Thrombopoietin receptor agonists: ten years later

A case with a novel GATA1 variant mimicking immune thrombocytopenia attacks

One of the leading thrombocytopenia occasions in childhood is immune thrombocytopenia (ITP). Small number of these patients do not respond to treatment methods known to be effective for ITP such as corticosteroids, intravenous immunoglobulin and thrombopoietin receptor agonists (eltrombopag, romiplostim, etc.) and have serious bleeding symptoms. We present a case in which a molecular genetic analysis was performed due to challenging responses to medical treatment for severe systemic bleeding symptoms which were similar to ITP. A hemizygous variant was detected in the GATA1 gene and a homozygous variant in the ATP2A1 gene for Brody myopathy. Eltrombopag, romiplostim, IVIG and corticosteroid were applied to resistant thrombocytopenia of the patient without knowing the cause. Patient had response in platelet counts in some occasions. This situation attracted our attention after the detection of this GATA variant in the etiopathogenesis of thrombocytopenia. Further investigations should be performed for much more rare causes of thrombocytopenia in patients with refractory thrombocytopenia attacks.

Treatment Landscape in Pediatric Immune Thrombocytopenia: Addressing Unmet Needs

Pediatric immune thrombocytopenia (ITP) is associated with a multifaceted burden on children and their parents/caregivers due to bleeding, fatigue, activity restrictions, and psychological distress. Most children recover within 12 months, but up to 30% develop chronic ITP. While emergent therapies, such as steroids and intravenous immunoglobulin, are effective in many children and transiently raise platelet counts, 38-47% of children require subsequent therapies. The choice of subsequent therapy for individual children with ITP is often complex and the absence of head-to-head comparisons of available therapies and the use of nonstandardized outcomes in randomized clinical trials complicates treatment decisions. Furthermore, medication access varies globally and by age. Additional unmet needs in pediatric ITP include a lack of support and educational resources allowing children and parents/caregivers to effectively participate in treatment decisions, inadequate prediction of treatment response and disease chronicity, heterogeneous approaches to diagnostic evaluation of ITP, scarcity of novel treatments for children unresponsive to current therapies, and the need for a multispecialty approach to support the mental health of children and their families. This review summarizes the known impact of ITP on children and their families, current treatment strategies, and unmet needs in pediatric ITP.

Efficacy and safety of romiplostim and eltrombopag in management of thrombocytopenia in Wiskott-Aldrich syndrome patients

Wiskott-Aldrich syndrome (WAS) is a life-threatening inborn error of immunity associated with bleeding risk due to profound thrombocytopenia. We previously demonstrated that romiplostim is effective for thrombocytopenia treatment in 60% of WAS patients. In this prospective trial, 28 WAS patients (aged 0-17 years) were treated with thrombopoietin receptor agonists (TPO-RAs) to evaluate the comparative efficacy and safety of romiplostim versus eltrombopag and to assess the benefit of switching these molecules in individual subjects. We demonstrate that both drugs are effective, with the probability of achieving an overall platelet response (complete response-platelet count of 100 × 109/L or more and partial response-platelet count increase of 30 × 109/L or higher above baseline) of 73% for romiplostim and 43% for eltrombopag. Switching to an alternative TPO-RA allowed the achievement of a complete platelet response in 33% of patients after switching to eltrombopag and in 43% after romiplostim initiation. The cumulative efficacy of TPO-RAs, taking into account alternative therapy, was 87%. There was a grade 2 adverse event (AE) and a severe grade 4 AE related to eltrombopag-reversible acute liver failure associated with metabolic acidosis and encephalopathy. TPO-RAs proved to be an effective treatment for WAS patients waiting for stem cell transplantation or opting for a conservative treatment.

The 'Stop TPO-RA in ITP Patients' study: Clinical and immune modulatory effects of romiplostim tapering

Sustained remissions off-treatment (SROTs) after tapering of thrombopoietin receptor agonists (TPO-RAs) have been reported in 15%-50% of patients with immune thrombocytopenia (ITP). The STIP (Stop TPO-Receptor Agonist in ITP Patients) study is a prospective trial aimed to investigate the clinical effects of romiplostim tapering. Adult patients (22/40) with ITP ≥3 months received romiplostim for 1 year, were tapered and followed for 1 year. Anti-platelet antibodies (APAs), TPO levels and indium-111 platelet scintigraphy were assessed before, during and after romiplostim. Censored survival analysis showed that the probability of SROT at 1 year after tapering was 23.6% (95% confidence interval: 11.0%-50.5%). Patients with SROT had higher platelet levels on romiplostim (median: 332.5 vs. 84.5 × 109/L) and lower romiplostim doses at the start of tapering (median: 1.0 vs. 4.5 μg/kg) compared to those with a non-sustained response (NSR). APAs were detected in 8/25 patients at baseline, of which 5 showed a substantial decrease during romiplostim. The indium-111 scan revealed an improved platelet survival at the start of tapering for 50% of patients with SROT (2/4, missing n = 1) versus none with an NSR (0/14, missing n = 3). Overall, the STIP study demonstrated a probability of SROT of 23.6% in a diverse and largely chronic group of adult patients with ITP.

Targeting CCR5 with miltefosine as a therapeutic strategy for thrombocytopenia

Thrombocytopenia remains a challenging clinical condition with limited treatment options. Here, we demonstrated that miltefosine stimulated megakaryocyte (MK) differentiation in vitro. Miltefosine significantly accelerated platelet recovery, enhanced platelet function, and boosted MK production and differentiation in irradiated mice. RNA sequencing revealed association of CCR5, MAPK, and JAK2/STAT3 signaling pathways in miltefosine-mediated MK differentiation. Molecular docking, drug affinity responsive target stability (DARTS), and surface plasmon resonance (SPR) assays confirmed direct binding of miltefosine to CCR5. Inhibition of CCR5 disrupted miltefosine's effects on MK differentiation and activation of MAPK and JAK2/STAT3 signaling pathways, as well as key transcription factors GATA1, EGR1, and TAL1. Similarly, blockade of the MAPK or JAK2/STAT3 signaling pathways hindered miltefosine-induced MK differentiation and transcription factor activation. Our findings establish CCR5 as a therapeutic target for thrombocytopenia and identify miltefosine as a CCR5 agonist that promotes MK differentiation and platelet production via MAPK and JAK2/STAT3 signaling.

Efficacy and safety of avatrombopag in the treatment of thrombocytopenia after umbilical cord blood transplantation

BACKGROUND

Delayed platelet engraftment is a common complication after umbilical cord blood transplantation (UCBT), and there is no standard therapy. Avatrombopag (AVA) is a second-generation thrombopoietin (TPO) receptor agonist (TPO-RA) that has shown efficacy in immune thrombocytopenia (ITP). However, few reports have focused on its efficacy in patients diagnosed with thrombocytopenia after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

We conducted a retrospective study at the First Affiliated Hospital of the University of Science and Technology of China to evaluate the efficacy of AVA as a first-line TPO-RA in 65 patients after UCBT; these patients were compared with 118 historical controls. Response rates, platelet counts, megakaryocyte counts in bone marrow, bleeding events, adverse events and survival rates were evaluated in this study. Platelet reconstitution differences were compared between different medication groups. Multivariable analysis was used to explore the independent beneficial factors for platelet implantation.

