Effect of postdose fasting duration on hetrombopag olamine pharmacokinetics and pharmacodynamics in healthy volunteers

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

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

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.

Efficacy and Safety of Hetrombopag for Thrombocytopenia in Patients with Advanced Solid Tumors: A Retrospective Study

Objective. To analyze and evaluate the clinical value of hetrombopag in cancer therapy-induced thrombocytopenia (CTIT) caused by antitumor therapy for malignant tumors and to provide scientific evidence support for clinical application in the real-world setting. Methods. The clinical data of CTIT patients with advanced solid tumors who received hetrombopag were analyzed retrospectively. The proportion of patients with different characteristics who recovered platelet count to ≥75 × 109/L at day 14 and the effective rate of platelet elevation was compared by the χ2 test or Fisher exact probability method. $P<0.05$ was considered statistically significant. Results. A total of 60 CTIT patients who received hetrombopag at our site from July 2021 to October 2022 were finally included in this study. The proportion of patients who achieved therapeutic effect within (7 ± 2) days after treatment was 26.7% (16/60), among which 20.0% (12/60) patients had platelet count recovered to ≥100 × 109/L, and 25.0% (15/60) patients had platelet count increase from baseline ≥50 × 109/L. Within (14 ± 2) days of treatment with hetrombopag, 66.7% (40/60) of patients achieved treatment response, of whom 56.7% (34/60) had platelet counts ≥100 × 109/L and 53.3% (32/60) had platelet counts ≥50 × 109/L increase from baseline. In addition, no treatment-related adverse events occurred during the treatment period. Conclusion. This retrospective study provides preliminary evidence that hetrombopag increases platelets in CTIT patients receiving antitumor therapy for advanced solid tumors.

Thrombopoietin-receptor agonists for adult patients with immune thrombocytopenia: a narrative review and an approach for managing patients fasting intermittently

Introduction

Thrombopoietin-receptor agonist (TPO-RAs) currently represent the state of art for treating immune thrombocytopenia. Their different molecular structures contribute to the difference in their pharmacodynamics and pharmacokinetics. This narrative review aims to provide an overview of the current TPO-RAs approved for primary immune thrombocytopenia (romiplostim, eltrombopag, avatrombopag) and the effect of intermittent fasting in adult patients receiving TPO-RAs.

Areas covered

Literature was searched with no limits on date or language, using various combinations of keywords. Data on the pharmacokinetics, pharmacodynamics, efficacy, and safety of TPO-RAs and the effect of intermittent fasting were summarized.

Expert opinion

Switching between TPO-RAs is a useful strategy to tackle some associated limitations. Romiplostim and avatrombopag have an advantage over eltrombopag as they do not require any dietary restrictions. In cases where romiplostim and avatrombopag are unavailable, patients should be educated on the appropriate administration, possible interactions, and dietary restrictions before initiating eltrombopag.

A phase I, single-sequence, open-label study to evaluate the drug-drug interaction between hetrombopag and cyclosporine in healthy Chinese subjects

AIMS

This study aims to evaluate the drug-drug interaction (DDI) between hetrombopag and cyclosporine in healthy Chinese subjects.

METHODS

Twenty-six eligible subjects enrolled in this single-centre, single-sequence, open-label, DDI study with 3 treatment periods, receiving 5 mg hetrombopag once on Day 1, 100 mg cyclosporine twice daily from Day 11 to Day 15 and 5 mg hetrombopag + 100 mg cyclosporine on Day 16. Serial blood samples were collected for pharmacokinetic evaluation. Adverse events were monitored throughout the study.

RESULTS

The plasma hetrombopag geometric mean ratios (90% confidence interval) of maximum plasma concentration, area under the plasma concentration-time curve (AUC) from predose to time of last quantifiable sample and AUC to infinity of coadministration of hetrombopag with cyclosporine vs. hetrombopag alone were 95.97% (70.08-131.43%), 105.75% (75.04-149.04%) and 104.19% (74.71-145.32%), respectively, indicating multiple doses of cyclosporine had minimal effects on hetrombopag exposure. The geometric mean ratios (90% confidence interval) of maximum blood concentration and AUC at steady state during a dosing interval for blood cyclosporine of coadministration vs. cyclosporine alone were 100.49% (91.89-109.89%) and 100.81% (107.88-103.82%), respectively, suggesting a single dose of hetrombopag had no impact on the exposure of cyclosporine. Coadministration of hetrombopag with cyclosporine was generally well tolerated.

