Efficacy of Recombinant Human Thrombopoietin for the Treatment of Secondary Failure of Platelet Recovery After Allogeneic HSCT.

Secondary failure of platelet recovery (SFPR) is a life-threatening complication that may affect up to 20% of patients after allogeneic hematopoietic stem cell transplantation (HSCT). In this study, to evaluate the efficacy of recombinant human thrombopoietin (rhTPO), we retrospectively analyzed 29 patients who received continuous rhTPO for the treatment of SFPR. Overall response and complete response were observed in 24 (82.8%) patients and 10 (34.5%) patients, at a median time of 21.5 days (range, 3-41 days) and 39.5 days (range, 7-53 days) after initiation of rhTPO treatment, respectively. Among the responders, the probability of keeping overall response and complete response at 1 year after response was 77.3% and 80.0%, respectively. In multivariate analysis, higher CD34+ cells (≥3 × 106/kg) infused during HSCT (HR: 7.22, 95% CI: 1.53-34.04, P = 0.01) and decreased ferritin after rhTPO treatment (HR: 6.16, 95% CI: 1.18-32.15, P = 0.03) were indicated to associate with complete response to rhTPO. Importantly, rhTPO was well tolerated in all patients without side effects urging withdrawal and clinical intervention. The results of this study suggest that rhTPO may be a safe and effective treatment for SFPR.

Treatment patterns in adults with immune thrombocytopenia before, during and after use of thrombopoietin receptor agonists: a longitudinal prescription database study from Germany.

OBJECTIVE: To assess real-world treatment patterns in patients with immune thrombocytopenia (ITP) who received thrombopoietin receptor agonists (TPO-RAs) in Germany. METHODS: This was a longitudinal, retrospective study using anonymized patient-level data (IQVIA healthcare prescription database, covering 82% of German statutory prescriptions). Eligible patients (aged ≥18 years) had received ≥1 TPO-RA prescription (romiplostim/eltrombopag) from July 2016 to June 2019 (treatment duration ≥30 days). ITP medication use was assessed for 18 months prior to, during and for ≥6 months after TPO-RA treatment. RESULTS: A total of 3553 patients (median age 64 years) were included. Median persistence on TPO-RAs was 12 months (range 1-34). In the periods before, during and after TPO-RA treatment, oral corticosteroids were the most commonly used therapy (64.4%, 43.4% and 36.1% of patients, respectively); median cumulative doses across each period were 2521.9, 2000.0 and 2277.8 mg. The median total duration of corticosteroid use before, during and after TPO-RA therapy was 15, 18 and 32 weeks, respectively. The total median cumulative corticosteroid dose was 6799.7 mg. CONCLUSION: We identified a potential overuse of corticosteroids in patients with ITP in Germany. Earlier use of TPO-RA therapy after a short course of corticosteroids could avoid side effects associated with long-term use.

Recombinant human thrombopoietin improved platelet engraftment after autologous hematopoietic stem cell transplantation in patients with newly diagnosed multiple myeloma.

BACKGROUND: To evaluate the efficacy and safety of recombinant human thrombopoietin (rhTPO) for hematopoietic reconstitution after autologous stem cell transplant (ASCT) in patients with newly diagnosed multiple myeloma (NDMM). METHOD: Thirty-five cases with NDMM had been enrolled into a prospective clinical trial from March 2014. The hematopoietic reconstitution was compared between these 35 cases (rhTPO group) and 98 historic cases not receiving rhTPO (control group) after stem cell reinfusion. RESULTS: Thirty-five (100%) cases receiving rhTPO achieved both neutrophil and platelet engraftment within 30 days post-transplant. The median time to neutrophil and platelet engraftment was the 10th day and 11th day after stem cell reinfusion, respectively. Multivariate analysis showed that rhTPO administration was an independent factor for accelerating platelet engraftment (HR 2.013, 95% CI 1.336-3.034, p = 0.001). Subgroup analysis showed that rhTPO improved platelet engraftment and alleviated platelet transfusion needs in patients with inadequate re-infused CD34+ cell counts of <2 × 109 /L. All the 35 patients tolerated rhTPO well. Survival analysis showed no decrease in time to progression (TTP) or overall survival (OS) by rhTPO administration. CONCLUSION: rhTPO accelerated the platelet engraftment after ASCT in patients with NDMM with good tolerability and long-term safety, especially for those patients with poor CD34+ cell reinfusion. rhTPO might be recommended to be used early after ASCT for patients with NDMM.

