Results of a phase I dose escalation study of eltrombopag in patients with advanced soft tissue sarcoma receiving doxorubicin and ifosfamide

Hetrombopag for the management of chemotherapy-induced thrombocytopenia in patients with advanced solid tumors: a multicenter, randomized, double-blind, placebo-controlled, phase II study

Background

Chemotherapy-induced thrombocytopenia (CIT) increases the risk of bleeding, necessitates chemotherapy dose reductions and delays, and negatively impacts prognosis.

Objectives

This study aimed to evaluate the efficacy and safety of hetrombopag for the management of CIT in patients with advanced solid tumors.

Design

A multicenter, randomized, double-blind, placebo-controlled, phase II study.

Methods

Patients with advanced solid tumors who experienced a chemotherapy delay of ⩾7 days due to thrombocytopenia (platelet count <75 × 109/L) were randomly assigned (1:1) to receive oral hetrombopag at an initial dose of 7.5 mg once daily or a matching placebo. The primary endpoint was the proportion of treatment responders, defined as patients resuming chemotherapy within 14 days (platelet count ⩾100 × 109/L) and not requiring a chemotherapy dose reduction of ⩾15% or a delay of ⩾4 days or rescue therapy for two consecutive cycles.

Results

Between 9 October 2021 and 5 May 2022, 60 patients were randomized, with 59 receiving ⩾1 dose of assigned treatment (hetrombopag/placebo arm, n = 28/31). The proportion of treatment responders was significantly higher in the hetrombopag arm than in the placebo arm [60.7% (17/28) versus 12.9% (4/31); difference of proportion: 47.6% (95% confidence interval (CI): 26.0-69.3); odds ratio = 10.44 (95% CI: 2.82-38.65); p value (nominal) based on the Cochran-Mantel-Haenszel: <0.001)]. During the double-blind treatment period, grade 3 or higher adverse events (AEs) occurred in 35.7% (10/28) of patients with hetrombopag and 38.7% (12/31) of patients on placebo. The most common grade 3 or higher AEs were decreased neutrophil count [35.7% (10/28) versus 35.5% (11/31)] and decreased white blood cell count [17.9% (5/28) versus 19.4% (6/31)]. Serious AEs were reported in 3.6% (1/28) of patients with hetrombopag and 9.7% (3/31) of patients with placebo.

Conclusion

Hetrombopag is an effective and well-tolerated alternative for managing CIT in patients with solid tumors.

Trial registration

ClinicalTrials.gov identifier: NCT03976882.

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.

Optimal biological dose: a systematic review in cancer phase I clinical trials

BACKGROUND

Classical phase 1 dose-finding designs based on a single toxicity endpoint to assess the maximum tolerated dose were initially developed in the context of cytotoxic drugs. With the emergence of molecular targeted agents and immunotherapies, the concept of optimal biological dose (OBD) was subsequently introduced to account for efficacy in addition to toxicity. The objective was therefore to provide an overview of published phase 1 cancer clinical trials relying on the concept of OBD.

METHODS

We performed a systematic review through a computerized search of the MEDLINE database to identify early phase cancer clinical trials that relied on OBD. Relevant publications were selected based on a two-step process by two independent readers. Relevant information (phase, type of therapeutic agents, objectives, endpoints and dose-finding design) were collected.

RESULTS

We retrieved 37 articles. OBD was clearly mentioned as a trial objective (primary or secondary) for 22 articles and was traditionally defined as the smallest dose maximizing an efficacy criterion such as biological target: biological response, immune cells count for immunotherapies, or biological cell count for targeted therapies. Most trials considered a binary toxicity endpoint defined in terms of the proportion of patients who experienced a dose-limiting toxicity. Only two articles relied on an adaptive dose escalation design.

CONCLUSIONS

In practice, OBD should be a primary objective for the assessment of the recommended phase 2 dose (RP2D) for a targeted therapy or immunotherapy phase I cancer trial. Dose escalation designs have to be adapted accordingly to account for both efficacy and toxicity.

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.

