Gender and duration of disease differentiate responses to rituximab-dexamethasone therapy in adults with immune thrombocytopenia

Immune thrombocytopenia in adolescents and young adults

Previous guidelines for the treatment of immune thrombocytopenia (ITP) have traditionally focused on a dichotomy between pediatric and adult ITP. Adolescents and young adults (AYAs) do not neatly fit into either the pediatric or adult ITP group. A deeper understanding of ITP's natural history, risk factors for chronicity, and outcomes in AYAs is a crucial first step toward developing tailored treatment algorithms. Such data could form the basis for recommendations targeting this underrepresented yet clinically distinct population. Ultimately, age-adapted trials may improve long-term outcomes, reduce toxicity, and enhance quality of life for AYAs with ITP. The AYAs collaboration-drawing on data from the Pediatric and Adult Registry on Chronic ITP (PARC-ITP), Registre Midi- Pyrénéen-France (CARMEN-France) adult registry in Toulouse, and the National Prospective Cohort for Children with Chronic Autoimmune Cytopenia (OBS'CEREVANCE) in Bordeaux, France-aims to address the information gap in AYAs with ITP. To date, four analyses have been undertaken (using data from 2004 to 2021), each addressing the major clinical aspects of ITP in patients aged 12-25 years: (1) newly diagnosed ITP, (2) chronic disease, (3) refractory courses, and (4) secondary (sITP) forms.

Immune thrombocytopenia and pregnancy: challenges and opportunities in diagnosis and management

INTRODUCTION

Immune thrombocytopenia (ITP) affecting pregnancy is a diagnostic and often a therapeutic challenge.

AREAS COVERED

We review the current diagnostic criteria for ITP in pregnancy and the potential utility of laboratory tests. We discuss the impact of ITP on pregnancy outcomes and the effects of pregnancy on patients living with chronic ITP.  We describe the criteria for intervention, the evidence supporting first-line treatment approaches and the therapeutic decisions and challenges in cases refractory to steroids and IVIG. We review the evidence supporting the potential use of thrombopoietin receptor agonists for refractory thrombocytopenia. Finally, we describe the diagnostic, prognostic, and treatment approaches to neonatal ITP and considerations regarding breastfeeding. We searched the terms 'immune thrombocytopenia' and 'pregnancy' on PubMed to identify the relevant literature published before 31 December 2023, including within cited references.

EXPERT OPINION

Decreased platelet production may play a role in pregnancy-related ITP exacerbation. Putative mechanisms include placental hormones, such as inhibin. Although IVIG and prednisone usually suffice to achieve hemostasis for delivery, second-line agents are sometimes required to allow for neuraxial anesthesia. There is growing evidence supporting the use of romiplostim during pregnancy; however, its risk of venous thromboembolism warrants further evaluation.

Rituximab as a treatment for refractory immune thrombocytopenia during pregnancy

Immune thrombocytopenia (ITP) is most common in women during their reproductive years. When a low platelet count occurs for the first time during pregnancy, the differential diagnosis includes pregnancy-specific conditions. Although ITP is the most common cause of thrombocytopenia early in pregnancy, pregnancy-related thrombocytopenia develops mainly in late gestation. As maternal and neonatal outcomes are usually favourable, ITP per se is not a contraindication for pregnancy. We report the case with a literature review of patient with ITP, whose diagnosis was established in early pregnancy. This condition was refractory to first-line treatments, such as high-dose steroids and intravenous immunoglobulin and other splenectomy-sparing approaches, as rituximab, having the control been reached on the third trimester after splenectomy. Although not effective in this case, we still believe that rituximab should be considered before surgery during pregnancy.

Zuberitamab, an innovative anti-CD20 monoclonal antibody, for patients with primary immune thrombocytopenia in China: a randomized, double-blind, placebo-controlled, phase 2 study

Background

Primary immune thrombocytopenia (ITP) is an autoimmune disease, and rituximab (RTX) induces long-term effect as second-line treatments. Zuberitamab is an innovative anti-CD20 monoclonal antibody, which was first developed in China and launched in diffuse large B lymphoma. This study aimed to investigate the safety, efficacy, and anticipated therapeutic dose of zuberitamab in Chinese ITP patients.

Methods

This randomised, double-blind, placebo-controlled, phase 2 study was conducted at 26 hospitals in China. Eligible patients were aged 18-70 years, had primary immune thrombocytopenia for more than 6 months, and did not respond or relapsed after previous treatment and had a pre-treatment platelet count of <30 × 109/L. Patients randomly received zuberitamab in a dose escalation (100/300/600 mg) or placebo once-weekly for 4 weeks and followed up to 24 weeks. The primary endpoint is the proportion of patients with a platelet count ≥50 × 109/L at week 8. Secondary endpoints include the proportion of patients with platelet counts ≥50 × 109/L or ≥100 × 109/L at least once within week 12/24, the proportion of patients experiencing platelets increased twice more than baseline as well as ≥30 × 109/L at least once during the treatment. Adverse events, pharmacokinetic, B cell depletion and immunogenicity were also assessed. This study is registered with https://www.chictr.org.cn/as ChiCTR2100050513.

