Prolonged thrombocytopenia after allogeneic hematopoietic stem cell transplantation: associations with impaired platelet production and increased platelet turnover

Immature platelet fraction levels predict the development of prolonged thrombocytopenia after haematopoietic stem cell transplantation

Prolonged thrombocytopenia (PT) is a serious complication after haematopoietic stem cell transplantation (HSCT). PT has been suggested to be associated with an increased platelet transfusion requirement and poor outcomes after transplantation. Due to the complex mechanism of PT development, it is difficult to diagnose in the early post-transplant period. Our study aimed to identify an early predictive marker for PT after HSCT. Previous studies showed that the clinical utility of immature platelet fraction (IPF) predicts platelet recovery after chemotherapy and successful engraftment. However, the relationship between IPF and PT after HSCT remains unclear. Fifty-two patients with malignant haematological diseases who underwent HSCT were included in the study. We observed the kinetics of recovery of haematological parameters after transplantation and performed receiver operating characteristics (ROC) curve analysis using data from the 52 HSCT patients. The days to rise and peak of IPF, absolute IPF count (A-IPF) and highly fluorescent IPF (H-IPF) were almost synchronised in all patients, at day 10 and day 15, respectively. The begin to rise levels of IPF, H-IPF and A-IPF were all significantly lower in the PT group than in the good engraftment (GE) group (p=0.0016, p=0.0094, p=0.0086, respectively). The peak levels of IPF were significantly lower in the PT group than the GE group (p=0.0036). However, the peaks of H-IPF and A-IPF were not statistically significant between the two groups (p=0.3383, p=0.0887, respectively). The area under the ROC curve (AUC) of IPF rise was 0.739 (95% CI 0.583-0.896; p<0.05) and the cut-off value was 3.5%, while the AUC of IPF peak was 0.800 (95% CI 0.637-0.962; p<0.01) and the cut-off value was 8.0%. In conclusion, early low levels of IPF predict the development of PT after HSCT. These findings may help improve the management and treatment strategies for PT after HSCT.

A comparison of haploidentical versus HLA-identical sibling outpatient hematopoietic cell transplantation using reduced intensity conditioning in patients with acute leukemia

Background

Hematopoietic cell transplantation (HCT) increases survival for acute leukemia. Outpatient allogeneic HCT reduces costs and increases transplant rates in developing countries. We report outcomes of outpatient HLA-identical and haploidentical HCT in acute leukemia.

Methods

This single-center retrospective cohort study analyzed 121 adult patients with acute myeloblastic (AML) and acute lymphoblastic leukemia (ALL) receiving an outpatient allogeneic HCT with peripheral blood allografts after reduced-intensity conditioning (RIC) from 2012-2022.

Results

There were 81 (67%) haploidentical and 40 (33%) HLA-identical transplants. Complete chimerism (CC) at day +100 was not different in HLA-identical compared to haploidentical HCT (32.5% and 38.2%, P=0.054). Post-HCT complications, including neutropenic fever (59.3% vs. 40%), acute graft-versus-host-disease (aGVHD) (46.9% vs. 25%), cytokine release syndrome (CRS) (18.5% vs. 2.5%), and hospitalization (71.6% vs 42.5%) were significantly more frequent in haploidentical HCT. Two-year overall survival (OS) was 60.6% vs. 46.9%, (P=0.464) for HLA-identical and haplo-HCT, respectively. There was no difference in the 2-year disease-free-survival (DFS) (33.3% vs. 35%, P=0.924) between transplant types. In multivariate analysis, positive measurable residual disease (MRD) at 30 days (HR 8.8, P=0.018) and 100 days (HR 28.5, P=0.022) was associated with lower OS, but not with non-relapse mortality (NRM) (P=0.252 and P=0.123, univariate). In univariate analysis, both 30-day and 100-day MRD were associated with lower DFS rates (P=0.026 and P=0.006), but only day 30 MRD was significant in multivariate analysis (P=0.050). In the case of relapse, only MRD at day 100 was associated with increased risk in the univariate and multivariate analyses (HR 4.48, P=0.003 and HR 4.67, P=0.008). Chronic graft-versus-host-disease (cGVHD) was protective for NRM (HR 0.38, P=0.015). There was no difference in cumulative incidence of relapse (CIR) between transplant types (P=0.126). Forty-four (36.4%) patients died, with no difference between HCT type (P=0.307). Septic shock was the most frequent cause of death with 17 cases, with no difference between transplant types.

Conclusions

Outpatient peripheral blood allogenic HCT after RIC is a valid and effective alternative for adult patients suffering acute myeloblastic or lymphoblastic leukemia in low-income populations.

Thrombopoietin Receptor Agonists in Post-Hematopoietic Cell Transplantation Complicated by Prolonged Thrombocytopenia: A Comprehensive Review

Hematopoietic cell transplantation (HCT) is a well-established procedure that has become a therapeutic mainstay for various hematological conditions. Prolonged thrombocytopenia following HCT is associated with a significant risk of morbidity and mortality, yet no universally recognized treatment protocol exists for such a complication. First-generation thrombopoietin receptor (TpoR) agonists as well as second-generation agents are known for their role in enhancing platelet production, and their use is expanding across various thrombocytopenic conditions. Therefore, we conducted this comprehensive review of the literature to provide an updated evaluation of the use of TpoR agonists and explore their efficacy and safety in the treatment of extended post-HCT thrombocytopenia. The literature search was conducted using PubMed database from 1996 through December 2023, using a predefined strategy with medical subject headings terms. We identified 64 reports on the utility of TpoR agonists, five of them were randomized controlled trials and the rest were retrospective observational studies and case series, with a total number of 1730 patients. Second-generation TpoR agonists appear more convenient than subcutaneous recombinant human thrombopoietin (rhTpo) as they can be orally administered and exhibit similar efficacy in platelet recovery, as indicated by recent trial results. Among these agents, avatrombopag, unlike eltrombopag, does not require any dietary restrictions, which could be more favorable for patients. However, eltrombopag remains the most extensively studied agent. TpoR agonists had promising effects in the treatment of post-HCT thrombocytopenia with a good safety profile so far, highlighting the potential benefit of their use.

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 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

In summary, 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).

Eltrombopag treatment in thrombocytopenia following hematopoietic stem cell transplantation: A multicenter real-world experience

INTRODUCTION

Thrombocytopenia is among the most common complications following hematopoietic stem cell transplantation and is associated with increased mortality and morbidity with no standard treatment yet. In this multicenter and retrospective study, we aim to present our multi-center experience of Eltrombopag treatment in patients with isolated thrombocytopenia following HSCT.

MATERIAL-METHOD

A total of 73 patients from 5 centers who underwent autologous or allogeneic stem cell transplantation, had no primary disease relapse, all of whom had neutrophil engraftment, complete chimerism, and who were diagnosed with Prolonged Isolated Thrombocytopenia (PIT) or Secondary Failure Of Platelet Recovery (SFPR) were included in the study. The patients were initiated on Eltrombopag at a dose of 50-150 mg. Complete response was defined as a platelet count >50×109/L for 7 consecutive days with no transfusion support.

RESULTS

A total of 50.3% of the patients underwent Autologous and 49.7% Allogeneic Stem Cell Transplantation, 54.8% were diagnosed with PIT, and 45.2% were diagnosed with SFPR, and the treatment with 50-150 mg/day Eltrombopag was initiated on the median day +42. Complete response was achieved in 71.2% of these patients on the median day 23 of the treatment. No significant effects of the initial dose (50-150 mg/day) were detected in the Complete Response in the multivariate analysis on response. An insufficient number of Megakaryocytes in the bone marrow before Eltrombopag treatment was determined as an independent risk factor in determining the response (OR 3.57, 95% CI 1.21-10.55). The overall survival of the patients who did not respond to Eltrombopag was found to be significantly worse than that of patients who responded (p=0.022, HR:2.74, 95% CI 1.12-6.54).

CONCLUSION

As a result of the present study, Eltrombopag treatment was found to be effective and safe in thrombocytopenia that develops following hematopoietic stem cell transplantation. It was concluded that its use may be more effective in patients with sufficient bone marrow megakaryocytes before the treatment and an initial dose of 50 mg/day may be appropriate in terms of cost, effectiveness, and toxicity. Large-scale randomized and controlled prospective studies are needed to determine the roles of Eltrombopag treatment in patients with post-transplant PIT and SFPR.