Discovery of the anti-angiogenesis effect of eltrombopag in breast cancer through targeting of HuR protein

HuR (human antigen R), an mRNA-binding protein responsible for poor prognosis in nearly all kinds of malignancies, is a potential anti-tumor target for drug development. While screening HuR inhibitors with a fluorescence polarization (FP) based high-throughput screening (HTS) system, the clinically used drug eltrombopag was identified. Activity of eltrombopag on molecular level was verified with FP, electrophoretic mobility shift assay (EMSA), simulation docking and surface plasmon resonance (SPR). Further, we showed that eltrombopag inhibited in vitro cell proliferation of multiple cancer cell lines and macrophages, and the in vivo anti-tumor activity was also demonstrated in a 4T1 tumor-bearing mouse model. The in vivo data showed that eltrombopag was efficient in reducing microvessels in tumor tissues. We then confirmed the HuR-dependent anti-angiogenesis effect of eltrombopag in 4T1 cells and RAW264.7 macrophages with qRT-PCR, HuR-overexpression and HuR-silencing assays, RNA stability assays, RNA immunoprecipitation and luciferase assays. Finally, we analyzed the in vitro anti-angiogenesis effect of eltrombopag on human umbilical vein endothelial cells (HUVECs) mediated by macrophages with cell scratch assay and in vitro Matrigel angiogenesis assay. With these data, we revealed the HuR-dependent anti-angiogenesis effect of eltrombopag in breast tumor, suggesting that the existing drug eltrombopag may be used as an anti-cancer drug.

Management of Thrombocytopenia in Cancer Patients

Chemotherapy-induced thrombocytopenia (CIT) is a frequent complication of cancer therapy, leading to increased risk of bleeding, when the thrombocytopenia is severe (<10,000/mcL). However, the major clinical relevance of CIT is the subsequent delay or dose reduction in chemotherapy. CIT, therefore, leads to reduced relative dose intensity (RDI) of cancer therapy. Reduced RDI has been shown in several studies to impact progression-free survival and other cancer outcomes. While there are a number of factors leading to reduced RDI, CIT is a common cause. We review the causes and clinical manifestations of CIT, the current recommendations for management, and the status of research to develop targeted therapies to treat CIT.

Drug-Induced Hematological Cytopenia in Kidney Transplantation and the Challenges It Poses for Kidney Transplant Physicians

Drug-induced hematological cytopenia is common in kidney transplantation. Various cytopenia including leucopenia (neutropenia), thrombocytopenia, and anemia can occur in kidney transplant recipients. Persistent severe leucopenia or neutropenia can lead to opportunistic infections of various etiologies. On the contrary, reducing or stopping immunosuppressive medications in these events can provoke a rejection. Transplant clinicians are often faced with the delicate dilemma of balancing cytopenia and rejection from adjustments of immunosuppressive regimen. Differentials of drug-induced cytopenia are wide. Identification of culprit medication and subsequent modification is also challenging. In this review, we will discuss individual drug implicated in causing cytopenia and correlate it with corresponding literature evidence.

The impact of chemotherapy-associated hemoglobin on prognosis of colorectal cancer patients receiving adjuvant chemotherapy

BACKGROUND AND OBJECTIVE

The association of chemotherapy-associated hemoglobin and survival of colorectal cancer (CRC) receiving adjuvant chemotherapy is uncertain. We sought to explore the prognostic value of chemotherapy-associated hemoglobin in CRC receiving adjuvant chemotherapy and the best cut point affecting prognosis.

METHODS

Three hundred and twenty stage II and III CRC patients receiving adjuvant FOLFOX chemotherapy from March 2003 to March 2012 were enrolled. The associations between chemotherapy-associated hemoglobin (the absolute levels of post-chemotherapy) or chemotherapy-associated hemoglobin change (change between the pre- and post-chemotherapy hemoglobins) and disease free survival (DFS) or overall survival (OS) of CRC, and the best cut point were investigated.

RESULTS

Log rank test showed the best cut points for chemotherapy-associated hemoglobin and chemotherapy-associated hemoglobin change were respectively 90 g/L, 30 g/L. Cox regression model showed chemotherapy-associated hemoglobin < 90 g/L was the independent prognostic factor for DFS (HR, 2.221; 95% CI = 1.157-4.262), OS (HR, 2.058; 95% CI = 1.009-4.197), respectively, but no association of chemotherapy-associated hemoglobin change ⩾ 30g/L and DFS (HR, 2.063; 95% CI = 0.929-4.583), OS (HR, 1.386; 95% CI = 0.553-3.471) was found.