RESULTS

Fifty-two patients were given AVA within 30 days post-UCBT, and the treatment was continued for more than 7 days to promote platelet engraftment (AVA group); the other 13 patients were given AVA for secondary failure of platelet recovery (SFPR group). The median time to platelet engraftment was shorter in the AVA group than in the historical control group (32.5 days vs . 38.0 days, Z  = 2.095, P  = 0.036). Among the 52 patients in the AVA group, 46 achieved an overall response (OR) (88.5%), and the cumulative incidence of OR was 91.9%. Patients treated with AVA only had a greater 60-day cumulative incidence of platelet engraftment than patients treated with recombinant human thrombopoietin (rhTPO) only or rhTPO combined with AVA (95.2% vs . 84.5% vs . 80.6%, P  <0.001). Patients suffering from SFPR had a slightly better cumulative incidence of OR (100%, P  = 0.104). Patients who initiated AVA treatment within 14 days post-UCBT had a better 60-day cumulative incidence of platelet engraftment than did those who received AVA after 14 days post-UCBT (96.6% vs . 73.9%, P  = 0.003).

CONCLUSION

Compared with those in the historical control group, our results indicate that AVA could effectively promote platelet engraftment and recovery after UCBT, especially when used in the early period (≤14 days post-UCBT).

Efficacy and safety of dapsone in adult primary immune thrombocytopenia

ABSTRACT

To assess efficacy and safety of dapsone in adult immune thrombocytopenia (ITP), a multicenter randomized controlled trial (RCT) and a real-world cohort study were performed. Participants were adults with primary ITP, transient response to corticosteroids with/without intravenous immunoglobulin, and a platelet count of ≤30 × 109/L (or ≤50 × 109/L with bleeding). Patients in the RCT were randomized in arm A (prednisone × 3 weeks + dapsone for 12 months) or arm B (prednisone alone). The observational study involved dapsone initiation at 100 mg/d with standard follow-up. The primary end point was the response rate (platelet count of >30 × 109/L and ≥2× baseline level) at 52 weeks, with the response rate at 24 weeks and adverse events as secondary end points. The RCT enrolled 93 patients (54.8% female), with median age of 48.5 years (46 years in arm A; and 47 years in arm B). In the intention-to-treat analysis, 78.3% of patients in arm A discontinued dapsone after a median of 4.6 weeks because of adverse events (66.7%) or lack of efficacy (33.3%). The response rate at week 52 was 21.7% (95% confidence interval [CI], 10.9-36.4) in arm A vs 8.5% (95% CI, 2.7-18.6) in arm B (P = .17). The observational study, which was conducted after the end of the RCT, included 46 patients (52.2% female), median age of 50.7 years. Adverse events occurred in 30.4%, leading to discontinuation of dapsone in 23.9%, and 13.6% (95% CI 5.2-27.4) met the primary efficacy end point. Results from both studies showed an unfavorable risk-benefit ratio for the use of dapsone in adult primary ITP and suggest that, whenever available, second-line options should be used. This trial was registered at www.ClinicalTrials.gov as #NCT02627417 and #NCT02877706.

Small molecule BLVRB redox inhibitor promotes megakaryocytopoiesis and stress thrombopoiesis in vivo

Biliverdin IXβ reductase (BLVRB) is an NADPH-dependent enzyme previously implicated in a redox-regulated mechanism of thrombopoiesis distinct from the thrombopoietin (TPO)/c-MPL axis. Here, we apply computational modeling to inform molecule design, followed by de novo syntheses and screening of unique small molecules retaining the capacity for selective BLVRB inhibition as a novel platelet-enhancing strategy. Two distinct classes of molecules are identified, and NMR spectroscopy and co-crystallization studies confirm binding modes within the BLVRB active site and ring stacking between the nicotinamide moiety of the NADP+ cofactor. A diazabicyclo derivative displaying minimal off-target promiscuity and excellent bioavailability characteristics promotes megakaryocyte speciation in biphenotypic (erythro/megakaryocyte) cellular models and synergizes with TPO-dependent megakaryocyte formation in hematopoietic stem cells. Upon oral delivery into mice, this inhibitor expands platelet recovery in stress thrombopoietic models with no adverse effects. In this work, we identify and validate a cellular redox inhibitor retaining the potential to selectively promote megakaryocytopoiesis and enhance stress-associated platelet formation in vivo distinct from TPO receptor agonists.

Utility of Thrombopoietin Receptor Agonists for Prolonged Thrombocytopenia After Chimeric Antigen Receptor T-cell Therapy

Chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment landscape for various hematological malignancies. However, it is associated with a range of hematologic complications, including severe and often prolonged thrombocytopenia. Currently, there are no known effective preventative or management measures against CAR-T-induced thrombocytopenia. At the University of Chicago Medical Center, thrombopoietin receptor agonists (TPO-RAs) eltrombopag and romiplostim have been utilized intermittently, per attending preference, in patients post CAR-T treatment presenting with prolonged thrombocytopenia (platelets <50 × 103 cells/μL for at least 14 days). However, whether these treatments yield positive outcomes in this context remains uncertain. This study aims to evaluate the efficacy and safety of TPO-RAs in patients with CAR-T-induced thrombocytopenia. The primary objective is to compare the incidence of platelet recovery (defined as two consecutive platelet counts of ≥50 × 103 cells/μL) in patients who received TPO-RAs versus those who did not for CAR-T-associated prolonged thrombocytopenia between January 1, 2018, and June 30, 2023. The secondary objectives include time to platelet recovery, incidence of clinically relevant bleed, hospital length of stay, incidence of adverse effects associated with TPO-RA administration, overall survival, and financial toxicity. This is a single-center, retrospective study conducted at the University of Chicago Medical Center. Eighty-five patients with prolonged, CAR-T-induced thrombocytopenia were enrolled in the study; 12 of these patients were managed with TPO-RA therapy while the remaining 73 received supportive care. Statistical analysis was performed using STATA, incorporating the Chi-squared test for nominal data and the Wilcoxon Rank-sum test for continuous data. A P value of <.05 was used to determine statistical significance. The incidence of platelet recovery was similar between the two groups; in the supportive care group, 53 patients (73%) experienced resolution of thrombocytopenia, compared to 9 patients (75%) in the TPO-RA treated group (P = 1.0). The median time to thrombocytopenia resolution was 56 days in the TPO-RA-treated group and 41 days in those not managed with TPO-RAs (P = .14). The median time to TPO-RA initiation postinfusion was 45 days. There were no statistically significant differences in incidence of clinically relevant bleed or readmission within 1 year of CAR-T infusion between the two groups, but 25% of patients receiving TPO-RA therapy experienced associated arthralgia requiring treatment modification. Additionally, the median cost of a course of eltrombopag was estimated at $86,921.52 per patient at the reported average wholesale price. While TPO-RAs represent a theoretical therapeutic option for CAR-T patients based on their role in chemotherapy-induced thrombocytopenia, our study showed that their use did not provide significant clinical benefit compared to the supportive care approaches. Therefore, without larger, randomized, prospective trials, we are unable to recommend TPO-RA use in this setting, given the current lack of demonstrated efficacy, potential adverse effects, and concerns regarding financial impact.

Long-term safety and efficacy of fostamatinib in Japanese patients with primary immune thrombocytopenia

Fostamatinib had superior efficacy to a placebo and acceptable safety profiles for at least 1 year in a phase 3 study of Japanese patients with primary immune thrombocytopenia. Here, we report the 3-year safety and efficacy of fostamatinib in that study. Data from 33 patients who received at least one dose of fostamatinib were analyzed. A platelet response > 50,000/µL (at two consecutive visits at least 28 days apart while receiving fostamatinib) was achieved in 16 patients (48%). The median total duration of a platelet response > 50,000/µL was 589 (range: 106-1003) days. Gastrointestinal disorders, such as diarrhea, hypertension, and hepatic enzyme elevation, were the most common fostamatinib-related adverse events. Most events occurred within 12 weeks of treatment. No thromboembolisms, treatment-related infections, or moderate or severe treatment-related bleeding events were observed. In summary, this extension study of a clinical trial found a sustained platelet response without new safety signals during 3-year treatment with fostamatinib.

