Dapsone for primary immune thrombocytopenia in adults and children: an evidence-based review

[Differential diagnosis and therapy of immune thrombocytopenia]

Immune thrombocytopenia is caused by autoantibodies against surface antigens on platelets. Since only about 50 % of cases will allow the identification of glycoprotein-specific antibodies, ITP remains a diagnosis of exclusion. Apart from EDTA-induced pseudo thrombocytopenia, other diseases like secondary thrombocytopenia due to medication, a large number of other disease and hereditary thrombocytopenias must be taken into account. The first-line therapy of ITP includes corticosteroids and intravenous immunoglobulins. The second line consists of thrombopoietin receptor agonists, rituximab, or splenectomy. For further lines of therapy, Fostamatinib and non-steroidal immunosuppressives are available.

Lipoprotein lipids and apolipoproteins in primary immune thrombocytopenia: Results from a clinical characteristics and causal relationship verification, potential drug target identification by Mendelian randomization analyses

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease. Cellular and systemic lipid metabolism plays a significant role in the regulation of immune cell activities. However, the role of lipoprotein lipids and apolipoproteins in ITP remains elusive. The automatic biochemistry analyser was used to measure the levels of serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I (apoA-I), apoB, apoE and lipoprotein a [LP(a)]. Genetic variants strongly associated with circulating lipoprotein lipids and apolipoproteins (LDL-C, apoB, TG, HDL-C and apoA-I) were extracted to perform Mendelian randomization (MR) analyses. Finally, drug-target MR and passive ITP mice model was used to investigate the potential druggable targets of ITP. Levels of HDL-C, apoA-I, decreased and LP(a) increased in ITP patients compared with healthy controls. Low HDL-C was causally associated with ITP susceptibility. Through drug-target MR and animal modelling, ABCA1 was identified as a potential target to design drugs for ITP. Our study found that lipid metabolism is related to ITP. The causative association between HDL-C and the risk of ITP was also established. The study provided new evidence of the aetiology of ITP. ABCA1 might be a potential drug target for ITP.

Pediatric refractory immune thrombocytopenia: A systematic review

Pediatric immune thrombocytopenia (ITP) is an acquired disorder associated with autoimmune destruction and impairment of platelet production in children. Some children exhibit poor or transient response to ITP-directed treatments and are referred to as having refractory ITP (rITP). There is currently no consensus on the definition of rITP, nor evidence-based treatment guidelines for patients with rITP. After a survey of pediatric ITP experts demonstrated lack of consensus on pediatric rITP, we pursued a systematic review to examine the reported clinical phenotypes and treatment outcomes in pediatric rITP. The search identified 253 relevant manuscripts; following review, 11 studies proposed a definition for pediatric rITP with no consensus amongst them. Most definitions included suboptimal response to medical management, while some outlined specific platelet thresholds to define this suboptimal response. Common attributes identified in this study should be used to propose a comprehensive definition, which will facilitate outcome comparisons of future rITP studies.

A retrospective analysis of 122 immune thrombocytopenia patients treated with dapsone: Efficacy, safety and factors associated with treatment response

BACKGROUND

The optimum second-line treatment or best sequence of treatments for immune thrombocytopenia (ITP) are yet to be determined. Our institution has accumulated extensive experience regarding the use of dapsone as second-line therapy for ITP.

OBJECTIVES

We aimed to assess the efficacy rate and safety of dapsone treatment in ITP patients.

PATIENTS/METHODS

Here we report our experience in a retrospective study, including 122 patients, with a median treatment duration with dapsone of 6 months and a median follow-up period of 3.4 years.

RESULTS

The overall response rate in this cohort was 66%, including 24% of complete responses. Among responders, in 24% a relapse occurred while on treatment. Therefore, a sustained response was observed in 51% of patients. Interestingly, 81% of the responders maintained the response after the interruption of treatment, for a median time of 26 months. Side effects were reported in 16% of the patients in this cohort and treatment was interrupted due to side effects in 11% of patients. The main cause in these cases was hemolytic anemia and methemoglobinemia. Reductions in hemoglobin levels during the use of dapsone were seen in 94% of the patients. Responders presented significantly greater reductions in their hemoglobin levels than nonresponders did: median hemoglobin drop of 1.9 g/dl vs. 1.2 g/dl (p = .004).

CONCLUSIONS

Our findings suggest that dapsone has adequate efficacy and is well tolerated. Although the mechanism of action is still unclear, our observation that the degree in the drop of hemoglobin is greater in responders suggest a possible role of the blockage of the reticuloendothelial system in the therapeutic effect of the drug.