Herombopag for the treatment of persistent thrombocytopenia following hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) stands as a pivotal treatment for hematologic malignancies, often considered the sole effective treatment option. A frequent complication following allo-HSCT is poor graft function (PGF), with one of its primary manifestations being persistent thrombocytopenia (PT), comprising prolonged isolated thrombocytopenia (PIT) and secondary failure of platelet recovery (SFPR). Conventional treatment methods have had poor efficacy and a high transplantation-associated mortality rate. In recent years, the efficacy of eltrombopag has been reported in the treatment of post-transplantation PT, and additional thrombopoietin receptor agonists (TPO-RA) have been developed. Herombopag is a next-generation TPO-RA which has strong proliferation-promoting effects on human TPO-R-expressing cells (32D-MPL) and hematopoietic progenitor cells in vitro. We reviewed eighteen patients with transplantation-associated thrombocytopenia who received herombopag when eltrombopag was ineffective or poorly tolerated and evaluated its efficacy including effects on survival. Herombopag was administered at a median time of 197 days post-transplantation. Six patients achieved complete response (CR), with a median time to CR of 56 days. Five patients achieved partial response (PR), and the median time to PR was 43 days. Seven patients were considered to have no response (NR). The overall response (OR) rate was 61.1%, and the cumulative incidence (CI) of OR was 90.2%. No patients developed herombopag-associated grade 3-4 toxicity. The median follow-up period was 6.5 months. Twelve patients survived and six patients died, with an overall survival rate of 66.7%. This is the first study to demonstrate the efficacy and safety of herombopag in transplantation-associated thrombocytopenia after failing eltrombopag, introducing a new approach in the treatment of PT following allo-HSCT.

Eltrombopag can promote platelet implantation after allogeneic hematopoietic stem cell transplantation as safely and similarly to thrombopoietin

Background

Eltrombopag has demonstrated efficacy in treating low platelet (PLT) levels, but it remains unclear whether eltrombopag can promote PLT engraftment after hematopoietic stem cell transplantation (HSCT).

Methods

Forty-one HSCT patients received eltrombopag 50 mg/d from +1 day until PLT >50 × 109/L or 1 month after HSCT. Fifty-one patients in the same period received thrombopoietin (TPO) to promote PLT graft after HSCT and served as a control group.

Results

A total of 51 patients who applied TPO during the same period were treated as a control. In the eltrombopag group, the median time to white blood cells (WBC) graft was 12 days (range, 10-17 days) and the PLT graft was 15 days (range, 10-30 days), whereas for the patients in the TPO group, the median time to WBC and PLT graft was 12 days (range, 9-23 days) and 15.5 days (range, 9-41 days), respectively. In the first month after HSCT, the median WBC count in the eltrombopag group was 4.41 × 109/L (range, 0.87-40.01 × 109/L) and the median PLT was 89x109/L (range, 30-401 × 109/L); the median WBC and PLT \counts in the TPO group were 4.65 × 109/L (range, 0.99-23.63 × 109/L) and 86 × 109/L (range, 5-512 × 109/L), respectively. Patients in the TPO or eltrombopag group did not experience serious side effects after drug administration, and the difference in side effects on liver and kidney function between the two groups was not statistically significant.

Conclusion

Eltrombopag is safe and similarly promotes platelet engraftment to thrombopoietin after allogeneic HSCT.

Eltrombopag improves platelet engraftment after haploidentical bone marrow transplantation: Results of a Phase II study

Slow platelet recovery frequently occurs after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with bone marrow graft and post-transplant cyclophosphamide (PCy)-based graft-versus-host disease (GVHD) prophylaxis. Improved platelet recovery may reduce the need for transfusions and improve outcomes. We investigated the safety and efficacy of eltrombopag, a thrombopoietin receptor agonist, at enhancing platelet recovery post-haplo-HSCT. The prospective study included patients ≥18 years of age who received haplo-HSCT with bone marrow graft and PCy. Patients received eltrombopag 300 mg/day starting on Day +5. The primary objective was to estimate platelet engraftment (>50 000/μL by Day 60). In a post hoc analysis, they were compared to a contemporary matched control group who did not receive eltrombopag. One hundred ten patients were included in the analysis (30 eltrombopag and 80 control). Seventy-three percent and 50% of patients in the eltrombopag group and control group, respectively, attained >50 000/μL platelet count by Day 60 (p = .043). No eltrombopag-related grade ≥4 adverse events were observed. Median time to platelet recovery (>20 000/μL) was 29 days with eltrombopag and 31 days for controls (p = .022), while its cumulative incidence was 90% (95% confidence interval [CI]: 78%-100%) with eltrombopag versus 67.5% (95% CI: 57%-78%) for controls (p = .014). Number of platelet transfusions received, overall survival, progression-free survival, GVHD rate, relapse rate, and non-relapse mortality were similar between groups. Overall, eltrombopag is safe and improves platelet recovery in patients undergoing haplo-HSCT with bone marrow graft and PCy.

The nuclear factor erythroid 2-related factor 2 agonist tert-butylhydroquinone improves bone marrow mesenchymal stromal cell function in prolonged isolated thrombocytopenia after allogeneic haematopoietic stem cell transplantation

Prolonged isolated thrombocytopenia (PT) is a life-threatening comorbidity associated with allogeneic haematopoietic stem cell transplantation (allo-HSCT). Our previous study indicated that dysfunctional bone marrow mesenchymal stromal cells (BM MSCs) played a role in PT pathogenesis and that reactive oxygen species (ROS) accumulation was related to BM MSC senescence and apoptosis. However, the mechanism of the increase in ROS levels in the BM MSCs of PT patients is unknown. In the current case-control study, we investigated whether nuclear factor erythroid 2-related factor 2 (NRF2), which is a central regulator of the cellular anti-oxidant response that can clear ROS in human BM MSCs, was associated with PT after allo-HSCT. We evaluated whether an NRF2 agonist (tert-butylhydroquinone, TBHQ) could enhance BM MSCs from PT patients in vitro. We found that BM MSCs from PT patients exhibited increased ROS levels and reduced NRF2 expression. Multivariate analysis showed that low NRF2 expression was an independent risk factor for primary PT [p = 0.032, Odds ratio (OR) 0.868, 95% confidence interval (CI) 0.764-0.988]. In-vitro treatment with TBHQ improved the quantity and function of BM MSCs from PT patients by downregulating ROS levels and rescued the impaired BM MSC support of megakaryocytopoiesis. In conclusion, these results suggested that NRF2 downregulation in human BM MSCs might be involved in the pathogenesis of PT after allo-HSCT and that BM MSC impairment could be improved by NRF2 agonist in vitro. Although further validation is needed, our data indicate that NRF2 agonists might be a potential therapeutic approach for PT patients after allo-HSCT.

What Causes Aplastic Anaemia: Results of Transplants from Genetically-Identical Twins

Background

Aplastic anaemia has diverse aetiologies. Distinguishing between these is, in part, testable by analyzing results of haematopoietic cells transplants between genetically-identical twins one of whom has aplastic anaemia.

Objective

Describe outcomes of genetically-identical twin transplants for aplastic anaemia with and without pretransplant conditioning.

Methods

We interrogated data from an observational database of 59 consecutive recipients of genetically-identical twin transplants for aplastic anaemia reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) 2000-2019.

Results

38 subjects were male. Median age was 18 years (Interquartile Range [IQR], 11-32 years). Median interval from diagnosis to transplant was 2 months (IQR 1-3 months). 11 subjects received a 1st transplant without pretransplant conditioning. 2 of recovered normal bone marrow function. The other 9 received a 2nd transplant with pretransplant conditioning 7 of whom recovered. 48 subjects received pretransplant conditioning before a 1st or 2nd transplant all of whom recovered.

Conclusion

Only some genetically-identical twins with aplastic anaemia recover normal bone marrow function after a 1st haematopoietic cell transplant without pretransplant conditioning whereas most subjects recover when a transplant is preceded by pretransplant conditioning. These data are consistent with an immune-mediated aetiology of aplastic anaemia in most cases.

Multipotent mesenchymal stromal cells as treatment for poor graft function after allogeneic hematopoietic cell transplantation: A multicenter prospective analysis

Introduction

Poor graft function (PGF) is a rare but serious complication of allogeneic hematopoietic cell transplantation (alloHCT). Due to their hematopoietic supporting properties and immune regulatory effects, multipotent mesenchymal stromal cells (MSC) could be considered a good candidate to help to restore bone marrow (BM) niches homeostasis and facilitate hematopoiesis after alloHCT.

Methods

We prospectively assessed the efficacy and safety of ex-vivo expanded BM-derived MSC from third-party donor in a series of 30 patients with prolonged severe cytopenia and PGF after alloHCT. This multicenter trial was registered at www.clinicaltrials.gov (#NTC00603330).