Application of thrombopoietic agents in cancer therapy-induced thrombocytopenia: A comprehensive review

Cancer therapy-induced thrombocytopenia (CT-IT) is one of the most common hematological toxicities of anti-cancer therapy, often leading to treatment dose reduced, postponed, or treatment plans altered or even discontinued. Thrombopoietin (TPO) is the only key regulatory factor in platelet production, and TPO receptor is considered an ideal target for the treatment of thrombocytopenia. Thrombopoietic agents, including recombinant human thrombopoietin (rhTPO) and thrombopoietin receptor agonists (TPO-RAs), bind to different regions of the TPO receptor, activating downstream signaling pathways to increase platelet levels. In recent years, numerous studies have demonstrated the effectiveness of thrombopoietic agents in the management of CT-IT. These agents can reduce bleeding risk, decrease platelet transfusions, and maintain relative dose intensity (RDI) of anti-cancer treatments. This article provides a review of the current progress in the application of thrombopoietic agents for CT-IT management.

Case Report: Dangerous liaisons between splenectomy and eltrombopag-induced chronic thromboembolic pulmonary hypertension in patients with immune thrombocytopenia: report of two cases and review of the literature

Introduction

Primary immune thrombocytopenia is an autoimmune bleeding disorder characterized by variable immune-mediated platelet destruction. These patients have reported thrombotic complications, both venous and arterial, in addition to bleeding. Splenectomy and thrombopoietin receptor agonists are recommended for patients who do not respond to steroids or immunosuppressive treatments. Chronic thromboembolic pulmonary hypertension is a rare disease that results from a persistent, organized thromboembolic obstruction of the pulmonary arteries due to an incompletely resolved pulmonary embolism.

Case presentations

We report two cases of chronic thromboembolic pulmonary hypertension induced by a thrombotic mechanism after treatment with splenectomy and Eltrombopag, a thrombopoietin receptor agonist, for refractory primary immune thrombocytopenia. Consequently, the patients were referred for surgical pulmonary thromboendarterectomy therapy as suggested.

Conclusion

In older patients, those with a history of thrombotic manifestations, or those with high-risk factors, clinicians should evaluate and monitor the risk of thrombotic events and chronic thromboembolic pulmonary hypertension when treating primary immune thrombocytopenia with splenectomy and Eltrombopag.

Avatrombopag in adults with immune thrombocytopenia: A multicentre real-life observational study in Madrid, Spain (AVAMAD study)

Immune thrombocytopenia (ITP) is a rare acquired disorder where thrombopoietin-receptor agonists have become mainstays of ITP treatment. With the recent approval of avatrombopag (AVA), real-world studies are essential to evaluate its efficacy and safety. Our study of 66 adult ITP patients treated with AVA showed a high response rate. After starting AVA, 74.2% did not require rescue medications, with minimal adverse effects. Additionally, 56.0% of patients reduced other ITP medications, and all patients aged ≥65 years responded to AVA. Results should be confirmed in larger studies, but AVA appears to be an effective and safe treatment for ITP patients.

Bloodless Management of Severe Refractory ITP and Acute Hemorrhage in a Jehovah's Witness Patient

In patients with severe refractory immune thrombocytopenia (ITP), especially those unable to receive blood transfusions due to religious beliefs, alternative non-cytotoxic therapies are important to avoid worsening cytopenias. Immunomodulatory agents such as mycophenolate mofetil and daratumumab should be used alongside traditional therapies including steroids, IVIG and rituximab.

Impact of Thrombopoietin Receptor Agonists on Pathophysiology of Pediatric Immune Thrombocytopenia

Immune thrombocytopenia (ITP) in pediatric patients is a common cause of isolated thrombocytopenia. Various pathophysiological mechanisms are implicated in ITP pathogenesis, including the production of autoantibodies against components of platelets (PLTs) by B-cells, the activation of the complement system, phagocytosis by macrophages mediated by Fcγ receptors, the dysregulation of T cells, and reduced bone marrow megakaryopoiesis. ITP is commonly manifested with skin and mucosal bleeding, and it is a diagnosis of exclusion. In some ITP cases, the disease is self-limiting, and treatment is not required, but chronic-persistent disease can also be developed. In these cases, anti-CD20 monoclonal antibodies, such as rituximab and thrombopoietin (TPO) receptor agonists, can be used. TPO agonists have become standard of care today. It has been reported in the published literature that the efficacy of TPO-RAs can be up to 80% in the achievement of several end goals, such as PLT counts. In the current literature review, the data regarding the impact of TPO agonists in the pathogenesis of ITP and treatment outcomes of the patients are examined. In the era of precision medicine, targeted and individualized therapies are crucial to achieving better outcomes for pediatric patients with ITP, especially when chronic refractory disease is developed.

Observation on the efficacy of TPO receptor agonists and platelet transfusion in chemotherapy-induced thrombocytopenia in malignant tumors

OBJECTIVE

To observe the clinical efficacy of TPO receptor agonists and platelet transfusion in chemotherapy-induced thrombocytopenia in malignant tumors.

METHODS

Clinical data from 120 patients with malignant tumors who developed thrombocytopenia following chemotherapy at our hospital were retrospectively collected and randomly divided into three groups: A, B, and C, with 40 patients in each group. Group A was treated with a TPO receptor agonist (avatrombopag), group B received autologous platelet transfusion, and group C received a combination of both treatments. The clinical efficacy of the three groups was compared, including platelet levels at different time points during treatment, platelet recovery time (time to reach < 50 × 109/L, ≥ 75-100 × 109/L, and ≥ 100 × 109/L), changes in serum cytokine levels (PF4, TPO, vWF) before and after treatment, and fluctuations in coagulation function indicators (APTT, PT, FIB) before and after treatment to analyze the effectiveness of each treatment regimen.

RESULTS

About clinical efficacy, the effectiveness in group A was comparable to that in group B (P > 0.05), while the effective rate in group C was significantly higher than that in groups A and B (P < 0.05). Regarding platelet counts, repeated measures analysis of variance showed significant differences in the time effect, group effect, and interaction effect for platelet counts (PLT) among the three groups (P < 0.05). Concerning platelet recovery time, the time to reach PLT < 50 × 109/L, the time to recover to 75-100 × 109/L, and the time to recover to ≥ 100 × 109/L were similar in groups A and B (P > 0.05). However, the time for these parameters in group C was significantly shorter than in groups A and B (P < 0.05). In terms of changes in platelet parameters, post-treatment levels of PF4, TPO, and vWF in all three groups were significantly higher than pre-treatment levels. The PF4, TPO, and vWF levels in groups A and B were similar (P > 0.05), whereas group C had significantly higher levels compared to groups A and B (P < 0.05). Regarding coagulation indices, post-treatment levels of APTT and PT decreased, while FIB levels increased in all three groups (P < 0.05). There were no significant differences in APTT and FIB levels between groups A and B (P > 0.05). However, group C had significantly lower APTT and higher FIB levels compared to groups A and B (P < 0.05). There were no significant differences in PT levels among the three groups post-treatment (P > 0.05).

CONCLUSION

Autologous platelet transfusion and TPO receptor agonists are effective clinical methods for treating chemotherapy-induced thrombocytopenia. The combined use of both treatments yields better therapeutic results.

Eltrombopag for the treatment of refractory connective tissue disease-related thrombocytopenia: a pilot study of 52 cases

BACKGROUND

The objective of this study was to investigate the therapeutic effectiveness and safety profile of Eltrombopag, a thrombopoietin receptor agonist, as prolonged therapy in refractory CTD-ITP patients.

METHODS

We conducted a pilot observational study of Eltrombopag in CTD-ITP patients who were unresponsive to or intolerant of conventional medications. Eltrombopag was administered orally at 25-75 mg/qd and adjusted on the basis of tolerance and efficacy until a minimum dosage of 25 mg/qd was reached. Clinical and laboratory data were collected and analysed monthly. The therapeutic response, relapse, and adverse events during the follow-up were also reviewed and evaluated.