Dapsone for Pneumocystis jirovecii pneumonia prophylaxis - applying theory to clinical practice with a focus on drug interactions

Pneumocystis jirovecii pneumonia (PJP) is a potentially life-threatening infection that occurs in immunocompromised individuals. The incidence can be as high as 80% in some groups but can be reduced to less than 1% with appropriate prophylaxis. HIV-infected patients with a low CD4 count are at the highest risk of PJP. Others at substantial risk include haematopoietic stem cell and solid organ transplant recipients, those with cancer (particularly haematologic malignancies), and those receiving glucocorticoids, chemotherapeutic agents, and other immunosuppressive medications. Trimethoprim-sulfamethoxazole is an established first-line line agent for prevention and treatment of PJP. However, in some situations, this medication cannot be used and dapsone is considered a suitable cost-effective second line agent. However, information on potential interactions with drugs commonly used in immunosuppressed patients is lacking or contradictory. In this this article we review the metabolic pathway of dapsone with a focus on interactions and clinical significance particularly in patients with haematological malignancies. An understanding of this process should optimise the use of this agent.

Report of a 'consensus' on the lines of therapy for primary immune thrombocytopenia in adults, promoted by the Italian Gruppo di Studio delle Piastrine

Despite the publication in 2009 of a paper on 'terms and definitions of immune thrombocytopenia' (ITP), some unresolved issues remain and are reflected by the disagreement in the treatment suggested for primary ITP in adults. Considering that these disagreements could be ascribed to non-shared goals, we generated a 'consensus' on some terms, definitions, and assertions useful for classifying the different lines of treatment for primary ITP in adults according to their indications and goals. Agreement on the appropriateness of the single assertions was obtained by consensus for the following indicators: 1. classification of four 'lines of therapy'; 2. acceptance of the expression 'sequences of disease' for the indications of the respective four lines of treatment; 3_I . practicability of splenectomy; 3_Ib . acceptance, with only some exceptions, of a 'timing for elective splenectomy of 12 months'; and 4_a-d . 'goals of the four lines of therapy.' On the basis of the consensus, a classification of four lines of treatment for primary ITP in adults was produced. In our opinion, this classification, whose validity is not influenced by the recently published new guidelines of the American Society of Hematology (ASH) and reviews, could reduce the disagreement that still exists regarding the treatment of the disease.

Dapsone: An Old but Effective Therapy in Pediatric Refractory Immune Thrombocytopenia

There are no definitive guidelines for management of chronic or refractory immune thrombocytopenia (ITP) in children. Dapsone is an inexpensive and efficacious, yet neglected, therapeutic option for treatment of chronic ITP. We evaluated the efficacy and safety of dapsone in the management of chronic ITP in children. Children with chronic ITP < 14 years with minimum grade 2 bleeds refractory to either splenectomy/rituximab/eltrombopag; who were offered dapsone therapy were retrospectively analyzed. Dapsone intolerance and G6PD deficiency were excluded. Dapsone was started at a dose of 1-2 mg/kg/day. Response to dapsone as per international working group definitions, time to response along with side-effects were noted. Forty-four children enrolled; 29 analyzed. Nineteen were refractory to rituximab, 8 to splenectomy and 6 to eltrombopag. Median age was 9.8 years (3-14) with 16/29 males. Median dapsone dose was 1.59 mg/kg/day (range 1-2.1). Overall response was seen in 21/29 (72%): Complete Response in 7/29 (24%), Partial Response in 14/29 (48%). All responses were sustained for minimum 3 months. Median duration to response was 2.9 months (2-6.6). Median follow up was 28 months (6-73) and relapse rate-21%. Major side effects noted: Methemoglobinemia-01, skin ulceration-02. In three cases dapsone could be tapered and stopped without relapse. Dapsone is an economical and efficacious agent with good safety profile in childhood chronic/refractory ITP.

Efficacy and safety of dapsone as second line therapy for adult immune thrombocytopenia: A retrospective study of 42 patients

Dapsone is recommended as a second line therapy in immune thrombocytopenia (ITP), but is underused because of its potential side effects. The medical charts of 42 ITP patients treated with dapsone (100 mg/day) were retrospectively reviewed in order to assess its efficacy and safety in daily clinical practice. The overall response rate was 54.8% (n = 22, with a complete response in 38.1%) with a median time to response of 29 days (24-41 days). Patients with complete response had shorter disease duration whereas no difference was observed between responders and non-responders regarding age, sex or previous treatments received. Importantly, after dapsone withdrawal, a sustained response was observed in 5 patients, representing 12% of the whole cohort. Twenty percent of patients (n = 8) relapsed on therapy after 8.1 (6.5-13.6) months. Side effects occurred in 31% (n = 13) of patients, and required dapsone withdrawal in 22% (n = 9) or dosage reduction in 10% (n = 4) of the cases. Side effects resolved in all but one case. Overall, these data support dapsone as an interesting second line therapy in ITP, with a good safety and efficacy profile at a low cost.

