Phase II study of avatrombopag in thrombocytopenic patients with cirrhosis undergoing an elective procedure

Thromboelastography-Guided versus Standard-of-Care or On-Demand Platelet Transfusion in Patients with Cirrhosis and Thrombocytopenia Undergoing Procedures: A Randomized Controlled Trial

PURPOSE

To determine the rate of platelet transfusion in patients with cirrhosis and severe thrombocytopenia (platelet counts <50 × 109/L) undergoing high-risk invasive procedures when prescribed by thromboelastography (TEG) compared with empirical and on-demand transfusion strategies.

MATERIALS AND METHODS

This was a single-center, single-blinded, randomized controlled trial. Patients with cirrhosis and severe thrombocytopenia undergoing high-risk invasive procedures were randomized into 3 groups: TEG group, transfusions based on TEG parameters; standard of care (SOC) group, 3 units of random donor platelets before procedure; and on-demand group, transfusions based on procedural adverse events/clinician's discretion. The primary outcome was periprocedural platelet transfusion in each arm.

RESULTS

Eighty-seven patients were randomized (29 in each group) with no significant differences in demographics/coagulation profile/procedures. The median platelet count was 33 × 109/L (interquartile range, 26-43 × 109/L). Percutaneous liver biopsy was the most common procedure (46, 52.9%). Significantly lower number of patients in the TEG group received platelets (4 cases, 13.8%; 95% CI, 3.9-31.7) compared with SOC group (100%; 95% CI, 88.1-100; P < .001). Four patients in the on-demand group received platelets (13.8%; 95% CI, 3.9-31.7). Minor (World Health Organization [WHO] Grade 2) procedure-related bleeding occurred in 3 (10%; 95% CI, 2.2-27.4) patients in the TEG-guided transfusion group compared with 1 (3.4%; 95% CI, 0.1-17.8) patient each in the SOC and on-demand groups (P = .43), although the study was not powered for comparison of bleeding rates. No bleeding-related mortality was observed in any of the 3 groups.

CONCLUSIONS

TEG-prescribed transfusion reduced prophylactic transfusions in patients with cirrhosis and severe thrombocytopenia undergoing high-risk invasive procedures.

Efficacy and safety of avatrombopag in combination with immunosuppressive therapy in treatment-naïve and relapsed/refractory severe aplastic anaemia: protocol for the DIAAMOND-Ava-FIRST and DIAAMOND-Ava-NEXT Bayesian Optimal Phase II trials

INTRODUCTION

Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and ciclosporin is standard of care for patients with severe aplastic anaemia (sAA) not eligible or suitable for allogeneic stem cell transplant. While patients respond to IST, few achieve complete responses and a significant proportion are refractory or relapse. The addition of eltrombopag, a thrombopoietin-receptor agonist (TPO-A), to IST has been shown to improve haematological responses in sAA. Avatrombopag is a second-generation TPO-A with potential advantages over eltrombopag. However, to date avatrombopag has not been studied in sAA.

METHODS AND ANALYSIS

Investigator-initiated, single-arm registry-based Bayesian Optimal Phase II trial of avatrombopag conducted in two cohorts, patients with untreated sAA (FIRST cohort) and in patients with sAA that has relapsed or is refractory to IST (NEXT cohort). In the FIRST cohort, participants receive IST (equine ATG and ciclosporin) plus avatrombopag from day 1 until day 180 at 60 mg oral daily, with dose adjusted according to platelet count. Participants in the NEXT cohort receive avatrombopag at 60 mg oral daily from day 1 until day 180, with or without additional IST at the discretion of the treating clinician.For each cohort, two primary endpoints (haematological response and acquired clonal evolution) are jointly monitored and the trial reviewed at each interim analysis where a 'go/no-go' decision is made by evaluating the posterior probability of the events of interests.

ETHICS AND DISSEMINATION

The trial has received ethics approval (Monash Health RES-18-0000707A). The trial conduct will comply with ICH-GCP and all applicable regulatory requirements. The results of the trial will be submitted to a peer-review journal for publication.

TRIAL REGISTRATION NUMBER

ACTRN12619001042134, ACTRN12619001043123.

Cost-Effectiveness of Thrombopoietin Mimetics in Patients with Thrombocytopenia: A Systematic Review

OBJECTIVES

Thrombopoietin (TPO) mimetics are a potential alternative to platelet transfusion to minimize blood loss in patients with thrombocytopenia. This systematic review aimed to evaluate the cost-effectiveness of TPO mimetics, compared with not using TPO mimetics, in adult patients with thrombocytopenia.

METHODS

Eight databases and registries were searched for full economic evaluations (EEs) and randomized controlled trials (RCTs). Incremental cost-effectiveness ratios (ICERs) were synthesized as cost per quality-adjusted life year gained (QALY) or as cost per health outcome (e.g. bleeding event avoided). Included studies were critically appraised using the Philips reporting checklist.

RESULTS

Eighteen evaluations from nine different countries were included, evaluating the cost-effectiveness of TPO mimetics compared with no TPO, watch-and-rescue therapy, the standard of care, rituximab, splenectomy or platelet transfusion. ICERs varied from a dominant strategy (i.e. cost-saving and more effective), to an incremental cost per QALY/health outcome of EUR 25,000-50,000, EUR 75,000-750,000 and EUR > 1 million, to a dominated strategy (cost-increasing and less effective). Few evaluations (n = 2, 10%) addressed the four principal types of uncertainty (methodological, structural, heterogeneity and parameter). Parameter uncertainty was most frequently reported (80%), followed by heterogeneity (45%), structural uncertainty (43%) and methodological uncertainty (28%).

CONCLUSIONS

Cost-effectiveness of TPO mimetics in adult patients with thrombocytopenia ranged from a dominant strategy to a significant incremental cost per QALY/health outcome or a strategy that is clinically inferior and has increased costs. Future validation and tackling the uncertainty of these models with country-specific cost data and up-to-date efficacy and safety data are needed to increase the generalizability.

Use of thrombopoietin receptor agonists in adults with immune thrombocytopenia: a systematic review and Central European expert consensus

There are currently three thrombopoietin receptor agonists (TPO-RAs) approved in Europe for treating patients with immune thrombocytopenia (ITP): romiplostim (Nplate®), eltrombopag (Revolade®), and avatrombopag (Doptelet®). However, comparative clinical data between these TPO-RAs are limited. Therefore, the purpose of this study was to perform a literature review and seek expert opinion on the relevance and strength of the evidence concerning the use of TPO-RAs in adults with ITP. A systematic search was conducted in PubMed and Embase within the last 10 years and until June 20, 2022. A total of 478 unique articles were retrieved and reviewed for relevance. The expert consensus panel comprised ITP senior hematologists from eight countries across Central Europe. The modified Delphi method, consisting of two survey rounds, a teleconference and email correspondence, was used to reach consensus. Forty articles met the relevancy criteria and are included as supporting evidence, including five meta-analyses analyzing all three European-licensed TPO-RAs and comprising a total of 31 unique randomized controlled trials (RCTs). Consensus was reached on seven statements for the second-line use of TPO-RAs in the management of adult ITP patients. In addition, the expert panel discussed TPO-RA treatment in chronic ITP patients with mild/moderate COVID-19 and ITP patients in the first-line setting but failed to reach consensus. This work will facilitate informed decision-making for healthcare providers treating adult ITP patients with TPO-RAs. However, further studies are needed on the use of TPO-RAs in the first-line setting and specific patient populations.

Avatrombopag is effective in patients with chemoradiotherapy-induced aplastic anemia: a single-center, retrospective study

Aplastic anemia (AA) secondary to radiotherapy presents a difficult situation in the treatment of both the malignant tumor and AA itself. We aimed to evaluate the efficacy of avatrombopag (AVA), a thrombopoietin receptor agonist, in patients with AA secondary to chemoradiotherapy. In this retrospective study, patients with malignant tumors who were diagnosed with AA after radiotherapy and chemotherapy and accepted AVA between September 2020 and October 2021 at Peking Union Medical College Hospital were selected. A total of 34 patients were enrolled, including 13 (38.2%) men, with a median age of 60 (20-71) years. At a median of 8 (6-18) months of follow-up, the overall response rates (ORRs) at 1, 3, and 6 months were 32.4%, 55.9%, and 58.8%, respectively, and the complete response rates (CRRs) were 5.9%, 14.7%, and 23.5%, respectively. The median time to respond was 3 (1-6) months. In total, 15.0% of patients relapsed during follow-up, but no clonal evolution was noticed. Mild side effects were observed in 17.6% of patients without drug withdrawal. At the end of follow-up, 17.6% of patients had tumors relapsed. Four patients died, three from tumor relapse and one from cerebral hemorrhage. The ORR and CRR did not correlate with eltrombopag before AVA (p > 0.05) but increased when the total exposure of AVA increased (p = 0.011), and the threshold for AVA response was a cumulative dose > 3,000 mg (p = 0.013). AVA yielded good response and tolerance in patients treated for AA secondary to chemoradiotherapy, and a higher dose may correlate with better response.