RESULTS

Fifty-two patients were enrolled and followed monthly for a median of 6 months. Thirty-six (90%) patients achieved durable overall remission. The remission rates were 67.5% at month 1, 87.5% at month 2, 97.5% at month 3, and 95% at month 6. The platelet count of the patients improved significantly, with the median reaching 50 × 109/L within 2 weeks (p = 0.003). Disease activity indices were reduced in SLE and pSS patients (p = 0.016), allowing glucocorticoid tapering (p = 0.004). One patient had no response, four relapsed, and fifteen (28.8%) experienced clinically relevant adverse events. In the analyses, protopathy, comorbidity, and prior treatment were associated with efficacy.

CONCLUSIONS

For refractory CTD-ITP patients, Eltrombopag demonstrated significant clinical improvement, safety, and a steroid-sparing effect with prolonged use. Patient characteristics at baseline may affect treatment efficacy.

Long-term follow-up of the STOPAGO study

ABSTRACT

In an open prospective, multicenter study enrolling 48 selected patients with chronic immune thrombocytopenia who achieved complete response for 1 year on thrombopoietin receptor agonists, half of the patients maintained a sustained response off treatment 4 years after treatment discontinuation.

Hematological causes of acute ischemic stroke in younger individuals

Ischemic stroke is a common cause of morbidity and mortality worldwide. The majority of affected individuals are older, with clear cardiovascular or embolic risk factors; however, up to a fifth of cases may occur in patients under the age of 50 years. In this review, we discuss some common hematological causes of ischemic stroke in this age range, with a focus on antiphospholipid syndrome, myeloproliferative neoplasms, immune thrombocytopenic purpura, and sickle cell disease. We review the etiology of stroke associated with these conditions and explore important management considerations that may be unique to these settings. These include the choice of antithrombotic agents, cytoreduction in myeloproliferative neoplasms, management of thrombocytopenia in immune thrombocytopenic purpura, and treatment of sickle cell disease.

A case report of refractory immune thrombocytopenia: Challenges in choice of therapies in resource limiting center

INTRODUCTION AND IMPORTANCE

Refractory immune thrombocytopenic purpura (ITP) is a rare but serious condition causing significant morbidity and mortality due to inadequate response to standard treatments, resulting in persistent thrombocytopenia and increased bleeding risk.

CASE PRESENTATION

An 18-year-old female patient, diagnosed with ITP two years prior following excessive vaginal bleeding and fatigue, was initially treated with oral prednisolone for two months and discharged in improved condition. Eighteen months after treatment cessation, she presented with recurrent excessive vaginal bleeding, intermittent bilateral nasal bleeding, skin rash, blurred vision, fatigue, tinnitus, vertigo, and intermittent headaches (one-month duration). Following a one-month admission during which she proved unresponsive to steroids, she received rituximab 500 mg IV weekly for four weeks, along with supportive care.

CLINICAL DISCUSSION

Refractory ITP in conjunction with COVID-19 is a rare and serious condition associated with significant morbidity and mortality, and a low survival rate. Effective, coordinated medical and surgical management, along with comprehensive rehabilitation from COVID-19, are crucial for improving outcomes in this severe condition.

CONCLUSION

Refractory ITP is a challenging and rare condition that can result in significant health complications, economic burdens, and a reduced quality of life for those affected.

Oxymatrine, a novel TLR2 agonist, promotes megakaryopoiesis and thrombopoiesis through the STING/NF-κB pathway

Radiation-induced thrombocytopenia (RIT) faces a perplexing challenge in the clinical treatment of cancer patients, and current therapeutic approaches are inadequate in the clinical settings. In this research, oxymatrine, a new molecule capable of healing RIT was screened out, and the underlying regulatory mechanism associated with magakaryocyte (MK) differentiation and thrombopoiesis was demonstrated. The capacity of oxymatrine to induce MK differentiation was verified in K-562 and Meg-01 cells in vitro. The ability to induce thrombopoiesis was subsequently demonstrated in Tg (cd41:enhanced green fluorescent protein (eGFP)) zebrafish and RIT model mice. In addition, we carried out network pharmacological prediction, drug affinity responsive target stability assay (DARTS) and cellular thermal shift assay (CETSA) analyses to explore the potential targets of oxymatrine. Moreover, the pathway underlying the effects of oxymatrine was determined by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, Western blot (WB), and immunofluorescence. Oxymatrine markedly promoted MK differentiation and maturation in vitro. Moreover, oxymatrine induced thrombopoiesis in Tg (cd41:eGFP) zebrafish and accelerated thrombopoiesis and platelet function recovery in RIT model mice. Mechanistically, oxymatrine directly binds to toll-like receptor 2 (TLR2) and further regulates the downstream pathway stimulator of interferon genes (STING)/nuclear factor-kappaB (NF-κB), which can be blocked by C29 and C-176, which are specific inhibitors of TLR2 and STING, respectively. Taken together, we demonstrated that oxymatrine, a novel TLR2 agonist, plays a critical role in accelerating MK differentiation and thrombopoiesis via the STING/NF-κB axis, suggesting that oxymatrine is a promising candidate for RIT therapy.

Predictors of Splenectomy Response in Immune Thrombocytopenia: A Multicentric Italian Study

Background/Objectives: Splenectomy leads to a high rate of remission in chronic primary immune thrombocytopenia (ITP), but its unpredictable long-term positive outcomes and that it is a irreversible surgical approach discourage clinicians and patients. The identification of predictors of response may redefine the timing of splenectomy. In this retrospective, multicentric study we aimed to investigate clinical-histological predictors of splenectomy response in ITP patients and provide an easy-to-use score to predict splenectomy response in ITP. Methods: We considered a discovery set (n = 17) and a validation set (n = 30) of adult ITP patients, who underwent splenectomy for refractory disease in three Italian referral centers for ITP. Results: We found that the presence of autoimmune comorbidities, daily steroid dose prior to splenectomy, age at diagnosis and age at splenectomy were significantly associated with the outcome. Variables singly associated with an adverse outcome were combined into a clinical and a clinical-pathological score, allowing us to define a "high-risk" group which accounted for about 80% of the disease relapses observed in this cohort. At the same time, a certain clinical-pathological score indicated a "high-risk" group characterized by significantly poorer outcomes. Results were confirmed in the validation cohort. Conclusions: An integrated set of clinical and histological parameters may predict the response to splenectomy in ITP patients. While these findings provide valuable insights, they were derived from a small cohort of patients and therefore require validation in larger, more diverse populations to ensure their generalizability and robustness.

Efficacy and safety of TPO receptor agonists in treatment of ITP associated with predominantly antibody deficiencies

ABSTRACT

Predominantly antibody deficiencies have an estimated prevalence of >1 in 25 000. Their classical phenotype entails the association of autoimmune manifestations with increased susceptibility to infections. Up to 8% of these patients ultimately develop immune thrombocytopenic purpura (ITP). Reducing the risk for infections and considering nonimmunosuppressive treatments, such as thrombopoietin receptor agonists (TPO-RAs), are important considerations for these patients. This nationwide retrospective case series assessed the outcomes and safety of TPO-RAs as treatment for ITP in adults diagnosed with predominantly antibody deficiencies. Response and complete response to treatment were defined as platelet count reaching 30 × 109/L and 100 × 109/L, respectively. We analyzed data from 28 patients. The median follow-up time after introduction of the first TPO-RAs was 33 months (range, 2 weeks to 10.6 years). After 6 weeks of follow-up, response was achieved in 24 of the 28 patients (85.7%), and among those, 21 patients (75%) displayed a complete response. At the last available follow-up visit, only 7 patients (25%) needed second-line therapies for ITP, and among those, only 5 patients (17.9%) received immunosuppressants. Only 3 patients (10.7%) reported laboratory-confirmed hepatobiliary adverse events of light or mild severity and 3 patients (10.7%) reported thrombotic events. In conclusion, TPO-RAs seemed to be an effective and safe option of treatment in these case series. Our results suggest that eltrombopag or romiplostim should be considered as second-line therapy for ITP related to predominantly antibody deficiencies.