Dapsone therapy for refractory immune thrombocytopenia patients: a case series

Background

Dapsone has been recommended as a second-line immunosuppressive agent for patients with immune thrombocytopenia (ITP).

Methods

We retrospectively analyzed the efficacy and safety of dapsone therapy in patients with ITP.

Results

Nine ITP patients were treated with dapsone at a dose of 50–100 mg/day between May 2013 and March 2016. All patients were refractory to multiple previous treatments, with a median of 7 agents (range, 4–8), and 3 patients had undergone a previous splenectomy. The median pre-treatment platelet count was 4×10⁹/L (range, 3–27×10⁹/L). Only 1 patient (11.1%) responded to dapsone therapy. No severe adverse events were observed, except for 1 case of dapsone hypersensitivity syndrome.

Conclusion

Although dapsone is still useful for some patients, it may be ineffective in heavily pretreated patients with profound thrombocytopenia.

Second-line therapies in immune thrombocytopenia

Immune thrombocytopenia (ITP) is a rare, acquired autoimmune condition characterized by a low platelet count and an increased risk of bleeding. Although many children and adults with ITP will not need therapy beyond historic first-line treatments of observation, steroids, intravenous immunoglobulin (IVIG), and anti-D globulin, others will have an indication for second-line treatment. Selecting a second-line therapy depends on the reason for treatment, which can vary from bleeding to implications for health-related quality of life (HRQoL) to likelihood of remission and patient preference with regard to adverse effects, route of administration, and cost. Published studies of these treatments are limited by lack of comparative trials, in addition to inconsistent outcome measures, definitions, and efficacy endpoints. This article provides an up-to-date comparison of the second-line treatments, highlighting important outcome measures including bleeding, HRQoL, fatigue, and platelet counts, which influence treatment selection in a shared decision-making model.

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.

How we manage immune thrombocytopenia in the elderly

With prolonged life expectancy, immune thrombocytopenia (ITP) is frequent in elderly people. In this setting, ITP diagnosis is challenging because of the concern about an underlying myelodysplastic syndrome. Studies of older adults are lacking, and recommendations for treatment are based mainly on expert opinion. The therapeutic strategy differs from that for younger patients and must take into account the greater risk of bleeding and thrombosis, presence of comorbidities, possible impaired cognitive performance or poor life expectancy and concomitant medications, such as anticoagulant and antiplatelet therapy. Steroids and intravenous immunoglobulin (IVIg) therapy remain the first-line treatments in elderly patients, but prolonged treatment with steroids should be avoided and IVIg treatment may lead to renal failure. Splenectomy is less effective than in young patients and risk of thrombosis is increased. Severe co-morbidities can also contraindicate surgery. Therefore, other second-line treatments are frequently preferred. Danazol and dapsone can be an option for the less severe ITP form. Rituximab is a good option except in patients with a history of infection or with hypogammaglobulinaemia. Thrombopoietin agonists are attractive, especially for patients with severe comorbidities or with limited life expectancy but the risk of thrombosis is a concern.

Platelet receptor expression and shedding: glycoprotein Ib-IX-V and glycoprotein VI

Quantity, quality, and lifespan are 3 important factors in the physiology, pathology, and transfusion of human blood platelets. The aim of this review is to discuss the proteolytic regulation of key platelet-specific receptors, glycoprotein(GP)Ib and GPVI, involved in the function of platelets in hemostasis and thrombosis, and nonimmune or immune thrombocytopenia. The scope of the review encompasses the basic science of platelet receptor shedding, practical aspects related to laboratory analysis of platelet receptor expression/shedding, and clinical implications of using the proteolytic fragments as platelet-specific biomarkers in vivo in terms of platelet function and clearance. These topics can be relevant to platelet transfusion regarding both changes in platelet receptor expression occurring ex vivo during platelet storage and/or clinical use of platelets for transfusion. In this regard, quantitative analysis of platelet receptor profiles on blood samples from individuals could ultimately enable stratification of bleeding risk, discrimination between causes of thrombocytopenia due to impaired production vs enhanced clearance, and monitoring of response to treatment prior to change in platelet count.