Findings

From October 2021 to March 2023, 50 patients were screened for eligibility, of whom 32 patients were enrolled and randomly assigned to placebo (n = 4), zuberitamab 100 mg (n = 10), 300 mg (n = 8) and 600 mg (n = 10) groups. The primary endpoint (PLT ≥50 × 109/L at week 8) was achieved by 40% of patients in the 100 mg group, while none in the other groups. Within 12 weeks, the proportions of patients in each treatment group achieving at least one instance of platelet count ≥50 × 109/L or ≥100 × 109/L or an increase twice more than baseline as well as ≥30 × 109/L were (70%, 38%, 50%), (60%, 13%, 30%), and (80%, 50%, 70%) in zuberitamab 100/300/600 mg groups, respectively. By week 24, the proportions of patients achieving these secondary endpoints remained relatively stable or showed a mild increase of around 10%. The anticipated therapeutic dose of zuberitamab was 100 mg. The plasma concentration of zuberitamab showed an increasing trend with dose (100 mg-600 mg) and linear pharmacokinetic behavior. CD19+ B cells and CD20+ B lymphocytes rapidly declined to 0% within one week and consistently maintained reduced levels throughout the entire treatment phase in three groups. Adverse events occurred in all patients with most of them were mild to moderate, no severe infections occurred. A slight decrease in immunoglobulins was observed in the 600 mg group, but gradually recovered at week 20. Three patients (2 in 100 mg and 1 in 600 mg group) were tested positive for anti-zuberitamab antibodies. We also observed that women, disease duration <12 months, and MAIPA + patients may have higher response rates.

Interpretation

This study preliminarily confirmed that 100 mg zuberitamab was safe and effective in treating ITP and was recommended to support further investigation.

Funding

National Natural Science Foundation of China and Zhejiang Bioray Biopharmaceutical Co. Ltd.

Immune thrombocytopenia (ITP) in pregnancy

Immune thrombocytopenia (ITP) in pregnancy is challenging for both mother and fetus. Understanding the pathophysiology, treatments, and risks to the mother and fetus leads to proper management resulting in successful pregnancy and delivery in almost all cases.1 ITP in a pregnant woman has many similarities to ITP not in pregnancy although gestational thrombocytopenia can be confused with ITP. However, recognizing differences is instrumental in avoiding bleeding complications and toxicities of treatment. This Nutshell review focuses on the natural history of ITP in pregnancy, its treatment, and dilemmas.

Pathogenesis of refractory ITP: Overview

A subset of individuals with 'primary' or 'idiopathic' immune thrombocytopenia (ITP) who fail to respond to conventional first- and second-line agents or who lose responsiveness are considered to have 'refractory' disease (rITP), placing them at increased risk of bleeding and complications of intensive treatment. However, the criteria used to define the refractory state vary among studies, which complicates research and clinical investigation. Moreover, it is unclear whether rITP is simply 'more severe' ITP, or if there are specific pathogenic pathways that are more likely to result in refractory disease, and whether the presence or development of rITP can be established or anticipated based on these differences. This paper reviews potential biological features that may be associated with rITP, including genetic and epigenetic risk factors, dysregulation of T cells and cytokine networks, antibody affinity and specificity, activation of complement, impaired platelet production and alterations in platelet viability and clearance. These findings indicate the need for longitudinal studies using novel clinically available methodologies to identify and monitor pathogenic T cells, platelet antibodies and other clues to the development of refractory disease.

Chronic refractory immune thrombocytopenia in adolescents and young adults

Defining immune thrombocytopenia (ITP) in two age groups-children and adults-overlooks the specific clinical features and needs of adolescents and young adults (AYAS). We previously reported a high risk of chronic disease at 12 months (50%); however, data on the course of chronic ITP, the risk of refractoriness and treatment strategies in AYAS are limited. Data from patients aged 12-25 years with chronic primary ITP at 12 months were extracted from three large registries between 2004 and 2021. Clinical and laboratory data were evaluated until 48 months of follow-up (FU). Refractory ITP was defined as the administration of ≥3 different lines of therapy. A total of 427 AYAS (64% female) with chronic ITP were included. Overall, 7% and 14% were classified as 'refractory' at 12 and 48 months of FU respectively. The proportion of males was greater in the refractory group than in the non-refractory group (43% vs. 35%). AYAS with refractory disease displayed lower median platelet counts, more bleeding and a higher need for treatment at initial diagnosis and FU than non-refractory patients. This study reveals that refractory ITP is uncommon in AYAS; however, AYAS with refractory ITP display a high disease burden at all time points, including at initial diagnosis.