CONCLUSION

No clinically significant DDI was observed when coadministration of hetrombopag with cyclosporine. The results of this study will inform the appropriate use of this combination therapy both in clinical trials and clinical settings.

Chinese expert consensus on managing thrombocytopenia in patients with cancer and liver injury

Abstract

Thrombocytopenia and liver injury are serious clinical problems in patients with cancer. The etiology of thrombocytopenia in patients with cancer and liver injury (TCLI) is complicated. Managing cancer therapy-induced thrombocytopenia has gradually become standardized, and managing liver injury-associated thrombocytopenia has become more effective with the approval and marketing of relevant drugs. However, the optimal strategy for managing thrombocytopenia in patients with cancer and liver injury remains unclear, and the superposition of thrombocytopenia and liver injury further increases the difficulty of cancer treatment. Therefore, the Committee of Cancer Support Therapy of the Chinese Anti-Cancer Association has organized experts to analyze and discuss relevant literature to form a Chinese expert consensus on managing thrombocytopenia in patients with cancer and liver injury (2022 Edition) to guide clinical practice.

Novel Therapies to Address Unmet Needs in ITP

Primary immune thrombocytopenia (ITP) is an autoimmune disorder that causes low platelet counts and subsequent bleeding risk. Although current corticosteroid-based ITP therapies are able to improve platelet counts, up to 70% of subjects with an ITP diagnosis do not achieve a sustained clinical response in the absence of treatment, thus requiring a second-line therapy option as well as additional care to prevent bleeding. Less than 40% of patients treated with thrombopoietin analogs, 60% of those treated with splenectomy, and 20% or fewer of those treated with rituximab or fostamatinib reach sustained remission in the absence of treatment. Therefore, optimizing therapeutic options for ITP management is mandatory. The pathophysiology of ITP is complex and involves several mechanisms that are apparently unrelated. These include the clearance of autoantibody-coated platelets by splenic macrophages or by the complement system, hepatic desialylated platelet destruction, and the inhibition of platelet production from megakaryocytes. The number of pathways involved may challenge treatment, but, at the same time, offer the possibility of unveiling a variety of new targets as the knowledge of the involved mechanisms progresses. The aim of this work, after revising the limitations of the current treatments, is to perform a thorough review of the mechanisms of action, pharmacokinetics/pharmacodynamics, efficacy, safety, and development stage of the novel ITP therapies under investigation. Hopefully, several of the options included herein may allow us to personalize ITP management according to the needs of each patient in the near future.

Alternatives for managing patients with newly diagnosed immune thrombocytopenia: a narrative review

INTRODUCTION

Primary immune thrombocytopenia (ITP) is an acquired bleeding disorder. Conventionally, first-line ITP therapy aims to obtain a rapid response and stop or decrease the risk of bleeding by increasing the platelet count. At this point, the duration of the response, the tolerability, and the long-term safety of pharmacologic interventions are considered less of a priority. Combination treatments that simultaneously address multiple disease mechanisms are an attractive strategy to increase efficacy in acute ITP therapy. In this review, we discuss the treatment of newly diagnosed ITP patients, emphasizing the use of new combinations to benefit from their synergy.

AREAS COVERED

This article summarizes conventional treatment, recent and novel combinations, and COVID-19 management recommendations of newly diagnosed ITP patients.

EXPERT OPINION

The key areas for improvement consider the long-term effects of conventional first-line therapy, reducing relapse rates, and extending responses to achieve long-term remission. Although corticosteroids remain first-line therapy, restricting their use to avoid toxicity and the increasing use of rituximab and TPO-RAs in the first three months after diagnosis open the landscape for future interventions in frontline therapy for ITP. First-line therapy intensification or synergistic drug combination offers a potential and realistic shift in future treatment guidelines.

