Thrombopoietin Receptor Agonists: Clinical Use and Evaluation of Treatment Efficacy

Idiopathic thrombocytopenic purpura (ITP), or primary immune thrombocytopenia, is an orphan disease associated with thrombocytopenia. One of the most recent and promising approaches to ITP treatment is the use of thrombopoietin receptor agonists (TPO-RAs). The scope of TPO-RA use is expanding rapidly, which stimulates the development of both innovator and generic (or biosimilar) medicines. The aim of the paper was to assess TPO-RA role in ITP treatment, methodological approaches to TPO-RA development, and feasibility of using the platelet count as a pharmacodynamic marker in bioequivalence studies of peptide TPO-RAs in healthy volunteers. Clinical development of new medicines for the treatment of thrombocytopenia includes comparative, parallel-group trials lasting about a year. The standard approach to bioequivalence studies, which is based on the results of comparative pharmacokinetic studies, can be used in marketing authorisation applications for generic non-peptide TPO agonists, while peptide TPO agonists have to comply with specific requirements for biosimilar products. The orphan status of ITP does not affect the development strategy and study design, but it limits the number of patients that could be included into the study. In the absence of valid surrogate biomarkers of efficacy, demonstration of comparable clinical efficacy of the biosimilar and reference drug is usually required in a randomised, parallel, preferably double-blind comparative study. On the other hand, clinical comparability of the biosimilar and reference drug can also be demonstrated in comparative pharmacodynamic studies, if the selected biomarker is a well-established and valid surrogate marker which correlates with patient clinical outcome. Platelet count is a key parameter in both diagnosis of diseases associated with low platelet levels and assessment of treatment efficacy. Therefore, it can be used as a pharmacodynamic marker in bioequivalence studies of biosimilar peptide TPO-RAs. It was concluded that such studies could be performed in healthy volunteers, and not in patients, whose participation in clinical trials is limited due to the orphan status of ITP.

Download Full-text

Short Term Treatment With Thrombopoietin-Receptor Agonists For Patients With Immune Thrombocytopenic Purpura (ITP) Before Splenectomy

Blood ◽

10.1182/blood.v122.21.1086.1086 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1086-1086 ◽

Cited By ~ 1

Author(s):

Yosef Kalish ◽

Galia Spectre ◽

David Varon

Keyword(s):

Platelet Count ◽

Immune Thrombocytopenic Purpura ◽

Complete Blood Count ◽

Conflicts Of Interest ◽

Short Term Treatment ◽

Thrombocytopenic Purpura ◽

Thrombopoietin Receptor Agonists ◽

Receptor Agonists ◽

Short Course ◽

Thrombopoietin Receptor

Abstract The thrombopoietin-receptor agonists (romiplostim and eltrombopag) were approved recently as treatments for patients with immune thrombocytopenic purpura (ITP). Splenectomy remains a common second line treatment for ITP with the highest remission rate compared with alternative therapies. It has been reported that splenectomy can be safely performed in patients with a platelet count of 40-50,000 per cubic millimeter but many patients do not reach these values. Intravenous immune globulins (IVIG) are often used before splenectomy in order to increase the platelet count before surgery. The aim of this study was to determine whether a short course of thrombopoietin-receptor agonists can be used as a reliable and safe treatment to increase the platelet count in patients with ITP before splenectomy. Between 2010 and 2012, fifteen patients with ITP, all refractory to steroids, were scheduled for splenectomy. Treatment with thrombopoietin-receptor agonists (romiplostim or eltrombopag) was started 3 weeks before splenectomy. Eight patients received eltrombopag at a dose of 50 mg/day orally until 3 days before splenectomy. For romiplostim, a subcutaneous injection of 3 mcg/kg was given weekly to 7 patients. The last injection was given one week before splenectomy. Complete blood count was repeated every week and the dose of romiplostim was adjusted (up to 10 mcg/kg or down to 1 mcg/kg) based on the platelet count increment. Response was defined as a platelet count of 50,000 or more per cubic millimeter. Mean platelet count before treatment was 11,000±8,000 cells per cubic millimeter. All patients, except one patient on romiplostim, responded to the treatment with a mean platelet count of 74± 25 cells per cubic millimeter on the day of splenectomy (p<0.01). Similar effect was noticed among responders of the two drugs. Four patients from the romiplostim group responded to a 3 mcg/kg dose. Two patients responded to increased doses of 7 and 10 and 10 mcg/kg. One patient did not respond to 10 mcg/kg of romiplostim but later responded to IVIG. The two drugs were well tolerated with no side effects except for mild liver function abnormalities in one patient in the eltrombopag group. No thromboembolic complications or excessive bleeding were reported for these patients. In summary, we report that a short course of thrombopoietin-receptors agonists can effectively and safely increase the platelet count in steroid resistant ITP patients before splenectomy. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Second-line administration of thrombopoietin receptor agonists in immune thrombocytopenia: Italian Delphi-based consensus recommendations