Effectiveness and Safety of Avatrombopag in Liver Cancer Patients with Severe Thrombocytopenia: Real-World Data and Challenges

Background

Avatrombopag has been approved in patients who have severe thrombocytopenia (<50 × 10⁹/L) and chronic liver disease (CLD) while receiving invasive procedures. The real-world application and effectiveness of avatrombopag in the subgroup patients with liver cancer remain unknown.

Methods

Liver cancer patients (including primary liver cancer and colorectal cancer liver metastasis) who had severe thrombocytopenia and received avatrombopag were retrospectively enrolled. Avatrombopag dose, peak and absolute platelet count increase, combination treatment with other thrombopoietic agents, responder (peak count ≥50 × 10⁹/L with absolute increase ≥20 × 10⁹/L) rate, and anticancer treatment effect were analyzed. Thrombosis and bleeding events were assessed.

Results

In total, 93 patients were enrolled, with 72 and 21 in the CLD and non-CLD groups, respectively. Patients with CLD had hepatitis B or C, larger spleen volume, and a higher cirrhosis degree. Baseline platelet counts were similar between two groups (median, 37.0 × 10⁹/L vs. 39.0 × 10⁹/L; P=0.594), while patients without CLD had higher peak platelet (median, 134.0 × 10⁹/L vs. 74.0 × 10⁹/L; P=0.015) and absolute increase (median, 101.0 × 10⁹/L vs. 41.0 × 10⁹/L; P=0.020) after avatrombopag treatment. The responder rate was higher in patients without CLD (100% vs. 76.4%; P=0.010). Combined avatrombopag with other thrombopoietic agents significantly increased platelet count; repeated use of avatrombopag produced similar effects with that of initial treatment. Concerning anticancer treatment effect, patients who responded to avatrombopag had a higher disease control rate. No thrombosis or hemorrhagic events were observed, even in patients with portal vein tumor thrombosis.

Conclusion

Avatrombopag was safe and effective and ensured successful implementation of anticancer treatment in liver cancer patients with severe thrombocytopenia, accompanied with or without CLD.

Preprocedural prophylaxis with blood products in patients with cirrhosis: Results from a survey of the Italian Association for the Study of the Liver (AISF)

INTRODUCTION

The concept of rebalanced hemostasis in cirrhosis challenges the policy of transfusing plasma or platelets before invasive procedures in patients with prolonged PT or severe thrombocytopenia. Recent guidelines recommend against plasma transfusion and suggest avoiding/minimizing platelet transfusions.

AIM

We assessed how hepato-gastroenterologists manage prolonged PT/INR or severe thrombocytopenia before invasive procedures.

METHODS

On May 2021, AISF members were sent a questionnaire addressing the PT/INR and platelet thresholds required before invasive procedures, the use of other markers of bleeding risk or other hemostatic treatments and the burden of pre-emptive plasma and platelet transfusions.

RESULTS

Of 62 respondents, 94% and 100% use PT/INR and platelet count to assess bleeding risk, respectively. Only 37% and 32% require less conservative PT/INR or platelet counts thresholds for low-risk procedures, respectively. As for those applying single thresholds, 68% require PT/INR <1,5 and 86% require platelet counts ≥50 × 10⁹/L. Half respondents use additional indicators of bleeding risk and 63% other hemostatic treatments. Low-risk procedures account for 70% of procedures, and for 50% and 59% of plasma and platelets units transfused, respectively.

CONCLUSIONS

the survey indicates lack of compliance with guidelines that advise against plasma and platelet transfusions before invasive procedures and the need for prospective studies and inter-society consensus workshops.

Clinical efficacy of avatrombopag and recombinant human thrombopoietin in the treatment of chronic liver disease-associated severe thrombocytopenia: A real-world study

Purpose: To investigate the clinical efficacy of avatrombopag, an oral thrombopoietin receptor agonist, versus subcutaneous recombinant human thrombopoietin (rh-TPO) in the treatment of severe thrombocytopenia (TCP) associated with chronic liver disease (CLD).

Methods: Clinical data of 250 patients with severe TCP associated with CLD were collected in a single hospital from January 2019 to January 2022. The main parameters measured were the therapeutic response rate, changes in platelets (PLTs), and adverse events. Propensity score matching (PSM) was used to avoid possible selection bias.

Results: After PSM, a total of 154 patients were enrolled in the study: 77 in the avatrombopag group and 77 in the rh-TPO group. There was no statistically significant difference between the two groups in the effect of increasing the PLT count (Waldχ2 = 1.659, p = 0.198; Waldχ2 = 0.220, p = 0.639). In addition, no interaction between time and different medications was found (Waldχ2 = 0.540, p = 0.910; Waldχ2 = 1.273, p = 0.736). Interestingly, in the subgroup analysis, both before and after PSM, avatrombopag showed better clinical efficacy than rh-TPO in the treatment of TCP associated with CLD in Child‒Pugh Class A (88.89% vs. 63.41%, p =0.003; 81.33% vs. 61.76%, p = 0.043). Fewer patients reported dizziness in the avatrombopag group than in the rh-TPO group both before and after PSM (7.8% vs. 25.0%; 7.8% vs. 24.7%, p &lt; 0.05).

Conclusion: Both before and after PSM, avatrombopag showed better clinical efficacy than rh-TPO in the treatment of TCP associated with CLD in Child‒Pugh Class A and showed a lower incidence of dizziness in all patients.

Generation of a thrombopoietin-deficient thrombocytopenia model in zebrafish

BACKGROUND

The production of platelets is tightly regulated by thrombopoietin (THPO). Mutations in the THPO gene cause thrombocytopenia. Although mice lacking Thpo present with thrombocytopenia, predicting phenotypes and pathogenicity of novel THPO mutations in mice is limited. Zebrafish can be a powerful tool for fast validation and study of candidate genes of human hematological diseases and have already been used as a model of human thrombocytopenia.

OBJECTIVES

We aim to investigate the role of Thpo in zebrafish thrombopoiesis and to establish a Thpo-deficient zebrafish model. The model could be applied for illustrating the clinically discovered human THPO variants of which the clinical significance is not known and to evaluate the effect of THPO receptor agonists (THPO-Ras), as well as a screening platform for new drugs.

METHODS

We generated a thpo loss-of-function zebrafish model using CRISPR/Cas9. After disruption of zebrafish thpo, thposzy6 zebrafish presented with a significant reduction of thpo expression and developed thrombocytopenia. Furthermore, we performed in vivo studies with zebrafish with the thposzy6 mutation and found two human clinical point mutations (c.091C > T and c.112C > T) that were responsible for the thrombocytopenia phenotype. In addition, effects of THPO-RAs used as therapeutics against thrombocytopenia were evaluated in the Tg(mpl:eGFP);thposzy6 line.

RESULTS AND CONCLUSIONS

Zebrafish with the mutation thposzy6 presented with a significant reduction of thpo expression and developed thrombocytopenia. Thpo loss-of-function zebrafish model can serve as a valuable preclinical model for thrombocytopenia caused by thpo-deficiency, as well as a tool to study human clinical THPO variants and evaluate the effect of THPO-RAs.

Avatrombopag ethnic sensitivity analysis in chronic liver disease and thrombocytopenia patients: individual-level pooled analysis

INTRODUCTION

Few data have been published on the ethnic sensitivity of effectiveness, pharmacokinetics (PK), and pharmacodynamics (PD) of avatrombopag for the management of thrombocytopenia in patients with chronic liver disease (CLD).

METHODS

An ethnic sensitivity analysis was performed based on the results from two phase III studies (ADAPT-1 and ADAPT-2), with a primary endpoint of the proportion of patients without the requirement of platelet transfusion or rescue treatment for bleeding after randomization to 7 days following a scheduled procedure, and three phase I studies in healthy subjects. Cochran-Mantel-Haenszel and Fisher's exact tests were used to compare the differences in effectiveness in different ethnicities and overall population.

RESULTS

In total, 435 patients (placebo, n = 158; avatrombopag, n = 277) were stratified into various ethnic groups: 121 East Asians, including the subgroup of 27 Chinese, and 259 Caucasians. The proportion of patients who did not receive a platelet transfusion and those with a platelet count ⩾50 × 10⁹/L in the avatrombopag 40 and 60 mg groups were higher than that of placebo for all ethnicities and in the overall population. Statistical significance was obtained in the overall population and for all ethnicities other than Chinese patients, a group with a very small sample size. No significant difference was observed in the proportion of responders in each ethnic group compared to overall population (p > 0.05). The incidence of adverse events in East Asians was similar to that in both Caucasians and the overall population.