Results

Within 90 days post-MSC infusion, 53% (95% CI, 35 - 71%) of patients improved at least one cytopenia (overall response, OR) and 37% (95% CI, 19 - 54%) achieved a complete hematological response (CR: absolute neutrophil count, ANC >0.5 x 10⁹/L, Hb > 80g/L and platelet count > 20 x 10⁹/L with transfusion independence). Corresponding response rates increased to 67% (95% CI, 50 - 84%) OR and 53% (95% CI, 35 - 71%) CR within 180 days after MSC infusion. A significant decrease in red blood cells and platelets transfusion requirement was observed after MSC (median of 30-days transfusion requirement of 0.5 and 0 from d90-120 post-MSC versus 5 and 6.5 before MSC, respectively, p ≤0.001). An increase in ANC was also noted by day +90 and +180, with 3/5 patients with severe neutropenia having recovered an ANC > 1 x 10⁹/L within the 90-120 days after MSC infusion. Overall survival at 1 year post-MSC was 70% (95% CI, 55.4 - 88.5), with all but one of the patients who achieved CR being alive. A single infusion of third-party MSC appeared to be safe, with the exception of one deep vein thrombotic event possibly related to the intervention.

Discussion

In conclusion, a single i.v. infusion of BM-derived MSC from third party donor seemed to improve hematological function after alloHCT, although spontaneous amelioration cannot be excluded. Comparative studies are warranted to confirm these encouraging results.

Low-dose decitabine for refractory thrombocytopenia following allogeneic hematopoietic stem cell transplantation in children: A pilot study

Refractory thrombocytopenia is a critical complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), which is not sensitive to conventional treatment and often leads to lower overall survival and disease-free survival. Previous studies have showed the efficacy and safety of low-dose decitabine for adults' refractory prolonged isolated thrombocytopenia in hematologic malignancy after allo-HSCT. However, clinical data on pediatric patients or non-hematologic malignancies are lacking. Herein, we evaluated the safety and efficacy of low-dose decitabine in nine children with persistent thrombocytopenia after HSCT. Patients received decitabine at 3.5 mg/m², 5 mg/m² or 10 mg/m² respectively for three to five consecutive days according to underlying diseases and hyperplastic state of bone marrow. Six patients reached sustained platelets count more than 100 × 10⁹/L, two patients achieved platelet transfusion independence. The total response rate was 88.8 % (8/9). One patient died from severe infection because of persistent agranulocytosis longer than 3 weeks. In conclusion, the present study supports the safety and efficacy of low-dose decitabine for treatment of refractory thrombocytopenia after allogeneic HSCT in children.

Oral eltrombopag versus subcutaneous recombinant human thrombopoietin for promoting platelet engraftment after allogeneic stem cell transplantation: A prospective, non-inferiority, randomized controlled trial

Delayed platelet engraftment (DPE) is associated with poor survival and increased transplantation-related mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Therefore, treatments are needed to improve platelet engraftment and prevent DPE. We performed a phase three, non-inferior, randomized controlled study of eltrombopag or recombinant human thrombopoietin (rhTPO) to promot platelet engraftment after allo-HSCT. Candidates for allo-HSCT were randomly assigned to receive oral eltrombopag (50 mg daily) or subcutaneous rhTPO (15000U daily) from the first-day post-transplantation. The primary endpoint was the cumulative numbers of platelet engraftment (platelet recovery ≥20 × 10⁹ /L, without transfusion, for seven consecutive days) on day 60 after transplantation. We performed intention-to-treat analyses with a non-inferior margin of -15%. A total of 92 participants underwent randomization. 44 and 48 patients were randomized to the eltrombopag and rhTPO groups, respectively. The median duration of follow-up was 360 days (range: 12-960 days). The cumulative incidence of platelet engraftment on day 60 after transplantation in eltrombopag group was 86.4% (38/44) compared with 85.4% (41/48) in the rhTPO group (absolute risk difference [ARD] 1%, one-sided lower limit of 95% confidence interval [CI] -13.28%, P_{non-inferirioty}  = 0.014). The rate of DPE in the eltrombopag group was 6.8% (3/44) compared with 12.5% (6/48) in the rhTPO group (ARD -5.7%, one-sided higher limit of 95% CI 6.28%, P_{non-inferirioty}  = 0.063). Approximately, three-fourths of non-hematologic adverse events were not observed in the eltrombopag group but three patients (3/48, 6%) experienecd them in the rhTPO group. In addition, platelet transfusions unite from day 0 to day 21, or from day 22 to day 60, progression-free survival, overall survival were not significantly different between both groups. Eltrombopag was non-inferior to rhTPO in promoting platelet engraftment post allo-HSCT for patients with hematological malignancy. Oral eltrombopag was more convenient for patients than subcutaneous rhTPO (NCT03515096).

Prognostic Value of Thrombocytopenia in Myelodysplastic Syndromes After Hematopoietic Stem Cell Transplantation

Prolonged isolated thrombocytopenia (PT) is a common complication affecting the outcome of stem cell transplantation. In this study, we undertook a real-world study of 303 myelodysplastic syndrome (MDS) patients who received allogeneic hematopoietic stem cell transplantation (HSCT) between December 2007 and June 2018. 28.4% of MDS patients suffered from PT after HSCT. Survival analysis indicated that PT was associated with worse overall survival (OS) in MDS patients. The 2-year and 5-year OS in MDS patients with PT after HSCT were 49% and 47%, significantly worse than that of 68% and 60% in patients without PT (P=0.005). For RFS, patients with PT did not have an increased risk of disease relapse (P=0.964). After multivariate adjustment, PT was proved to be the independent risk factor associated with the worse OS (HR 1.49, 95% CI 1.00-2.21, P =0.048). We further analyzed risk factors associated with the occurrence of PT in MDS patients. Multiple logistic regression identified grade II-IV aGVHD, extensive chronic GVHD, hemorrhagic cystitis, and CMV activation as significant risk factors for developing PT. Among these variables, the Odds Ratio (OR) of grade II-IV aGVHD was the highest (P =0.001, OR: 2.65, 95% CI: 1.51-4.64). These data indicated the prognostic value of PT in MDS after HSCT. The identification of risk factors for PT may help improve patient management and lead to the design of effective treatment strategies.

Eltrombopag may induce bone marrow fibrosis in allogeneic hematopoietic stem cell transplant recipients with prolonged thrombocytopenia

Poor graft function (PGF) and secondary failure of platelet recovery (SFPR) are significant causes of transplant related morbidity and mortality. Although thrombopoietin receptor agonists (TPO-RA), particularly Eltrombopag (EPAG), have been reported to be efficacious in the treatment of prolonged thrombocytopenia, potential long term adverse effects remain to be elucidated. This retrospective study was performed to determine the efficacy and toxicity profile of TPO-RAs in allogeneic hematopoietic stem cell transplant (alloHCT) recipients. Medical records of 27 patients [median age: 55(21-73) years; male/female: 15/12] who received posttransplant EPAG for SFPR or PGF were analysed. Eltrombopag was started on day 110(33-670) after transplant. Median initial dose was 25(25-50) mg/day which was properly escalated to a maximum dose of 75(50-100) mg/day. Duration of the treatment was median 120(31-377) days. Overall response rate (ORR) was 59.3% in the study population. Time-to-treatment response was 42(3-170) days. Mild-to-moderate bone marrow fibrosis was detected in the posttreatment biopsies of 12/22 patients (54.5%), 9 of whom did not represent any grade of myelofibrosis in their inital biopsies. The grade of posttreatment fibrosis was significantly increased when time-to-treatment response was longer (p = 0.008). Long term use of TPO-RAs may be considered as a potential cause of myelofibrosis in alloHCT recipients.

The pathobiology of platelet and megakaryocyte extracellular vesicles: A (c)lot has changed

Platelet-derived extracellular vesicles (PEVs) were originally studied for their potential as regulators of coagulation, a function redundant with that of their parent cells. However, as the understanding of the diverse roles of platelets in hemostasis and disease has developed, so has the understanding of PEVs. In addition, the more recent revelation of constitutively released megakaryocyte-derived extracellular vesicles (MKEVs) in circulation provides an interesting counterpoint and avenue for investigation. In this review, we highlight the historical link of PEVs to thrombosis and hemostasis and provide critical updates. We also expand our discussion to encompass the roles that distinguish PEVs and MKEVs from their parent cells. Furthermore, the role of extracellular vesicles in disease pathology, both as biomarkers and as exacerbators, has been of great interest in recent years. We highlight some of the key roles that PEVs and MKEVs play in autoimmune blood cell disorders, liver pathology, and cardiovascular disease. We then look at the future of PEVs and MKEVs as candidates for novel therapeutics.

