Combination therapy for refractory idiopathic thrombocytopenic purpura in adolescents

Refractory primary immune thrombocytopenia (ITP): current clinical challenges and therapeutic perspectives

Chronic primary immune thrombocytopenia (ITP) can today benefit from multiple therapeutic approaches with proven clinical efficacy, including rituximab, thrombopoietin receptor agonists (TPO-RA), and splenectomy. However, some ITP patients are unresponsive to multiple lines of therapy with prolonged and severe thrombocytopenia. The diagnosis of refractory ITP is mainly performed by exclusion of other disorders and is based on the clinician's expertise. However, it significantly increases the risk of drug-related toxicity and of bleedings, including life-threatening events. The management of refractory ITP remains a major clinical challenge. Here, we provide an overview of the currently available treatment options, and we discuss the emerging rationale of new therapeutic approaches and their strategic combination. Particularly, combination strategies may target multiple pathogenetic mechanisms and trigger additive or synergistic effects. A series of best practices arising both from published studies and from real-life clinical experience is also included, aiming to optimize the management of refractory ITP.

Identifying and treating refractory ITP: difficulty in diagnosis and role of combination treatment

Immune thrombocytopenia (ITP) is the most common acquired thrombocytopenia after chemotherapy-induced thrombocytopenia. Existing guidelines describe the management and treatment of most patients who, overall, do well, even if they present with chronic disease, and they are usually not at a high risk for bleeding; however, a small percentage of patients is refractory and difficult to manage. Patients classified as refractory have a diagnosis that is not really ITP or have disease that is difficult to manage. ITP is a diagnosis of exclusion; no specific tests exist to confirm the diagnosis. Response to treatment is the only affirmative confirmation of diagnosis. However, refractory patients do not respond to front-line or other treatments; thus, no confirmation of diagnosis exists. The first section of this review carefully evaluates the diagnostic considerations in patients with refractory ITP. The second section describes combination treatment for refractory cases of ITP. The reported combinations are divided into the era before thrombopoietin (TPO) and rituximab and the current era. Current therapy appears to have increased effectiveness. However, the definition of refractory, if it includes insufficient response to TPO agents, describes a group with more severe and difficult-to-treat disease. The biology of refractory ITP is largely unexplored and includes oligoclonality, lymphocyte pumps, and other possibilities. Newer treatments, especially rapamycin, fostamatinib, FcRn, and BTK inhibitors, may be useful components of future therapy given their mechanisms of action; however, TPO agents, notwithstanding failure as monotherapy, appear to be critical components. In summary, refractory ITP is a complicated entity in which a precise specific diagnosis is as important as the development of effective combination treatments.

How I treat refractory immune thrombocytopenia

This article summarizes our approach to the management of children and adults with primary immune thrombocytopenia (ITP) who do not respond to, cannot tolerate, or are unwilling to undergo splenectomy. We begin with a critical reassessment of the diagnosis and a deliberate attempt to exclude nonautoimmune causes of thrombocytopenia and secondary ITP. For patients in whom the diagnosis is affirmed, we consider observation without treatment. Observation is appropriate for most asymptomatic patients with a platelet count of 20 to 30 × 109/L or higher. We use a tiered approach to treat patients who require therapy to increase the platelet count. Tier 1 options (rituximab, thrombopoietin receptor agonists, low-dose corticosteroids) have a relatively favorable therapeutic index. We exhaust all Tier 1 options before proceeding to Tier 2, which comprises a host of immunosuppressive agents with relatively lower response rates and/or greater toxicity. We often prescribe Tier 2 drugs not alone but in combination with a Tier 1 or a second Tier 2 drug with a different mechanism of action. We reserve Tier 3 strategies, which are of uncertain benefit and/or high toxicity with little supporting evidence, for the rare patient with serious bleeding who does not respond to Tier 1 and Tier 2 therapies.