CONCLUSION

Avatrombopag was effective and safe in the management of thrombocytopenia in Chinese patients with CLD. Ethnicity does not appear to influence the efficacy, safety, PK, or PD of avatrombopag.

Avatrombopag for the Treatment of Adult Patients with Chronic Immune Thrombocytopenia (cITP): Focus on Patient Selection and Perspectives

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a reduced number of circulating platelets due to immune-mediated destruction and decreased platelet production in the bone marrow. Thrombopoietin receptor agonists (TPO-RAs) are highly effective and widely used in the treatment of patients with steroid treatment failure or dependency. Avatrombopag represents a new supplement to the TPO-RAs family. It was originally approved for the treatment of thrombocytopenia in patients with chronic liver disease who are scheduled to undergo an invasive procedure. However, labeled indications for avatrombopag have been relatively recently expanded to include treatment of chronic ITP in adults with insufficient response to the previous treatments. In this article, we provide an overview of pharmacodynamics and pharmacokinetics of avatrombopag as well as results of the clinical trials related to safety and efficacy of avatrombopag with a perspective on current clinical use. Available data so far suggests that avatrombopag can be effectively used in ITP patients and has a favorable safety profile. Though further studies are needed to affirm the efficacy and safety, avatrombopag has the potential to become a TPO agonist of choice for many patients with ITP.

Cirrhosis and Coagulopathy: Mechanisms of Hemostasis Changes in Liver Failure and Their Management

Cirrhosis is an end-stage liver disease that can cause changes in any component of the hemostatic system. The net effects of the complicated hemostatic changes have long been unknown due to concurrent changes in pro-and antihemostatic drivers. Coagulation disorders are caused by various factors, including decreased clotting and inhibitor factor synthesis, reduced clearance of activated factors, quantitative and qualitative platelet defects, hyperfibrinolysis, and increased intravascular coagulation. This review discusses the pathogenesis of coagulopathy and multiple studies related to its clinical presentations. This article also highlights an additional problem in the diagnostic and therapeutic approach to this group of patients: the fact that traditional coagulation tests and transfusional strategies may not be reliable for assessing and managing bleeding or thrombotic risks. Hence, multiple management options have been assessed for bleeding and thrombosis in liver disease.

Phase 2 study of avatrombopag in Japanese patients with chronic liver disease and thrombocytopenia

AIM

Avatrombopag, a thrombopoietin receptor agonist, can reduce the need for platelet transfusions or rescue interventions for bleeding in patients with chronic liver disease (CLD) and thrombocytopenia undergoing scheduled procedures. A model analysis indicated that the effect of avatrombopag on platelet production was reduced in East Asian versus non-East Asian patients; however, the difference was deemed not clinically significant. Furthermore, a subgroup analysis of pooled Phase 3 trials showed similar avatrombopag efficacy across racial subgroups. The aim of this Phase 2 study was to corroborate the efficacy and safety of avatrombopag in Japanese patients with thrombocytopenia due to CLD.

METHODS

Japanese patients with CLD and thrombocytopenia were randomized to receive placebo or avatrombopag 20, 40, or 60 mg daily for 5 days. The primary endpoint was responder rate in platelet counts at Visit 4 (10-13 days after treatment initiation), defined as the proportion of patients with platelet count ≥50 × 10⁹ /L and ≥20 × 10⁹ /L increase from baseline.

RESULTS

Thirty-nine patients were randomized and completed the study (placebo, n = 11; avatrombopag 20 mg, n = 7; 40 mg, n = 11; 60 mg, n = 10). Avatrombopag treatment was associated with significant increases in responder rate at Visit 4 in the 40 mg (63.6%; p = 0.004) and 60 mg (40%; p = 0.024) groups versus placebo (9.1%). Avatrombopag was well tolerated and no new safety signals were detected.

CONCLUSIONS

Efficacy and safety results from this study were consistent with previous studies in patients with CLD and thrombocytopenia undergoing elective procedures, supporting treatment with avatrombopag in the Japanese population.

CLINICALTRIALS

gov identifier: NCT02227693.

The efficacy and safety of thrombopoietin receptor agonists in patients with chronic liver disease undergoing elective procedures: a systematic review and meta-analysis

Thrombopoietin receptor agonists (TPO-RAs) can mitigate preprocedural thrombocytopenia in patients with chronic liver disease (CLD) however their effects on procedural outcomes is unclear. In this meta-analysis, we aimed to better define the efficacy, thrombotic risk and bleeding mitigation associated with the use of preoperative TPO-RAs in patients with CLD. We performed a systematic review and meta-analysis of randomized placebo-controlled clinical trials to assess the use of preprocedural TPO-RAs in patients with CLD, searching MEDLINE, EMBASE and the Cochrane library database. Six publications comprising eight randomized trials (1229 patients; 717 received TPO-RAs, 512 received placebo) and three unique TPO-RAs were retrieved. The majority of the included procedures were endoscopic. TPO-RAs were significantly more likely to result in a preoperative platelet count greater than 50 x 109/L (72.1% vs 15.6%, RR 4.8, 95% CI 3.6-6.4 p < .00001. NNT 1.8) and reduced the incidence of platelet transfusions (22.5% vs 67.8%, RR 0.33, 95% CI 0.3-0.4 p < .00001. NNT 2.2). Total periprocedural bleeding was decreased in patients who received TPO-RAs (11.6% vs 15.6%, RR 0.64, 95% CI 0.5-0.9 p = .01. NNT 24.7) and there was no increase in the rate of thrombosis (2.2% vs 1.8% RR 1.25, 95% CI 0.6-2.9 p = .60. NNH 211.1). In patients with CLD the use of preprocedural TPO-RAs resulted in significant increased platelet counts, and decreased the incidence of platelet transfusions as compared to placebo. TPO use likewise decreased the incidence of total periprocedural bleeding without increasing the rate of thrombosis.

Treatment algorithm for thrombocytopenia in patients with chronic liver disease undergoing planned invasive procedures

Thrombocytopenia is highly prevalent in patients with chronic liver disease (CLD) and these patients often require invasive procedures that carry a risk of bleeding. To prevent bleeding, guidelines recommend increasing platelet counts in patients with CLD who have thrombocytopenia and are planned to undergo invasive procedures. There are currently two options to increase platelet counts in patients in this setting: platelet transfusion or thrombopoietin receptor agonists (TPORAs). Several treatment algorithms have been developed in the US to help physicians choose the best course of treatment for each patient; however, to date, no such algorithm has been proposed in other countries, where the choice of treatment has been based on each physician's judgment and experience. Here, we discuss the pathogenesis and treatment of thrombocytopenia in patients with CLD, we review and present current evidence of the efficacy of TPORAs for the treatment of thrombocytopenia in patients with CLD, and we present our expert opinion on a Japanese treatment algorithm for thrombocytopenia in patients with CLD who are planned to undergo invasive procedures. This algorithm aims to provide guidance for optimal decision making in the selection of TPORA therapy or platelet transfusion based on the latest evidence and according to actual clinical practice.

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.

Pre-procedural use of thrombopoietin-receptor agonists in cirrhosis and severe thrombocytopenia: A systematic review and meta-analysis

BACKGROUND

Severe thrombocytopenia in cirrhosis can preclude invasive procedures. Platelet transfusion is recommended if platelet count pre-procedure is potential alternative to platelet transfusion is thrombopoietin-receptor (TPO) agonists.

AIM

Evaluate TPO-agonist efficacy and safety in cirrhotic patients with severe thrombocytopenia undergoing invasive procedures.

METHODS

Randomized control trials (RCT) from electronic reference databases were searched from inception till December 2019. PRISMA guidelines were followed. Primary outcome was platelet transfusion avoidance. Secondary outcomes were weighted mean difference (WMD) in platelet count from baseline to pre-procedure and rates of major adverse events (AE). Pooled Odds Ratio (OR) were estimated using a random-effects model.

RESULTS

Six RCTs with 1,229 patients were included. All studies had low risk of bias. Compared with placebo, those treated with TPO-agonists had a pooled OR of 0.12(0.08-0.17), P<0.01 for platelet transfusion avoidance, and WMD in platelet count (x10 3 /µL) of 35.6(28.6-42.7), P<0.01. Major AE did not differ between groups [Pooled OR: 0.87(0.47-1.62), P=0.66].

CONCLUSION

Compared to placebo, TPO-agonists used in cirrhotic patients with severe thrombocytopenia prior to elective invasive procedures had 88% reduced odds of requiring peri-procedural platelet transfusion and increased platelet count pre-procedure, with no difference in AE rates.

