Recombinant human thrombopoietin (rh-TPO) for the prevention of severe thrombocytopenia induced by high-dose cytarabine: a prospective, randomized, self-controlled study

A real-world observation on thrombopoietic agents for patients with cancer treatment-induced thrombocytopenia in China: A multicenter, cross-sectional study

BACKGROUND

Studies on various thrombopoietic agents for cancer treatment-induced thrombocytopenia (CTIT) in China are lacking. This study aimed to provide detailed clinical profiles to understand the outcomes and safety of different CTIT treatment regimens.

METHODS

In this retrospective, cross-sectional study, 1664 questionnaires were collected from 33 hospitals between March 1 and July 1, 2021. Patients aged >18 years were enrolled who were diagnosed with CTIT and treated with recombinant interleukin 11 (rhIL-11), recombinant thrombopoietin (rhTPO), or a thrombopoietin receptor agonist (TPO-RA). The outcomes, compliance, and safety of different treatments were analyzed.

RESULTS

Among the 1437 analyzable cases, most patients were treated with either rhTPO alone (49.3%) or rhIL-11 alone (27.0%). The most common combination regimen used was rhTPO and rhIL-11 (10.9%). Platelet transfusions were received by 117 cases (8.1%). In multivariate analysis, rhTPO was associated with a significantly lower proportion of platelet recovery, platelet transfusion, and hospitalization due to chemotherapy-induced thrombocytopenia (CIT) than rhIL-11 alone. No significant difference was observed in the time taken to achieve a platelet count of >100 × 109/L and chemotherapy dose reduction due to CIT among the different thrombopoietic agents. The outcomes of thrombocytopenia in 170 patients who received targeted therapy and/or immunotherapy are also summarized. The results show that the proportion of platelet recovery was similar among the different thrombopoietic agents. No new safety signals related to thrombopoietic agents were observed in this study. A higher proportion of physicians preferred to continue treatment with TPO-RA alone than with rhTPO and rhIL-11.

CONCLUSIONS

This survey provides an overview of CTIT and the application of various thrombopoietic agents throughout China. Comparison of monotherapy with rhIL-11, rhTPO, and TPO-RA requires further randomized clinical trials. The appropriate application for thrombopoietic agents should depend on the pretreatment of platelets, treatment variables, and risk of bleeding.

PLAIN LANGUAGE SUMMARY

To provide an overview of the outcome of cancer treatment-induced thrombocytopenia in China, our cross-sectional study analyzed 1437 cases treated with different thrombopoietic agents. Most of the patients were treated with recombinant interleukin 11 (rhIL-11) and recombinant thrombopoietin (rhTPO). rhTPO was associated with a significantly lower proportion of platelet recovery and platelet transfusion compared with rhIL-11.

A contrast-enhanced CT-based whole-spleen radiomics signature for early prediction of oxaliplatin-related thrombocytopenia in patients with gastrointestinal malignancies: a retrospective study

Background

Thrombocytopenia is a common adverse event of oxaliplatin-based chemotherapy. Grade 2 or higher oxaliplatin-related thrombocytopenia may result in dose reduction, discontinuation or delay initiation of chemotherapy and may adversely affect the therapeutic efficacy and even overall survival of patients. Early recognition of patients at risk of developing grade 2 or higher thrombocytopenia is critical. However, to date there is no well-established method to early identify patients at high risk. The aims of this study were to develop and validate a contrast-enhanced CT-based whole-spleen radiomics signature for early prediction of grade 2 or higher thrombocytopenia in patients with gastrointestinal malignancies treated with oxaliplatin-based chemotherapy and to explore the incremental value of combining the radiomics signature and conventional clinical factors for risk prediction.

Methods

A total of 119 patients with gastrointestinal malignancies receiving oxaliplatin-based chemotherapy from March 2017 to December 2020 were retrospectively included and randomly divided into a training cohort (n = 85) and a validation cohort (n = 34). Grade 2 or higher thrombocytopenia occurred in 26.1% of patients (22 and nine patients in the training and validation cohort, respectively) with a median time interval of 101 days from the start of chemotherapy. The whole-spleen radiomics features were extracted on the portal venous phase of the first follow-up CT images. The least absolute shrinkage and selection operator (LASSO) algorithm was applied to select radiomics features and to build the radiomics signature for the prediction of grade 2 or higher thrombocytopenia. A clinical model that included clinical factors only and a clinical-radiomics model that incorporated clinical factors and radiomics signature were constructed. The performances of both models were evaluated and compared in the training, validation and the whole cohorts.