A multicenter phase II study on the efficacy and safety of hetrombopag in patients with severe aplastic anemia refractory to immunosuppressive therapy

Background:

In this single-arm phase II study (NCT03557099), we evaluated the efficacy and safety of hetrombopag, a small molecule thrombopoietin (TPO) receptor agonist, in patients with severe aplastic anemia (SAA) who were refractory to standard first-line immunosuppressive therapy (IST).

Methods:

SAA patients who were refractory to standard first-line IST were given hetrombopag orally at an initial dose of 7.5 mg once daily to a maximum of 15 mg once daily, for a total of 52 weeks. The primary endpoint was proportion of patients achieving hematologic responses in ⩾1 lineage at week 18.

Results:

A total of 55 eligible patients were enrolled and received hetrombopag treatment. This study met its primary endpoint, with 23 [41.8%, 95% confidence interval (CI) = 28.7–55.9] patients achieving hematologic response in ⩾1 lineage at week 18 after initiation of hetrombopag treatment. Twenty-four (43.6%, 95% CI = 30.3–57.7) and 27 (49.1%, 95% CI = 35.4–62.9) of the 55 patients responded in ⩾1 lineage at weeks 24 and 52, respectively. Median time to initial hematologic response was 7.9 weeks (range = 2.0–32.1). The responses were durable, with a 12-month relapse-free survival rate of 82.2% (95% CI = 62.2–92.2). Adverse events occurred in 54 (98.2%) patients, and 28 (50.9%) patients had treatment-related adverse events. Seventeen (30.9%) patients had adverse events of grade ⩾3. Serious adverse events occurred in 15 (27.3%) patients and three deaths (5.5%) were reported.

Conclusion:

Hetrombopag showed encouraging efficacy with durable hematologic responses in patients with SAA who were refractory to IST. Hetrombopag was well tolerant and safe for long-term use.

ClinicalTrials.gov identifier:

NCT03557099

A pharmacokinetic study to comparatively evaluate the bioequivalence and safety of a humanized recombinant monoclonal antibody targeting human epidermal growth factor receptor-2 with the reference Herceptin in healthy Chinese subjects

PURPOSE

This study aimed to compare the safety, tolerability, pharmacokinetics (PK), and bioequivalence of a test humanized recombinant monoclonal antibody targeting human epidermal growth factor receptor-2 (HER-2) with the reference Herceptin®.

MATERIALS AND METHODS

The trial consisted of two parts (part I and part II). Part I was an open-label, sequential-cohort dose-escalation study, where 16 healthy subjects were either intravenously infused with QLHER2 (test) at single doses escalating from 0.2 to 6 mg/kg (0.2, 1, 2, 4, and 6 mg/kg) or given 4 mg/kg Herceptin (reference) for evaluating the safety, tolerability, and PK of QLHER2. Part II was a randomized, double-blind, parallel-group study to evaluate the bioequivalence of QLHER2 and Herceptin in 60 subjects.

RESULTS

Following a 1.5-h intravenous infusion of single ascending doses of QLHER2 (1, 2, 4, or 6 mg/kg) in part I, C_max and T_max were 19.43-120.01 μg/mL and 68.91-157.87 h, respectively. AUC_0-t and CL were 1.91-34.21 h·μg/mL and 0.54-0.12 mL/h/kg, indicating lower clearance at higher doses, with a greater than proportional increase in AUC_0-t and t_1/2 of 68.91-157.87 h. In part II, serum concentrations were comparable between QLHER2 and Herceptin over a 70-day sampling period, and the QLHER2/Herceptin ratios of C_max and AUC_0-t were 105.90% [90% confidence interval (CI): 95.69%-117.26%] and 95.79% (90% CI: 87.74%-106.40%), respectively.