Impact of Platelet Count on Perioperative Bleeding in Patients With Cirrhosis Undergoing Surgical Treatments of Liver Cancer

In patients with cirrhosis with severe thrombocytopenia (platelet count [PC] <50 × 10⁹/L) and undergoing invasive procedures, it is common clinical practice to increase the PC with platelet transfusions or thrombopoietin receptor agonists to reduce the risk of major periprocedural bleeding. The aim of our study was to investigate the association between native PC and perioperative bleeding in patients with cirrhosis undergoing surgical procedures for the treatment of hepatocellular carcinoma (HCC). We retrospectively evaluated 996 patients with cirrhosis between 1996 and 2018 who underwent surgical treatments of HCC by liver resection (LR) or radiofrequency ablation (RFA) without prophylactic platelet transfusions. Patients were allocated to the following three groups based on PC: high (>100 × 10⁹/L), intermediate (51‐100 × 10⁹/L), and low (≤50 × 10⁹/L). PC was also analyzed as a continuous covariate on multivariable analysis. The primary endpoint was major perioperative bleeding. The overall event rate of major perioperative bleeding was 8.9% and was not found to differ significantly between the high, intermediate, and low platelet groups (8.1% vs. 10.2% vs. 10.8%, P = 0.48). On multivariable analysis, greater age, aspartate aminotransferase, lower hemoglobin, and treatment with LR (vs. RFA) were found to be significant independent predictors of major perioperative bleeding, with associations with disease etiology and year of surgery also observed. After adjusting for these factors, the association between PC and major perioperative bleeding remained nonsignificant. Conclusion: Major perioperative bleeding was not significantly associated with PC in patients with cirrhosis undergoing surgical treatment of HCC, even when their PC was <50 × 10⁹/L. With the limit of a retrospective analysis, our data do not support the recommendation of increasing PC in patients with severe thrombocytopenia in order to decrease their perioperative bleeding risk.

Avatrombopag: A Review in Thrombocytopenia

Avatrombopag (Doptelet^®) is an orally administered second generation thrombopoietin receptor agonist (TPO-RA) approved for the treatment of primary chronic immune thrombocytopenia (ITP) in adult patients who are refractory or have an unsatisfactory response to other treatments, as well as for the treatment of thrombocytopenia in adult patients with chronic liver disease (CLD) scheduled to undergo an invasive procedure. In phase III studies, avatrombopag was associated with a significantly greater platelet response than placebo in patients with chronic ITP, and was superior to placebo in reducing the requirement for platelet transfusion or rescue procedures for bleeding caused by surgery in patients with CLD with a platelet count < 50 × 10⁹/L at baseline. Longer term data indicate that avatrombopag is associated with high durable response rates in ITP and may have corticosteroid-sparing effects. The drug was generally well tolerated in both indications. Avatrombopag thus represents a convenient and effective second-line treatment for patients with chronic ITP and can prevent bleeding events in patients with CLD scheduled to undergo a procedure, offering a useful alternative to other available treatments in both indications.

Avatrombopag (Doptelet^®) is an orally administered drug that mimics the natural compound (thrombopoietin) responsible for stimulating the production of platelets, an essential component of the clotting process that prevents excessive bleeding. Several conditions can cause reduced platelet levels (thrombocytopenia) to the point that intervention is needed to prevent excessive blood loss. Avatrombopag is approved for the treatment of primary chronic immune thrombocytopenia (ITP) and to prevent bleeding caused by surgery in patients with low platelet levels caused by chronic liver disease (CLD). Clinical trials in patients with ITP show that avatrombopag quickly increases platelet levels and that this increase is maintained in the longer term in many patients. Similarly, clinical trials in patients with low platelet levels because of CLD showed that giving avatrombopag prior to surgery reduced the need for platelet transfusions or rescue procedures for bleeding. Avatrombopag is thus a convenient and effective treatment for patients with chronic ITP and can prevent bleeding events in patients with CLD scheduled to undergo a procedure. In both indications avatrombopag offers a useful alternative to other available treatments.

Avatrombopag Use in Patient With Thromboembolic Risks Listed for Combined Coronary Artery Bypass Grafting and Liver Transplant: A Case Report

Thrombocytopenia commonly occurs in patients with advanced liver disease and can be a contraindication in patients needing combined coronary artery bypass grafting (CABG) and liver transplant (LT). Thrombopoietin receptor agonists, including avatrombopag, are part of a novel drug class and stimulate platelet production. Avatrombopag is indicated in the perioperative setting to avoid platelet transfusions, which carry several disadvantages. Avatrombopag was shown to be safe and effective in patients with chronic liver disease. This study describes the successful use of avatrombopag in a patient with thromboembolic risks in preparation for a combined CABG and LT. Larger clinical trials are necessary to validate our results.

Avatrombopag and lusutrombopag for thrombocytopenia in people with chronic liver disease needing an elective procedure: a systematic review and cost-effectiveness analysis

BACKGROUND

There have been no licensed treatment options in the UK for treating thrombocytopenia in people with chronic liver disease requiring surgery. Established management largely involves platelet transfusion prior to the procedure or as rescue therapy for bleeding due to the procedure.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of two thrombopoietin receptor agonists, avatrombopag (Doptelet^®; Dova Pharmaceuticals, Durham, NC, USA) and lusutrombopag (Mulpleta^®; Shionogi Inc., London, UK), in addition to established clinical management compared with established clinical management (no thrombopoietin receptor agonist) in the licensed populations.

DESIGN

Systematic review and cost-effectiveness analysis.

SETTING

Secondary care.

PARTICIPANTS

Severe thrombocytopenia (platelet count of < 50,000/µl) in people with chronic liver disease requiring surgery.

INTERVENTIONS

Lusutrombopag 3 mg and avatrombopag (60 mg if the baseline platelet count is < 40,000/µl and 40 mg if it is 40,000-< 50,000/µl).

MAIN OUTCOME MEASURES

Risk of platelet transfusion and rescue therapy or risk of rescue therapy only.

REVIEW METHODS

Systematic review including meta-analysis. English-language and non-English-language articles were obtained from several databases including MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials, all searched from inception to 29 May 2019.

ECONOMIC EVALUATION

Model-based cost-effectiveness analysis.

RESULTS

From a comprehensive search retrieving 11,305 records, six studies were included. Analysis showed that avatrombopag and lusutrombopag were superior to no thrombopoietin receptor agonist in avoiding both platelet transfusion and rescue therapy or rescue therapy only, and mostly with a statistically significant difference (i.e. 95% confidence intervals not overlapping the point of no difference). However, only avatrombopag seemed to be superior to no thrombopoietin receptor agonist in reducing the risk of rescue therapy, although far fewer patients in the lusutrombopag trials than in the avatrombopag trials received rescue therapy. When assessing the cost-effectiveness of lusutrombopag and avatrombopag, it was found that, despite the success of these in avoiding platelet transfusions prior to surgery, the additional long-term gain in quality-adjusted life-years was very small. No thrombopoietin receptor agonist was clearly cheaper than both lusutrombopag and avatrombopag, as the cost savings from avoiding platelet transfusions were more than offset by the drug cost. The probabilistic sensitivity analysis showed that, for all thresholds below £100,000, no thrombopoietin receptor agonist had 100% probability of being cost-effective.

LIMITATIONS

Some of the rescue therapy data for lusutrombopag were not available. There were inconsistencies in the avatrombopag data. From the cost-effectiveness point of view, there were several additional important gaps in the evidence required, including the lack of a price for avatrombopag.

CONCLUSIONS

Avatrombopag and lusutrombopag were superior to no thrombopoietin receptor agonist in avoiding both platelet transfusion and rescue therapy, but they were not cost-effective given the lack of benefit and increase in cost.

FUTURE WORK

A head-to-head trial is warranted.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019125311.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 51. See the NIHR Journals Library website for further project information.

The hemostatic and thrombotic complications of liver disease

Hepatic cirrhosis leads to numerous hematologic derangements resulting in a complex and tenuously rebalanced hemostatic milieu. The utility of common hematologic tests including the INR and aPTT in assessing hemostatic and thrombotic risk in patients with cirrhosis is limited, and consensus on transfusion thresholds and proper management of thrombotic complications continues to evolve. This review summarizes the pathophysiology of key derangements of hemostasis including those of platelets, von Willebrand factor, pro- and anticoagulation factors, and fibrin. Additionally, the pathogenesis, consequences, optimal management, and prevention of major thrombotic and bleeding complications in cirrhosis arte discussed.

Step by Step: Managing the Complications of Cirrhosis

According to the Centers for Disease Control and Prevention, chronic liver disease and cirrhosis is the 11th leading cause of death in the United States. Common causes of chronic liver disease include alcohol, viral hepatitis, and non-alcoholic steatohepatitis (NASH). Inflammation is a critical driver in the progression of liver disease to liver fibrosis and ultimately cirrhosis. While the severity of chronic liver disease extends over a continuum, the management is more easily differentiated between compensated and decompensated cirrhosis. In this review, we discuss pathophysiology, clinical features and management of common complications of liver cirrhosis based on literature review and the current clinical practice guidelines of the American Association for the Study of Liver Diseases (AASLD).