Let It Grow: The Role of Growth Factors in Managing Chemotherapy-Induced Cytopenia

Chemotherapy-induced cytopenia (CIC) is characterized by neutropenia, anemia, and thrombocytopenia, which are common and serious complications in cancer treatment. These conditions affect approximately 60% of patients undergoing chemotherapy and can significantly impact quality of life, treatment continuity, and overall survival. The use of growth factors, including granulocyte colony-stimulating factors (GCSFs), erythropoietin-stimulating agents (ESAs), and thrombopoietin receptor agonists (TPO-RAs), has emerged as a promising strategy for managing CIC. However, the use of these growth factors must be approached with caution. This review provides an overview of the mechanisms, efficacy, and safety of growth factors in the management of CIC. Additionally, we discuss predictive markers for treatment response, potential risks, and highlight areas for future research.

Effects of Acceptance and Commitment Care in the Treatment of Aplastic Anemia Patients with Recombinant Human Thrombopoietin

Background

This study was designed to determine the effects of acceptance and commitment care in the treatment of aplastic anemia (AA) patients with recombinant human thrombopoietin (rhTPO).

Methods

The clinical records of 100 AA patients treated at our hospital from March 2021 to March 2023 were analyzed in the retrospective study. All patients received immunosuppressants and rhTPO. Among them, 46 patients who received routine care from March 2021 to March 2022 were allocated to the control group, and the other 54 patients who received acceptance and commitment care from April 2022 to March 2023 were assigned to the study group. The quality of life (QoL) of the 2 groups was assessed by the MOS 36-Item Short-Form Health Survey (SF-36) before care and after 3 months of care. Blood-related indicators after care were compared in 2 groups.

Results

Before care, no significant inter-group discrepancy was observed in SF-36 scores in all dimensions (P > .05); whereas after nursing, the SF-36 scores of both groups increased conspicuously in all dimensions (P < .001), especially the study group (P < .001). After care, no significant differences were observed in hemoglobin (Hb), platelet count (PLT), and white blood cell count (WBC) between the 2 groups (P > .05). A conspicuously lower overall response rate was observed in the control group in contrast to the study group (P = .044), and no significant inter-group discrepancy was found in the total incidence of adverse reactions (P = .506).

Conclusion

Acceptance and commitment care is conducive to the patients with AA treated by rhTPO, because it substantially improves the QoL of patients, without increasing adverse reactions, so it is worth promoting.

Insights on treatment of adult ITP: algorithm for management and role of multimodal therapy

The management of immune thrombocytopenia (ITP) is continuously evolving with the development and introduction of newer therapies and a better understanding of the disease. Corticosteroids still represent the cornerstone of first-line treatment. Patients who fail to achieve remission with a short course of corticosteroids require subsequent therapy. Most guidelines recommend starting with either a thrombopoietin receptor agonist (TPO-RA), rituximab, or fostamatinib since these agents have been investigated in randomized trials and have well-characterized efficacy and safety profiles. Patients' involvement to reach a shared decision regarding choice of therapy is essential as these treatments have different modes of administration and mechanisms of action. Less than 10% will fail to respond to and/or be intolerant of multiple second-line therapeutic options and thus be considered to have refractory ITP and require a third-line therapeutic option. Such patients may require drugs with different targets or a combination of drugs with different mechanisms of action. Combining a TPO-RA and an immunomodulatory agent may be an appropriate approach at this stage. Many studies have been conducted during the last 2 decades investigating the efficacy and safety of combinations strategies for first and later lines of therapies. Yet none of these are recommended by current guidelines or have gained wide acceptance and consensus.

Efficacy and safety of avatrombopag in the treatment of chemotherapy-induced thrombocytopenia in children with acute lymphoblastic leukemia: a single-center retrospective study

Background

Chemotherapy-induced thrombocytopenia (CIT) commonly exacerbates the difficulty of cancer treatment, increasing bleeding risks and potentially reducing chemotherapy dosage, ultimately impacting its efficacy. However, there are limited studies about avatrombopag application in acute lymphoblastic leukemia (ALL) CIT.

Objectives

We aimed to evaluate the efficacy and safety of avatrombopag in treating CIT patients diagnosed with ALL.

Design

This retrospective study, using propensity score matching, included 42 pairs of cases treated with and without avatrombopag (CAT: 54 cases, CAT+: 30 cases).

Methods

Data of CIT-ALL children were retrospectively collected. The primary endpoint was platelet count (PC) response rate on day 10 ± 2 (defined as an increase of PC to ⩾75 × 109/L with the exclusion of platelet transfusion). Secondary efficacy endpoints, safety endpoints, and factors that predict PC response were also analyzed.

Results

In the avatrombopag group, the PC response rate was prominently higher on day 10 ± 2 (89.1%) versus the control group (56.4%, p = 0.005). On day 10 ± 2, the difference in median PC change from baseline was predominantly distinct in the avatrombopag group compared to the control group (p = 0.001). In the avatrombopag group, platelet recovery to ⩾25 and ⩾50 × 109/L was faster (p = 0.001, p = 0.002), and quicker platelet reaching ⩾75 × 109/L and ⩾100 × 109/L was achieved (p = 0.023, p = 0.011). The avatrombopag group not only increased the nadir PC (p = 0.009) but also reduced the total platelet transfusion compared to the control group (p = 0.047). Only one case (2.4%) experienced bleeding events after medication. Nine cases of secondary thrombocythemia were noted without other adverse events. There was no difference in event-free survival between the two groups (p = 0.648). Drug administration was prediction factor for PC response.

Conclusion

Avatrombopag is a potentially safe and effective treatment option for CIT in pediatric ALL.

Efficacy and safety of recombinant human thrombopoietin for the treatment of chronic primary immune thrombocytopenia in children and adolescents: A multicentre, randomized, double-blind, placebo-controlled phase III trial

The efficacy and safety of recombinant human thrombopoietin (rhTPO) in children and adolescent patients with chronic primary immune thrombocytopenia (ITP) remains unclear. A multicentre, randomized, double-blind, placebo-controlled phase III trial was performed. Patients aged 6-17 years, diagnosed with ITP and resistant or relapsed to corticosteroid treatment were included. For the trial, part 1 was exploratory and part 2 was the main analysis, with part 1 determining whether part 2 was stratified by age. Patients in part 1 were treated with rhTPO (the 6- to 11-/12- to 17-year-old groups; 1:1). Patients in part 2 were randomized (3:1) to receive either rhTPO treatment or placebo. Patients received rhTPO or placebo at a dose of 300 U/kg once daily for up to 14 days. A total of 68 patients were included [part 1 (12 patients), part 2 (56 patients)]. The total response rate (TRR) in part 1 was 50.0% (95% CI: 21.09%-78.91%). For part 2, the TRR was 58.5% (95% CI: 42.11%-73.68%) and 13.3% (95% CI: 1.66%-40.46%) in the rhTPO and placebo groups (FAS) respectively. The difference in TRR between the rhTPO group and placebo group was 45.2% (95% CI: 22.33%-68.08%) and 44.6% (95% CI: 21.27%-67.85%) on the FAS and per-protocol set (PPS), respectively, which indicates the superiority of rhTPO treatment.

