FAQ

1. What is ITP?

Immune thrombocytopenia (or idiopathic thrombocytopenic purpura ) (ITP) is a rare, serious and often chronic autoimmune disorder characterized by an abnormally low platelet count in the blood (thrombocytopenia). A normal platelet count is between 150,000 and 400,000/microliter of blood. If someone has a platelet count lower than 100,000/microliter of blood with no other reason for low platelets, that person is considered to have ITP1.

Platelets, which are also called thrombocytes, are specialized blood cells needed to prevent bleeding. Low platelet counts leave patients with ITP at risk for bruising and bleeding. The risk of a serious bleeding event increases when platelet counts drop to less than 30,000 platelets per microliter of blood. In extreme cases, death can occur due bleeding into the brain2.

2. What causes ITP?

ITP occurs when immune system cells (specialized lymphocytes) produce antibodies that cause the destruction of platelets in the spleen and other organs. As such, ITP historically has been considered a disease of platelet destruction. However, recent data also suggest that platelet counts in the blood may be caused by the inability of the body’s natural processes to produce platelets.

The specific cause of ITP is unknown. In some cases, ITP has appeared following a viral or bacterial infection, immunizations, exposure to a toxin, or in association with another illness such as lupus or the human immunodeficiency virus (HIV). ITP is not contagious.

3. How many people have ITP?

ITP occurs in children and adults. There are estimated to be about 90,000 adult chronic ITP patients each in Europe and the United States with increasing incidence in older age and equal distribution between men and women except in the mid-adult years (30-60 years), when the disease is more prevalent in women.

ITP is recognized as an orphan disease by U.S. Food and Drug Administration (FDA) and the European Medicines Agency.

4. What are the treatments for ITP?

Treatments for ITP include therapies that reduce the destruction of platelets (e.g. corticosteroids, intravenous immunoglobulin (IVIG), anti-RhD immunoglobulin (Anti-D), rituximab, cytotoxic drugs, having your spleen removed), or therapies that stimulate the production of new platelets called thrombopoietin receptor agonists (TPO-RAs).

  • Corticosteroids such as prednisone or dexamethasone are the most common initial treatment for most ITP patients. Approximately 80 percent of adult ITP patients require additional therapy once initial corticosteroids are stopped3
  • IVIG and Anti-D are effective in rapidly elevating platelets but their effects only last a few weeks so they are primarily used as a short-term treatment for ITP. Anti-D can only be used for non-splenectomised Rh+ patients
  • Rituximab is often used to treat patients with ITP but it not approved for this indication.
  • The TPO-RAs, eltrombopag (Promacta® (US)/Revolade (ROW)) and romiplostim (Nplate®) are the only approved therapies globally for the treatment of ITP.
  • The spleen is the primary site of antibody coated platelet destruction so having your spleen removed (splenectomy) removes the primary site of platelet destruction. A splenectomy is not appropriate for some patients due to preexisting medical conditions.

5. How effective are the current ITP current

Most patients will initially respond to treatment with traditional therapies like corticosteroids, IVIG and Anti-D. Treatment with newer therapies like the TPO-RAs or rituximab has also produced high response rates in ITP patients who have not had responded adequately to prior therapy.  

  • Corticosteroids

    While the majority of patients with ITP initially respond to treatment with corticosteroids, only 10% to 30% of adult patients enter stable remission once initial therapy is tapered or stopped.

  • IVIG and Anti-D

    Approximately 80% of patients will respond to either IVIG or Anti-D and the response only lasts for 3-4 weeks

  • TPO-RAs

    Eltrombopag and romiplostim have shown to be efficacious in splenectomized or nonsplenectomized patients with persistent or chronic thrombocytopenia producing responses in up to 80% of patients. However when these agents are discontinued, thrombocytopenia typically recurs.

  • Rituximab

    Platelet responses are usually noted within 4 to 8 weeks after the 1st infusion but may occur as late as 4 months. A complete or partial remission occurs in 25% to 50% of patients; durable responses (>1 yr) occur in a small percentage of patients4.

  • Splenectomy

    The published success rates for splenectomy associated with resolving ITP vary between 50-60 percent.

6. What are the side effects of the ITP treatments?

  • Corticosteroids

    Mood swings, steroid diabetes, weight gain, fluid retention, osteoporosis, peptic ulcers, hypertension, increased risk of infections

  • IVIG

    Headaches, renal insufficiency, aseptic memengitis, thrombosis, fever/chills, nausea

  • Anti-D

    Hemolytic anemia, fever/chills, renal failure, intravascular hemolysis

  • TPO-RAs

    Possible myelofibrosis, venous thrombosis, and rebound thrombocytopenia upon discontinuation. In addition, one agent can cause elevated liver enzymes

  • Rituximab

    Adverse effects include viral reactivation including progressive multifocal leukoencephalopathy (PML), hypogammaglobulinemia, and infusion-related side effects

  • Splenectomy

    Splenectomy has potential short- and long-term complications such as compromising the immune system putting patients at risk for serious infections.16 venous thrombosis (blood clots), and surgical complications ITP may recur after the procedure

7. How long do you have to take the current ITP drugs

The actual duration of therapy for a course of treatment varies considerably for the different treatment options.

  • Corticoisteroids are usually administered as an oral daily dose for 4 weeks and then therapy is tapered.
  • IVIG and Anti-D are administered as an intravenous infusion or injection over 1-2 days.
  • Rituximab is typically administered as 4 weekly intravenous infusions.
  • Eltrombopag is administered as a daily oral therapy
  • Romiplostim is administered as a weekly injection under the skin

Since only a small percentage of patients treated will maintain an elevated platelet count after therapy is discontinued continuous or repeated courses of treatment will be necessary

8. What is the annual patient cost for treatment?

The cost of treatment varies considerably depending on the therapy. Corticosteroid therapy is usually less than $100 a month while the biologic therapies such as IVIG, Anti-D, and rituximab can cost more than $10,000 for a course of treatment and the TPO-RAs may be approximately $5,000/month.

9. What is the total market for ITP drugs?

The two most recently approved therapies for ITP, Promacta® (US)/Revolade (ROW) and Nplate® generated sales of more than $700M in 2013 so the total market for ITP is assumed to be in excess of $1B.

References

  1. Rodeghiero F, Stasi R, Gernsheimer T, et al. Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: report from an international working group. Blood. 2009;113(11):2386-2393.
  2. Neunert C. et al. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood, 2011, 117: 4190-4207
  3. Neunert C. Current management of immune thrombocytopenia. Hematology Am Soc Hematol Educ Program. 2013: 276-82.
  4. Cines, D.B. and Bussel, J.B., How I treat idiopathic thrombocytopenic purpura (ITP). Blood, 2005 106: 2244-2251