An evaluation of avatrombopag for the treatment of thrombocytopenia

Introduction: The thrombopoietin receptor agonists (TPO-RAs) are a class of drugs that have been FDA-approved for immune thrombocytopenia (ITP), periprocedural thrombocytopenia in patients with chronic liver disease (CLD), aplastic anemia, and thrombocytopenia associated with antiviral treatment of hepatitis C. Avatrombopag is a TPO-RA that is currently FDA-approved for ITP and periprocedural thrombocytopenia in patients with CLD and is currently undergoing evaluation for chemotherapy-induced thrombocytopenia (CIT) in an international phase III clinical trial. Areas covered: This paper summarizes the chemistry, pharmacodynamics, and pharmacokinetics of avatrombopag. In addition, the authors review the efficacy and safety of avatrombopag, covering clinical trials in patients with ITP and in patients with CLD scheduled to undergo a procedure. Expert opinion: Avatrombopag has demonstrated efficacy in patients with ITP. With its low side-effect burden, absence of hepatotoxicity, ease of use as an oral medication, and lack of food-drug interactions, avatrombopag is a favorable option for ITP, though there is a lack of long-term safety data. In periprocedural thrombocytopenia in patients with CLD, avatrombopag is comparable to lusutrombopag, another TPO-RA. Finally, the results of the study of avatrombopag in CIT are eagerly awaited, as there are no currently approved medications for this indication in the USA.

Cost- Effectiveness of Avatrombopag for the Treatment of Thrombocytopenia in Patients with Chronic Liver Disease

Background and Aim

Thrombocytopenia is common in people with chronic liver disease, who frequently undergo invasive procedures. To minimize the risk of bleeding, prophylactic platelet transfusions have traditionally been used but carry many risks. The aim of this study was to evaluate the cost-effectiveness of avatrombopag compared with platelet transfusion and lusutrombopag as a treatment for thrombocytopenia in adult patients with chronic liver disease scheduled to undergo a medical procedure.

Methods

A decision-tree model was developed from a US payer perspective to capture acute events observed in phase 3 global randomized controlled clinical trials and, to support exploratory analyses, potential longer-term complications resulting from a major bleed or thromboembolic event. Treatment costs were taken from publicly available data sources. The interventions were evaluated in the overall trial populations and in subpopulations with higher and lower baseline platelet counts. Results were presented as incremental cost per platelet transfusion avoided. One-way and probabilistic sensitivity analyses were conducted.

Results

In the overall population, avatrombopag reduced the need for platelet transfusions and produced cost-savings compared with platelet transfusion (80% fewer prophylactic platelet transfusions, $4250 lower costs) and lusutrombopag (42% fewer prophylactic platelet transfusions, $5819 lower costs). Similar results were seen in both the higher and lower platelet count subpopulations. The one-way and probabilistic sensitivity analyses found that the use of avatrombopag is cost-saving with the incremental cost-effectiveness ratio in quadrant IV (decreased costs, prophylactic platelet transfusions avoided).

Conclusion

The use of avatrombopag is expected to be cost-saving while reducing the need for prophylactic platelet transfusions compared with platelet transfusion and lusutrombopag.

Thrombocytopenia in Chronic Liver Disease: New Management Strategies

Thrombocytopenia is common in advanced liver disease, and such patients frequently need invasive procedures. Numerous mechanisms for thrombocytopenia exist, including splenic sequestration and reduction of levels of the platelet growth factor thrombopoietin. Traditionally, platelet transfusions have been used to increase platelet counts before elective procedures, usually to a threshold of greater than or equal to 50,000/μL, but levels vary by provider, procedure, and specific patient. Recently, the thrombopoietin receptor agonists avatrombopag and lusutrombopag were studied and found efficacious for increasing platelet count in the outpatient setting for select patients with advanced liver disease who need a procedure.

Management of Hepatic Coagulopathy in Bleeding and Nonbleeding Patients: An Evidence-Based Review

Patients with varying degrees of hepatic dysfunction often present with presumed bleeding diathesis based on interpretation of routine measures of coagulation (prothrombin time [PT], international normalized ratio [INR], and activated partial thromboplastin time). However, standard markers of coagulation do not reflect the actual bleeding risk in this population and may lead to inappropriate administration of hemostatic agents and blood products. The concept of "rebalanced hemostasis" explains both the risk of bleeding and clotting seen in patients with liver dysfunction. The role of pharmacologic agents and blood products for prevention of bleeding during high-risk procedures and treatment of clinically significant bleeding remains unclear. Viscoelastic measurements of the clotting cascade provide information about platelets, fibrinogen/fibrin polymerization, coagulation factors, and fibrinolysis that might better represent hemostasis in vivo and may better inform management strategies. Due to the paucity of available data, firm recommendations for the use of blood products and pharmacologic agents in patients with hepatic coagulopathies are lacking, and thus, these products should not be routinely administered. Traditional laboratory tests such as PT/INR should not be the sole determinant of potential interventions. Rather, clinicians should assess factors such as the severity of bleed or bleeding risk of the procedure, the patient's risk of thromboembolism, and the strength of available evidence for specific agents and blood products to guide decision-making.

Avatrombopag, an Alternate Treatment Option to Reduce Platelet Transfusions in Patients with Thrombocytopenia and Chronic Liver Disease-Integrated Analyses of 2 Phase 3 Studies

AIMS

Thrombocytopenia complicates the management of patients with chronic liver disease (CLD) undergoing invasive procedures with a bleeding risk. Until recently, prophylactic platelet transfusion was the only treatment option, but has significant safety and efficacy limitations. Phase 3 data demonstrated the superiority of avatrombopag to placebo in reducing platelet transfusions for bleeding, supporting its recent approval.

METHODS

Integrated analyses of pooled data (N = 435) from two randomized, double-blind, placebo-controlled, phase 3 studies assessed the original efficacy endpoints. Additional analyses included subgroup analyses, alternate Baseline platelet count definitions, and another efficacy endpoint.

RESULTS

Avatrombopag was superior to placebo in increasing patients not requiring a platelet transfusion or rescue procedure, those achieving a platelet count ≥50 × 10⁹/L on Procedure Day, and the change in platelet counts from Baseline. The avatrombopag treatment effect was consistently positive across clinically important disease and Baseline clinical characteristic subgroups, and using alternate Baseline platelet count cohort definitions. Similarly, more avatrombopag-treated patients achieved ≥50 × 10⁹/L platelets with an increase of ≥20 × 10⁹/L from Baseline. The incidence and severity of adverse events were similar between avatrombopag and placebo. Further, safety data demonstrated a low risk for thromboembolic events and hepatotoxicity.

CONCLUSION

These integrated analyses confirmed the superiority of avatrombopag to placebo in reducing platelet transfusions or rescue procedures for bleeding in patients with thrombocytopenia and CLD scheduled to undergo an invasive procedure, and its tolerable safety profile. Importantly, these data warrant reconsideration of clinical decision making regarding the need to treat thrombocytopenia in patients with CLD. This trial was registered with NCT01972529 and NCT01976104.

ACG Clinical Guideline: Disorders of the Hepatic and Mesenteric Circulation

Disorders of the mesenteric, portal, and hepatic veins and mesenteric and hepatic arteries have important clinical consequences and may lead to acute liver failure, chronic liver disease, noncirrhotic portal hypertension, cirrhosis, and hepatocellular carcinoma. Although literature in the field of vascular liver disorders is scant, these disorders are common in clinical practice, and general practitioners, gastroenterologists, and hepatologists may benefit from expert guidance and recommendations for management of these conditions. These guidelines represent the official practice recommendations of the American College of Gastroenterology. Key concept statements based on author expert opinion and review of literature and specific recommendations based on PICO/GRADE analysis have been developed to aid in the management of vascular liver disorders. These recommendations and guidelines should be tailored to individual patients and circumstances in routine clinical practice.