Rituximab resistance in ITP and beyond

The pathophysiology of immune thrombocytopenia (ITP) is complex and encompasses innate and adaptive immune responses, as well as megakaryocyte dysfunction. Rituximab is administered in relapsed cases and has the added benefit of inducing treatment-free remission in over 50% of patients. Nevertheless, the responses to this therapy are not long-lasting, and resistance development is frequent. B cells, T cells, and plasma cells play a role in developing resistance. To overcome this resistance, targeting these pathways through splenectomy and novel therapies that target FcγR pathway, FcRn, complement, B cells, plasma cells, and T cells can be useful. This review will summarize the pathogenetic mechanisms implicated in rituximab resistance and examine the potential therapeutic interventions to overcome it. This review will explore the efficacy of established therapies, as well as novel therapeutic approaches and agents currently in development.

Alternatives for managing patients with newly diagnosed immune thrombocytopenia: a narrative review

INTRODUCTION

Primary immune thrombocytopenia (ITP) is an acquired bleeding disorder. Conventionally, first-line ITP therapy aims to obtain a rapid response and stop or decrease the risk of bleeding by increasing the platelet count. At this point, the duration of the response, the tolerability, and the long-term safety of pharmacologic interventions are considered less of a priority. Combination treatments that simultaneously address multiple disease mechanisms are an attractive strategy to increase efficacy in acute ITP therapy. In this review, we discuss the treatment of newly diagnosed ITP patients, emphasizing the use of new combinations to benefit from their synergy.

AREAS COVERED

This article summarizes conventional treatment, recent and novel combinations, and COVID-19 management recommendations of newly diagnosed ITP patients.

EXPERT OPINION

The key areas for improvement consider the long-term effects of conventional first-line therapy, reducing relapse rates, and extending responses to achieve long-term remission. Although corticosteroids remain first-line therapy, restricting their use to avoid toxicity and the increasing use of rituximab and TPO-RAs in the first three months after diagnosis open the landscape for future interventions in frontline therapy for ITP. First-line therapy intensification or synergistic drug combination offers a potential and realistic shift in future treatment guidelines.

Single-dose versus low-dose rituximab in corticosteroid-resistant or relapsed ITP: A multicenter, randomized, controlled study

Primary immune thrombocytopenia (ITP) is an autoimmune bleeding disorder, in which rituximab (RTX) induces the best long-term effect among recommended second-line treatments. Nevertheless, the optimal regimen of RTX remains unclear. We herein conducted a prospective, multicenter, open-label, randomized controlled trial to compare the efficacy and safety of RTX at two different dosage regimens in patients with corticosteroid-resistant or relapsed ITP. Recruited patients were randomly assigned (1:1) to receive either RTX at a repeated low dose (100 mg weekly for 4 weeks, LD-RTX) or at a single dose (375 mg/m² , S-RTX). Overall response was achieved in 64.3% of patients who received LD-RTX versus 67.4% of those receiving S-RTX (p = .759). The complete response (CR) rate was 23.8% after LD-RTX and 28.3% after S-RTX (p = .635). In health-related quality of life, S-RTX improved patients' psychological status, quality of life, social activities, and work compared with LD-RTX. Furthermore, S-RTX significantly reduced physician visits without compromising efficacy. Our findings demonstrate that a S-RTX is comparable to LD-RTX in effectiveness and safety for treatment of corticosteroid-resistant or relapsed ITP. The single-dosage regimen optimizes the use of medical resources, improves the cost-effectiveness of RTX, and represents a promising and more convenient replacement for LD-RTX in ITP. This study has been completed and is registered with ClinicalTrials.gov, number NCT03258866.

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.

A modified regimen of low-dose rituximab therapy for patients with refractory immune thrombocytopenia associated with systemic lupus erythematosus

Background:

Severe and refractory immune thrombocytopenia (ITP) affects the life expectancy of patients with systemic lupus erythematosus (SLE) and poses a challenge in their clinical management. This intervention study employed a small sample size to evaluate the efficacy and safety of a modified low-dose rituximab (RTX) regimen in patients with SLE-associated refractory ITP.

Methods:

Eight patients with severe SLE-associated refractory ITP were enrolled in this intervention study. They received an infusion of intravenous RTX (200 mg) on days 1 and 15. The dose of corticosteroids (prescribed previously) was gradually tapered, and immunosuppressants were withdrawn. Patients were followed up at 1, 3, 6, and 12 months; platelet counts, other laboratory indicators, and side effects were recorded. We used intention-to-treat analysis to calculate the response rate.

Results:

Seven participants (87.5%) completed the study. At 1 month, two patients (25.0%) achieved partial response (PR); the PR rate increased to 87.5% at 3 months. At 6 months, three patients (37.5%) achieved complete response (CR). However, the CR rate dropped to 25.0% at 12 months. The overall responses (ORs) were 25.0% (2/8), 87.5% (7/8), 75.0%(6/8), and 75.0%(6/8) at 1, 3, 6, and 12 months, respectively. Two patients developed a mild infusion reaction and one discontinued the study due to herpes zoster virus infection and an allergic reaction 2 weeks after the first dose of RTX.