Real-world evidence of avatrombopag for the treatment of immune thrombocytopenia intolerant or ineffective to eltrombopag/hetrombopag

Due to the limited real-world research on the application of avatrombopag (AVA) for immune thrombocytopenia (ITP) in China, we evaluated the effectiveness and safety of AVA in clinical practice. We included 121 adult ITP patients treated with AVA across three medical centres. Based on the reasons for choosing AVA, these patients were divided into eltrombopag (ELT)/hetrombopag (HET) intolerance group (IG), and ELT/HET unresponsive group (UG). Compared with UG, more patients in IG had a history of liver disease and received fewer treatments before AVA. Amongst all patients, 83% had platelet response (≥30 × 109/L) after AVA and 62% achieved complete response (≥100 × 109/L, CR). Sixty-two percent in IG and 56% in UG were able to discontinue more than one concomitant ITP medication. A total of 17 patients underwent multiple switches of thrombopoietin receptor agonists (TPO-RAs), resulting in an 88% platelet response rate. Sixty-three patients discontinued AVA, 27% were due to unaffordability. AVA was well tolerated in most patients. In the ITP population, AVA proved effective and safe, particularly in patients intolerant or unresponsive to ELT/HET. Patients benefited from TPO-RAs switches, particularly those undergoing multiple switches. However, many patients struggled with the long-term financial burden of AVA.

A study of platelet function in patients with chronic immune thrombocytopenia treated with thrombopoietin receptor agonists

BACKGROUND

Thrombopoietin receptor agonists (TPO-RAs) are widely used in immune thrombocytopenia (ITP) and are associated with increased thrombotic risk. However, data regarding their impact on platelet function is scarce.

METHODS

Platelet function was evaluated in chronic ITP patients enrolled over one year, using light transmission aggregometry and platelet-derived microparticle (PMP) levels measurement with flow cytometry. Aggregation responses to various concentrations of ADP, collagen, ristocetin, and PMP levels were compared between TPO-RA-treated patients, patients treated with other agents and healthy individuals.

RESULTS

TPO-RA-treated patients (n = 24) displayed significantly reduced aggregation responses to 2.5 μM, 5 μM, and 10 μM of ADP and collagen compared to 15 healthy individuals (59.5 % vs. 87.6 %, p < .0001, 43.6 % vs. 79.9 %, p < .0001, 26.1 % vs. 75.2 %, p < .0001, 67.2 % vs. 86 %, p < .0001, respectively). Reduced responses to ADP and collagen were also recorded in patients treated with other agents (n = 16) compared to healthy controls but without difference between the two treatment groups. Aggregation response to ristocetin was normal in all three groups. None of the patients yielded enhanced platelet aggregation. In TPO-RA-treated patients, a strong positive correlation between platelet counts and aggregation response to ristocetin was observed (rs = 0.65, p = .0005). PMP levels were significantly elevated in TPO-RA-treated patients compared to patients treated with other agents (49.5 vs 4.5 events/uL, p < .0001) and healthy controls (5 events/uL, p < .0001).

CONCLUSIONS

These results suggest that TPO-RAs may not enhance platelet aggregation responses, whereas impaired responses may be a disease feature. Furthermore, TPO-RAs may increase PMP levels and thus be implicated in the modulation of platelet function in ITP patients.

Efficacy and safety of avatrombopag in combination with standard immunosuppressive therapy for severe aplastic anemia

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure disease. The addition of eltrombopag to immunosuppressive therapy (IST) improves the response rate, but its hepatotoxicity is concerning. Avatrombopag (AVA), a small-molecule thrombopoietin-receptor agonist without hepatotoxicity, has unknown efficacy in SAA treatment. This retrospective study assessed the efficacy and safety of AVA added to IST 42 SAA patients compared to a historical cohort of 84 patients receiving IST alone, using propensity score matching. The median age was 31.5 (6.0-67.0 years) years old in group A and 26 (16.0-45.0 years) years old in group B. At 3 months, group A showed higher complete response (CR) and overall response (OR) rates than group B (CR: 19.0% vs. 4.8%, p = 0.024; OR: 54.8% vs. 39.3%, p = 0.145). Higher CR and OR rates were also found at 6 months in group A than in group B (CR: 31.0% vs. 14.3%, p = 0.145; OR 71.4% vs. 51.2%, p = 0.048). In multivariate analysis of group A, a shorter interval from disease onset to antithymocyte globulin (ATG) treatment (≤6 months) (p = 0.005) predicted better responses rate at 6 months. Event-free survival was also improved in group A (60.7% vs. 49.6%). AVA was well-tolerated, with no hepatic injury observed during treatment, even in those with pre-existing hepatic impairment. The addition of AVA to IST improves both the response rate and response quality in patients with SAA while ensuring safety.

Thromboembolism adverse event profiles of thrombopoietin receptor agonists: a real-world, pharmacovigilance study

BACKGROUND

Thrombopoietin receptor agonists (TPO-RAs) are currently approved for the treatment of thrombocytopenia in different conditions. The relationship between TPO-RAs and thromboembolic events (TEEs) remains controversial.

RESEARCH DESIGN AND METHODS

We extracted TPO-RAs adverse reaction reports after their marketing until now, using the FDA adverse event reporting system (FAERS). Positive signals were detected by reporting odds ratios (RORs). And the Weibull shape parameter test was utilized to analyze the time-to-onset profiles.

RESULT

Thromboembolic events accounted for 8.97% among TPO-RAs reports. Increased reporting of TEEs was related to TPO-RAs treatment compared with the entire FAERS database [ROR = 2.65 (2.56, 2.73)]. In addition, venous thrombotic events [ROR = 4.13 (3.92, 4.35)] were reported more frequently than arterial events ROR = 1.81 (1.7, 1.93)]. Age over 60 years [odds ratio (OR) = 1.10 (1.01, 1.20), p = 0.029] and weight over 80 kg [OR = 1.36 (1.17, 1.58), p < 0.001] of patients might have higher risk of TEEs during TPO-RAs therapy.

CONCLUSION

Evidence from the real world suggested that TPO-RAs were associated with higher incidence of TEEs, particularly venous thrombosis. The risk of TPO-RAs-associated TEEs mostly happened in the early stages of treatment and decreased over time.

Romiplostim, low-dose rituximab and high-dose dexamethasone for newly diagnosed immune thrombocytopenia: A pilot study

Therapies such as corticosteroids, thrombopoietin receptor agonists and immunomodulators have been consistently under the spotlight in the search for a better treatment for immune thrombocytopenia (ITP). However, none of them has been widely embraced as a new standard. In this pilot study, we investigated feasibility, safety and preliminary efficacy of romiplostim, low-dose rituximab and high-dose dexamethasone for newly diagnosed ITP. We conducted a single-centre single-arm pilot. One-month treatment adherence was 100%. The 1-month overall response rate was 92.3%. Complete response occurred in 11 (84.6%) patients. Median duration of response was 4.13 monts (range 0.2-25). No serious adverse events presented.

Exploratory study on the individualized application of eltrombopag in paediatric immune thrombocytopenia guided by therapeutic drug monitoring

There are variations in individual eltrombopag concentrations that may impact efficacy and adverse drug reactions (ADRs) in paediatric immune thrombocytopenia (ITP). To solve this problem, we tailored the eltrombopag dosage refer to concentration, then followed up to assess concentration value in paediatric ITP. This is a single-centre, prospective, observational study. The eltrombopag dosage was adjusted, and children were divided into three groups: the maintenance, discontinuation, and increase groups. Concentration and other data were compared to explore concentration value in guiding the individualized treatment of paediatric ITP. Thirty-nine patients were enrolled, including 23 in the maintenance group, 3 in the discontinued group and 13 in the increase group. 3 patients discontinued eltrombopag due to ADRs, which was significantly higher than patients in the maintenance group (t = 3.606, p = 0.001). In all, 13 patients increased their dosage due to poor response, whose concentration and platelet count were significantly lower than patients in the maintenance group (t = 2.461, p = 0.019; t = 4.633, p < 0.001). Two months after the increase, the number of patients reaching CR and R respectively increased by 2 and 3, while the median platelet count was significantly raised (Z = -2.411, p = 0.016). Concentration could be used as a reference index for the individualized treatment of eltrombopag in paediatric ITP.