CONCLUSION

The 90% CI value of C_max and AUC_0-t for QLHER2/Herceptin ratio ranged between 80.0%-125.00%, indicating that QLHER2 was bioequivalent to Herceptin. These results support further evaluation of QLHER2. Trial registration number: ChiCTR2000041577 and ChiCTR2100041802. Date of registration: 30th December, 2020 and 5th January 2021.

The structure, function, and clinical use of the thrombopoietin receptor agonist avatrombopag

Thrombopoietin regulates platelet production through activation of the thrombopoietin receptor (TPO-R). TPO-R agonists (TPO-RAs) are available to treat thrombocytopenia in chronic immune thrombocytopenia (ITP), chronic liver disease (CLD) patients who are undergoing a procedure, severe aplastic anemia (SAA), and hepatitis C virus (HCV) infection. There are four TPO-RAs approved in the US and Europe: romiplostim (ITP), eltrombopag (ITP, SAA, HCV), avatrombopag (ITP, CLD), and lusutrombopag (CLD). It is important to understand pharmacological characteristics of these agents when evaluating treatment options. Avatrombopag interacts with the transmembrane domain of the TPO-RA and does not compete with endogenous thrombopoietin for TPO-R binding. Structural differences between avatrombopag and other TPO-RAs may impart differential downstream effects on cell signaling pathways, potentially resulting in clinically relevant differences in outcome. Avatrombopag has a favorable pharmacological profile with similar exposure in Japanese, Chinese, or Caucasian patients and no drug-drug interactions, food interactions, or potential for chelation.

Impact of target-mediated drug disposition on hetrombopag pharmacokinetics and pharmacodynamics in Chinese healthy subjects and patients with chronic idiopathic thrombocytopenic purpura

AIMS

The pharmacokinetics (PK) of hetrombopag were found to be nonlinear across evaluated dose ranges. The aim of this study was to develop a mechanism-based population pharmacokinetic/pharmacodynamic (PopPK/PD) model and to provide a reasonable expected therapeutic dose for a future confirmatory clinical study of hetrombopag.

METHODS

Nonlinear mixed-effects modelling was performed using pooled 2168 hetrombopag concentrations and 1526 platelet counts from 72 healthy subjects and 32 chronic idiopathic thrombocytopenic purpura (ITP) patients from two phase I studies and one phase II study. The final model was evaluated via goodness-of-fit plots, visual predictive check and nonparametric bootstrap. Simulations from the validated PopPK/PD model were used to devise an expected therapeutic dose for later confirmatory clinical study.

RESULTS

The pharmacokinetic data of hetrombopag were well described by a modified target-mediated drug disposition (TMDD) model with dual sequential first-order absorption. Mean parameter estimates (interindividual variability) were CL/F 7.66 L/h (63.5%), V_c /F 30.0 L (77.2%) and K_deg 0.693/h (87.1%). The pharmacodynamic profile was well described by a five-compartment lifespan model with four-transit and one-platelet compartments. Simulation results suggested that chronic ITP patients following 10 mg once-daily hetrombopag would able to achieve an ideal platelet count level (50-200 × 10⁹ /L).

CONCLUSION

TMDD was the primary reason leading to nonlinear PK profile of hetrombopag. Our PK/PD modelling and simulation results support 10 mg once-daily as the recommended therapeutic dose for chronic ITP patients in subsequent confirmatory clinical study of hetrombopag.

Novel therapies for immune thrombocytopenia

Current therapies for immune thrombocytopenia (ITP) are successful in providing a haemostatic platelet count in over two-thirds of patients. Still, some patients have an inadequate response and there is a need for other therapies. A number of novel therapies for ITP are currently being developed based upon the current pathophysiology of ITP. Many therapies are targetted at reducing platelet destruction by decreasing anti-platelet antibody production by immunosuppression with monoclonal antibodies targetted against CD40, CD38 and the immunoproteasome or physically reducing the anti-platelet antibody concentration by inhibition of the neonatal Fc receptor. Others target the phagocytic system by inhibiting FcγR function with staphylococcal protein A, hypersialylated IgG, polymeric Fc fragments, or Bruton kinase. With a recognition that platelet destruction is also mediated by complement, inhibitors of C1s are also being tested. Inhibition of platelet desialylation may also play a role. Other novel therapies promote platelet production with new oral thrombopoietin receptor agonists or the use of low-level laser light to improve mitochondrial activity and prevent megakaryocyte apoptosis. This review will focus on these novel mechanisms for treating ITP and assess the status of treatments currently under development. Successful new treatments for ITP might also provide a pathway to treat other autoimmune disorders.