Eltrombopag for Treatment of Thrombocytopenia After Hematopoietic Stem Cell Transplantation

Objective:

This study aimed to evaluate the efficacy and safety of eltrombopag (ELT) in the treatment of thrombocytopenia following hematopoietic stem cell transplantation (HSCT).

Materials and Methods:

Forty-eight patients treated with ELT for thrombocytopenia after allogeneic or autologous transplantation at the Erciyes University Bone Marrow Transplantation Center between July 2017 and July 2021 were evaluated retrospectively.

Results:

Forty-eight HSCT recipients were included in this study. Thirty (62.5%) patients were evaluated as having experienced delayed platelet recovery (DPR) and 18 (37.5%) patients as having experienced secondary failure of platelet recovery (SFPR). The median platelet count before ELT treatment was 13x10⁹/L (range: 3-20x10⁹/L). Twenty-three patients responded to treatment and the cumulative incidence of successful platelet recovery was 48%. Patients with both DPR and SFPR responded, but patients with DPR had a higher response rate (50% vs. 44%). The median platelet count of the 23 responding patients was 12x10⁹/L (5-19x10⁹/L) before treatment and 68x10⁹/L (52-266x10⁹/L) after treatment (p<0.0001). While the number of bone marrow megakaryocytes before treatment was adequate in 22 (46%) cases, it was decreased in 26 (54%) cases. Patients with adequate bone marrow megakaryocytes had a better response rate than those without (77% vs. 23%, p<0.0001). The group with adequate megakaryocytes responded to treatment at a median of 33 days (range: 9-174 days). Patients with decreased megakaryocytes responded at a median of 55 days (30-164 days) (p=0.002). No drug-related side effects were observed in any patients.

Conclusion:

This real-life experience demonstrates that ELT is an effective and safe treatment option for thrombocytopenia after HSCT. The adequacy of bone marrow megakaryocytes before ELT treatment was an important factor affecting response to treatment.

Development of an Automated Chemiluminescent Enzyme Immunoassay for Measuring Thrombopoietin in Human Plasma

Plasma thrombopoietin (TPO) measurements help distinguish between different types of thrombocytopenia but are not feasible in routine clinical practice. We developed a fully automated quantitative chemiluminescent enzyme immunoassay (CLEIA) for measuring TPO (TPO-CLEIA), which is a one-step sandwich-type assay. This assay utilizes a mouse monoclonal capture antibody, which has the neutralizing epitope of the interaction between TPO and the TPO receptor, and a newly generated rabbit monoclonal detector antibody. In analytical performance studies, this assay showed good linearity over the measuring range and high sensitivity. The limit of quantification (LoQ) of this assay was 3.4 pg/mL; low TPO concentration values of almost all healthy individuals exceeded the LoQ value. In clinical validation studies, TPO levels obtained from patients with aplastic anemia (AA) significantly increased, whereas those of patients with immune thrombocytopenia (ITP) were normal or slightly increased. The cutoff value for TPO-CLEIA corresponding to the previously reported values was useful for distinguishing between ITP and AA. These results suggest that TPO-CLEIA can quantify human plasma TPO levels with high accuracy and sensitivity and has the potential to facilitate routine clinical measurement of TPO in patients with various types of thrombocytopenia.

Efficacy and safety of thrombopoietin receptor agonists in the treatment of thrombocytopenia after hematopoietic stem cell transplantation: a meta-analysis and systematic review

Thrombocytopenia is a tough complication after hematopoietic stem cell transplantation (HSCT) with elusive pathogenesis and lack of well-established therapies. Thrombopoietin receptor agonists (TPO-RAs) have been used for thrombocytopenia post HSCT in recent years, but the outcomes remain debatable. We conducted this meta-analysis and systematic-review to evaluate the efficacy and safety of TPO-RAs for platelet recovery after HSCT. We searched PubMed, EMBASE, and Cochrane databases for studies on the application of TPO-RAs (eltrombopag and romiplostim) in the settings of primary or secondary thrombocytopenia after HSCT by 17 March 2021. Efficacy outcomes included response rate and survival rate, and adverse events were also evaluated. A total of 19 studies involving 378 patients were included. The pooled response rate was 73% (95%CI: 68-78%), which was significantly higher than recombinant human thrombopoietin (rhTPO) (27.8%). The pooled survival rate was 66% (95%CI: 54-77%), and infection was found to be the main cause of death. In addition, the pooled rate of adverse events was 3% (95%CI: 1-7%), with no severe adverse events reported. TPO-RAs could effectively and safely promote the recovery of platelets in patients after HSCT.

Eltrombopag in the treatment of patients with persistent thrombocytopenia after haploidentical peripheral blood stem cell transplantation: a single-center experience

Persistent thrombocytopenia (PT) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with an increased risk of bleeding and poor survival. The exact pathogenesis underlying PT remains unclear, and its management is difficult. Here we conducted a retrospective study to evaluate the efficacy and safety of eltrombopag (EPAG) in 34 patients with PT after allo-HSCT. Seven patients suffered from prolonged isolated thrombocytopenia (PIT), and 27 had secondary failure of platelet recovery (SFPR). For most patients, the initial dose was 25 mg or 50 mg daily, then adjusted to the maximum dose of 50-100 mg per day according to the response of platelet recovery and toleration of patients. The cumulative incidence (CI) of platelet recovery to at least 20 × 10⁹/L and 50 × 10⁹/L without transfusion support for at least 7 days was 72.1% and 60.7%, respectively. Nineteen (86.4%) of 22 responders were able to taper off the medication; furthermore, the platelet counts remained stable 1 month after withdrawal of EPAG. Although two patients discontinued EPAG during treatment due to headache and nausea, no patients developed grade 3 or 4 toxicities. Hypoplasia of bone marrow and decreased megakaryocytes (MKs) were found to be risk factors for overall response (OR) and complete response (CR) in multivariate analysis, respectively. Overall, our results indicated that EPAG can be used in the treatment of PT and that continuous exposure to EPAG may not be necessary.

Poor survival and prediction of prolonged isolated thrombocytopenia post umbilical cord blood transplantation in patients with hematological malignancies

Prolonged isolated thrombocytopenia (PIT) is a common complication after umbilical cord blood transplantation (UCBT). However, data on PIT prediction and impacts on transplantation outcomes for UCBT patients are rare. We retrospectively analyzed 244 patients with hematological malignancies who received single-unit UCBT at the First Affiliated Hospital of USTC between August 2018 and December 2019. Among them, PIT occurred in 49 recipients, with a crude incidence of 20.1%. In the PIT patients, the 2-year cumulative incidence of transplant-related mortality (TRM) was significantly higher, and the probabilities of 2-year overall survival, leukemia-free survival and graft-versus-host disease (GVHD)-free relapse-free survival were significantly poorer (57.1% vs. 88.6%; 53.1% vs. 81.9%; 22.4% vs. 59.8%; p < 0.001), without remarkable increases in the cumulative incidence of relapse or chronic GVHD. Importantly, the multivariate analysis revealed that lower high-resolution HLA compatibility (≤6/10), lower infused CD34⁺ cell count (≤1.78 × 10⁵ /kg), grade II-IV acute GVHD preplatelet engraftment, a lower pretransplantation platelet count (≤100 × 10⁹ /L), and a longer neutrophil engraftment time (≥17 days) were independent risk factors for PIT after UCBT. These results demonstrate that PIT is common after UCBT, predicting inferior survival and the need for more monitoring during the early phase.

Eltrombopag for treatment of thrombocytopenia after allogeneic hematopoietic cell transplantation in children: Single-centre experience

Delayed recovery of thrombocytopenia is a well-known complication after allogeneic HSCT. Eltrombopag (ELT), a thrombopoietin receptor agonist (TRAs), induces platelet maturation and release. Mostly conducted in adults, some of the previous studies have shown that ELT seems to enhance platelet recovery for post-allogeneic HSCT thrombocytopenia, appears efficacious, and offers transfusion independence. To evaluate the safety and efficacy of ELT in pediatric patients with prolonged isolated thrombocytopenia (PIT) or secondary failure of platelet recovery (SFPR) after alloHSCT. Retrospective analysis of childhood patients who received treatment with ELT for persistent thrombocytopenia after alloHSCT between May 2016 and August 2019. We evaluated the safety and efficacy of ELT in 18 childhood patients with PIT or SFPR after alloHSCT. Eltrombopag (50 mg/d) treatment was started in all patients, above 6 years of age and 20 kg weight, who had thrombocytopenia despite neutrophil engraftment on the 30th day of HSCT. Our objective was to decrease the need for platelet transfusion and have a platelet count of more than 50 000/µL. The overall response rate was 77.7%. The median time to achieve a platelet level above 30 000/µL and 50 000/µL was 21 and 44 days, respectively. In four patients, platelet count never reached 30 000/mm³ . In two patients, the treatment was discontinued due to grade 3 hepatotoxicity. Our study supports the efficacy and relative safety of ELT use for the treatment of PIT and SFPR seen after alloHSCT in children.