Conclusion:

Modified low-dose RTX therapy (two infusions of 200 mg every 2 weeks) could be a promising new option for patients with SLE-associated refractory ITP with a satisfactory response rate.

Treatment lines of childhood chronic ITP: A retrospective single-center analysis

Immune thrombocytopenia (ITP) is the most common cause of thrombocytopenia in children. Approximately 20–25% of children develop a chronic course of the disease. Many treatment options are available, including chronic use of first-line therapies, e.g., corticosteroids, intravenous immunoglobulin or anti-Rh-D, and second-line therapies, including dexamethasone, high-dose methylprednisolone, intensive immunosuppressants, rituximab, thrombopoietin receptor agonists (TPO-RAs), splenectomy, and many others; however, none of these treatments have been determined to be the best. In this study, we retrospectively reviewed the course, response to different treatment lines and outcome of children with chronic ITP over a period of ten years to compare the efficacy of different treatment options, aiming to determine a scale of priority for selecting the most costeffective treatment. A retrospective study was conducted and included children diagnosed with chronic ITP from January 2008 until December 2018 who were followed at the Pediatric Hematology Unit of Mansoura University Children Hospital, Mansoura, Egypt. The study proposal was approved on February 14, 2017 (approval No 17.02.59) by the Institutional Review Board (IRB) of the Faculty of Medicine, Mansoura University, Egypt. All research steps were conducted according to the Declaration of Helsinki. The diagnosis of chronic ITP was based upon the persistence of thrombocytopenia lasting for more than 1 year with or without therapy. Bone marrow aspiration was performed for all patients to confirm the diagnosis of chronic ITP and exclude other causes of thrombocytopenia. Data relevant to chronic ITP patients diagnosed from 2008 to 2018 were retrieved from the Electronic Data System of Hospital Management of Mansoura University Children Hospital, including age, sex, diagnosis date, duration of chronicity, treatment given during the chronic phase and response. Treatment regimen was immune modulatory therapies (high-dose dexamethasone, IV rituximab or low-dose dexamethasone + azathioprine), thrombopoietin receptor agonists (TPO-RAs) (eltrombopag or romiplostim). Out of 405 newly diagnosed ITP patients in a period of 10 years in our center, 103 progressed to chronic disease, of whom 29 were lost to follow-up, while 74 patients were followed at the hematology outpatient clinic and enrolled in the current study (32 males and 42 females, median age – 10 years, median initial platelet count – 16 × 109 /l). Approximately one-third of patients (25~33.8%) were managed conservatively; of them, 19 patients achieved sustained remission, and 6 patients needed another treatment line. Forty-six (62%) patients received immunomodulatory therapies. Twentyeight patients (37.8%) were treated with TPO-RAs. No differences were observed between the 3 types of immunomodulatory therapies regarding relapse-free survival and duration of remission (р value: 0.7). Additionally, no differences were noted according to relapse-free survival among those treated with eltrombopag and romiplostim (р value: 0.7). The number of male children who had a sustained response was significantly higher than that of female children among patients receiving immunomodulatory therapies (71.4% vs 28.6%, respectively) (р value 0.01). There were significantly more patients on TPO-RA with a sustained response than patients on immune modulators, and consequently, the number of patients who relapsed on immunomodulators was higher than that of those on TPO-RA (67.9% vs 30.4% compared to 69.9% vs 32.1%, р value 0.01). Many of our patients who received immunomodulators and failed to achieve or lost a response before 2015 were switched to TPO-RAs with comparable efficacy apart from sustainability, which was in favor of the latter. Additionally, among the types of immunomodulators, rituximab did not show superior efficacy compared to other types, with lower costs for the latter, leading to the abandonment of its use, particularly in limited resource countries such as ours.

Clinical Phenotype and Response to Different Lines of Therapy in Elderly with Immune Thrombocytopenia: A Retrospective Study

Purpose

Insufficient knowledge of primary immune thrombocytopenia purpura (ITP) in the elderly, together with a lack of clinical trial data, has resulted in wide variation in treatments. Here, we present a study focused on clinical characteristics of ITP in older subjects at diagnosis integrated with the subsequent course of the disease and treatment history.

Methods

In a retrospective monoinstitutional study, we evaluated >65-year-old patients with primary ITP. Clinical characteristics at the time of diagnosis were described and analyzed. We aimed to delineate whether subsequent lines of therapy influenced the number of relapses. In addition to initial regimens, we reported subsequent treatments and the impact on relapse trends.

