Platelet fluctuations during thrombopoietin-receptor agonist treatment: correlation with platelet apoptosis

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.

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.

Switching thrombopoietin receptor agonist treatments in patients with primary immune thrombocytopenia

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

Enhancing autophagy protects platelets in immune thrombocytopenia patients

Background

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder and involves increased apoptosis of platelets. Autophagy is an essential process for platelets to maintain their life and physiological functions. However, the role of autophagy in ITP platelets was previously unclear.

Methods

In the present study, the expression of autophagy-related protein and autophagy flux were detected in platelets from ITP patients and healthy controls by immunofluorescence staining and immunoblotting, and the influence of autophagy on the viability and apoptosis of ITP platelets was further explored.

Results

We found that platelet autophagy was diminished in ITP patients. Platelet autophagy in ITP was regulated by the PI3K/AKT/mTOR pathway, with mTOR (mammalian target of rapamycin) as a negative regulator and class III PtdIns3K playing a crucial role in the process. Importantly, the small-molecule compound ABO (6-amino-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine) enhanced autophagy in ITP platelets. Enhancing platelet autophagy alleviated platelet destruction by inhibiting apoptosis and improving platelet viability.

Conclusions

These results suggest a role for autophagy regulation in the pathogenesis of ITP, and offer a novel treatment for these patients.

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.