Rapid blood cell recovery with immunosuppressive therapy combined with romiplostim in a patient with very severe hepatitis-associated aplastic anemia who underwent liver transplantation.

Patients with hepatitis-associated aplastic anemia (HAA) who undergo living-donor liver transplantation (LDLT) have a poor prognosis with infections and bleeding complications. Rapid recovery of blood cells is critical for preventing these complications and improving the outcome. Immunosuppressive therapy (IST) combined with thrombopoietin receptor agonists is considered effective for aplastic anemia. However, there are no data on the benefits of adding thrombopoietin receptor agonists to IST for HAA. We present the case of a child with severe HAA who underwent LDLT, and who achieved rapid blood cell recovery with IST combined with romiplostim, a thrombopoietin receptor agonist. In addition, despite having undergone LDLT, the patient had no adverse events such as serious liver dysfunction or thrombosis. This case suggests that IST combined with thrombopoietin receptor agonists may be a promising treatment option for HAA patients undergoing LDLT.

Real-world use of thrombopoietin receptor agonists in older patients with primary immune thrombocytopenia.

The efficacy and safety of thrombopoietin receptor agonists (TRAs) in older patients with primary immune thrombocytopenia (ITP) are unknown. We investigated TRA response and switch, thrombotic/hemorrhagic risk, and sustained responses off-treatment (SROTs) in 384 patients with ITP aged ≥60 years. After 3 months, 82.5% and 74.3% of eltrombopag- and romiplostim-treated patients, respectively, achieved a response; 66.7% maintained the response (median follow-up, 2.7 years). Eighty-five (22.2%) patients switched to the alternative TRA; although no cross-toxicity was observed, 83.3% of resistant patients had a response after the switch. Thirty-four major thromboses (3 fatal) and 14 major hemorrhages (none fatal) occurred in 18 and 10 patients, respectively, while on TRAs and were associated with thrombosis history (subdistribution hazard ratio, 2.04, P = .05) and platelet count <20 × 109/L (subdistribution hazard ratio, 1.69; P = .04), respectively, at TRA start. A recurrent event occurred in 15.6% of patients surviving thrombosis, in all cases but 1 during persisting TRA treatment (incidence rate, 7.7 per 100 patient-years). All recurrences occurred in the absence of adequate antithrombotic secondary prophylaxis. Sixty-two (16.5%) responding patients discontinued TRAs; 53 (13.8%) patients maintained SROTs, which were associated with TRA discontinuation in complete response (P < .001). Very old age (≥75 years; 41.1%) was associated with the more frequent start of TRAs in the persistent/acute phase but not with response or thrombotic/hemorrhagic risk. TRAs are effective in older patients with ITP, with no fatal hemorrhages and with SROTs in a significant portion of patients. Caution is warranted in patients with a history of thrombosis, and a careful risk/benefit balance should be considered.

Clinical overview and practical considerations for optimizing romiplostim therapy in patients with immune thrombocytopenia.

The fundamental treatment goal for patients with immune thrombocytopenia (ITP) is reduced or ameliorated bleeding. Although various treatment options exist for the management of ITP, recent advances have led to the approval of three thrombopoietin receptor agonists (TPO-RAs; romiplostim, eltrombopag, and avatrombopag) in the United States and European Union. Current treatment guidelines for ITP indicate that medical therapy is preferred over surgical therapy and support the use of TPO-RAs as early as 3 months after disease onset. More recent data are available on the use of romiplostim in patients who have had ITP for <1 year, and romiplostim is now indicated for the treatment of adults who have not responded adequately to initial treatment, as well as children aged ≥1 year who have had ITP for ≥6 months. Here we review the role of romiplostim in the management of ITP, with a focus on efficacy and safety data, emerging data on early use (beginning within 3 months of disease onset) and treatment-free remission, and practical considerations for optimal management of ITP.

The role and mechanism of miR-557 in inhibiting the differentiation and maturation of megakaryocytes in immune thrombocytopenia.