Eltrombopag plus diacerein vs eltrombopag in patients with ITP: a multicenter, randomized, open-label phase 2 trial

ABSTRACT

This study aimed to compare the efficacy and safety of eltrombopag plus diacerein vs eltrombopag alone in patients with primary immune thrombocytopenia (ITP) who were previously unresponsive to 14 days of eltrombopag treatment at the full dose. Recruited patients were randomly assigned 1:1 to receive either eltrombopag plus diacerein (n = 50) or eltrombopag monotherapy (n = 52). Overall response rate, defined as a platelet count of ≥30 × 109/L, at least doubling of the baseline platelet count, and no bleeding, was reached in 44% of patients in the eltrombopag plus diacerein group compared with 13% in the eltrombopag group at day 15 (P = .0009), and reached in 42% of patients in the combination group compared with 12% in the monotherapy group at day 28 (P = .0006). The addition of diacerein to eltrombopag also led to a longer duration of response (P = .0004). The 2 most common treatment-emergent adverse events were respiratory infection and gastrointestinal reactions in the combination group, and fatigue and respiratory infection in the eltrombopag group. In conclusion, eltrombopag plus diacerein was well tolerated, and induced higher overall response rates and longer duration of response than eltrombopag alone, offering a rejuvenating salvage therapy for patients with ITP unresponsive to 14 days of full dosage eltrombopag. Our work has the potential to enhance the care of patients treated with thrombopoietin receptor agonists, reducing the need for rapid transitions to less-preferable therapies. This study is registered at ClinicalTrials.gov as #NCT04917679.

Diagnosis and management of acquired aplastic anemia in childhood. Guidelines from the Marrow Failure Study Group of the Pediatric Haemato-Oncology Italian Association (AIEOP)

Acquired aplastic anemia (AA) is a rare heterogeneous disorder characterized by pancytopenia and hypoplastic bone marrow. The incidence is 2-3 per million population per year in the Western world, but 3 times higher in East Asia. Survival in severe aplastic anemia (SAA) has improved significantly due to advances in hematopoietic stem cell transplantation (HSCT), immunosuppressive therapy, biologic agents, and supportive care. In SAA, HSCT from a matched sibling donor (MSD) is the first-line treatment. If a MSD is not available, options include immunosuppressive therapy (IST), matched unrelated donor, or haploidentical HSCT. The purpose of this guideline is to provide health care professionals with clear guidance on the diagnosis and management of pediatric patients with AA. A preliminary evidence-based document prepared by a group of pediatric hematologists of the Bone Marrow Failure Study Group of the Italian Association of Pediatric Hemato-Oncology (AIEOP) was discussed, modified and approved during a series of consensus conferences that started online during COVID 19 and continued in the following years, according to procedures previously validated by the AIEOP Board of Directors.

The immune thrombocytopenia paradox: Should we be concerned about thrombosis in ITP?

Despite the predisposition to bleeding, patients with immune thrombocytopenia (ITP) may also have an increased risk of arterial and venous thrombosis, which can contribute to significant morbidity. The risk of thrombosis increases with age and the presence of cardiovascular risk factors. This narrative review explores the multifactorial nature of thrombosis in ITP, focusing on new pathological mechanisms, emerging evidence on the association between established treatments and thrombotic risk, the role of novel treatment approaches, and the challenges in assessing the balance between bleeding and thrombosis in ITP. The review also explores the challenges in managing acute thrombotic events in ITP, since the platelet count does not always reliably predict either the risk of bleeding or thrombosis and antithrombotic strategies lack specific guidelines for ITP. Notably, second-line therapeutic options, such as splenectomy and thrombopoietin receptor agonists (TPO-RAs), exhibit an increased risk of thrombosis especially in older individuals or those with multiple thrombotic risk factors or previous thrombosis, emphasizing the importance of careful risk assessment before treatment selection. In this context, it is important to consider second-line therapies such as rituximab and other immunosuppressive agents, dapsone and fostamatinib, which are not associated with increased thrombotic risk. In particular, fostamatinib, an oral spleen tyrosine kinase inhibitor, has promisingly low thrombotic risk. During the current era of the emergence of several novel ITP therapies that do not pose additional risks for thrombosis, it is critical to outline evidence-based strategies for the prevention and treatment of thrombosis in ITP patients.

Identification of Active Molecules against Thrombocytopenia through Machine Learning

Thrombocytopenia, which is associated with thrombopoietin (TPO) deficiency, presents very limited treatment options and can lead to life-threatening complications. Discovering new therapeutic agents against thrombocytopenia has proven to be a challenging task using traditional screening approaches. Fortunately, machine learning (ML) techniques offer a rapid avenue for exploring chemical space, thereby increasing the likelihood of uncovering new drug candidates. In this study, we focused on computational modeling for drug-induced megakaryocyte differentiation and platelet production using ML methods, aiming to gain insights into the structural characteristics of hematopoietic activity. We developed 112 different classifiers by combining eight ML algorithms with 14 molecule features. The top-performing model achieved good results on both 5-fold cross-validation (with an accuracy of 81.6% and MCC value of 0.589) and external validation (with an accuracy of 83.1% and MCC value of 0.642). Additionally, by leveraging the Shapley additive explanations method, the best model provided quantitative assessments of molecular properties and structures that significantly contributed to the predictions. Furthermore, we employed an ensemble strategy to integrate predictions from multiple models and performed in silico predictions for new molecules with potential activity against thrombocytopenia, sourced from traditional Chinese medicine and the Drug Repurposing Hub. The findings of this study could offer valuable insights into the structural characteristics and computational prediction of thrombopoiesis inducers.

Correction of Thrombocytopenia before Elective Surgery / Invasive Procedures in Patients with Liver Cirrhosis (Experts’ Agreement)

Introduction. As a result of portal hypertension (sequestration of platelets in an enlarged spleen) and liver failure (decreased production of thrombopoietin in the liver) in liver cirrhosis, thrombocytopenia develops, which is associated with the risk of periprocedural/perioperative bleeding complications. There are still unresolved questions regarding risk stratification of bleeding complications, the prognostic role of thrombocytopenia, as well as the need for treatment of thrombocytopenia and its methods.

Materials and methods. The Russian Scientific Liver Society selected a panel of experts in the field of therapeutic and surgical hepatology, hematology, transfusion medicine to make reasoned statements and recommendations on the issue of treatment of thrombocytopenia before elective surgery / invasive procedures in patients with liver cirrhosis.

Results. Relevant clinical issues were determined based on the PICO principle (patient or population, intervention, comparison, outcome). The Delphi panel made five questions and gave reasoned answers, framed as ‘clinical practice recommendations and statements’ with evidence-based comments. The questions and statements were based on the results of search and critical analysis of medical literature using keywords in English- and Russian-language databases. The formulated questions could be combined into four categories: bleeding risk stratification, the prognostic value of thrombocytopenia, the necessity and methods of thrombocytopenia drug correction, and bleeding risk reduction.

Conclusions. The results of experts' work are directly related to high-quality management of patients with liver cirrhosis and thrombocytopenia, who have scheduled invasive procedures/surgery. Thus, this recommendations and statements can be used in clinical practice.