CONCLUSIONS

Chemotherapy-associated hemoglobin < 90 g/L has a significant prognostic value in CRC receiving adjuvant chemotherapy, which is a significant biomarker in the individualized management and may suggest the simple indication for the treatment of anemia in adjuvant chemotherapy in CRC.

Thrombopoietin receptor agonists for prevention and treatment of chemotherapy-induced thrombocytopenia in patients with solid tumours

BACKGROUND

Chemotherapy-induced thrombocytopenia (CIT) is defined as a peripheral platelet count less than 100×109/L, with or without bleeding in cancer patients receiving myelosuppressive chemotherapy. CIT is a significant medical problem during chemotherapy, and it carries the risk of sub-optimal overall survival and bleeding. Alternative interventions to platelet transfusion are limited. Different stages of preclinical and clinical studies have examined the thrombopoietin receptor agonists (TPO-RAs) for CIT in patients with solid tumours.

OBJECTIVES

To assess the effects of TPO-RAs to prevent and treat CIT in patients with solid tumours:(1) to prevent CIT in patients without thrombocytopenia before chemotherapy, (2) to prevent recurrence of CIT, and (3) to treat CIT in patients with thrombocytopenia during chemotherapy.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, to 28 September 2017), MEDLINE (from 1950 to 28 September 2017), as well as online registers of ongoing trials (Clinical Trials, Chinese Clinical Trial Register, Australian New Zealand Clinical Trial Registry, WHO ICTRP Search Portal, International Standard Randomised Controlled Trial Number registry, GlaxoSmithKline Clinical Study Register, and Amgen Clinical Trials) and conference proceedings (American Society of Hematology, American Society of Clinical Oncology, European Hematology Association, European Society of Medical Oncology, and Conference Proceedings Citation Index-Science, from 2002 up to September 2017) for studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing TPO-RAs alone, or in combination with other drugs, to placebo, no treatment, other drugs, or another TPO-RAs for CIT in patients with solid tumours.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the search strategies, extracted data, assessed risk of bias, and analysed data according to standard methodological methods expected by Cochrane.

MAIN RESULTS

We identified six trials eligible for inclusion, of which two are ongoing, and one awaiting classification study. The three included trials were conducted at many different sites in Europe, America, and Asia. All of the three studies recruited adult and elder participants (no children were included) with solid tumours, and compared TPO-RAs with placebo. No studies compared TPO-RAs alone, or in combination with other drugs, to no treatment, or other drugs, or another TPO-RAs.We judged the overall risk of bias as high as we found a high risk for detection bias. We assessed the risk of bias arising from inadequate blinding of outcome assessors as high for number and severity of bleeding episodes (one of the primary outcomes).To prevent CIT: We included two trials (206 participants) comparing TPO-RAs (eltrombopag, multiple-dose oral administration with chemotherapy) with placebo. The use of TPO-RAs may make little or no difference to the all-cause mortality at 33 weeks of follow-up (RR 1.35, 95% CI 0.53 to 3.45; one trial, 26 participants; low quality of evidence). There is not enough evidence to determine whether TPO-RAs reduce the number of patients with at least one bleeding episode of any severity (RR 0.62, 95% CI 0.22 to 1.78; two trials, 206 participants; very low quality of evidence). There is not enough evidence to determine whether TPO-RAs reduce the number of patients with at least one severe/life-threatening bleeding episode (RR 0.36, 95% CI 0.06 to 2.06; two trials, 206 participants; very low quality of evidence). No studies were found that looked at overall survival (one of the primary outcomes), the number of treatment cycles with at least one bleeding episode, the number of days on which bleeding occurred, the amount of bleeding, or quality of life.To prevent recurrence of CIT: We included one trial (62 participants) comparing TPO-RAs (romiplostim, single-dose subcutaneous administration with chemotherapy) with placebo. There is not enough evidence to determine whether TPO-RAs reduce the number of patients with at least one bleeding episode of any severity (RR 2.80, 95% CI 0.17 to 47.53; one trial, 62 participants; very low quality of evidence). There is not enough evidence to determine whether TPO-RAs reduce the number of patients with at least one severe/life-threatening bleeding episode (no severe/life-threatening bleeding episodes; one trial, 62 participants; very low quality of evidence). No studies were found that looked at overall survival (one of the primary outcomes), the number of treatment cycles with at least one bleeding episode, the number of days on which bleeding occurred, the amount of bleeding, or quality of life. We found one ongoing study (expected recruitment 74 participants), it is planned to give TPO-RAs (romiplostim, subcutaneous administration with chemotherapy) to participants, but to date this trial has not reported any outcomes.To treat CIT: We found one ongoing study (expected recruitment 83 participants), which is planned to give TPO-RAs (eltrombopag, seven days orally) to participants when their platelet counts are less than 75×109/L during chemotherapy. This trial was originally planned to complete in March 2017, however, the completion date has passed and no results are reported.The one awaiting classification study included patients without thrombocytopenia before chemotherapy (to prevent CIT), patients with thrombocytopenia during chemotherapy (to prevent recurrence of CIT), and other patients during chemotherapy (uncertain whether CIT had happened). There was no evidence for a difference in the number of patients with at least one bleeding episode of any severity (RR 0.27, 95% CI 0.07 to 1.02; one trial, 75 participants). There was no evidence for a difference in the number of patients with at least one severe/life-threatening bleeding episode (RR 0.44, 95% CI 0.03 to 6.77; one trial, 75 participants). This study did not address overall survival or quality of life.