Current Advance in Thrombopoietin Receptor Agonists in the Management of Thrombocytopenia Associated With Chronic Liver Disease: Focus on Avatrombopag

Chronic liver disease (CLD) is a condition that progresses over time toward advanced disease state which is known as liver cirrhosis. Liver cirrhosis leads to dangerous health problems among people living across the world. One such problem that observed in about 75% of cirrhotic patients is thrombocytopenia; which in turn associated with poor prognosis and recovery from CLD. Beyond these, thrombocytopenia in cirrhotic patients led to impairment of coagulation cascade and significantly influenced the utilization of effective mechanism in the management of CLD. By nature, treatment of CLD involves invasive diagnostic and treatment procedures; therefore, in the presence of thrombocytopenia implementing these methods put the lives of patients in a critical health problem due to increased risk of bleeding and mortality. Because of these reasons, prophylactic transfusion of platelets is considered to be one of the most effective options that reduce the risk of bleeding in patients with CLD that required to undergo an invasive procedure. Although platelet transfusion presented with significant advantages in facilitating the invasive procedure in patients with CLD, refractoriness with repeated use and various problems associated with its transfusion limit the continuous utilization of this important option. With these challenges and current advance in the knowledge of thrombopoiesis, the development of relatively safe and alternative drugs that enhance the production of platelets by interacting with thrombopoietin receptor agonists provides a promising option to platelet transfusion. The discovery and approval of romiplostim and eltrombopag in August 2008 and November 2008, respectively, for the treatment of chronic immune thrombocytopenia paved a way and followed by the Food and Drug Administration (FDA) approval of 2 potentially advantageous drugs, lusutrombopag, and avatrombopag, in 2018 for the treatment of thrombocytopenia in patients with CLD that required to undergo elective surgery. Therefore, this review aims to assess pathogenesis of thrombocytopenia and its challenges in the management of liver-related issues and, more importantly, gives emphasis to address the potential use of avatrombopag in the treatment of thrombocytopenia underlying CLD, its pharmacokinetics and pharmacodynamics, as well as its toxicological profiles by presenting the most commonly reported adverse events in various trials.

Avatrombopag for the treatment of immune thrombocytopenia and thrombocytopenia of chronic liver disease

Avatrombopag is an orally-administered small molecule thrombopoietin receptor agonist. It was the third thrombopoietin receptor agonist approved for the treatment of immune thrombocytopenia and the first approved to treat periprocedural thrombocytopenia in patients with chronic liver disease (thereby providing an alternative to blood transfusions for these patients). Unlike eltrombopag, avatrombopag does not require a 4 hr food-restricted window around its use and it has not been associated with hepatotoxicity in ITP patients or portal vein thrombosis in patients with chronic liver disease. In ITP patients it can often be dosed less frequently than once daily. It is overall well-tolerated with a side-effect profile similar to placebo in randomized clinical trials. This article will review the clinical development, efficacy, safety, and pharmacology of avatrombopag for use in patients with ITP and thrombocytopenia of chronic liver disease.

Thrombocytopenia and Procedural Prophylaxis in the Era of Thrombopoietin Receptor Agonists

Thrombocytopenia is common in patients with advanced liver disease. These patients frequently require invasive diagnostic or therapeutic procedures in the setting of thrombocytopenia. A common platelet goal before such procedures is ≥50,000/μL, but target levels vary by provider and the procedure. Platelet transfusion has disadvantages, including safety and cost. No other short‐term options for ameliorating thrombocytopenia before procedures were available until the thrombopoietin receptor agonists were recently approved. Avatrombopag and lusutrombopag can be used in certain patients with thrombocytopenia due to advanced liver disease undergoing elective invasive procedures; these new agents are highly effective in carefully selected patients, and real world data of safety and efficacy are awaited.

TPO receptor agonists are an exciting new development that can raise platelet counts in liver patients with thrombocytopenia before elective procedures. We review the strategies to address peri‐procedure thrombocytopenia including data on the most recent trials involving TPO receptor agonists.

Avatrombopag for the treatment of thrombocytopenia in patients with chronic liver disease

Introduction: Thrombocytopenia is a common hematological abnormality in patients with chronic liver disease (CLD), occurring in 64%~84% of patients with cirrhosis or fibrosis. Due to the increased risk of bleeding, thrombocytopenia potentially affects management of CLD, such as surgery or liver biopsy. Avatrombopag is a new oral thrombopoietin (TPO) receptor agonist, activating TPO receptor and increasing megakaryocytic proliferation/differentiation and platelet production. Areas covered: This review summarizes the collected data concerning pharmacokinetics, clinical efficacy, safety and tolerability profiles of avatrombopag for the management of thrombocytopenia in patients with CLD. Expert opinion: Avatrombopag is recently approved by Food and Drug Administration (FDA) for the treatment of thrombocytopenia in patients with CLD who are scheduled to undergo a procedure. Based on the available clinical trials, avatrombopag is superior to placebo in reducing the need for platelet transfusions or rescue procedures for bleeding. Avatrombopag is also recommended as alternative to platelet transfusions.

Efficacy and Safety of Avatrombopag in Patients With Thrombocytopenia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Avatrombopag is a novel oral, nonpeptide thrombopoietin receptor agonist (TPO-RA). A few studies have shown that avatrombopag is effective against thrombocytopenia. However, no systematic review has been conducted on the efficacy and safety of avatrombopag. Therefore, the aim of this study was to comprehensively assess the efficacy and safety of avatrombopag patients with thrombocytopenia. Methods: Databases including Medline, PubMed, Embase, the Cochrane Library and ClinicalTrials.gov were searched for randomized controlled trials that compared avatrombopag with placebo in patients with thrombocytopenia. The deadline was March 2019. Results: In total, 743 patients were analyzed in five clinical trials. Patients treated with avatrombopag achieved higher platelet response (OR: 17.71, 95% CI [11.01 to 28.48], p < 0.00001) than with placebo. Avatrombopag produced an absolute increment in platelet count (WMD: 31.13%, 95% CI [22.27 to 39.99], p < 0.00001) unlike the placebo. In addition, the incidence of serious adverse events (RR: 1.18, 95% CI [0.72 to 1.93], p = 0.51) and deaths (RR: 0.93, 95% CI [0.19 to 4.45], p = 0.93) in patients treated with avatrombopag was not significantly different from that in patients treated with placebo. The incidence of adverse events in patients treated with avatrombopag was slightly higher than that in patients treated with placebo (RR: 1.25, 95% CI [1.05 to 1.49], p = 0. 01) after one trial with high heterogeneity was removed. Conclusions: This meta-analysis showed that avatrombopag was an effective treatment for thrombocytopenia, but there is sufficient evidence to indicate that adverse events may occur.

AGA Clinical Practice Update: Coagulation in Cirrhosis

DESCRIPTION

This expert review was commissioned and approved by the AGA Institute Clinical Practice Updates Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership. The intent is to evaluate the current data on mechanism of altered coagulation in patients with cirrhosis, provide guidance on the use of currently available testing of the coagulation cascade, and help practitioners use anticoagulation and pro-coagulants appropriately in patients with cirrhosis.

METHODS

This review is framed around the best practice points, which were derived from the most impactful publications in the area of coagulation in cirrhosis and agreed to by all authors. BEST PRACTICE ADVICE 1: Global tests of clot formation, such as rotational thromboelastometry, thromboelastography, sonorheometry, and thrombin generation, may eventually have a role in the evaluation of clotting in patients with cirrhosis, but currently lack validated target levels. BEST PRACTICE ADVICE 2: In general, clinicians should not routinely correct thrombocytopenia and coagulopathy before low-risk therapeutic paracentesis, thoracentesis, and routine upper endoscopy for variceal ligation in patients with hepatic synthetic dysfunction-induced coagulation abnormalities. BEST PRACTICE ADVICE 3: Blood products should be used sparingly because they increase portal pressure and carry a risk of transfusion-associated circulatory overload, transfusion-related acute lung injury, infection transmission, alloimmunization, and/or transfusion reactions. BEST PRACTICE ADVICE 4: The following transfusion thresholds for management of active bleeding or high-risk procedures may optimize clot formation in advanced liver disease: hematocrit ≥25%, platelet count >50,000, and fibrinogen >120 mg/dL. Commonly utilized thresholds for international normalized ratio correction are not supported by evidence. BEST PRACTICE ADVICE 5: Thrombopoietin agonists are a good alternative to platelet transfusion, but require time (about 10 days) to elevate platelet levels. BEST PRACTICE ADVICE 6: The large volume of fresh frozen plasma required to reach an arbitrary international normalized ratio target, limitations of the usual target, minimal effect on thrombin generation, and adverse effects on portal pressure limit the utility of this agent significantly. BEST PRACTICE ADVICE 7: The 4-factor prothrombin complex concentrate contains both pro- and anticoagulant factors that offer an attractive low-volume therapeutic to rebalance a disturbed hemostatic system. However, dosage is, in part, based on international normalized ratio, which is problematic in cirrhosis, and published experience in liver disease is limited. BEST PRACTICE ADVICE 8: Anti-fibrinolytic therapy may be considered in patients with persistent bleeding from mucosal oozing or puncture wound bleeding consistent with impaired clot integrity. Both ε-aminocaproic acid and tranexamic acid inhibit clot dissolution. Neither is believed to generate a hypercoagulable state, although both may exacerbate pre-existing thrombi. BEST PRACTICE ADVICE 9: Desmopressin releases von Willebrand factor as its primary hemostatic mechanism. As this factor is usually elevated in cirrhosis, the agent lacks a sound evidence-based foundation, but may be useful in patients with concomitant renal failure. BEST PRACTICE ADVICE 10: Systemic heparin infusion is recommended for symptomatic deep vein thrombosis and portal and mesenteric vein thrombosis, but there are unresolved issues regarding monitoring with both the anti-Xa assay and the partial thromboplastin time due to cirrhosis-related antithrombin deficiency (heparin cofactor). BEST PRACTICE ADVICE 11: Treatment of incidental portal and mesenteric vein thrombosis depends on estimated impact on transplantation surgical complexity vs risks of bleeding and falls. Therapy with low-molecular-weight heparin, vitamin K antagonists, and direct-acting anticoagulants improve portal vein repermeation vs observation alone. BEST PRACTICE ADVICE 12: Direct-acting anticoagulants, such as the factor Xa and thrombin inhibitors, are relatively safe and effective in stable cirrhotic patients, but are in need of further study in patients with more advanced liver disease.