Cyclosporin A for persistent or chronic immune thrombocytopenia in children

Twenty percent of children with immune thrombocytopenia (ITP) develop a chronic course where treatment strategy is less established. Cyclosporin A (CSA) has been shown to be effective in small series of children with chronic ITP and might reduce the need for chronic steroid therapy and/or splenectomy. We reviewed consecutive patients below 18 years old with persistent or chronic ITP treated with CSA in our unit between January 1998 and June 2015. Thirty patients (14 boys and 16 girls) were included. The median age at initial diagnosis of ITP was 5 years (range 0.5-16.2 years). CSA was started at a median of 13.9 months (range 3.4-124 months) after initial diagnosis and given for a median duration of 9.3 months (range 0.2-63.9 months). The median platelet count before commencement was 12 × 10(9)/L (range 4-199 × 10(9)/L). The median dose of CSA was 6 mg/kg/day (range 2.4-7.5 mg/kg/day). Complete response (CR) or response (R) was achieved in 17 patients (57 %), and 7 (23 %) had sustained response. Side effects (most commonly hirsutism) were tolerable and reversible. CSA appeared effective in about half of persistent or chronic ITP patients and safe as a second-line agent in managing these children.

Management of immune thrombocytopenic purpura in children: potential role of novel agents

The treatment of immune thrombocytopenic purpura (ITP) in children is controversial, requiring individualized assessment of the patient and consideration of treatment options. If the platelet count is >10 000/μL and the patient is asymptomatic, a 'watch and wait' strategy is appropriate since most children with ITP will recover completely without pharmacotherapy. If therapy is indicated because of bleeding or a platelet count <10 000/μL, then treatment with glucocorticoids, intravenous immunoglobulin (IVIg), or anti-D are possible initial choices. Glucocorticoid treatment is the least expensive and is our usual first choice of therapy. Its use assumes that the blood counts and blood film have been evaluated to ensure the absence of evidence of alternative diagnoses, such as thrombotic thrombocytopenic purpura or incipient acute leukemia. IVIg is expensive and often causes severe headache, nausea and vomiting, and requires hospitalization at our institution. Anti-D therapy is also expensive and can only be used in patients who are Rhesus D positive. These therapies, even if only transiently effective, can be repeated if necessary. Children usually recover from newly diagnosed ITP, with or without multiple courses of medical therapy. If the disease becomes 'persistent' with severe thrombocytopenia and/or bleeding, and is no longer responsive to the three first-line therapies, the next approach includes the use of thrombopoietin receptor agonists or rituximab. When the disease persists for more than 1 year, it is considered chronic, and, if symptomatic, it may become necessary to consider third-line therapies, including splenectomy, alternative immunosuppressive agents, or combination or investigative chemoimmunotherapy. This review considers the indications, mechanism of action, and effectiveness of the traditional and novel treatment options for patients with ITP.

The efficacy of romiplostim in the treatment of severe thrombocytopenia associated to Evans syndrome refractory to rituximab

We present a case of a man diagnosed with systemic lupus erythematosus, associated antiphospholipid syndrome and Evans syndrome, who developed a severe thrombocytopenia refractory to treatment with first-line drugs, cyclophosphamide and rituximab, and who responded to romiplostim with a normalization of the platelet recount, which later enabled a therapeutic splenectomy to be performed.

Response to mercaptopurine for refractory autoimmune cytopenias in children

BACKGROUND

Several treatment strategies are available for children with severe immune thrombocytopenic purpura (ITP) and other immune cytopenias refractory to initial therapies. 6-Mercaptopurine (6MP) is one option, however it has not been well studied in children, especially as a single agent, and no pediatric case series have been reported since 1970.

PATIENTS AND METHODS

We reviewed the experience at our institution over 8 years, using 6MP as a steroid sparing treatment for children with ITP, auto-immune hemolytic anemia (AIHA) or Evans syndrome. A total of 29 pediatric patients were treated with 6MP from 2000 to 2007.

RESULTS

Response was defined as a rise in hemoglobin by at least 1.5 g/dl and to a level of 10 g/dl or greater in patients treated for anemia, or a platelet count >or=50 x 10(9)/L in patients treated for thrombocytopenia. We found an overall response rate of 83% among all patients. Fourteen percent of patients stopped drug because of side effects.

CONCLUSIONS

These results suggest that 6MP can be an effective single-agent treatment for refractory immune cytopenias in children. Prospective studies are warranted to determine long-term efficacy and toxicity and to more clearly define patient populations most likely to respond.