Specific miRNA in immune thrombocytopenia (ITP) was screened to explore its intervention effects and mechanisms in ITP. MTT assay and CFSE staining were used to detect the effects of gradient concentrations of thrombopoietin (TPO) on cell proliferation. Expressions of differentially expressed miRNAs were analysed via qRT-PCR in TPO-induced megakaryocytes and ITP plasma. Effects of miR-557 on cell physiological functions were examined by MTT and flow cytometry. Expressions of miR-557, apoptosis-associated genes and Akt/ERK pathways were detected by qRT-PCR and Western blot as needed. Multinucleation of TPO-induced megakaryocytes was determined by megakaryocyte colonies. The toe skin and intestinal bleeding of the ITP rat model were observed and evaluated. Effects of miR-557 on the numbers of platelets, megakaryocytes, and peripheral blood platelets and the expressions of CD4+ T cells, Treg cells, TGF-ß, IL-6 and miR-557 in the ITP rats were detected by Giemsa staining, flow cytometry, ELISA and qRT-PCR. MiR-557 was identified as an specific miRNA associated with both ITP and TPO treatment. MiR-557 inhibitor enhanced the physiological functions of TPO-induced megakaryocytes, while miR-557 mimic had the opposite effect. At the molecular level, the expressions of miR-557, cleaved Caspase-3 and Bax were further silenced by inhibitor, on the contrary, the expressions of bcl-2, p-Akt and p-ERK were upregulated. Animal experiments showed that, miR-557 inhibitor increased the numbers of platelets and megakaryocytes, and improved the symptoms of ITP model rats. Our results indicated that miR-557 inhibitor improved ITP by regulating apoptosis-related genes and cellular immunity and activating the Akt/ERK pathway.

Efficacy and safety of romiplostim in refractory aplastic anaemia: a Phase II/III, multicentre, open-label study.

A previous dose-finding study has suggested that romiplostim is effective in patients with refractory aplastic anaemia (AA) and 10 µg/kg once weekly was recommended as a starting dose. In this Phase II/III, multicentre, open-label study, romiplostim was administered subcutaneously at a fixed dose of 10 µg/kg once weekly for 4 weeks (weeks 1-4) followed by weekly doses (5, 10, 15 and 20 µg/kg) titrated by platelet response for up to 52 weeks (weeks 5-52). A total of 31 patients with AA who were refractory to immunosuppressive therapy (IST) and thrombocytopenia (platelet count of ≤30 × 109 /l) were enrolled. The primary efficacy endpoint of the proportion of patients achieving any haematological (platelet, neutrophil and erythrocyte) response at week 27 was 84% [95% confidence interval (CI) 66-95%]. Trilineage response was 39% (95% CI 22-58%) at week 53. The most common treatment-related adverse events (AEs) were headache and muscle spasms (each 13%). All AEs were mild or moderate except for three patients with Grade 3 hepatic AEs; no AEs necessitated romiplostim discontinuation. Two patients developed cytogenetic abnormalities, of whom one returned to normal karyotype at last follow-up. High-dose romiplostim is effective and well tolerated in the treatment of patients with AA refractory to IST.

Successful treatment of refractory secondary immune thrombocytopenia (antiphospholipid antibody syndrome-associated) with the combination of rituximab and romiplostim at the cost of severe bone pain: A case report and review of literature.

INTRODUCTION: Immune thrombocytopenia is an autoimmune disorder associated with increased thrombocyte destruction and impaired production in the bone marrow. Proposed mechanisms include an antibody or autoreactive T-cell-associated autoimmunity and thrombopoietin deficiency among others. Clinical manifestations are predominantly mucocutaneous hemorrhages including petechiae, purpura, mucosal bleeding in the urinary or the gastrointestinal tracts, menorrhagia, and epistaxis. The purpose of the treatment is to prevent bleeding rather than normalizing the platelet counts. First-line treatments include corticosteroids ± intravenous immunoglobulin and Anti-D which mainly decrease antibody-mediated platelet destruction and increase the number of peripheral Tregs. Second-line and subsequent therapies include splenectomy, chimeric anti-CD20 antibody (rituximab), which eliminates B cells and act as an immunomodulatory agent, and Thrombopoietin receptor agonists (romiplostim), which promote platelet production. CASE REPORT: We describe a 40-year-old male patient diagnosed with immune thrombocytopenia that was refractory to first-line corticosteroid and intravenous immunoglobulin and second-line romiplostim monotherapy treatments.Management and outcome: The patient was given the romiplostim and rituximab combination which not only successfully treated thrombocytopenia but also resulted in grade 3 bone pains and the patient's subsequent refusal to continue therapy. DISCUSSION: Common adverse effects of rituximab are infusion reactions and prolonged immunosuppression; those of romiplostim include thrombosis, headaches, arthralgia-myalgia, and gastrointestinal symptoms. This case shows that romiplostim has not caused any discernible side effects when given alone, while combination with rituximab resulted in severe bone and joint pains. We hypothesize that this combination regimen shows a synergistic effect both in terms of efficacy and adverse-effect probability and/or severity.