Avatrombopag for the treatment of immune thrombocytopenia

INTRODUCTION

Thrombopoietin-receptor agonists (TPO-RAs) are the only American Society of Hematology (ASH) guideline-advocated, second-line treatment for immune thrombocytopenia (ITP) that have been validated by randomized, controlled trials with a placebo comparator. Avatrombopag is a new candidate in this class that has been investigated as a treatment option for the treatment of ITP. Areas covered: In this Drug Profile, we provide a review of the clinical data of avatrombopag, which was approved in May 2018 by the United States Food and Drug Administration (FDA) for the treatment of thrombocytopenia in patients with chronic liver disease undergoing an invasive procedure, and an opinion of its potential place in the current evidence-based ITP treatment landscape. Expert commentary: Avatrombopag induces doubling of platelet counts, increasing them to above 50 X 10⁹/L, and prevents the need for platelet transfusions while minimizing the need for rescue medications. Treatment-emergent adverse events (TEAEs) are comparable to placebo. Oral delivery, a 5-day dosing schedule and good tolerability (<1% discontinuation rate) with no clinically significant hepatoxicity make it a promising entrant as a potential second-line treatment for ITP. Further, data from a phase 3 study in patients with ITP supports its utility in the treatment of patients with ITP.

Avatrombopag: First Global Approval

Avatrombopag (Doptelet^®) is an orally bioavailable, small molecule thrombopoietin receptor agonist that has been developed by Dova Pharmaceuticals for the treatment of thrombocytopenic disorders. In May 2018 avatrombopag received its first global approval, in the USA, for use in the treatment of thrombocytopenia in adult patients with chronic liver disease (CLD) who are scheduled to undergo a procedure. A Marketing Authorization Application for use of avatrombopag in this indication was submitted to the EMA in April 2018. Clinical development of avatrombopag in the treatment of other thrombocytopenic disorders, including immune thrombocytopenic purpura and chemotherapy-induced thrombocytopenia, is ongoing. This article summarizes the milestones in the development of avatrombopag leading to this first approval for the treatment of thrombocytopenia in adult patients with CLD.

Real-life experience of lusutrombopag for cirrhotic patients with low platelet counts being prepared for invasive procedures

BACKGROUND AND AIMS

The present study aimed to report our real-life experience of the TPO receptor agonist lusutrombopag for cirrhotic patients with low platelet counts.

METHODS

We studied platelet counts in 1,760 cirrhotic patients undergoing invasive procedures at our hospital between January 2014 and December 2017. In addition, we studied 25 patients who were administered lusutrombopag before invasive procedures between June 2017 and January 2018. Effectiveness of lusutrombopag to raise platelet counts and to avoid transfusion and treatment-related adverse events were analyzed.

RESULTS

In 1,760 cirrhotic patients without lusutrombopag prior to invasive procedures, proportion of patients whose platelet counts <50,000/μL and needed platelet transfusions were 66% (n = 27/41) for radiofrequency ablation, 43% (n = 21/49) for transarterial chemoembolization, and 55% (n = 21/38) for endoscopic injection sclerotherapy / endoscopic variceal ligation, respectively. In 25 cirrhotic patients treated by lusutrombopag prior to the invasive procedures, platelet counts significantly increased compared with baseline (82,000 ± 26,000 vs. 41,000 ± 11,000/μL) (p < 0.01). Out of 25 patients, only 4 patients (16%) needed platelet transfusion before the invasive procedures. The proportion of patients with low platelet count and who needed platelet transfusions was significantly low in patients treated with lusutrombopag compared to those not treated with lusutrombopag (16% (4/25) vs. 54% (69/128), p = 0.001). Platelet counts after lusutrombopag treatment and prior to invasive procedures were lower in patients with a baseline platelet count ≤30,000/μL (n = 8) compared with those with a baseline platelet count >30,000/μL (n = 17) (50,000 ± 20,000 vs 86,000 ± 26,000/μL, p = 0.002). Patients with a baseline platelet count ≤30,000/μL with spleen index (calculated by multiplying the transverse diameter by the vertical diameter measured by ultrasonography) ≥40 cm2 (n = 3) had a lower response rate to lusutrombopag compared to those with spleen index <40 cm2 (n = 5) (0% vs. 100%, p = 0.02). Hemorrhagic complication was not observed. Recurrence of portal thrombosis was observed and thrombolysis therapy was required in one patient who had prior history of thrombosis.

CONCLUSIONS

Lusutrombopag is an effective and safe drug for thrombocytopenia in cirrhotic patients, and can reduce the frequency of platelet transfusions.

Thrombopoietin receptor agonists and risk of portal vein thrombosis in patients with liver disease and thrombocytopenia: A meta-analysis

BACKGROUND

Treatment of thrombocytopenia with thrombopoietin receptor agonists (TPORAs) seems to be associated with portal vein thrombosis (PVT) in patients with chronic liver disease (CLD). We performed a meta-analysis of the trials carried out in this clinical setting to assess if such association is detectable.

METHODS

We performed a meta-analysis with studies that compared the effect of TPORAS vs placebo in patients with CLD and thrombocytopenia.

RESULTS

Four studies, including 1953 patients, reported the incidence of PVT in patients with CLD and thrombocytopenia treated with TPORAs or placebo. No significant difference was found for incidence of PVT in patients treated with TPORAs compared with placebo (O.R.: 2.8; 95% C.I., 0.97-8.16; p = 0.055). A significant association between PVT and TPORAs was observed only in patients treated with eltrombopag (O.R.: 3.8; 95% C.I., 1.14-13.2; p = 0.03). Three studies, including 514 patients who were undergoing an elective invasive procedure, analyzed the incidence of PVT in TPORAs-treated patients with CLD and thrombocytopenia; no significant difference was found for incidence of PVT in patients treated with TPORAs compared with placebo (O.R.: 2.6; 95% C.I., 0.6-11.6; p = 0.212). A significant difference was found for incidence of arterial and venous thrombo-embolic events in CLD patients treated with eltrombopag compared with placebo-treated patients (O.R.: 3.4; 95% C.I., 1.5-7.7; p = 0.003).

CONCLUSION

The results of this meta-analysis show that TPORAs are not associated with PVT in CLD patients even in the case of surgical procedure. PVT risk seems to be associated only with eltrombopag use.

Avatrombopag increases platelet count but not platelet activation in patients with thrombocytopenia resulting from liver disease

Essentials Thrombopoietin (TPO) lowers the threshold for platelet activation. TPO receptor agonists (RAs) may therefore also lead to platelet activation. Patients with chronic liver disease and thrombocytopenia participated in a randomized trial. The TPO-RA avatrombopag did not increase platelet activation in vivo or reactivity in vitro.

BACKGROUND

The thrombopoietin (TPO) receptor agonist (TPO-RA) avatrombopag has recently been Food and Drug Administration-approved for the treatment of thrombocytopenia in patients with chronic liver disease (CLD) scheduled for a procedure. The TPO receptor c-mpl is expressed on the platelet surface, and TPO lowers the threshold for platelet activation. TPO-RAs may therefore also lead to platelet activation.

OBJECTIVES

To evaluate the effects of avatrombopag on platelet activation.

PATIENTS/METHODS

CLD patients with thrombocytopenia participated in a randomized, double-blind, placebo-controlled, parallel-group study. No patient received a platelet transfusion within 10 days of study blood draws. Platelet activation was evaluated with whole blood flow cytometry (which, unlike other methods, is accurate in thrombocytopenic samples).