AUTHORS' CONCLUSIONS

No certain conclusions can be drawn due to the lack of strong evidence in the review. The available weak evidence did not support the use of TPO-RAs for preventing CIT or preventing recurrence of CIT in patients with solid tumours. There was no evidence to support the use of TPO-RAs for treating CIT in patients with solid tumours.

From chronic immune thrombocytopenia to severe aplastic anemia: recent insights into the evolution of eltrombopag

Thrombopoietin (TPO) is the most potent cytokine stimulating thrombopoiesis. Therapy with exogenous TPO is limited by the formation of antibodies cross-reacting with endogenous TPO. Mimetics of TPO are compounds with no antigenic similarity to TPO. Eltrombopag is an orally-active nonpeptide small molecule that binds to the transmembrane portion of the TPO receptor MPL. Initial trials of eltrombopag have centered on immune thrombocytopenia (ITP), which is due to both increased destruction and decreased production of platelets. Eltrombopag at 25-75 mg/day has been shown to be highly effective in raising the platelet count in ITP with suboptimal response to immunosuppression and splenectomy. These successful results led to the exploration of eltrombopag in other thrombocytopenic disorders. In hepatitis C viral infection, eltrombopag raises the platelet count sufficiently enough to allow treatment with ribavirin and pegylated interferon. Because MPL is expressed on hematopoietic cells, eltrombopag use in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) might enhance leukemic proliferation. Clinical trials of eltrombopag in MDS and AML, however, have shown amelioration of thrombocytopenia without promoting disease progression. In severe aplastic anemia (SAA) not responding to immunosuppression with anti-thymocyte globulin (ATG) and cyclosporine, eltrombopag as a single agent at 150-300 mg/day results in an overall response rate of 40-70%. At high doses, adverse effects including pigmentation, gastrointestinal upset and hepatic derangement have become evident. Current studies have examined the first-line use of eltrombopag in combination with ATG in SAA. In a recent study, eltrombopag used at 150 mg/day with horse ATG resulted in an overall response rate of 90% in newly diagnosed SAA patients, with a complete response rate of about 50%. Clonal karyotypic aberrations are, however, found in 10-20% of SAA patients treated with eltrombopag. The safety and efficacy of eltrombopag in SAA require further evaluation, particularly when it is used with less intensive immunosuppression.

Effects of Designer Hyper-Interleukin 11 (H11) on Hematopoiesis in Myelosuppressed Mice