Regulation of Antioxidant Stress-Responsive Transcription Factor Nrf2 Target Gene in the Reduction of Radiation Damage by the Thrombocytopenia Drug Romiplostim.

Ionizing radiation induces severe oxidative stress, resulting in individual death by acute radiation syndrome. The nuclear factor-erythroid-2-related factor 2 (Nrf2) plays an important role in the antioxidant response pathway. Recently, romiplostim (RP), an idiopathic thrombocytopenic purpura therapeutic drug, was reported to completely rescue mice exposed to lethal total-body irradiation (TBI). However, the details underlying the mechanism for reducing radiation damage remain largely unknown. To elucidate the involvement of the master redox regulator Nrf2 in the radio-mitigative efficacy of RP on TBI-induced oxidative stress, expression of Nrf2 target genes in hematopoietic tissues such as bone marrow, spleen, and lung from mice treated with RP for three consecutive days after 7 Gy of X-ray TBI was analyzed. RP promoted the recovery of bone marrow cells from day 10 and the significant up-regulation of reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) dehydrogenase quinone 1 (Nqo1), glutamate-cysteine ligase catalytic subunit (Gclc) and glutamate-cysteine ligase modifier subunit (Gclm) was observed compared to the TBI mice. RP also promoted the recovery of splenic cells on day 18, and the significant up-regulation of Nqo1, Gclc and Gclm in spleen both on day 10 and 18 and Nqo1 and Gclm in lung on day 10 was observed compared to the TBI mice. The present study suggests that the radio-mitigative effects of RP indicates on the activation of Nrf2 target genes involved in redox regulation and the antioxidative function, especially Nqo1, Gclc and Gclm. It is indicating the importance of these genes in the maintenance of biological homeostasis in response to radiation-induced oxidative stress.

Romiplostim is effective for eltrombopag-refractory aplastic anemia: results of a retrospective study.

Eltrombopag (EPAG) and romiplostim (ROM), thrombopoietin receptor-agonists with demonstrated efficacy against aplastic anemia (AA) in prospective controlled studies, were authorized in Japan for use in adults with aplastic anemia in 2017 and 2019, respectively. So far, no data are available on the potential contribution of switching from ROM to EPAG or vice versa in terms of efficacy or tolerance. Efficacies and tolerance profiles of ten patients, who failed to respond to the maximum dose of EPAG and then switched to ROM, were evaluated. All ten patients received a maximum dose of ROM (20 µg/kg/week). At a median follow-up of twelve months, seven of ten patients (70%) had achieved either neutrophil, erythroid, or platelet response, including one complete response. No patients showed platelet count fluctuations that were reported during ROM treatment for immune thrombocytopenia. In univariate analysis of the relationship between efficacy and demographics, the response had a correlation with neither factors. None of the patients stopped the ROM treatment because of adverse events. Although a larger number of patients and a longer follow-up period are needed to confirm our findings, our results show the efficacy of ROM in patients with EPAG-refractory AA.

High-dose dexamethasone plus recombinant human thrombopoietin vs high-dose dexamethasone alone as frontline treatment for newly diagnosed adult primary immune thrombocytopenia: A prospective, multicenter, randomized trial.

We conducted a prospective, multicenter, randomized, controlled clinical trial to compare the efficacy and safety of high-dose dexamethasone (HD-DXM) plus recombinant human thrombopoietin (rhTPO), vs HD-DXM alone in newly diagnosed adult immune thrombocytopenia (ITP) patients. Enrolled patients were randomly assigned to receive DXM plus rhTPO or DXM monotherapy. Another 4-day course of DXM was repeated if response was not achieved by day 10 in both arms. One hundred patients in the HD-DXM plus rhTPO arm and 96 patients in the HD-DXM monotherapy arm were included in the full analysis set. So, HD-DXM plus rhTPO resulted in a higher incidence of initial response (89.0% vs 66.7%, P < .001) and complete response (CR, 75.0% vs 42.7%, P < .001) compared with HD-DXM monotherapy. Response rate at 6 months was also higher in the HD-DXM plus rhTPO arm than that in the HD-DXM monotherapy arm (51.0% vs 36.5%, P = .02; sustained CR: 46.0% vs 32.3%, P = .043). Throughout the follow-up period, the overall duration of response was greater in the HD-DXM plus rhTPO arm compared to the HD-DXM monotherapy arm (P = .04), as estimated by the Kaplan-Meier analysis. The study drugs were generally well tolerated. In conclusion, the combination of HD-DXM with rhTPO significantly improved the initial response and yielded favorable SR in newly diagnosed ITP patients, thus could be further validated as a frontline treatment for ITP. This study is registered as clinicaltrials.gov identifier: NCT01734044.