Results

The radiomics signature yielded favorable performance in predicting grade 2 or higher thrombocytopenia, with the area under the curve (AUC), sensitivity and specificity being 0.865, 81.8% and 84.1% in the training cohort and 0.747, 77.8% and 80.0% in the validation cohort. The AUCs of the clinical-radiomics model in the training and validation cohorts reached 0.913 (95% CI [0.720-0.935]) and 0.867 (95% CI [0.727-1.000]), greater than the AUCs of the clinical model. Integrated discrimination improvement (IDI) index showed that incorporating radiomic signature into conventional clinical factors significantly improved the predictive accuracy by 17.0% (95% CI [4.9%-29.1%], p = 0.006) in the whole cohort.

Conclusions

Contrast-enhanced CT-based whole-spleen radiomics signature might serve as an early predictor for grade 2 or higher thrombocytopenia during oxaliplatin-based chemotherapy in patients with gastrointestinal malignancies and provide incremental value over conventional clinical factors.

Application and investigation of thrombopoiesis-stimulating agents in the treatment of thrombocytopenia

Platelets, derived from a certain subpopulation of megakaryocytes, are closely related to hemostasis, coagulation, metastasis, inflammation, and cancer progression. Thrombopoiesis is a dynamic process regulated by various signaling pathways in which thrombopoietin (THPO)-MPL is dominant. Thrombopoiesis-stimulating agents could promote platelet production, showing therapeutic effects in different kinds of thrombocytopenia. Some thrombopoiesis-stimulating agents are currently used in clinical practices to treat thrombocytopenia. The others are not in clinical investigations to deal with thrombocytopenia but have potential in thrombopoiesis. Their potential values in thrombocytopenia treatment should be highly regarded. Novel drug screening models and drug repurposing research have found many new agents and yielded promising outcomes in preclinical or clinical studies. This review will briefly introduce thrombopoiesis-stimulating agents currently or potentially valuable in thrombocytopenia treatment and summarize the possible mechanisms and therapeutic effects, which may enrich the pharmacological armamentarium for the medical treatment of thrombocytopenia.

The Clinical Efficacy and Economic Benefits of Recombinant Human Thrombopoietin for the Treatment of Chemotherapy or Chemoradiotherapy-Induced Thrombocytopenia

Even though cytopenia caused by either chemotherapy or radiotherapy is a common complication in cancer patients, chemoradiotherapy remains an essential treatment for the majority of patients. The purpose of this study was to look into the clinical efficacy and cost-effectiveness of recombinant human thrombopoietin (rhTPO) in treating chemo- or chemoradiotherapy-induced grade II, III, and IV thrombocytopenia. From December 2019 to November 2020, 233 lung cancer patients admitted to our hospital with chemotherapy- or chemoradiotherapy-induced thrombocytopenia were enrolled and treated with rhTPO. The study's findings revealed a significant disparity in the use of concurrent chemoradiotherapy in patients with grade II, III, and IV thrombocytopenia. All costs, including rhTPO treatment costs, platelet costs, drug costs, and nondrug costs, tended to rise as the severity of thrombocytopenia increased. In the treatment of chemotherapy or radiotherapy-induced thrombocytopenia, rhTPO has shown good clinical efficacy. In the treatment of grade II thrombocytopenia, rhTPO has a favorable economic evaluation. As a result, early intervention and thrombocytopenia treatment should be provided, which warrants further clinical investigation.

Systematic literature review and meta-analysis on use of Thrombopoietic agents for chemotherapy-induced thrombocytopenia

Background

Currently, there are no approved options to prevent or treat chemotherapy-induced thrombocytopenia (CIT). We performed a systematic literature review and meta-analysis on use of thrombopoietic agents for CIT.

Patients and methods

We searched Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, PubMed, EMBASE, ClinicalTrials.gov, and health technology assessments from January 1995 to March 2021 for studies evaluating thrombopoietic agents for CIT, including recombinant human thrombopoietin (rhTPO), megakaryocyte growth and development factor (MGDF), romiplostim, and eltrombopag. Random effects meta-analyses were conducted for efficacy and safety endpoints.