Results

A total of 50 patients (56% males, mean age 78 years) were included. With regard to clinical variables at diagnosis, statistical significance was found for Eastern Cooperative Oncology Group performance status 1 (46% of patients, p<0.0001), presence of three comorbidities (36% of patients, p<0.0001), World Health Organization grade 0 bleeding (46%, p=0.0001), and World Health Organization grade 1 bleeding (42%, p=0.0009). For bleeding sites, the most frequent were skin or mucosa (40%, p=0.0477). A decrease in platelet count was correlated with moderate or severe bleeding (ρ=-0.52, p=0.0001) and viscera or skin/mucosa + viscera site (ρ=-0.50, p=0.0002). Finally, a decreasing number of patients required treatment from first-line therapy to sixth (p<0.0001). Relapse was most frequent before second-line therapy (54%, p<0.0001) and less frequent before fivth and sixth (4%, p=0.0072; 2%, p=0.0027).

Conclusion

ITP in older age poses considerable challenges, so specific management strategies should be considered to optimize outcomes. Our findings provide evidence of an inverse relationship between lines of therapy and timing of relapses. This study does not exclude the possibility that agents used after first-line therapy may have an impact on the response and modify the unfavorable course of ITP.

Rituximab and immune thrombocytopenia in adults: The state of knowledge 20 years later

Rituximab has been used for immune thrombocytopenia (ITP) for almost 20 years and is now considered a valid off-label second-line treatment. About 60% to 70% of patients with ITP show initial response to rituximab, but in half of these patients, the disease will eventually relapse. Therefore, in 30% of patients with persistent or chronic ITP, one course of rituximab at 375 mg/m²/week for 4 weeks or 2 fixed 1000-mg rituximab infusions allows for a sustained response rate at 5 years. Unfortunately, to date, no robust predictor of long-term sustained response has been found to assist the physician in deciding to treat with rituximab on an individual basis, and the choice of rituximab or another second-line treatment must be individualized and shared with the patient. Retreatment with rituximab has been found efficient, with a similar or higher magnitude and duration of response in most patients. Rituximab is usually well tolerated, with mainly mild and easily manageable infusion-related adverse events. Severe infections are uncommon, including in the long-term, and occur in patients with at least another contributing factor in more than two thirds. Several issues remain to be resolved. Indeed, head-to-head comparisons with other and new treatments in ITP and robust predictors of long-term response are urgently needed to better determine the position of rituximab in the therapeutic armamentarium for adult ITP. Additionally, the place of combination therapies, maintenance therapy with rituximab and rituximab in newly-diagnosed ITP deserve additional studies.

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.

A megakaryocyte morphological classification-based predictive model for steroid sensitivity in primary immune thrombocytopenia

The first-line therapy for primary immune thrombocytopenia (ITP) is steroids, but about one-third of patients do not respond to steroids. Recent studies have shown megakaryocyte (MK) growth and development abnormalities and poorly compensated thrombopoiesis. Here, we attempted to determine the impact of MK morphological classification on steroid response. We enrolled 170 adult patients with primary ITP and divided them into steroid-sensitive ITP (109/170) and non-steroid-sensitive ITP (61/170) groups. In the univariate logistic model, female, reduced thrombocytogenic MK count (TMC), increased granular MK count to total MK count ratio (GMC/TM ratio), and elevated naked nucleus MK count to TM count ratio were significantly associated with steroid-sensitive ITP. In the multivariate logistic model, sex, reduced TMC, and increased GMC/TM ratio were independent predictors of steroid-sensitive ITP diagnosis. Based on the regression parameters, we established a predictive index with weighted risk score of 1 assigned each to sex, TMC, and GMC/TM ratio. A predictive index ≥2 points had the best area under the curve value (0.63) with 47.7% sensitivity and 78.7% specificity for predicting steroid sensitivity. These findings may help guide early treatment strategies in ITP.

Long-term safety and efficacy of rituximab in 248 adults with immune thrombocytopenia: Results at 5 years from the French prospective registry ITP-ritux

Rituximab is a second-line option in adults with immune thrombocytopenia (ITP), but the estimated 5-year response rate, only based on pooled retrospective data, is about 20%, and no studies have focused on long-term safety. We conducted a prospective multicenter registry of 248 adults with ITP treated with rituximab with 5 years of follow-up to assess its long-term safety and efficacy. The median follow-up was 68.4 [53.7-78.5] months. The incidence of severe infections was only 2/100 patient-years. Profound hypogammaglobulinemia (<5 g/L) developed in five patients at 15 to 31 months after the last rituximab infusion. In total, 25 patients died at a median age of 80 [69.5-83.9] years, corresponding to a mortality rate of 2.3/100 patient-years. Only three deaths related to infection that occurred 12 to 14 months after rituximab infusions could be due in part to rituximab. At 60 months of follow-up, 73 (29.4%) patients had a sustained response. On univariate and multivariate analysis, the only factor significantly associated with sustained response was a previous transient response to corticosteroids (P = .022). Overall, 24 patients with an initial response and then relapse received retreatment with rituximab, which gave a response in 92%, with a higher duration of response in 54%. As a result of its safety profile and its sustained response rate, rituximab remains an important option in the current therapeutic armamentarium for adult ITP. Retreatment could be an effective and safe option.