Efficacy and cost analysis of eltrombopag in thrombocytopenia and poor graft function post allogeneic hematopoietic cell transplantation

Eltrombopag has shown efficacy in the treatment of thrombocytopenia and poor graft function (PGF) after allogeneic hematopoietic cell transplantation (HCT) in retrospective observational studies, but is not approved for this indication. The cost of this drug is also a major concern in publicly funded health care systems. We collected data about patients who received eltrombopag for thrombocytopenia or PGF after HCT. Post-HCT thrombocytopenia, PGF, and eltrombopag response were defined as per previously published criteria. Primary outcome was treatment efficacy and secondary outcome was cost comparison between estimated treatment cost prior to and after initiation of eltrombopag. Seventeen patients (males 70.6%; median age = 58) received eltrombopag. Isolated thrombocytopenia was present in 11.8% (n = 2) patients while PGF was present in 88.2% (n = 15) of patients. After 8 weeks of treatment at the maximum dose of 150 mg orally daily, overall response rate (ORR) was seen in 76.5% (13/17) of patients: complete response (CR) in 10/13 patients and partial response (PR) in 3/13 patients. The use of eltrombopag was associated with an overall decrease in the total weekly care costs (5021 vs 2,524 CA$; P = 0.04). Thus, Eltrombopag is an efficacious and possibly cost-effective therapy for thrombocytopenia and PGF after allogeneic HCT.

Low-dose decitabine for refractory prolonged isolated thrombocytopenia after HCT: a randomized multicenter trial

Refractory prolonged isolated thrombocytopenia (RPIT) is an intractable complication after allogeneic hematopoietic cell transplantation (HCT), which often leads to poor prognosis. A clinical study was designed to validate the efficacy and safety of low-dose decitabine for RPIT after HCT and explore the related underlying mechanisms. Eligible patients were randomly allocated to receive 1 of 3 interventions: arm A, low-dose decitabine (15 mg/m2 daily IV for 3 consecutive days [days 1-3]) plus recombinant human thrombopoietin (300 U/kg daily); arm B, decitabine alone; or arm C, conventional treatment. The primary end point was the response rate of platelet recovery at day 28 after treatment. Secondary end points included megakaryocyte count 28 days after treatment and survival during additional follow-up of 24 weeks. Among the 91 evaluable patients, response rates were 66.7%, 73.3%, and 19.4% for the 3 arms, respectively (P < .001). One-year survival rates in arms A (64.4% ± 9.1%) and B (73.4% ± 8.8%) were similar (P = .662), and both were superior to that in arm C (41.0% ± 9.8%; P = .025). Megakaryocytes, endothelial cells (ECs), and cytokines relating to megakaryocyte migration and EC damage were improved in patients responding to decitabine. This study showed low-dose decitabine improved platelet recovery as well as overall survival in RPIT patients after transplantation. This trial was registered at www.clinicaltrials.gov as #NCT02487563.

Recombinant human thrombopoietin promotes platelet engraftment after umbilical cord blood transplantation

Delayed platelet engraftment is a common complication after umbilical cord blood transplantation (UCBT) accompanied by increased transplant-related complications or death. This study was designed to determine the safety and efficacy of recombinant human thrombopoietin (rhTPO) in promoting platelet engraftment after UCBT. A total of 120 patients scheduled to receive UCBT were randomly assigned to the rhTPO group (300 U/kg once daily from days 14 to 28 after UCBT, n = 60) or the control group (n = 60). The primary outcome was the 60-day cumulative incidence of platelet engraftment after single-unit cord blood transplantation. The 60-day cumulative incidence of platelet engraftment (platelet count ≥20 × 109/L) and the 120-day cumulative incidence of platelet recovery (platelet count ≥50 × 109/L) were both significantly higher in the rhTPO group than in the control group (83.1% vs 66.7%, P = .020; and 81.4% vs 65.0%, P = .032, respectively). In addition, the number of required platelet infusions was significantly lower in the rhTPO group than in the control group (6 vs 8 units, respectively; P = .026). The cumulative incidence of neutrophil engraftment and the probability of 2-year overall survival, disease-free survival, and graft-versus-host disease-free relapse-free survival did not differ between the 2 groups. Other transplant-related outcomes and complications did not differ between the 2 groups, and no severe adverse effects were observed in patients receiving rhTPO. This study demonstrated that rhTPO is well tolerated in patients and could effectively promote platelet engraftment after UCBT. This study was registered on the Chinese Clinical Trial Registry (http://www.chictr.org.cn/index.aspx) as ChiCTR-IPR-16009357.

Phase I Dose-Finding, Safety, and Tolerability Trial of Romiplostim to Improve Platelet Recovery After UCB Transplantation

Platelet recovery is delayed after umbilical cord blood transplant (UCBT). Romiplostim is a thrombopoietin receptor agonist that has the potential to improve platelet engraftment after UCBT. The purpose of this study was to determine the safety profile and maximum tolerated dose (MTD) of romiplostim and to investigate whether romiplostim accelerates platelet recovery post-UCBT. It was a single-center, dose-finding, safety and tolerability phase I trial of weekly romiplostim in 20 adult patients who failed to achieve an un-transfused platelet count of 20 × 10⁹/L by day +28 post-UCBT. Romiplostim was administered at the assigned dose as 6 weekly injections beginning by day +42 post-UCBT. Four dose levels (4, 6, 8, and 10 µg/kg per dose) were evaluated. The MTD of romiplostim was determined by the continual reassessment method, with a goal to identify a dose level with desired toxicity rate of ≤20%. Median age of the patients was 59.5 years, and 60% were female. Eleven patients received nonmyeloablative (NMA) double UCBT, seven patients received myeloablative single UCBT, and two patients received NMA single UCBT. Two patients received 4 µg/kg per dose, two received 6 µg/kg per dose, four received 8 µg/kg per dose, and the remaining 12 received 10 µg/kg per dose. Only five patients completed the full six doses of treatment. Of the 15 patients who received fewer than six doses, 12 were due to a platelet count of >100 × 10⁹/L, two were due to platelet count of >400 × 10⁹/L, and one was due to right upper extremity edema without thrombosis. All romiplostim-treated patients achieved platelet engraftment to 20 × 10⁹/L at a median of 45 days post-UCBT compared to 90% of controls at a median of 45 days (P = .08). Similarly, 90% of romiplostim-treated patients achieved platelet engraftment to 50 × 10⁹/L at a median of 48 days compared to 75% of controls at a median of 52 days (P = .09). All dose levels were effective with low toxicity; therefore, the MTD of romiplostim was 10 µg/kg per dose, and romiplostim is a safe and potentially effective therapy to counter delayed platelet recovery post-UCBT.

Eltrombopag for Post-Transplantation Thrombocytopenia: Results of Phase II Randomized, Double-Blind, Placebo-Controlled Trial

Prolonged thrombocytopenia occurs in up to 37% of patients after hematopoietic stem cell transplantation (HSCT) and is associated with adverse prognosis and increased risk of bleeding. Eltrombopag, a thrombopoietin receptor agonist, can increase platelet counts in thrombocytopenic patients. We conducted a phase II study, adaptively randomizing patients at ≥35 days post-HSCT to receive placebo or eltrombopag at a platelet count ≤20,000/µL for 7 days or platelet transfusion-dependent and a neutrophil count ≥1500/µL. Sixty patients were randomized to eltrombopag (n = 42) or placebo (n = 18) and received at least 1 dose. Fifteen patients (36%) in the eltrombopag arm achieved a platelet count of ≥30,000/µL, compared with 5 patients (28%) in the placebo arm, with a posterior probability of 0.75. (The protocol required this probability to be >0.975 to declare a winner; thus, the results are inconclusive.) However, 9 patients (21%) in the eltrombopag arm achieved a platelet count of ≥50,000/µL, compared with no patients in the placebo arm (P = .046). The overall survival, progression-free survival, relapse rate, and nonrelapse mortality were similar in the 2 arms. In conclusion, compared with placebo, treatment with eltrombopag led to a higher percentage of patients achieving a platelet count of ≥50,000/µL in patients with persistent thrombocytopenia after HSCT.