Therapeutic Advances in Hematology ◽

10.1177/20406207211048361 ◽

2021 ◽

Vol 12 ◽

pp. 204062072110483

Author(s):

Monica Carpenedo ◽

Erminia Baldacci ◽

Claudia Baratè ◽

Alessandra Borchiellini ◽

Francesco Buccisano ◽

...

Keyword(s):

Platelet Count ◽

Delphi Technique ◽

Immune Thrombocytopenia ◽

Daily Practice ◽

Second Line ◽

Thrombopoietin Receptor Agonists ◽

Receptor Agonists ◽

Line Therapy ◽

Thrombopoietin Receptor ◽

Primary Immune Thrombocytopenia

Introduction: In patients with primary immune thrombocytopenia (ITP), a short course of steroids is routinely given as first-line therapy. However, the response is often transient and additional therapy is usually needed. Thrombopoietin receptor agonists (TPO-RAs) are frequently used as second-line therapy, although there is little clinical guidance on the timing of their administration and on tapering/discontinuation of the drug. To provide clinical recommendations, we used the Delphi technique to obtain consensus for statements regarding administration and on tapering/discontinuation of second-line TPO-RAs among a group of Italian clinicians with expertise in management of ITP. Methods: The Delphi process was used to obtain agreement on five statements regarding initiation and on tapering/discontinuation of second-line TPO-RAs. Agreement was considered when 75% of participants approved the statement. Eleven experts participated in the voting. Results: Full consensus was reached for three of the five statements. The experts held that an early switch from corticosteroids to a TPO-RA has the dual advantage of sparing patients from corticosteroid abuse and improve long-term clinical outcomes. All felt that dose reduction of TPO-RAs can be considered in patients with a stable response and platelet count >100 × 109/L that is maintained for at least 6 months in the absence of concomitant treatments, although there was less agreement in patients with a platelet count >50 × 109/L. Near consensus was reached regarding the statement that early treatment with a TPO-RA is associated with an increase in clinically significant partial or complete response. The experts also agreed that optimization of tapering and discontinuation of TPO-RA therapy in selected patients can improve the quality of life. Conclusion: The present consensus can help to provide guidance on use of TPO-RAs in daily practice in patients with ITP. Plain language summary Second-line administration of thrombopoietin receptor agonists in immune thrombocytopenia There is little guidance on the timing of administration and tapering/discontinuation of thrombopoietin receptor agonists (TPO-RAs) in patients with primary immune thrombocytopenia (ITP). The Delphi technique was used to obtain consensus for five statements. The present consensus among Italian clinicians aims to provide guidance on second-line use of TPO-RAs for patients with ITP in daily practice.

Download Full-text

Mycophenolate Mofetil and Thrombopoietin Receptor Agonists in the Treatment of Refractory Thrombocytopenia in Patients with Autoimmune Lymphoproliferative Syndrome

Blood ◽

10.1182/blood.v118.21.2218.2218 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2218-2218

Author(s):

Leejah Chang ◽

Susan Price ◽

Katie Perkins ◽

Joie Davis ◽

Patricia Aldridge ◽

...