Results

We screened 1503 titles/abstracts, assessed 138 articles, and abstracted data from 39 publications (14 recombinant human thrombopoietin, 7 megakaryocyte growth and development factor, 9 romiplostim, 8 eltrombopag, and 1 romiplostim/eltrombopag). Random effects meta-analyses of data from multiple studies comparing thrombopoietic agents versus control (comparator, placebo, or no treatment) showed that thrombopoietic agents did not significantly improve chemotherapy dose delays and/or reductions (21.1% vs 40.4%, P = 0.364), grade 3/4 thrombocytopenia (39.3% vs 34.8%; P = 0.789), platelet transfusions (16.7% vs 31.7%, P = 0.111), grade ≥ 2 bleeding (6.7% vs 16.5%; P = 0.250), or thrombosis (7.6% vs 12.5%; P = 0.131). However, among individual studies comparing thrombopoietic agents with placebo or no treatment, thrombopoietic agents positively improved outcomes in some studies, including significantly increasing mean peak platelet counts (186 x 10⁹/L with rhTPO vs 122 x 10⁹/L with no treatment; P < 0.05) in one study and significantly increasing platelet count at nadir (56 x 10⁹/L with rhTPO vs 28 x 10⁹/L with not treatment; P < 0.05) in another study. Safety findings included thrombosis (n = 23 studies) and bleeding (n = 11), with no evidence of increased thrombosis risk with thrombopoietic agents.

Conclusion

Our analyses generate the hypothesis that thrombopoietic agents may benefit patients with CIT. Further studies with well-characterized bleeding and platelet thresholds are warranted to explore the possible benefits of thrombopoietic agents for CIT.

Treatment of drug-induced immune thrombocytopenias

Several therapeutic agents can cause thrombocytopenia by either immune-mediated or non-immune-mediated mechanisms. Non-immune-mediated thrombocytopenia is due to direct toxicity of drug molecules to platelets or megakaryocytes. Immune-mediated thrombocytopenia, on the other hand, involves the formation of antibodies that react to platelet-specific glycoprotein complexes, as in classic drug-induced immune thrombocytopenia (DITP), or to platelet factor 4, as in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT). Clinical signs include a rapid drop in platelet count, bleeding or thrombosis. Since the patient's condition can deteriorate rapidly, prompt diagnosis and management are critical. However, the necessary diagnostic tests are only available in specialized laboratories. Therefore, the most demanding step in treatment is to identify the agent responsible for thrombocytopenia, which often proves difficult because many patients are taking multiple medications and have comorbidities that can themselves also cause thrombocytopenia. While DITP is commonly associated with an increased risk of bleeding, HIT and VITT have a high mortality rate due to the high incidence of thromboembolic complications. A structured approach to drug-associated thrombocytopenia/thrombosis can lead to successful treatment and a lower mortality rate. In addition to describing the treatment of DITP, HIT, VITT, and vaccine-associated immune thrombocytopenia, this review also provides the pathophysiological and clinical information necessary for correct patient management.

Treatment of chemotherapy-induced thrombocytopenia in patients with non-hematologic malignancies

Chemotherapy-induced thrombocytopenia (CIT) is a common complication of the treatment of non-hematologic malignancies. Many patient-related variables (e.g., age, tumor type, number of prior chemotherapy cycles, amount of bone marrow tumor involvement) determine the extent of CIT. CIT is related to the type and dose of chemotherapy, with regimens containing gemcitabine, platinum, or temozolomide producing it most commonly. Bleeding and the need for platelet transfusions in CIT are rather uncommon except in patients with platelet counts below 25x10⁹/L in whom bleeding rates increase significantly and platelet transfusions are the only treatment. Nonetheless, platelet counts below 70x10⁹/L present a challenge. In patients with such counts, it is important to exclude other causes of thrombocytopenia (medications, infection, thrombotic microangiopathy, post-transfusion purpura, coagulopathy and immune thrombocytopenia). If these are not present, the common approach is to reduce chemotherapy dose intensity or switch to other agents. Unfortunately decreasing relative dose intensity is associated with reduced tumor response and remission rates. Thrombopoietic growth factors (recombinant human thrombopoietin, pegylated human megakaryocyte growth and development factor, romiplostim, eltrombopag, avatrombopag and hetrombopag) improve pretreatment and nadir platelet counts, reduce the need for platelet transfusions, and enable chemotherapy dose intensity to be maintained. National Comprehensive Cancer Network guidelines permit their use but their widespread adoption awaits adequate phase III randomized, placebo-controlled studies demonstrating maintenance of relative dose intensity, reduction of platelet transfusions and bleeding, and possibly improved survival. Their potential appropriate use also depends on consensus by the oncology community as to what constitutes an appropriate pretreatment platelet count as well as identification of patient-related and treatment variables that might predict bleeding.

