weeks.2 Severe side effects are very rare, and they include neutropenia and the reactivation of chronic infections like tuberculosis.4

Nplate®

Nplate (romiplostim) is a thrombopoietin receptor agonist medication. This TPO-RA drug functions like the hormone thrombopoietin, which is required for the production of platelets.8 

Nplate is indicated for adult or pediatric patients aged at least 1 year who have had ITP for at least 6 months and displayed an insufficient response to corticosteroids, immunoglobulins, or splenectomy.9 

Read more about Nplate

Promacta®

Promacta (eltrombopag) is another TPO-RA.10 This drug is useful in patients with chronic ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Promacta should only be used in patients with ITP whose degree of thrombocytopenia and clinical condition increase the risk of bleeding. It should not be utilized in an attempt to normalize platelet count.11

The most common adverse reactions that have been reported include nausea, vomiting, menorrhagia, myalgia, paresthesia, cataracts, dyspepsia, ecchymosis, thrombocytopenia, increased alanine transaminase and aspartate aminotransferase levels, and conjunctival hemorrhage.11

Read more about Promacta

References

  1. Justiz Vaillant AA, Gupta N. ITP-immune thrombocytopenic purpura. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2022. Updated July 8, 2022. Accessed October 24, 2022.
  2. Samson M, Fraser W, Lebowitz D. Treatments for primary immune thrombocytopenia: a review. Cureus. 2019;11(10):e5849. doi:10.7759/cureus.5849
  3. Provan D, Semple JW. Recent advances in the mechanisms and treatment of immune thrombocytopenia. EBioMedicine. 2022;76:103820. doi:10.1016/j.ebiom.2022.103820
  4. Warrier R, Chauhan A. Management of immune thrombocytopenic purpura: an update. Ochsner J. 2012;12(3):221-227.
  5. Jin F, Balthasar JP. Mechanisms of intravenous immunoglobulin action in immune thrombocytopenic purpura. Hum Immunol. 2005;66(4):403-410. doi:10.1016/j.humimm.2005.01.029
  6. ​​Immune thrombocytopenia treatments. UCSF Health. Accessed October 24, 2022. 
  7. Pietras NM, Pearson-Shaver AL. Immune thrombocytopenic purpura. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2022. Updated May 10, 2022. Accessed October 24, 2022.
  8. Nplate (romiplostim). GoodRx. Accessed October 24, 2022. 
  9. Nplate. Prescribing information. Amgen Inc; 2022. Accessed October 24, 2022.
  10. Promacta (eltrombopag). GoodRx. Accessed October 24, 2022. 
  11. Promacta. Prescribing information. GlaxoSmithKline; 2008. Accessed October 24, 2022.

Reviewed by Hasan Avcu, MD, on 10/30/2022.

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