Keyword(s):

Platelet Count ◽

High Dose ◽

Autoimmune Lymphoproliferative Syndrome ◽

Thrombopoietin Receptor Agonists ◽

Platelet Counts ◽

Receptor Agonists ◽

50Mg Daily ◽

Thrombopoietin Receptor ◽

Lymphoproliferative Syndrome

Abstract Abstract 2218 Autoimmune lymphoproliferative syndrome (ALPS), often due to an inherited defect in the FAS gene, presents with chronic non-malignant lymphadenopathy, splenomegaly, and autoimmune cytopenias (Oliveira JB et al. “Revised diagnostic criteria and classification for the autoimmune lymphoproliferative syndrome (ALPS): report from the 2009 NIH International Workshop”. Blood. 2010 Oct 7;116(14):e35-40). Thrombocytopenia has been noted in approximately 23% of ALPS patients. These patients, especially those with massive splenomegaly and hypersplenism, are often refractory to standard dose short-term corticosteroid regimens and intravenous immunoglobulins (IVIG). Mycophenolate mofetil (MMF) has been used for persistent thrombocytopenia as a steroid sparing long-term measure in 40 out of 245 ALPS patients in our cohort. The median age at initiation of MMF was 10.5 years (range 7 months to 43 years) with an average follow-up of 3.8 years on MMF (range 3 months to 11 years). Here we share our experience over the last 7 months related to the use of thrombopoietin receptor agonists in 3 ALPS patients who have persistent, severe, MMF-refractory thrombocytopenia (platelets <10,000/uL) (Figure). Patient 1 is a 21 year old man with ALPS-FAS and splenomegaly who has been on MMF for 2 years. He presented with monthly episodes of thrombocytopenia requiring high dose corticosteroids and IVIG followed by four weeks of rituximab and daily prednisone without any durable improvement in his thrombocytopenia. He was started on eltrombopag 50mg daily and was able to taper off prednisone in one month with sustained stable platelet count. Three months after starting eltrombopag, he was able to survive surgical intervention for a spontaneous pneumothorax while on eltrombopag and MMF. Patient 2 is an 18 year old woman with ALPS-FAS and surgical asplenia who has been on MMF for approximately 7 years. She began having significant, symptomatic thrombocytopenia refractory to high-dose corticosteroids with transient responses to IVIG. She was started on eltrombopag 50mg daily with MMF and initially responded. However, when MMF was discontinued her platelet count plummeted. Despite reinitiating MMF, her platelet counts never recovered on eltrombopag and she continued to require monthly IVIG. She was eventually switched to romiplostim, and was incrementally increased to the maximum dose of 10mcg/kg/week. Her platelet counts continue to fluctuate, but she has not required any IVIG in over one month. Patient 3 is a 19 year old man with ALPS-U and surgical asplenia who has been on MMF for the last 9 years. During the past year he has had episodes of symptomatic thrombocytopenia requiring monthly courses of high dose corticosteroids and IVIG. After initiation of eltrombopag, he had a significant rise in his platelet counts. However, upon discontinuation of MMF, his platelet counts plummeted. MMF was restarted and he was trialed on multiple, different eltrombopag dosing regimens leading to supratherapeutic responses with platelet counts over 1,000,000/uL. Eltrombopag was held during these periods to allow for the significant thrombocytosis to resolve, but withholding eltrombopag led to platelet counts to eventually fall precipitously. Furthermore, he also developed severe headaches due to MMF and MMF had to be discontinued. After multiple dosing regimens, he eventually maintained a stable platelet count on eltrombopag 50mg daily for 5 days alternating with eltrombopag 25mg for 2 days without the concomitant use of MMF. Recently, there has been increasing evidence supporting the use of thrombopoietin receptor agonists in the treatment of refractory immune thrombocytopenia. MMF continues to be well tolerated as a long-term corticosteroid sparing drug for patients with ALPS complicated by chronic, refractory thrombocytopenia. Our preliminary experience suggests that there may be a role for thrombopoietin receptor agonists, most likely in combination with an immunosuppressive agent such as MMF, in the treatment of refractory thrombocytopenia in patients with ALPS. However, schedule and duration of therapy with this class of drugs needs further long term evaluation. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Effects of thrombopoietin receptor agonists on procoagulant state in patients with immune thrombocytopenia