Use of thrombopoietin receptor agonists for immune thrombocytopenia in pregnancy: results from a multicenter study.

Management of immune thrombocytopenia (ITP) during pregnancy can be challenging because treatment choices are limited. Thrombopoietin receptor agonists (Tpo-RAs), which likely cross the placenta, are not recommended during pregnancy. To better assess the safety and efficacy of off-label use of Tpo-RAs during pregnancy, a multicenter observational and retrospective study was conducted. Results from 15 pregnant women with ITP (pregnancies, n = 17; neonates, n = 18) treated with either eltrombopag (n = 8) or romiplostim (n = 7) during pregnancy, including 2 patients with secondary ITP, were analyzed. Median time of Tpo-RA exposure during pregnancy was 4.4 weeks (range, 1-39 weeks); the indication for starting Tpo-RAs was preparation for delivery in 10 (58%) of 17 pregnancies, whereas 4 had chronic refractory symptomatic ITP and 3 were receiving eltrombopag when pregnancy started. Regarding safety, neither thromboembolic events among mothers nor Tpo-RA-related fetal or neonatal complications were observed, except for 1 case of neonatal thrombocytosis. Response to Tpo-RAs was achieved in 77% of cases, mostly in combination with concomitant ITP therapy (70% of responders). On the basis of these preliminary findings, temporary off-label use of Tpo-RAs for severe and/or refractory ITP during pregnancy seems safe for both mother and neonate and is likely to be helpful, especially before delivery.

Single-Dose Administration of Recombinant Human Thrombopoietin Mitigates Total Body Irradiation-Induced Hematopoietic System Injury in Mice and Nonhuman Primates.

PURPOSE: Recombinant human thrombopoietin (rhTPO) has been evaluated as a therapeutic intervention for radiation-induced myelosuppression. However, the immunogenicity induced by a repeated-dosing strategy raises concerns about the therapeutic use of rhTPO. In this study, single-dose administration of rhTPO was evaluated for efficacy in the hematopoietic response and survival effect on mice and nonhuman primates exposed to total body irradiation (TBI). METHODS AND MATERIALS: Survival of lethally (9.0 Gy) irradiated C57BL/6J male mice was observed for 30 days after irradiation. Hematologic evaluations were performed on C57BL/6J male mice given a sublethal dose of radiation (6.5 Gy). Furthermore, in sublethally irradiated mice, we performed bone marrow (BM) histologic evaluation and evaluated BM-derived clonogenic activity. Next, the proportion and number of hematopoietic stem cells (HSCs) were analyzed. Competitive repopulation experiments were conducted to assess the multilineage engraftment of irradiated HSCs after BM transplantation. Flow cytometry was used to evaluate DNA damage, cell apoptosis, and cell cycle stage in HSCs after irradiation. Finally, we evaluated the efficacy of a single dose of rhTPO administered after 7 Gy TBI in male and female rhesus monkeys. RESULTS: A single administration of rhTPO 2 hours after irradiation significantly mitigated TBI-induced death in mice. rhTPO promoted multilineage hematopoietic recovery, increasing peripheral blood cell counts, BM cellularity, and BM colony-forming ability. rhTPO administration led to an accelerated recovery of BM HSC frequency and multilineage engraftment after transplantation. rhTPO treatment reduced radiation-induced DNA damage and apoptosis and promoted HSC proliferation after TBI. Notably, a single administration of rhTPO significantly promoted multilineage hematopoietic recovery and improved survival in nonhuman primates after TBI. CONCLUSIONS: These findings indicate that early intervention with a single administration of rhTPO may represent a promising and effective radiomitigative strategy for victims of radiation disasters.

Treatment-free remission after thrombopoietin receptor agonist discontinuation in patients with newly diagnosed immune thrombocytopenia: an observational retrospective analysis in real-world clinical practice.