Childhood immune thrombocytopenic purpura: diagnosis and management

Immune thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by a low circulating platelet count caused by destruction of antibody-sensitized platelets in the reticuloendothelial system. ITP can be classified as childhood versus adult, acute versus chronic, and primary versus secondary. Persistence of thrombocytopenia defines the chronic form of the disorder. Secondary causes of ITP include collagen vascular disorders, immune deficiencies, and some chronic infections. This review focuses on the diagnosis and management of children who have acute and chronic ITP. Emphasis is placed on areas of controversy and new therapies.

Management of Evans syndrome

Evans syndrome is an uncommon condition defined by the combination (either simultaneously or sequentially) of immune thrombocytopenia (ITP) and autoimmune haemolytic anaemia (AIHA) with a positive direct antiglobulin test (DAT) in the absence of known underlying aetiology. This condition generally runs a chronic course and is characterised by frequent exacerbations and remissions. First-line therapy is usually corticosteroids and/or intravenous immunoglobulin, to which most patients respond; however, relapse is frequent. Options for second-line therapy include immunosuppressive drugs, especially ciclosporin or mycophenolate mofetil; vincristine; danazol or a combination of these agents. More recently a small number of patients have been treated with rituximab, which induces remission in the majority although such responses are often sustained for <12 months and the long-term effects in children are unclear. Splenectomy may also be considered although long-term remissions are less frequent than in uncomplicated ITP. For very severe and refractory cases stem cell transplantation (SCT) offers the only chance of long-term cure. The limited data available suggest that allogeneic SCT may be superior to autologous SCT but both carry risks of severe morbidity and of transplant-related mortality. Cure following reduced-intensity conditioning has now been reported and should be considered for younger patients in the context of controlled clinical trials.

[Splenectomy for thrombocytopenic purpura. Retrospective analysis of the postoperative course]

BACKGROUND

Idiopathic thrombocytopenic purpura (ITP) comprises approximately 8% of all haemorrhagic diseases. Typical findings are a very low platelet count which manifests as petechial bleeding. Therapy consists of medication and removal of the spleen if conservative therapy fails.

PATIENTS AND METHODS

Between 1988 and 1999, 47 patients with ITP were splenectomized in our surgical department. We examine the postoperative development of platelet counts and long-term results in 33 of these patients.

RESULTS

After splenectomy, more then 75% of our patients had normal platelet counts. In long-term examination, 58% remained in stable condition with normal platelet counts. Retrospectively we tried to identify preoperative clinical features that could predict the long-term outcome of splenectomy in ITP but were unable to find reliable factors.

CONCLUSION

Idiopathic thrombocytopenic purpura can be treated by surgical means but should be considered only when conservative treatment has failed. The long-term outcome of splenectomy is not predictable. Reliable predictive factors have to be identified through further research.

Childhood chronic immune thrombocytopenic purpura: unresolved issues

Chronic immune thrombocytopenic purpura (ITP), defined as a platelet count of below 150 x 109/L persisting for more than 6 months from onset of illness, occurs in approximately 20% to 25% of children with acute-onset ITP. A small subset of these patients (approximately 5%) will manifest symptomatic, severe thrombocytopenia (platelet counts <20 x 109/L) at 1 year or longer following diagnosis, and may require splenectomy. Complete/partial response rates following splenectomy in children with primary chronic ITP are of the order of 70% to 75%; response rates are lower in children with secondary ITP and those with complex autoimmune cytopenias (e.g., Evans syndrome). Laparoscopic splenectomy is increasingly preferred over open splenectomy. Patients should be immunized with the pneumococcal, Haemophilus type b and meningococcal vaccines before splenectomy; the duration of postsplenectomy antibiotic prophylaxis using penicillin or an equivalent antibiotic is controversial but should be at least until 5 years of age and for a minimum of 1 year postsplenectomy. Some experts advocate life-long antibiotic prophylaxis. Treatment of postsplenectomy failures is a challenge; partial/complete remission rates are low, and multimodality therapy may be more efficacious than monotherapy. The presence of an accessory spleen should be sought and removal considered if present. The role of newer treatment modalities such as anti-CD 20 remains to be established.