RESULTS

Avatrombopag, but not placebo, increased platelet counts. As measured by platelet surface P-selectin and activated glycoprotein IIb-IIIa: (i) the numbers of circulating activated platelets were not increased in avatrombopag-treated patients as compared with placebo-treated patients; and (ii) platelet reactivity to low and high concentrations of ADP and thrombin receptor-activating peptide was not increased in avatrombopag-treated patients as compared with placebo-treated patients.

CONCLUSIONS

In this randomized, double-blind, placebo-controlled, parallel-group study of CLD patients with thrombocytopenia, avatrombopag increased platelet counts but did not increase platelet activation in vivo or platelet reactivity in vitro.

Avatrombopag, an oral thrombopoietin receptor agonist: results of two double-blind, dose-rising, placebo-controlled Phase 1 studies

Avatrombopag is an oral thrombopoietin receptor agonist that has been recently approved for treating thrombocytopenia in chronic liver disease patients needing invasive procedures. Clinical trials supporting this new treatment were guided by two double‐blind, dose‐rising, placebo‐controlled Phase 1 studies in healthy adults reported here that assessed safety, tolerability and pharmacokinetic profile of avatrombopag, and its effect on platelet counts. Subjects were randomised (2:1) in the single‐dose study (N = 63) to avatrombopag (1, 3, 10, 20, 50, 75 and 100 mg) or placebo, and in the multiple‐dose study (N = 29) to avatrombopag (3, 10 and 20 mg) or placebo daily for 14 days. There were no serious adverse events (AEs), dose‐limiting toxicities, deaths, AEs causing withdrawal, thromboses or liver function abnormalities. In both studies, avatrombopag peak concentration and exposure increased proportionally relative to dose; half‐life was 18–21 h and independent of dose, supporting once‐daily dosing. Effects on platelet counts depended on dose, concentration and treatment duration. Platelet count increases began 3–5 days post‐administration, with maximum changes of >370 × 10⁹/l over baseline with 20 mg daily after 13–16 days. These data support continued development of avatrombopag for treatment of other thrombocytopenic conditions and provide important guidance for the haematologist in the use of this new thrombopoietin receptor agonist.

Phase 3 randomised study of avatrombopag, a novel thrombopoietin receptor agonist for the treatment of chronic immune thrombocytopenia

Avatrombopag, an oral thrombopoietin receptor agonist, was compared with placebo in a 6-month, multicentre, randomised, double-blind, parallel-group Phase 3 study, with an open-label extension phase, to assess the efficacy and safety of avatrombopag (20 mg/day) in adults with chronic immune thrombocytopenia (ITP) and a platelet count <30 × 10⁹ /l (ClinicalTrials.gov identifier NCT01438840). The primary endpoint was the cumulative number of weeks of platelet response (platelet count ≥50 × 10⁹ /l) without rescue therapy for bleeding; secondary endpoints included platelet response rate at day 8 and reductions in the use of concomitant medications. Amongst the 49 patients randomised, avatrombopag (N = 32) was superior to placebo (N = 17) in the median cumulative number of weeks of platelet response (12·4 vs. 0·0 weeks, respectively; P < 0·0001). At day 8, a greater platelet response rate was also observed for patients treated with avatrombopag compared with placebo (65·63% vs. 0·0%; P < 0·0001), and use of concomitant ITP medications was also reduced amongst patients receiving avatrombopag. The safety profile of avatrombopag was consistent with Phase 2 studies; the most common adverse events were headache and contusion. Overall, avatrombopag was well tolerated and efficacious for the treatment of chronic ITP.

Avatrombopag Before Procedures Reduces Need for Platelet Transfusion in Patients With Chronic Liver Disease and Thrombocytopenia

BACKGROUND & AIMS

Patients with thrombocytopenia and chronic liver disease (CLD) may require platelet transfusions before scheduled procedures to decrease risk of bleeding. We performed 2 randomized, placebo-controlled, phase 3 trials in patients with thrombocytopenia and CLD undergoing scheduled procedures to evaluate the safety and efficacy of avatrombopag in increasing platelet counts in this patient population.

METHODS

In the ADAPT-1 and ADAPT-2 studies, adults with thrombocytopenia and CLD (n = 231 and n = 204, respectively) were in 1 of 2 cohorts according to their baseline platelet count (below 40 × 10⁹/L or 40 to below 50 × 10⁹/L) and within each cohort were randomized (2:1) to receive 5 daily doses of avatrombopag (60 mg if baseline platelet count below 40 × 10⁹/L or 40 mg if 40 to below 50 × 10⁹/L) or placebo. ADAPT-1 was conducted at 75 study sites in 20 countries, from February 2014 through January 2017, and ADAPT-2 was conducted at 74 sites in 16 countries, from December 2013 through January 2017. The primary endpoint was the proportion of patients not requiring platelet transfusions or rescue procedures for bleeding up to 7 days after a scheduled procedure.

RESULTS

In the ADAPT-1 study, 65.6% of patients who received 60 mg avatrombopag and 88.1% of patients who received 40 mg avatrombopag met the primary endpoint compared with 22.9% and 38.2% of patients receiving placebo, respectively (P < .0001 for both). In the ADAPT-2 study, 68.6% of patients who received 60 mg avatrombopag and 87.9% of patients who received 40 mg avatrombopag met the primary endpoint compared with 34.9% and 33.3% of patients who received placebo, respectively (P < .001 for both). Avatrombopag led to a measured increase in platelet counts and increased the proportion of patients who achieved the target platelet count ≥ 50 × 10⁹/L on procedure day vs placebo. The incidence and severity of adverse events were similar for the avatrombopag and placebo groups and were consistent with those expected in the CLD population.

CONCLUSIONS

In 2 phase 3 randomized trials, avatrombopag was superior to placebo in reducing the need for platelet transfusions or rescue procedures for bleeding in patients with thrombocytopenia and CLD undergoing a scheduled procedure. ClinicalTrials.gov nos.: NCT01972529 and NCT01976104.

Cytokine control of megakaryopoiesis

Platelets are anuclear blood cells required for haemostasis and are implicated in other processes including inflammation and metastasis. Platelets are produced by megakaryocytes, specialized cells that are themselves generated by a process of controlled differentiation and maturation of bone-marrow stem and progenitor cells. This process of megakaryopoiesis involves the coordinated interplay of transcription factor-controlled cellular programming with extra-cellular cues produced locally in supporting niches or as circulating factors. This review focuses on these external cues, the cytokines and chemokines, that drive production of megakaryocytes and support the terminal process of platelet release. Emphasis is given to thrombopoietin (Tpo), the major cytokine regulator of steady-state megakaryopoiesis, and its specific cell surface receptor, the Mpl protein, including normal and pathological roles as well as clinical application. The potential for alternative or supplementary regulatory mechanisms for platelet production, particularly in times of acute need, or in states of infection or inflammation are also discussed.

Two cases of liver cirrhosis treated with lusutrombopag before partial splenic embolization

Lusutrombopag, a small molecule thrombopoietin receptor agonist, has been approved for the treatment of chronic liver disease-associated thrombocytopenia due to hypersplenism in patients scheduled to undergo elective invasive procedures in Japan. We performed partial splenic embolization (PSE) after administration of lusutrombopag in two patients with thrombocytopenia due to cirrhosis.　Case 1 involved a 50-year-old man who developed cirrhosis due to hepatitis B virus (HBV) infection and alcohol consumption. Case 2 involved a 30-year-old woman who developed cirrhosis due to HBV infection only. Lusutrombopag administration led to an increase in platelet count in both patients, and PSE was performed safely. However, in Case 2, the patient developed disseminated intravascular coagulation. Further study with a larger population is required to investigate the indications for and risks of the use of lusutrombopag.

Bleeding Risk with Invasive Procedures in Patients with Cirrhosis and Coagulopathy

PURPOSE OF REVIEW

Previous perceptions of cirrhosis as a hypocoagulable state have resulted in empirical blood product transfusions prior to invasive procedures. We evaluate procedure-related bleeding risks in patients with cirrhosis, assess the utility of conventional and newer global coagulation tests, and explore evidence surrounding prophylactic transfusion strategies.

RECENT FINDINGS

Recent literature supports the concept of a rebalanced, albeit fragile, haemostasis equilibrium in cirrhosis, with a potential hypercoagulable tendency in stable patients. Standard coagulation tests provide a poor reflection of bleeding risks and yet are relied upon for transfusion thresholds. Consequently, a sizeable proportion of patients receive unnecessary blood products. The role of viscoelastic tests to guide transfusions requires further evaluation. In stable cirrhotic patients, procedure-related bleeding rates appear low. Prophylactic transfusion strategies based on arbitrary thresholds lack evidence of clinical benefit. There is a pressing need for point-of-care coagulation tests that represent the complex coagulopathy of cirrhosis and well-powered randomised controlled trials to develop evidence-based pre-procedure transfusion guidelines.