The incidence of cancer is constantly increasing. Chemo/radiotherapy is one of major methods of treating cancer. Although adverse chemo/radiotherapy events, such as anemia and neutropenia, can be successfully cured, thrombocytopenia is still problematic. We constructed the Hyper-IL11 (H11) cytokine by linking soluble interleukin 11 receptor alpha (sIL-11Ralpha) with IL-11. In vivo H11 activity was examined in myelosuppressed mice. Myelosuppression was induced by either i) sublethal irradiation and carboplatin administration or ii) sublethal irradiation. A dose of 100 μg/kg of H11 or IL-11 was administered subcutaneously for 7 days. IL-11 and H11 accelerated leukocyte, hematocrit and platelet recovery. The effect on the attenuation of thrombocytopenia was significant. Moreover, both cytokines increased the cellularity and numbers of megakaryocyte, erythroid, and granulocyte/macrophage progenitors in the bone morrow and spleen compared with the control. Although H11 was administered at a molar concentration that was three times lower, its effects were comparable with or better than those of IL-11; thus, the activity of H11 was superior to that of IL-11. Because no toxicity was observed after the intravenous administration of H11, this hyper-cytokine may be potentially useful for treatment of thrombocytopenia and other IL-11-dependent disorders.

Safety and tolerability of eltrombopag versus placebo for treatment of thrombocytopenia in patients with advanced myelodysplastic syndromes or acute myeloid leukaemia: a multicentre, randomised, placebo-controlled, double-blind, phase 1/2 trial

BACKGROUND

Patients with myelodysplastic syndrome or acute myeloid leukaemia who are thrombocytopenic and unable to receive disease-modifying therapy have few treatment options. Platelet transfusions provide transient benefit and are limited by alloimmunisation. Eltrombopag, an oral thrombopoietin receptor agonist, increases platelet counts and has preclinical antileukaemic activity. We aimed to assess the safety and tolerability of eltrombopag for the treatment of thrombocytopenia in adult patients with advanced myelodysplastic syndrome, secondary acute myeloid leukaemia after myelodysplastic syndrome, or de-novo acute myeloid leukaemia.

METHODS

We did this multicentre, randomised, placebo-controlled, double-blind, phase 1/2 trial at 37 centres in ten countries in Europe, east Asia, and the Americas. Patients aged 18 years or older who had relapsed or refractory disease or were ineligible for standard treatments; had platelet counts of less than 30 × 10(9) platelets per L; had 10-50% bone-marrow blasts; or were platelet transfusion dependent were randomly assigned (2:1), via a telephone-based interactive voice-response system (GlaxoSmithKline Registration and Medication Ordering System) with a permuted-block randomisation schedule (block size of three), to receive once-daily eltrombopag or matching placebo dose adjusted from 50 mg to a maximum dose of 300 mg. Randomisation was stratified by presence of poor-prognosis (complex) karyotype (presence of at least three abnormalities, or chromosome 7 abnormalities, vs absence) and bone-marrow blast count (<20% vs ≥20%). Patients and study personnel were masked to treatment allocation. The primary endpoint was safety and tolerability, including adverse events, non-haematological laboratory grade 3-4 toxic effects, and changes in bone-marrow blast counts from baseline. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCT00903422.

FINDINGS

Between May 14, 2009, and May 9, 2013, we randomly assigned 98 patients to receive either eltrombopag (n=64) or placebo (n=34). 63 (98%) patients in the eltrombopag group and 32 (94%) patients in the placebo group had adverse events. The most common adverse events were pyrexia (27 [42%] vs 11 [32%]), nausea (20 [31%] vs 7 [21%]), diarrhoea (19 [30%] vs 6 [18%]), fatigue (16 [25%] vs 6 [18%]), decreased appetite (15 [23%] vs 5 [15%]), and pneumonia (14 [22%] vs 8 [24%]). Drug-related adverse events of grade 3 or higher were reported in six (9%) patients in the eltrombopag group and four (12%) patients in the placebo group. Increases in the proportion of peripheral blasts did not differ significantly between groups. Haemorrhage of grade 3 or higher was reported in ten (16%) patients given eltrombopag and nine (26%) patients given placebo. 21 (33%) patients receiving eltrombopag and 16 (47%) patients receiving placebo died while on treatment. No deaths in patients receiving eltrombopag and two deaths in patients receiving placebo were regarded as treatment related. Post-baseline bone-marrow examinations were done in 40 (63%) patients in the eltrombopag group and 17 (50%) patients in the placebo group. The most common reason for no examination was death before the scheduled 3 month assessment. There were no differences between median bone-marrow blast counts or proportions of peripheral blasts between groups.

INTERPRETATION

Eltrombopag doses up to 300 mg daily had an acceptable safety profile in patients with advanced myelodysplastic syndrome or acute myeloid leukaemia. The role of eltrombopag in these patients warrants further investigation.