Recombinant human thrombopoietin prior to mobilization chemotherapy facilitates platelet recovery in autologous transplantation in patients with lymphoma: Results of a prospective randomized study

Background

Chemotherapy plus granulocyte colony-stimulating factor (GCSF) regimen is one of the available approaches to mobilize peripheral blood progenitor cells (PBPCs). It causes thrombocytopenia and delays leukapheresis. This study aimed to evaluate the role of recombinant human thrombopoietin (rhTPO) before mobilization chemotherapy in facilitating leukapheresis in patients with lymphoma.

Methods

In this randomized open-label phase 2 trial, patients were randomly assigned in a 1:2 ratio to receive mobilization with rhTPO plus GCSF in combination with chemotherapy (the rhTPO plus GCSF arm) or GCSF alone in combination with chemotherapy (the GCSF alone arm). The recovery of neutrophils and platelets and the amount of platelet transfusion were monitored.

Results

Thirty patients were enrolled in this study between March 2016 and August 2018. Patients in the rhTPO plus GCSF arm (n = 10) had similar platelet nadir after mobilization chemotherapy (P=0.878) and similar amount of platelet transfusion (median 0 vs. 1 unit, P=0.735) when compared with the GCSF alone arm (n = 20). On the day of leukapheresis, the median platelet count was 86 × 10⁹/L (range 18–219) among patients who received rhTPO and 73 × 10⁹/L (range 42–197) among those who received GCSF alone (P=0.982). After the use of rhTPO, the incidence of platelet count <75 × 10⁹/L on the day of leukapheresis did not decrease significantly (30.0% vs. 50.0%, P=0.297). Platelet recovery after PBPC transfusion was more rapid in the rhTPO plus GCSF arm (median 8.0 days [95% confidence interval 2.9–13.1] to platelets ≥50 × 10⁹/L vs. 11.0 days [95% confidence interval 8.6–13.4], P=0.011). The estimated total cost of the mobilization and reconstitution phases per patient was similar between the two treatmtent groups (P=0.362 and P=0.067, respectively).

Conclusions

Our findings indicate that there was no significant clinical benefit of rhTPO use in facilitating mobilization of progenitor cells, but it may promote platelet recovery in the reconstitution phase after high-dose therapy.

Trial registration

This trial has been registered in Clinicaltrials.gov as NCT03014102.

A Real-World Observation of Eltrombopag and Recombinant Human Thrombopoietin (rhTPO) in Lymphoma Patients With Chemotherapy Induced Thrombocytopenia

This real-world, observational study aimed to assess and compare the clinical efficacy and safety of eltrombopag with recombinant human thrombopoietin (rhTPO) in the treatment of chemotherapy induced thrombocytopenia (CIT) in patients with lymphoma. One hundred and fifty-three patients who experienced grade 3 or 4 thrombocytopenia after chemotherapy for lymphoma were enrolled, 51 of which were treated with eltrombopag, 50 with rhTPO, and 52 patients with no drug treatment were served as the control group. The lowest platelet level and mean platelet counts at Day 5, Day 7, and Day 10 were significantly higher in both the eltrombopag group (P=.041,.003,.000,.000) and rhTPO group (P=.005,.005,.000,.000) than the control, but there was no difference between treatment with eltrombopag and rhTPO. Similarly, days required for the recovery of platelet counts to ≥50×10⁹/L and ≥75×10⁹/L were not different between the two treatment groups but significantly higher than the control group (P <.05). Rates of bleeding and platelet transfusion were all significantly reduced in patients treated with eltrombopag (P=.031,.032) or rhTPO (P=.017,.009) when compared to the control. Treatment-related adverse events (AEs) were reported in 7 (13.7%) and 6 (12.0%) patients in the eltrombopag and rhTPO groups, respectively, all being mild and transient in nature. In conclusion, both eltrombopag and rhTPO were effective and safe in the treatment of thrombocytopenia after chemotherapy for lymphoma.

Mechanisms and therapeutic prospects of thrombopoietin receptor agonists

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