Updated international consensus report on the investigation and management of primary immune thrombocytopenia

Over the last decade, there have been numerous developments and changes in treatment practices for the management of patients with immune thrombocytopenia (ITP). This article is an update of the International Consensus Report published in 2010. A critical review was performed to identify all relevant articles published between 2009 and 2018. An expert panel screened, reviewed, and graded the studies and formulated the updated consensus recommendations based on the new data. The final document provides consensus recommendations on the diagnosis and management of ITP in adults, during pregnancy, and in children, as well as quality-of-life considerations.

Mechanisms and therapeutic prospects of thrombopoietin receptor agonists

The second-generation thrombopoietin (TPO) receptor agonists eltrombopag and romiplostim are potent activators of megakaryopoiesis and represent a growing treatment option for patients with thrombocytopenic hematological disorders. Both TPO receptor agonists have been approved worldwide for the treatment of children and adults with chronic immune thrombocytopenia. In the EU and USA, eltrombopag is approved for the treatment of patients with severe aplastic anemia who have had an insufficient response to immunosuppressive therapy and in the USA for the first-line treatment of severe aplastic anemia in combination with immunosuppressive therapy. Eltrombopag has also shown efficacy in several other disease settings, for example, chemotherapy-induced thrombocytopenia, selected inherited thrombocytopenias, and myelodysplastic syndromes. While both TPO receptor agonists stimulate TPO receptor signaling and enhance megakaryopoiesis, their vastly different biochemical structures bestow upon them markedly different molecular and functional properties. Here, we review and discuss results from preclinical and clinical studies on the functional and molecular mechanisms of action of this new class of drug.

Immune Thrombocytopenia: Are We Stuck in the Mud or Is There Light at the End of the Tunnel?

The differences in diagnosis and management between immune thrombocytopenia (ITP) and leukemia are striking. Leukemia diagnosis and management have evolved substantially over the past 30 years and are now relatively precise. The tendency for leukemic cells to be the overwhelming majority of circulating and/or bone marrow cells certainly continues to facilitate developments, as does improved molecular assessment. Furthermore, randomized controlled clinical trials of competing regimens in well-defined populations have advanced treatment as well. Currently, ITP diagnosis and management depend very much on the experience and preferences of the hematologist. There are no unequivocally useful molecular tests, no agreement on which testing needs to be performed, and no consensus on treatment. Future studies using advanced techniques would ideally change this over time but, thus far, progress in ITP has been slow. However, the increasing ability to do single-cell DNA and RNA studies and flow cytometric dissection of small populations of cells could radically change the approach to ITP if critical distinctions were uncovered.

Rituximab in the treatment of immune thrombocytopenia: what is the role of this agent in 2019?

The use of rituximab for the treatment of immune thrombocytopenia was greeted enthusiastically: it led to up to 60% response rates, making it, nearly 20 years ago, the main alternative to splenectomy, with far fewer side effects. However, long-term follow-up data showed that only 20-30% of patients maintained the remission. No significant changes have been registered using different dose schedules and timing of administration, while the combination with other drugs seemed promising. Higher response rates have been observed in young women before the chronic phase, but apart from that, other clinical factors or biomarkers predictive of response are still lacking. In this review we examine the historical and current role of rituximab in the management of immune thrombocytopenia, 20 years after its first use for the treatment of autoimmune diseases.

Switching thrombopoietin receptor agonist treatments in patients with primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is a bleeding disorder that conventionally has been treated with steroids or other immunosuppressive treatments. The introduction of thrombopoietin receptor agonists (TPO-RAs), which increase platelet production, dramatically changed the treatment landscape for ITP by providing patients with well-tolerated, long-term treatment options. Two TPO-RAs, eltrombopag and romiplostim, have been approved in the United States and European Union for the treatment of ITP. Some patients do not benefit from the first TPO-RA they receive, so it is assumed that the alternate TPO-RA would have the same outcome. However, eltrombopag and romiplostim have distinct pharmacodynamic and pharmacokinetic properties and may have different tolerability and efficacy in individual patients with ITP. Published retrospective studies showed that >75% of patients who switched to the alternate TPO-RA maintained or achieved a response with the new treatment. Notably, most patients who switched due to lack of efficacy with the first TPO-RA responded to the alternate TPO-RA, which demonstrates an absence of cross-resistance between the two drugs. Therefore, switching to the alternate TPO-RA if the first TPO-RA fails to demonstrate a response should be considered before the use of a less-preferable option.