Hetrombopag: First Approval

Hetrombopag (Hengqu^®), an oral nonpeptide thrombopoietin receptor agonist, is being developed by Jiangsu Hengrui Pharmaceutical for the treatment of thrombocytopenia and aplastic anaemia. On 16 June 2021, hetrombopag received its first approval in China as a second-line treatment for primary immune thrombocytopenia (ITP) and severe aplastic anaemia (SAA) in adults. The drug is also undergoing phase III development in China for the treatment of chemotherapy-induced thrombocytopenia. This article summarizes the milestones in the development of hetrombopag leading to this first approval for ITP and SAA.

Emerging Therapies in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is a rare autoimmune disorder caused by peripheral platelet destruction and inappropriate bone marrow production. The management of ITP is based on the utilization of steroids, intravenous immunoglobulins, rituximab, thrombopoietin receptor agonists (TPO-RAs), immunosuppressants and splenectomy. Recent advances in the understanding of its pathogenesis have opened new fields of therapeutic interventions. The phagocytosis of platelets by splenic macrophages could be inhibited by spleen tyrosine kinase (Syk) or Bruton tyrosine kinase (BTK) inhibitors. The clearance of antiplatelet antibodies could be accelerated by blocking the neonatal Fc receptor (FcRn), while new strategies targeting B cells and/or plasma cells could improve the reduction of pathogenic autoantibodies. The inhibition of the classical complement pathway that participates in platelet destruction also represents a new target. Platelet desialylation has emerged as a new mechanism of platelet destruction in ITP, and the inhibition of neuraminidase could dampen this phenomenon. T cells that support the autoimmune B cell response also represent an interesting target. Beyond the inhibition of the autoimmune response, new TPO-RAs that stimulate platelet production have been developed. The upcoming challenges will be the determination of predictive factors of response to treatments at a patient scale to optimize their management.

Effect of postdose fasting duration on hetrombopag olamine pharmacokinetics and pharmacodynamics in healthy volunteers

AIMS

Hetrombopag olamine is a novel small-molecule, nonpeptide thrombopoietin receptor agonist developed for immune thrombocytopenia treatment. This study aims to determine the safety and the effect of fasting duration after administration of hetrombopag on pharmacokinetics and pharmacodynamics in Chinese healthy subjects.

METHODS

A randomized, open-label, single-dose, 3-period crossover, self-control trial was conducted. 15 eligible subjects were enrolled and received hetrombopag 7.5 mg at day 1 of each period followed by a standard meal 4 hours postdose (treatment A/fasting condition), or a high-calorie, high-fat meal 1 hour postdose (treatment B), or a high-calorie, high-fat meal 2 hours postdose (treatment C). The plasma concentrations of hetrombopag were determined by validated liquid chromatography-tandem mass spectrometry, platelet counts were quantified by blood test. Analysis was performed using a mixed model, including treatment, period as fixed effects and participant as a random effect.

RESULTS

Compared with treatment A, peak concentration and area under concentration-time curve extrapolated to infinity decreased by 56 and 74.6%, and 44 and 61% in treatments B and C, respectively. The mean platelet number on day 6 increased by 15.8, 6.96 and 10.26%, respectively, in treatments A, B and C in comparison with baseline platelet level. No severe adverse events happened in any of the 3 treatments.

CONCLUSION

Hetrombopag was well tolerated in healthy male subjects under fasted/fed conditions. The shorter fasting duration resulted in lower hetrombopag exposure, corresponding to a lower level of platelet elevation. Therefore, we recommended oral administration of hetrombopag on an empty stomach (fasting condition) or at least 2 hours before a meal to achieve maximum bioavailability.