FUNDING

GlaxoSmithKline.

Thrombocytopenia in cancer patients

Thrombocytopenia is a frequent complication of cancer and its treatment. The causes of thrombocytopenia in cancer patients can be diverse and multifactorial. Systemic chemotherapy is the most frequent cause of thrombocytopenia. The degree and duration thrombocytopenia depends upon whether the chemotherapeutic treatment is myeloablative, as used in stem cell transplants, or non-myeloablative, as typically used in solid non-hematologic malignancies. Additional causes of significant thrombocytopenia include tumor involvement of bone marrow and spleen; microangiopathic disorders such as disseminated intravascular coagulation, thrombotic thrombocytopenic purpura or hemolytic uremia syndrome. Lymphoproliferative malignancies can also be associated with secondary immune thrombocytopenia. Due to the broad differential diagnosis associated with cancer related thrombocytopenia, a careful diagnostic evaluation is indicated. The goal of treatment should be to maintain a safe platelet count to allow effective treatment of the underlying malignancy, prevent bleeding complications and to minimize the use of platelet product transfusion.

Safety and Efficacy of Eltrombopag in Post-hematopoietic Stem Cell Transplantation (HSCT) Thrombocytopenia

Twelve adult patients (median age 29.5 years) were started on Eltrombopag 25-50 mg/day for post-hematopoietic stem cell transplantation (HSCT) thrombocytopenia. All patients were having primary thrombocytopenia after HSCT. No patient had other secondary cause for thrombocytopenia. Two patients were allogenic subsets (1 acute myeloid leukemia i.e., AML and 1 aplastic anemia), and 10 were autologous transplants (3 multiple myeloma, 6 lymphoma and 1 AML). Nine patients were males, three were females. The median time of starting Eltrombopag was 21 days post-stem cell infusion (range day +17 to +60) at a median platelet count of 9,000/cmm (range 3,000-11,000/cmm). The median duration for treatment was 29 days. Median total dose of 812.5 mg was received by patients and they had a median platelet increment of 36,000/cmm. We observed that there were no adverse effects in these patients and there was a gradual increase in platelet count so that none of the patients had any complication due to thrombocytopenia. The cost of treatment was less than the cost of extended hospitalization and irradiated single donor platelet transfusion.

Modeling and simulation support eltrombopag dosing in thrombocytopenic patients with chronic HCV infection

PURPOSE

The pharmacokinetics of eltrombopag and its stimulation of platelet production were characterized in patients with chronic hepatitis C virus (HCV) infection to optimize an eltrombopag dosing regimen for treatment of HCV-related thrombocytopenia before and throughout peginterferon (pegIFN)-based antiviral therapy.

METHODS

Population pharmacokinetic analysis for eltrombopag included 663 individuals (healthy subjects, n = 28; patients with HCV, n = 635). Population pharmacokinetic/pharmacodynamic analysis for platelet response involved patients with HCV only. Simulations were conducted using various dosing scenarios in the same patient population.

RESULTS

Eltrombopag pharmacokinetics were described by a two-compartment model with dual sequential first-order absorption and elimination. Age, race, sex, and severity of hepatic impairment were predictors of eltrombopag clearance. The effect of eltrombopag on platelet counts was adequately described by a model with four transit compartments in which eltrombopag concentrations stimulated the production rate of platelet precursors in an Emax manner.

CONCLUSIONS

Modeling and simulation results support once-daily eltrombopag 25 mg as an appropriate starting dosing regimen followed by biweekly dose escalation (in 25-mg increments) up to once-daily eltrombopag 100 mg to raise platelet counts sufficiently for initiation of pegIFN-based antiviral therapy in patients with HCV. Biweekly dose adjustment allows patients to stay on the lowest possible eltrombopag dose during antiviral therapy.