Interleukin-18 and Hematopoietic Recovery after Allogeneic Stem Cell Transplantation

Simple Summary

We have previously shown that high pre-conditioning levels of Interleukin-18 were associated with worse survival after allogeneic stem cell transplantation due to increased non-relapse mortality. While no correlations with acute graft-versus-host disease were observed, interleukin-18-related excess mortality was mainly driven by fatal infectious complications. In multiple studies, delayed hematopoietic recovery and poor graft function following allogeneic stem cell transplantation has been demonstrated as a powerful predictor of non-relapse mortality. The present study links high interleukin-18 to delayed platelet recovery in allografted patients. Given the functions of interleukin-18 in regulating the quiescence of hematopoietic stem/progenitor cells, our findings may be explained by Interferon gamma-independent inhibitory effects of interleukin-18 on stem cell proliferation and hematopoietic reconstitution in allografted patients. Importantly, considering recent successful interleukin-18-neutralizing approaches in autoimmune disorders, our results provide a rationale to explore modulation of interleukin-18 for improving hematopoietic recovery and outcomes in allogeneic stem cell transplantation recipients.

Abstract

Interleukin-18 (IL-18) is an immunoregulatory cytokine and a context-dependent regulator of hematopoietic stem/progenitor cell (HSPC) quiescence in murine models. In a previous study, high pre-conditioning levels of IL-18 were associated with increased non-relapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). To investigate the clinical impact of IL-18 status on hematopoietic function, the associations of pre-conditioning and day 0–3 cytokine levels with platelet and neutrophil recovery were analyzed in a training cohort of 714 allografted patients. In adjusted logistic regression analyses, both increasing pre-conditioning and day 0–3 IL-18 levels had a significantly higher adjusted odds ratio (aOR) of delayed platelet and neutrophil recovery on day +28 post-transplant (aOR per two-fold increase: 1.6–2.0). The adverse impact of high pre-conditioning IL-18 on day +28 platelet recovery was verified in an independent cohort of 673 allografted patients (aOR per two-fold increase: 1.8 and 1.7 for total and free IL-18, respectively). In both cohorts, a platelet count ≤20/nL on day +28 was associated with a significantly increased hazard of NRM (hazard ratio 2.13 and 2.94, respectively). Our findings support the hypothesis that elevated peritransplant IL-18 levels affect post-transplant HSPC function and may provide a rationale to explore modulation of IL-18 for improving alloSCT outcomes.

Evaluation of eltrombopag in thrombocytopenia post Hematopoietic cell transplantation: Rertrospective observational trial

BACKGROUND

Thrombocytopenia remains a life-threatening late complication of HCT with an incidence of 5-20%. Currently, there is no approved drug for the treatment of persistent thrombocytopenia post HCT and platelet transfusion is the maintain stay of treatment. Eltrombopag is approved for the treatment of thrombocytopenia associated with different diseases, however; data on eltrombopag treatment post HCT are limited.

METHODS

This is a retrospective cohort study evaluating the effect of eltrombopag on platelet recovery in patients with persistent thrombocytopenia post HCT. The primary endpoint was platelet recovery to ≥ 20,000/μL for 7 consecutive days without transfusion support after starting eltrombopag. Secondary endpoint was platelet recovery to ≥ 50,000/μL for 7 consecutive days.

RESULTS

Twenty-one patients were included. Twelve (75%) of 16 patients became independent from platelet transfusions. Median time from starting eltrombopag to last transfusion was 60 days (range, 9-226 days). Ten (63%) of 16 transfusion dependent patients with platelet count < 20,000/μL achieved the primary endpoint. Seven (33%) patients of 21 included had successful platelet recovery (ie, ≥50,000/μL without transfusion support) and the median time to platelet recovery in patients who achieved it was 32 days (range, 13-265 days). Ten patients (48%) were able to successfully discontinue eltrombopag without recurrence of thrombocytopenia.

CONCLUSION

Our findings demonstrated that eltrombopag appears to have a clinically significant impact on platelet recovery in persistent thrombocytopenic patients post HCT.

Eltrombopag for thrombocytopenia following allogeneic hematopoietic stem cell transplantation in children

Persistent thrombocytopenia is a common complication after allogeneic hematopoietic stem cell transplantation (HSCT). While the use of thrombopoietin receptor agonists was retrospectively investigated in adults, data in pediatric posttransplant thrombocytopenia are lacking. We evaluated the safety and efficacy of eltrombopag in nine children with platelet transfusion-dependent persistent thrombocytopenia after HSCT. Eltrombopag was started at a median of 147 days after allo-SCT and continued for a median period of 64 days, the starting dose being 50 mg per day. The therapy was well tolerated. After a median time of treatment of 36 days, eight patients (88%) reached sustained platelets count >50 000/μL.

The assessment of platelet function by thromboelastometry as a point-of-care test to guide Intercept-treated platelet support in hemato-oncological patients and hematopoietic stem cell transplantation recipients

BACKGROUND

Pathogen inactivation (PI) techniques for platelet concentrates (PCs) are one of the latest innovations to improve blood safety and reduce the risk of transfusion‐transmitted infections (TTIs). An impaired function and in vivo recovery of platelets as well as an increased PC demand are concerns regarding these techniques. The intent of this study was to evaluate the hemostatic effect of PCs treated with the Intercept™ System by thromboelastometry (TEM) and to assess the clinical validity of its results in comparison to post‐transfusion increase (PTI) and corrected count increment (CCI).

STUDY‐DESIGN AND METHODS

This prospective‐observational study included 47 patients (m:f = 25:22; median age: 54 years [21‐70]) of our Bone Marrow Transplantation unit with hemato‐oncological malignancies transfused with Intercept™‐treated PCs. Serial TEM measurements were performed just before and 1 hour after PC transfusion and were analyzed for their correlation with PTI and CCI as well as for clinical variables.

RESULTS

The majority of our patients had received a hematopoietic stem cell transplantation (HSCT) (n = 41; 87%). In median 9 (1‐50) PCs were transfused. Serial TEM, PTI, and CCI measurements were available for 150 transfusion episodes. The median platelet dose transfused was 2.65 × 10¹¹/unit (1.8‐6). The median CCI was 9.250 (0‐28.000). We observed a significant improvement in TEM parameters (p < 0.05) after transfusion of PI PCs, which did not mandatory correlate with the 1‐hour PTI and CCI.

CONCLUSION

Serial TEM measurements indicate the hemostatic effect of Intercept™‐treated PCs. The 1‐hour PTI and CCI may not appropriately reflect the in vivo function of platelets after PI PC transfusion.

Romiplostim in patients undergoing hematopoietic stem cell transplantation: results of a phase 1/2 multicenter trial

Persisting severe thrombocytopenia more than 6 weeks after allogeneic stem cell transplantation is a common problem associated with adverse prognosis. Peffault de Latour et al report the results of the first trial of the thrombopoietin mimetic, romiplostim, in this setting, demonstrating recovery of platelet counts in 18 of 24 patients.

Incidence, Risk Factors, and Outcomes of Primary Prolonged Isolated Thrombocytopenia after Haploidentical Hematopoietic Stem Cell Transplant

The aim of this study was to evaluate the incidence, risk factors, and outcomes of primary prolonged isolated thrombocytopenia (PT) after haploidentical hematopoietic stem cell transplant (haplo-HSCT). We retrospectively analyzed patients who received haplo-HSCT for various hematologic malignancies at Peking University Institute of Hematology between January 2015 and December 2016. Of the 918 patients, 93 (10.1%) developed primary PT. We designed a propensity score method-based study. For each primary PT patient control subjects (1:3) were selected using a propensity score-matching method. A total of 372 recipients were enrolled in the study: 93 in the PT group and 279 in the control group. Multivariate analysis showed that age older than 25 years (P = .002), median mononuclear cells (P = .000), median CD34⁺ counts (P = .003), history of grades II to IV acute graft-versus-host disease (GVHD; P = .000), and Epstein-Barr virus (EBV) infection after haplo-HSCT (P = .016) were independent risk factors for primary PT. Primary PT was significantly associated with higher transplant-related mortality (TRM; P < .001), inferior overall survival (P = .001), and disease-free survival (P = .005). In conclusion, the incidence of primary PT after haplo-HSCT was 10.1%. Primary PT was associated with poorer survival and higher TRM along with older age, grades II to IV acute GVHD, and EBV infection after haplo-HSCT.