Thrombopoietin receptor agonists (TPO-RAs) are used for treatment of chronic immune thrombocytopenia (ITP). Several studies have shown that TPO-RAs induce remission and sustained response, despite long-term discontinuation of therapy. Furthermore, TPO-RAs are effective in patients with newly diagnosed ITP. Here, we retrospectively assessed all patients with ITP who received TPO-RAs in our hospital, focusing on newly diagnosed, non-splenectomized patients who had discontinued TPO-RAs due to sustained complete response (CR, platelet count ≥ 100 × 109/L). Moreover, we explored predictive factors related to sustained treatment-free remission (TFR) without additional ITP treatment. Seventy-seven consecutive patients with ITP received TPO-RAs from 2011 to 2018. Twenty-seven newly diagnosed patients achieved CR and discontinued TPO-RAs. The overall response and discontinuation rates in all patients with ITP were 79.2% and 41.6%, respectively. In newly diagnosed patients who discontinued TPO-RAs, the 2-year TFR rate, cumulative incidence of loss of CR, and response (R) rate (platelet count ≥ 30 × 109/L) were 66.4%, 46.7%, and 34.0%, respectively. Patients who achieved R within 14 days from the start of TPO-RA administration exhibited a higher 2-year TFR rate, compared with patients who did not (87.5% vs. 48.5%, p = 0.0106). In conclusion, patients with newly diagnosed ITP who achieve sustained response should consider discontinuation of TPO-RAs.

Assessment of romiplostim immunogenicity in adult patients in clinical trials and in a global postmarketing registry.

Antibodies to first-generation recombinant thrombopoietin (TPO) neutralized endogenous TPO and caused thrombocytopenia in some healthy subjects and chemotherapy patients. The second-generation TPO receptor agonist romiplostim, having no sequence homology to TPO, was developed to avoid immunogenicity. This analysis examined development of binding and neutralising antibodies to romiplostim or TPO among adults with immune thrombocytopenia (ITP) in 13 clinical trials and a global postmarketing registry. 60/961 (6·2%) patients from clinical trials developed anti-romiplostim-binding antibodies post-baseline. The first positive binding antibody was detected 14 weeks (median) after starting romiplostim, at median romiplostim dose of 2 µg/kg and median platelet count of 29.5 × 109 /l; most subjects had ≥98·5% of platelet assessments showing response. Neutralising antibodies to romiplostim developed in 0·4% of patients, but were unrelated to romiplostim dose and did not affect platelet count. Thirty-three patients (3·4%) developed anti-TPO-binding antibodies; none developed anti-TPO-neutralising antibodies. In the global postmarketing registry, 9/184 (4·9%) patients with spontaneously submitted samples had binding antibodies. One patient with loss of response had anti-romiplostim-neutralising antibodies (negative at follow-up). Collectively, anti-romiplostim-binding antibodies developed infrequently. In the few patients who developed neutralising antibodies to romiplostim, there was no cross-reactivity with TPO and no associated loss of platelet response.

Thrombopoietin enhances hematopoietic stem and progenitor cell homing by impeding matrix metalloproteinase 9 expression.

We reported a novel function of recombinant human thrombopoietin (TPO) in increasing hematopoietic stem and progenitor cell (HSPC) homing to the bone marrow (BM). Single doses of TPO treatment to the recipients immediately after BM transplantation showed significantly improved homing of HSPCs to the BM, which subsequently resulted in enhanced short- and long-term engraftment of HSPCs in mice. We found that TPO could downregulate the expression and secretion of matrix metalloproteinase 9 in BM cells. As a result, SDF-1α level was increased in the BM niche. Blocking the interaction of SDF-1α and CXCR4 on HSPCs by using AMD3100 could significantly reverse the TPO-enhanced HSPC homing effect. More importantly, a single dose of TPO remarkably promoted human HSPC homing and subsequent engraftment to the BM of nonobese diabetic/severe combined immunodeficiency mice. We then performed a clinical trial to evaluate the effect of TPO treatment in patients receiving haploidentical BM and mobilized peripheral blood transplantation. Surprisingly, single doses of TPO treatment to patients followed by hematopoietic stem cell transplantation significantly improved platelet engraftment in the cohort of patients with severe aplastic anemia (SAA). The mean volume of platelet and red blood cell transfusion was remarkably reduced in the cohort of patients with SAA or hematological malignancies receiving TPO treatment. Thus, our data provide a simple, feasible, and efficient approach to improve clinical outcomes in patients with allogenic hematopoietic stem cell transplantation. The clinical trial was registered in the Chinese Clinical Trial Registry website (www.chictr.org.cn) as ChiCTR-OIN-1701083.