Thrombopoietin receptor agonists regulate myeloid-derived suppressor cell-mediated immunomodulatory effects in ITP

TPO receptor agonists (TPO-RAs) are a class of clinical second-line regimens for the treatment of primary immune thrombocytopenia (ITP). It can promote megakaryocyte maturation and increase platelet production, but its effect on immunosuppressive cells in patients with ITP has not been explored. Sixty-two ITP patients and 34 healthy controls (HCs) were included in this study. The proportion and functions of myeloid-derived immunosuppressive cells (MDSCs) in ITP patients and HCs were investigated. We found that the proportion and function of MDSCs in ITP patients treated with TPO-RAs were significantly higher than those treated with glucocorticoids (GCs), which was correlated with the clinical efficacy. The proportion and function of cytotoxic Th1 cells and CD8+T cells decreased, while the proportion and immunosuppressive function of Treg cells increased in ITP patients treated with TPO-RAs. We further proved, through MDSC depletion tests, that the inhibitory effect of MDSCs on Th1 cells and the promotion of Treg cells in the original immune micro-environment of GCs-treated ITP patients were impaired; however, these MDSCs' functions were improved in TPO-RAs-treated patients. Finally, we found that the KLF9 gene in MDSCs cells of ITP patients treated with TPO-RAs was down-regulated, which contribute to the higher mRNA expression of GADD34 gene and improved function of MDSCs. These results demonstrate a novel mechanism of TPO-RAs for the treatment of ITP through the assessment of MDSCs and their subsequent impact on T cells, which provides a new basis for TPO-RAs as first-line treatment approach to the treatment of ITP.

Update on the Use of Thrombopoietin-Receptor Agonists in Pediatrics

This review summarizes the rationale and current data on the use of thrombopoietin receptor agonists (TPO-RAs) for treating severe thrombocytopenia in infants, children, and adolescents. It focuses on substances that have been approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) for pediatric patients. Romiplostim and eltrombopag are already established as second-line treatment for persistent or chronic immune thrombocytopenia (ITP). As in adults, TPO-RAs are currently also evaluated in severe aplastic anemia (SAA), chemotherapy-induced thrombocytopenia (CIT), myelodysplastic syndromes (MDS), and poor engraftment after hematopoietic stem cell transplantation in pediatric and adolescent patients. Moreover, studies on the implication of TPO-RA in treating rare inherited thrombocytopenias, such as Wiskott-Aldrich syndrome (WAS), congenital amegakaryocytic thrombocytopenia (CAMT), or MYH9-associated thrombocytopenia, deserve future attention. Current developments include testing of avatrombopag and lusutrombopag that are approved for the treatment of thrombocytopenia associated with chronic liver disease (CLD) in adult patients. In pediatric and adolescent medicine, we expect in the near future a broader use of TPO-RAs as first-line treatment in primary ITP, thereby considering immunomodulatory effects that increase the rate of sustained remission off-treatment, and a selective use in rare inherited thrombocytopenias based on current clinical trials.

The Differences of Serum Thrombopoietin Levels Between Acquired Aplastic Anemia and Immune Thrombocytopenia in Pediatric Patients

Thrombopoietin (TPO) is the critical regulator of platelet production. However, the role of TPO in pediatric patients with thrombocytopenic disorders has not been fully elucidated. In the present study, we attempted to investigate serum TPO levels in patients with acquired aplastic anemia (aAA) and immune thrombocytopenia (ITP). We analyzed the endogenous plasma concentration of TPO and platelet count at the time of TPO measurement in 166 patients with aAA and 280 patients with ITP retrospectively. We further observed a correlation between platelet counts and TPO. Serum TPO levels were significantly higher in aAA compared with ITP (1142 vs. 77.99 pg/mL, P <0.001). In patients with aAA, an elevation for TPO levels in very severe AA (VSAA) was seen when compared with non-severe AA (NSAA) (1360 vs. 984.4 pg/mL, P <0.05). In contrast, the circulating TPO levels with chronic ITP (CITP) showed a decrease than newly diagnosed ITP (NITP) and persistent ITP (PITP) (62.28 vs. 81.56 pg/mL, P <0.01, 62.28 vs. 87.82 pg/mL, P <0.05, respectively). There was a negative correlation between platelet counts and TPO levels in aAA (r s =-0.3325, P <0.001) as well as ITP (r s =-0.2570, P <0.001). Especially, TPO levels were inversely correlated with platelet counts in NSAA (r s =-0.3672, P <0.001) and NITP (r s =-0.3316, P <0.001). After grouping by age or sex, there were no statistical differences in aAA or ITP. Serum TPO levels were markedly elevated in pediatric patients with aAA compared with ITP. It was higher in VSAA and lower in CITP, suggesting that serum TPO level could play a role in classifying disease severity or clinical course in aAA and ITP.

Avatrombopag as alternative therapy for severe aplastic anemia patients who are intolerant or unresponsive to eltrombopag

Introduction

Eltrombopag (EPAG), a thrombopoietin receptor agonist, was approved for the treatment of severe aplastic anemia (SAA) combined with immunosuppressive therapy (IST). However, EPAG contains a typical biphenyl structure, which causes liver function damage.

Methods

Twenty patients with SAA who were intolerant or refractory to EPAG were enrolled in a multicenter prospective registry of the Chinese Eastern Collaboration Group of Anemia (ChiCTR2100045895) from October 2020 to June 2023.

Results

Eight patients who were ineffective to EPAG, six with kidney impairment, and nine with abnormal liver function (two with concomitant liver and kidney impairment) were converted to avatrombopag (AVA) therapy with the median duration of AVA treatment was 6 (3-24) months. 17 cases (85%) achieved trilineage hematological response (HR): complete remission (CR) in 3 cases (15%), good partial remission (GPR) in 4 cases (20%), partial remission (PR) in 10 cases (50%), and no response (NR) in 3 cases (15%). The median time to response was 1.7 (0.5-6.9) months, with 16 cases (94%) achieving response within six months and 17 cases (100%) within 12 months. 9 cases (50%) achieved transfusion independence. AVA converted treatment was associated with higher neutrophil counts (0.8×109/L vs 2.2×109/L, p=0.0003), platelet counts (11×109/L vs 39×109/L, p=0.0008), hemoglobin count (59g/L vs 98g/L, p=0.0002), red cell count (1.06×1012/L vs 2.97×1012/L, p=0.001), and absolute reticulocyte count (31.99 ×109/L vs 67.05×109/L p=0.0004) were all significantly elevated compared with the pre-treatment level. After the conversion to AVA therapy, liver and kidney function indexes were maintained within the normal range, no AVA related grade 2 or higher adverse events occurred, and no thrombotic events occurred.

Conclusion

The conversion to AVA was an optimal choice for patients with SAA who were EPAG intolerant or refractory.

Clinical trial registration

http://www.chictr.org.cn/showproj.html?proj=125480, identifier ChiCTR2100045895.

Platelet-derived TGF-β1 induces functional reprogramming of myeloid-derived suppressor cells in immune thrombocytopenia

ABSTRACT

Platelet α-granules are rich in transforming growth factor β1 (TGF-β1), which is associated with myeloid-derived suppressor cell (MDSC) biology. Responders to thrombopoietin receptor agonists (TPO-RAs) revealed a parallel increase in the number of both platelets and MDSCs. Here, anti-CD61 immune-sensitized splenocytes were transferred into severe combined immunodeficient mice to establish an active murine model of immune thrombocytopenia (ITP). Subsequently, we demonstrated that TPO-RAs augmented the inhibitory activities of MDSCs by arresting plasma cells differentiation, reducing Fas ligand expression on cytotoxic T cells, and rebalancing T-cell subsets. Mechanistically, transcriptome analysis confirmed the participation of TGF-β/Smad pathways in TPO-RA-corrected MDSCs, which was offset by Smad2/3 knockdown. In platelet TGF-β1-deficient mice, TPO-RA-induced amplification and enhanced suppressive capacity of MDSCs was waived. Furthermore, our retrospective data revealed that patients with ITP achieving complete platelet response showed superior long-term outcomes compared with those who only reach partial response. In conclusion, we demonstrate that platelet TGF-β1 induces the expansion and functional reprogramming of MDSCs via the TGF-β/Smad pathway. These data indicate that platelet recovery not only serves as an end point of treatment response but also paves the way for immune homeostasis in immune-mediated thrombocytopenia.