Long-term fostamatinib treatment of adults with immune thrombocytopenia during the phase 3 clinical trial program

Two randomized, double-blind, placebo-controlled studies demonstrated responses (≥50 000/μL) to fostamatinib in adults with long-standing immune thrombocytopenia (ITP). The long-term safety and efficacy of fostamatinib were evaluated in a follow-on, open-label extension (OLE) study. Patients received double-blind fostamatinib in the randomized trials, and responders continued the same dose, 100 to 150 mg BID, in the OLE study. Nonresponders received 100 mg BID for 4 weeks and could escalate to 150 mg BID at week 4. Endpoints included stable response, platelet count ≥50 000/μL at 4/6 biweekly (randomized trials) or 2/3 monthly visits (OLE), and overall response, ≥1 platelet count ≥50 000/μL during weeks 1 to 12. A total of 146 patients received fostamatinib including 123 in the OLE study. Median treatment duration was 6.7 months. Baseline median ITP duration was 8 years and median platelet count was 16 000/μL; prior treatments included thrombopoietic (TPO) agents (47%), splenectomy (35%), and rituximab (32%). Twenty-seven (18%) patients achieved a stable response with median duration of >28 months and a median platelet count of 89 000/μL. Sixty-four (44%) patients achieved an overall response (including stable responders) with a median platelet count of 63 000/μL and a median response duration of >28 months. Twenty-four of 71 (34%) patients who had failed TPO agents achieved overall responses to fostamatinib. The most common adverse events (AEs) were diarrhea, hypertension, nausea, epistaxis, and abnormal liver function tests. Most AEs were mild/moderate and resolved or were managed with dose reduction, dose interruption, and/or secondary medication. Almost half of the patients achieved an overall response, and most of these maintained their responses for >2 years. No new or increased frequency of AEs was seen at up to 31 months of treatment.

Management of immune thrombocytopenia in elderly patients

Despite the improvement in understanding its pathogenesis and the introduction of novel treatment options, the management of primary immune thrombocytopenia (ITP) still remains challenging. Considering its increased incidence with aging and prolonged life-expectancy, ITP is often diagnosed in elderly patients, a subset that deserves some special precautions. Ensure the diagnosis is a crucial step, and carefully attention must be given in excluding other causes of thrombocytopenia, especially among older people that frequently suffer from many comorbidities. When it comes to treatment decision, it is worth keeping into account that the elderly have an increased risk of bleeding, thrombosis and infections, that they often require many concomitant therapies, including antiplatelet or anticoagulant agents, and that treatment-related toxicities are often increased and sometimes more dangerous that the disease itself. There are not dedicated guidelines, and only few specific studies. Steroids with or without IVIG remain the first-line treatment. Splenectomy is less effective than in youngers and burdened by an increased thrombotic and infectious risk. Rituximab is a good option in non-immunocompromised patients, but long-term remissions are few. Eltrombopag and romiplostim have a good safety and efficacy profile, and have become a prominent drug in this subset, even if they are associated with a possible increased risk of thrombosis, and long-term toxicity is unknown. Other drugs, such as dapsone and danazol, have a well-known efficacy and safety profile, and still represent a valid option among elderly patients.

Resolution of sinus bradycardia, high-grade heart block, and left ventricular systolic dysfunction with rituximab therapy in Henoch-Schonlein purpura

Henoch-Schonlein purpura (HSP) is a rare, typically self-limited, multi-organ vasculitis. Cardiac involvement with HSP carries high morbidity and mortality, thus requiring early aggressive immunosuppressive therapy. We report a case of HSP complicated with acute systolic left ventricular (LV) dysfunction, symptomatic sinus bradycardia and high-grade atrio-ventricular (AV) heart block. Cyclophosphamide, a commonly used agent in HSP, was contraindicated due to the patient's presentation with acute renal failure. Treatment with monoclonal antibody rituximab and corticosteroids was initiated with an improvement in and resolution of LV systolic dysfunction, sinus bradycardia and AV block. We believe this is the first published report on rituximab treatment in HSP with cardiac involvement manifesting with severe LV systolic dysfunction, sinus bradycardia and high-grade AV block.

Eltrombopag-based combination treatment for immune thrombocytopenia

Immune thrombocytopenia (ITP) is a bleeding disorder caused by a decrease in platelet count resulting from increased destruction and insufficient production of platelets. Although impaired regulatory T-lymphocyte activity plays a critical role in platelet destruction, many other immunologic abnormalities are also likely to be involved. Importantly, patients with ITP appear to have defects in a thrombopoietin-mediated physiological mechanism that compensates for a decrease in platelet count by increasing platelet production. Thus, simultaneous treatment of multiple pathogenic pathways involved in ITP could potentially result in synergistic efficacy. While conventional treatments for ITP suppress or modulate the immune system to reduce platelet destruction, a unique class of ITP therapy, namely thrombopoietin receptor agonists (TPO-RAs), improves platelet production by activating the thrombopoietin pathway. As hypothesized, preliminary studies show that combinations of eltrombopag, an oral TPO-RA, with conventional treatments improve outcomes in both newly diagnosed and refractory patients. In this review, the clinical experience with eltrombopag-based combinations in patients with ITP is summarized and the implications of the available data are discussed.