Eltrombopag: Role in Cytopenias Following Hematopoietic Stem Cell Transplantation

Eltrombopag is a small molecule oral agonist of the thrombopoietin receptor. Initially used for improving thrombocytopenia in chronic immune thrombocytopenia (ITP), it was later found to be efficacious in various other etiologies of thrombocytopenia as well as inherited marrow failure syndromes. Lately, it has been used for thrombocytopenia and poor graft function after allogeneic hematopoietic stem cell transplantation (HSCT) without any severe adverse events. Although prospective evidence of the efficacy is limited, there are increasing reports on the safety and efficacy with Eltrombopag in post HSCT thrombocytopenia and poor graft function. This provides an exciting opportunity for further research to evaluate both efficacy and cost-effectiveness of the use of Eltrombopag in this scenario. Here we review the current evidence on the indications for the use of Eltrombopag in the post allogeneic hematopoietic stem cell transplant setting.

Loss of Lkb1 impairs Treg function and stability to aggravate graft-versus-host disease after bone marrow transplantation

Accumulating evidence suggests that a reduction in the number of Foxp3⁺ regulatory T cells (Tregs) contributes to the pathogenesis of acute graft-versus-host disease (aGVHD), which is a major adverse complication that can occur after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the precise features and mechanism underlying the defects in Tregs remain largely unknown. In this study, we demonstrated that Tregs were more dramatically decreased in bone marrow compared with those in peripheral blood from aGVHD patients and that bone marrow Treg defects were negatively associated with hematopoietic reconstitution. Tregs from aGVHD patients exhibited multiple defects, including the instability of Foxp3 expression, especially in response to IL-12, impaired suppressor function, decreased migratory capacity, and increased apoptosis. Transcriptional profiling revealed the downregulation of Lkb1, a previously identified critical regulator of murine Treg identity and metabolism, and murine Lkb1-regulated genes in Tregs from aGVHD patients. Foxp3 expression in human Tregs could be decreased and increased by the knockdown and overexpression of the Lkb1 gene, respectively. Furthermore, a loss-of-function assay in an aGVHD murine model confirmed that Lkb1 deficiency could impair Tregs and aggravate disease severity. These findings reveal that Lkb1 downregulation contributes to multiple defects in Tregs in human aGVHD and highlight the Lkb1-related pathways that could serve as therapeutic targets that may potentially be manipulated to mitigate aGVHD.

Pulmonary Infection Within 100 Days After Transplantation Impaired Platelet Recovery in Patients with Hematologic Malignancies: A Propensity-Score-Matched Analysis

Background

Pulmonary infection is one of the life-threatening complications occurring during allogeneic hematopoietic stem cell transplantation (alloHSCT), even when prophylactic measures have been employed. Few studies have investigated whether pulmonary infection affects platelet recovery during alloHSCT.

Material/Methods

We retrospectively reviewed 253 consecutive patients with hematologic diseases who received alloHSCT in our institute. Among them, 62 patients (25%) had pulmonary infection within 100 days after alloHSCT. Using the one-to-two propensity-score matching logistic model, 50 patients with pulmonary infection and 100 patients without were included based on age, disease and stage, time from diagnosis to transplantation, infused CD34⁺ cells, and mononuclear cells.

Results

The incidences of prolonged thrombocytopenia in patients with pulmonary infection were 44% (22/50) and 9% (9/100) in the corresponding matched group (P<0.001). The mean time for platelet engraftment in patients with and without pulmonary infection were 19.29±13.96 days and 13.94±4.12 days (P=0.012), respectively. Multivariable logistic regression showed that pulmonary infection was an independent risk factor for impaired platelet recovery (OR: 5.335, 95% CI: 2.735–10.407, P<0.001). Impaired platelet recovery was associated with shorter survival and higher treatment-related mortality.

Conclusions

Our results indicate that patients with pulmonary infection within 100 days after alloHSCT are more likely to suffer from impaired platelet recovery and have inferior long-term survival.

Reduced β2-GPI is associated with increased platelet aggregation and activation in patients with prolonged isolated thrombocytopenia after allo-HSCT

We aimed to measure platelet function and its relationship with β2-GPI in prolonged isolated thrombocytopenia (PT) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Fifty-six patients with PT and 60 allo-HSCT recipients without PT (non-PT controls) were enrolled. Platelet aggregation and activation, β2-GPI and anti-β2-GPI antibody levels, vWF antigen, and vWF activity were analyzed. The effect of β2-GPI on platelet aggregation was also measured ex vivo. Results showed that ADP-induced platelet aggregation significantly increased (39%±7.5% vs. 23%±8.5%, P=0.032), and the platelet expression of both CD62p (33.6%±11.6% vs. 8.5%±3.5%, P<0.001) and PAC-1 (42.4%±7.6% vs. 6.8%±2.2%, P<0.001) was significantly higher in patients with PT than in those without PT. Significantly lower β2-GPI levels (164.2±12 μg mL^-1 vs. 234.2±16 μg mL^-1, P<0.001), higher anti-β2-GPI IgG levels (1.78±0.46 U mL^-1 vs. 0.94±0.39 U mL^-1, P<0.001), and increased vWF activity (133.06%±30.50% vs. 102.17%±25.90%, P<0.001) were observed in patients with PT than in those without PT. Both ADP-induced platelet aggregation (n=116, r²=-0.5042, P<0.001) and vWF activity (n=116, r²=-0.2872, P<0.001) were negatively correlated with β2-GPI levels. In summary, our data suggested that platelet aggregation and activation were significantly higher in patients with PT than in those without PT, which might be associated with reduced β2-GPI levels. The reduced β2-GPI levels might be due to the existence of anti-β2-GPI IgG.

Day +100 Platelet Count Predicts Survival After Allogeneic Hematopoietic Stem-Cell Transplantation in Children With Hematologic Malignancies

INTRODUCTION

Recovery of platelet count by day 100 after hematopoietic stem-cell transplantation (HSCT) is affected by many factors and has been reported to be a predictor of overall survival (OS) in a variety of diseases and donor types. We investigated the correlation between day +100 platelet count and OS after allogeneic HSCT in a relatively homogeneous cohort of pediatric patients with hematologic malignancies.

PATIENTS AND METHODS

We conducted a retrospective study of 152 consecutive patients who underwent allogeneic HSCT at the Children's Cancer Hospital Egypt between 2009 and 2015 with a minimum follow-up duration of 1 year after transplantation. All eligible patients received myeloablative conditioning, and all had matched related donors. Patients who survived without relapse until day 100 after HSCT were divided into 2 groups: early platelet recovery (EPR; platelet count ≥ 100 × 10⁹/L at day +100 after transplantation) and delayed platelet recovery (DPR; platelet count < 100 × 10⁹/L at day +100 after transplantation).

RESULTS

At day +100, 113 patients (74%) had EPR and 39 patients (26%) had DPR. With a median follow-up of 41 months (range, 12-93 months), 41 patients (27.2%) died, 35 of relapsed disease. The 3-year disease-free survival (DFS) and OS were 68 ± 7.84% and 71.9 ± 7.84%, respectively. The 3-year OS was 77.9% in the EPR group and 57.1% in the DPR group (P = .006). Three-year DFS of the EPR and DPR groups were 73.2 ± 9% and 54.8 ± 16.3%, respectively (P = .02). Incidence of disease relapse for EPR and DPR patients was 22.6% and 39.5%, respectively (P = .04). Multivariate analysis for survival identified DPR as a predictor of decreased survival (P = .002).

CONCLUSION

Patients with a robust platelet count at day 100 are likely to do well. However, patients who do not experience a platelet count of ≥ 100 × 10⁹/L have inferior long-term OS and DFS and may require further evaluation at the day 100 time point.

Placenta-Derived Adherent Stromal Cell Therapy for Hematopoietic Disorders: A Case Study of PLX-R18

The ephemeral placenta provides a noncontroversial source of young, healthy cells of both maternal and fetal origin from which cell therapy products can be manufactured. The 2 advantages of using live cells as therapeutic entities are: (a) in their environmental-responsive, multifactorial secretion profile and (b) in their activity as a “slow-release drug delivery system,” releasing secretions over a long time frame. A major difficulty in translating cell therapy to the clinic involves challenges of large-scale, robust manufacturing while maintaining product characteristics, identity, and efficacy. To address these concerns early on, Pluristem developed the PLacental eXpanded (PLX) platform, the first good manufacturing practice–approved, 3-dimensional bioreactor-based cell growth platform, to enable culture of mesenchymal-like adherent stromal cells harvested from the postpartum placenta. One of the products produced by Pluristem on this platform is PLX-R18, a product mainly comprising placental fetal cells, which is proven in vivo to alleviate radiation-induced lethality and to enhance hematopoietic cell counts after bone marrow (BM) failure. The identified mechanism of action of PLX-R18 cells is one of the cell-derived systemic pro-hematopoietic secretions, which upregulate endogenous secretions and subsequently rescue BM and peripheral blood cellularity, thereby boosting survival. PLX-R18 is therefore currently under study to treat both the hematopoietic syndrome of acute radiation (under the US Food and Drug Administration [FDA]’s Animal Rule) and the incomplete engraftment after BM transplantation (in a phase I study). In the future, they could potentially address additional hematological indications, such as aplastic anemia, myelodysplastic syndrome, primary graft failure, and acute or chronic graft versus host disease.