Thrombosis and Haemostasis ◽

10.1160/th13-10-0873 ◽

2014 ◽

Vol 112 (07) ◽

pp. 65-72 ◽

Cited By ~ 12

Author(s):

María Álvarez Román ◽

Ihosvany Bello ◽

Elena G. Arias-Salgado ◽

María Isabel Pollmar ◽

Víctor Yuste ◽

...

Keyword(s):

Platelet Count ◽

Immune Thrombocytopenia ◽

Low Frequency ◽

Compensatory Mechanism ◽

Thrombopoietin Receptor Agonists ◽

Receptor Agonists ◽

Thrombopoietin Receptor ◽

Before And After ◽

Healthy Control ◽

Bleeding Episodes

SummaryThrombopoietin receptor agonists (TPO-RA) have recently been introduced for the treatment of immune thrombocytopenia (ITP), an antiplatelet-antibodies autoimmune disease. The observation of a low frequency of bleeding episodes despite their thrombocytopenia suggests the existence of a compensatory mechanism. This study aimed to evaluate the effect of TPO-RA treatment on platelet function and on the procoagulant state in ITP patients before (ITP-bR) and after responding (ITP-aR) to treatment. Plasma- and microparticle (MP)-associated procoagulant capacity from ITP patients was similar before and after responding to the TPO-RA regimen but higher than the healthy control values. High MP-associated procoagulant activity did not seem to be due to increased platelet activation, since platelet stimulation by agonists was reduced in ITP-bR and ITP-aR patients. It could be related to increased platelet apoptosis, evaluated in terms of surface phosphatidylserine (PS), observed in both ITP groups. In summary, TPO-RA treatment increased platelet count but did not ameliorate their function and did not change plasma- and MP-associated procoagulant state of ITP patient responders to this therapy.

Download Full-text

Thrombopoietin Receptor Agonists in Children with Immune Thrombocytopenia: A New Therapeutic Era

Endocrine Metabolic & Immune Disorders - Drug Targets ◽

10.2174/1871530320666200531142244 ◽

2020 ◽

Vol 20 ◽

Author(s):

Giuseppe Lassandro ◽

Valentina Palladino ◽

Giovanni Carlo Del Vecchioa ◽

Viviana Valeria Palmieri ◽

Paola Carmela Corallo ◽

...

Keyword(s):

Immune Thrombocytopenia ◽

Treatment Options ◽

Thrombopoietin Receptor Agonists ◽

Receptor Agonists ◽

Thrombopoietin Receptor ◽

Related Quality ◽

Health Related

Background and Objective: Immune thrombocytopenia (ITP) is a common bleeding disorder in childhood. The management of ITP in children is controversial, requiring personalized assessment of patients and therapeutic choices. Thrombopoietin receptor agonists (TPO-RAs), eltrombopag and romiplostim, have been shown to be safety and effective for the treatment of pediatric ITP. The aim of our research is defining the role of thrombopoietin receptor agonists in the management of pediatric ITP. Method: This review focuses on the use of TPO-RAs in pediatric ITP, in randomized trials and in clinical routine, highlighting their key role in management of the disease. Results: Eltrombopag and romiplostim appear effective treatment options for children with ITP. Several clinical studies have assessed that the use of TPO-RAs increases platelet count, decreases bleeding symptoms and improves health-related quality of life. Moreover, TPO-RAs are well tolerated with minor side effects. Conclusion: Although TPO-RAs long term efficacy and safety still require further investigations, their use is gradually expanding in clinical practice of children with ITP.

Download Full-text