Transitioning patients with immune thrombocytopenia to second-line therapy: Challenges and best practices

In patients with immune thrombocytopenia who do not adequately respond to first-line therapy, there is no clear consensus on which second-line therapy to initiate and when. This situation leads to suboptimal approaches, including prolonged exposure to treatments that are not intended for long-term use (eg, corticosteroids) and overuse of off-label therapies (eg, rituximab) while approved, more efficacious options exist. These approaches may not only fail to address symptoms and burden of disease, but may also worsen health-related quality of life. A better understanding of available second-line treatments may ensure best use of therapeutic options and thereby optimize patient outcomes.

Advances in chemical pharmacotherapy for the treatment of pediatric immune thrombocytopenia

INTRODUCTION

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder of heterogeneous pathophysiological mechanisms. Treatment endpoints include elevation of platelets and reduction of bleeding risk, elevation of quality of life, reduction of concomitant therapies and prevention from bleeding. Persistent and chronic ITP is more common in adults but occurs in children. Standard therapies include corticosteroids and immunoglobulins, both associated with side effects. There are new treatments, such as thrombopoietin-receptor agonists and promising investigational drugs.

AREAS COVERED

Experience from the management of adults is valuable for children with persistent and chronic symptomatic ITP. In this review first- and second-line therapies, but also investigational drugs for children with ITP are discussed.

EXPERT OPINION

Although time-consuming and based on experience, children with no or mild bleeding can be safely managed with a watch and wait strategy. Chronic symptomatic immune thrombocytopenia is an area of second-line treatments based on a highly individualized approach. Furthermore, there are investigational drugs, which may also be of benefit for children with chronic symptomatic ITP.

Recent advances in understanding and management of acquired thrombocytopenia

There are numerous congenital and acquired causes of thrombocytopenia. Thrombocytopenia could be a result of decreased bone marrow production, increased consumption, increased destruction, splenic sequestration or a combination of these causes. In this review, we have focused on some of the serious acquired causes of thrombocytopenia. There have been some significant advances in our understanding of the pathophysiology, diagnostic testing, and treatment of immune thrombocytopenia, heparin-induced thrombocytopenia, thrombotic thrombocytopenic purpura, and atypical hemolytic uremic syndrome over the past five years. These advances have resulted in a significant decrease in mortality and morbidity of patients with these disorders. Despite these advances, we are still faced with numerous unanswered questions in the pathophysiology and management of these complex thrombocytopenic disorders.

Treatment of Children with Persistent and Chronic Idiopathic Thrombocytopenic Purpura: 4 Infusions of Rituximab and Three 4-Day Cycles of Dexamethasone

OBJECTIVES

To assess initial and long-term outcome of children with persistent/chronic idiopathic thrombocytopenic purpura (ITP) treated with 4 infusions of rituximab and three 4-day cycles of dexamethasone (4R+3Dex) including cohorts with most benefit and/or treatment associated toxicity.

STUDY DESIGN

All pediatric patients with ITP at Weill-Cornell who received 4R+3Dex were included in this retrospective study. Duration was median time from first rituximab infusion to treatment failure. Patient cohort included 33 children ages 1-18 years with persistent/chronic ITP; 19 were female, 10 of whom were adolescents. Every patient had failed more than 1 and usually several ITP treatments.

RESULTS

Children were treated with rituximab, 375 mg/m² weekly for 4 weeks and three 4-day courses of dexamethasone 28 mg/m² (40 mg max). Average age of nonresponders was 7.75 years, and initial responders averaged 12.7 years (P = .0073); 30% maintained continuing response at 60 months or last check-up. Eight of the 10 patients who underwent remission were female with ITP <24 months prior to initiating 4R+3Dex. All responding male patients except 2 relapsed.

CONCLUSIONS

Durable unmaintained ITP remission after 4R+3Dex was seen almost exclusively in female adolescents with <24 months duration of ITP. This provides a new therapeutic paradigm for a subpopulation with hard-to-treat chronic ITP. The pathophysiology of ITP underlying this distinction requires further elucidation.

Pathogenesis and Therapeutic Mechanisms in Immune Thrombocytopenia (ITP)

Immune thrombocytopenia (ITP) is a complex autoimmune disease characterized by low platelet counts. The pathogenesis of ITP remains unclear although both antibody-mediated and/or T cell-mediated platelet destruction are key processes. In addition, impairment of T cells, cytokine imbalances, and the contribution of the bone marrow niche have now been recognized to be important. Treatment strategies are aimed at the restoration of platelet counts compatible with adequate hemostasis rather than achieving physiological platelet counts. The first line treatments focus on the inhibition of autoantibody production and platelet degradation, whereas second-line treatments include immunosuppressive drugs, such as Rituximab, and splenectomy. Finally, third-line treatments aim to stimulate platelet production by megakaryocytes. This review discusses the pathophysiology of ITP and how the different treatment modalities affect the pathogenic mechanisms.