Eltrombopag for Treating Thrombocytopenia after Allogeneic Stem Cell Transplantation

Thrombocytopenia after allogeneic hematopoietic stem cell transplantation (allo-SCT) can pose significant problems in management of patients. Eltrombopag is a small-molecule thrombopoietin receptor agonist that has been approved for use in immune thrombocytopenic purpura and aplastic anemia; but its use after allo-SCT is limited. Between 2014 and 2017, we treated 13 patients with eltrombopag for poor platelet engraftment without evidence of relapse at the time of initiation, including 6 patients with primary platelet engraftment failure and 7 with secondary platelet engraftment failure. Eltrombopag was started at an initial dose of 25 or 50 mg per day, and dose adjustments were made in accordance with the manufacturer's recommendation. The cumulative incidence of platelet recovery to ≥50,000/μL without the need for transfusion for at least 7 days was defined as response. The overall response rate was 62% (n = 8). Of the 6 patients with primary isolated platelet failure, 3 (50%) responded, and of the 7 patients with secondary platelet failure, 5 (71%) responded. The median time to response was 33 days (range, 11 to 68 days). In addition, no significant differences in platelet recovery were noted in patients with adequate and decreased bone marrow megakaryocytic reserve (60% and 67%, respectively). Although eltrombopag was well tolerated, and no patient discontinued treatment because of adverse events, only 3 patients were alive at the end of the observation period, with relapse and graft-versus-host disease accounting for majority of the deaths. This suggested that despite the relatively good overall response rate to eltrombopag, inadequate platelet engraftment is a harbinger of poor outcome in allo-SCT.

Eltrombopag is an effective and safe therapy for refractory thrombocytopenia after haploidentical hematopoietic stem cell transplantation

Refractory thrombocytopenia is a frequent and severe complication after haploidentical allogeneic hematopoietic stem cell transplantation (haplo-HSCT) and lacks effective treatment strategies. Eltrombopag has shown promising results in several thrombocytopenia disorders. We report 38 patients treated with eltrombopag for refractory thrombocytopenia after haplo-HSCT. Eight patients had delayed platelet engraftment, 15 patients had secondary failure of platelet recovery, and 15 patients had poor graft function (PGF). Eltrombopag was initiated at 25 or 50 mg daily, and the dosage was adjusted to a maximum of 50-100 mg daily to maintain platelet between 50 × 10⁹/L and 100 × 10⁹/L. The cumulative incidence of platelet recovery to transfusion independence was 63.2% and to ≥50 × 10⁹/L without transfusion support was 52.3%. Furthermore, neutrophil counts and hemoglobin were also increased in the nine responders with PGF. Nineteen (79.2%) of the 24 responders were able to taper off eltrombopag, and the remaining 5 patients were able to begin a taper. The median duration of treatment was 64 (range 14-195) days. The presence of megakaryocyte before initiation was the only independent factor influencing the efficacy of eltrombopag (P = 0.044). Eltrombopag was well tolerated in all patients. In summary, eltrombopag was a safe and effective therapy for refractory thrombocytopenia after haplo-HSCT.

N-acetyl-L-cysteine improves mesenchymal stem cell function in prolonged isolated thrombocytopenia post-allotransplant

Prolonged isolated thrombocytopenia (PT) is a serious complication of allogeneic haematopoietic stem cell transplantation (allo-HSCT). Murine studies and in vitro experiments suggest that mesenchymal stem cells (MSCs) can, not only to support haematopoiesis, but also preferentially support megakaryocytopoiesis in bone marrow (BM). However, little is known about the quantity and function of BM MSCs in PT patients. In a case-control study, we found that BM MSCs from PT patients exhibited significantly reduced proliferative capacities, increased reactive oxygen species and senescence. Antioxidant (N-acetyl-L-cysteine, NAC) treatment in vitro not only quantitatively and functionally improved BM MSCs derived from PT patients through down-regulation of the p38 (also termed MAPK14) and p53 (also termed TP53) pathways but also partially rescued the impaired ability of BM MSCs to support megakaryocytopoiesis. Subsequently, a pilot study showed that the overall response of NAC treatment was obtained in 7 of the enrolled PT patients (N = 10) without significant side effects. Taken together, the results indicated that dysfunctional BM MSCs played a role in the pathogenesis of PT and the impaired BM MSCs could be improved by NAC in vitro. Although requiring further validation, our data indicate that NAC might be a potential therapeutic approach for PT patients after allo-HSCT.

Inflammation-Associated Cytokines IGFBP1 and RANTES Impair the Megakaryocytic Potential of HSCs in PT Patients after Allo-HSCT

Prolonged isolated thrombocytopenia (PT) is a severe complication in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Whether the megakaryoctic potential of hematopoietic stem cells (HSCs) in bone marrow is intact and what factors drive the pathological process of PT remain elusive. A retrospective study in patients (n = 285) receiving HSCT revealed that the occurrence of PT was approximately 8% and the number of platelets and megakaryocytes in PT patients is much lower compared with control subjects. To test whether the deficiency of thrombopoiesis was caused by the activities of HSCs, the megakaryocytic differentiation potential of HSCs before or after transplantation was assessed. Interestingly, a substantial decrease of megakaryocytic differentiation was observed 2 weeks after transplantation of HSCs in all of the allo-HSCT recipients. However, 4 weeks after transplantation, the ability of HSCs to generate CD41⁺CD42b⁺ megakaryocytes in successful platelet engraftment patients recovered to the same level as those of HSCs before implantation. In contrast, HSCs derived from PT patients throughout the postimplantation period exhibited poor survival and failed to differentiate properly. A protein array analysis demonstrated that multiple inflammation-associated cytokines were elevated in allo-HSCT recipients with PT. Among them, insulin-like growth factor-binding protein 1 and regulated on activation, normal T cell expressed and secreted were found to significantly suppress the proliferation and megakaryocytic differentiation of HSCs in vitro. Our results suggested that the occurrence of PT may be attributed, at least partially, to the damage to HSC function caused by inflammation-associated cytokines after HSCT. These findings shed light on the mechanism underlying HSC megakaryocytic differentiation in PT patients and may provide potential new strategies for treating PT patients after HSCT.

Eltrombopag for secondary failure of platelet recovery post-allogeneic hematopoietic stem cell transplant in children

Secondary failure of platelet engraftment occurs in 20% of patients undergoing allogeneic HSCT and is associated with poor outcome. Currently, there are no guidelines for treatment of late thrombocytopenia and platelet transfusion is the mainstay of treatment. Here, we describe the use of Eltrombopag to treat secondary failure of platelet recovery following HSCT in a child with severe aplastic anemia. Eltrombopag resulted in recovery of platelet count with no need for platelet transfusion support with no reported side effects. Eltrombopag may be used successfully in children with secondary failure of platelet recovery post-HSCT for SAA.

Recombinant Human Thrombopoietin Promotes Platelet Engraftment and Improves Prognosis of Patients with Myelodysplastic Syndromes and Aplastic Anemia after Allogeneic Hematopoietic Stem Cell Transplantation

Poor platelet graft function (PPGF) is a significant complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, no optimal treatment has been recommended. This study investigated aspects of platelet recovery after allo-HSCT, including prognostic value and the effect of recombinant human thrombopoietin (rhTPO). We retrospectively analyzed 275 patients who received allo-HSCT in our center. Of them, 135 (49.1%) patients had good platelet graft function (GPGF) and 140 (50.9%) had PPGF. The latter included 59 (21.5%) patients with primary PPGF and 81 (29.4%) with secondary PPGF. Multivariate analysis showed that male gender (P = .024), lower CD34⁺ cell count (P = .04), and no use of rhTPO (P <.001) were associated with PPGF. The 3-year overall survival rate of patients with PPGF (58%) was significantly less than that of patients with GPGF (82%; P <.001). We further analyzed the effect of rhTPO on prognosis of patients after allo-HSCT. Although no advantage was apparent when analyzing the entire cohort, for patients with myelodysplastic syndromes and aplastic anemia, rhTPO was associated with a significant survival advantage (P = .014).