Eltrombopag with gemcitabine-based chemotherapy in patients with advanced solid tumors: a randomized phase I study

Preventing chemotherapy-induced thrombocytopenia could avoid chemotherapy dose reductions and delays. The safety and maximum tolerated dose of eltrombopag, an oral thrombopoietin receptor agonist, with gemcitabine-based therapy was evaluated. Patients with advanced solid tumors and platelets ≤300 × 10⁹/L receiving gemcitabine plus cisplatin or carboplatin (Group A) or gemcitabine monotherapy (Group B) were randomized 3:1 to receive eltrombopag or placebo at a starting dose of 100 mg daily administered on days −5 to −1 and days 2–6 starting from cycle 2 of treatment. Nineteen patients (Group A, n = 9; Group B, n = 10) received eltrombopag 100 mg and seven (Group A, n = 3; Group B, n = 4) received matching placebo. Nine eltrombopag patients in Group A and eight in Group B had 38 and 54 occurrences of platelet counts ≥400 × 10⁹/L, respectively. Mean platelet nadirs across cycles 2–6 were 115 × 10⁹/L and 143 × 10⁹/L for eltrombopag-treated patients versus 53 × 10⁹/L and 103 × 10⁹/L for placebo-treated patients in Groups A and B, respectively. No dose-limiting toxicities were reported for eltrombopag; however, due to several occurrences of thrombocytosis, a decision was made not to dose-escalate eltrombopag to >100 mg daily. In Groups A and B, 14% of eltrombopag versus 50% of placebo patients required chemotherapy dose reductions and/or delays for any reason across cycles 3–6. Eltrombopag 100 mg once daily administered 5 days before and after day 1 of chemotherapy was well tolerated with an acceptable safety profile, and will be further tested in a phase II trial. Fewer patients receiving eltrombopag required chemotherapy dose delays and/or reductions compared with those receiving placebo.

Usefulness of short-term eltrombopag treatment as a supportive treatment in hepatocellular carcinoma patients with cirrhosis and severe thrombocytopenia: A report of two cases

Eltrombopag is an oral thrombopoietin (TPO) receptor agonist that increases platelet counts in patients with idiopathic thrombocytopenic purpura and in patients with liver cirrhosis. When cirrhotic patients with thrombocytopenia undergo elective invasive procedures, eltrombopag treatment reduces the requirement for platelet transfusions. However, TPO is known to have proliferative effects on hepatic progenitor cells and hepatic sinusoidal endothelial cells, which indicates that eltrombopag may accelerate tumor progression. Thus, the effect of eltrombopag on hepatocellular carcinoma (HCC) progression is an important issue. The current study describes two cases of HCC with cirrhosis-related thrombocytopenia. A two-week administration of eltrombopag increased platelet counts from 4.8 to 11.3×10⁴ /μl in case 1 and 4.5 to 23.2×10⁴ /μl in case 2. However, no changes were identified in the serum levels of tumor markers or HCC size following eltrombopag administration in the two cases. These HCCs were curatively treated by radiofrequency ablation without platelet transfusions or serious bleeding. Thus, short-term eltrombopag administration may not accelerate HCC proliferation and may be beneficial for invasive HCC treatment in cirrhotic patients with thrombocytopenia.

Population PK/PD modeling of eltrombopag in subjects with advanced solid tumors with chemotherapy-induced thrombocytopenia

PURPOSE

Eltrombopag, a thrombopoietin receptor agonist, is being evaluated for the treatment of chemotherapy-induced thrombocytopenia. Due to the delay in platelet response after the administration of eltrombopag or chemotherapy, a modeling and simulation approach was used to optimize the eltrombopag dosing regimen.

METHODS

Pharmacokinetic (PK) data from 2 studies in healthy subjects and PK and platelet data from a Phase II study in subjects with cancer receiving carboplatin/paclitaxel (where eltrombopag was given 10 days after chemotherapy) were used to develop a nonlinear mixed-effects PK/PD model. Alternative eltrombopag dosing regimens were then simulated.

RESULTS

The PK model was a linear two-compartment model with first-order absorption. Being Asian, female, and >50 years of age were associated with higher eltrombopag exposure. The time course of platelet counts was described by a four-compartment transit model. Carboplatin inhibited platelet precursor production linearly with dose, with increased effect with each cycle of chemotherapy. Eltrombopag stimulated platelet precursor production, proportional to plasma eltrombopag concentration, and stimulation (slope of the concentration effect) was attenuated with each cycle of chemotherapy.

CONCLUSIONS

Simulations indicated that eltrombopag administered 5 days before and 5 days after chemotherapy minimizes the decrease and fluctuations in platelet counts relative to other evaluated dosing regimens.