Lusutrombopag increases hematocytes in a compensated liver cirrhosis patient

Dualistic role of platelets in living donor liver transplantation: Are they harmful?

Platelets are anucleate fragments mainly involved in hemostasis and thrombosis, and there is emerging evidence that platelets have other nonhemostatic potentials in inflammation, angiogenesis, regeneration and ischemia/reperfusion injury (I/R injury), which are involved in the physiological and pathological processes during living donor liver transplantation (LDLT). LDLT is sometimes associated with impaired regeneration and severe I/R injury, leading to postoperative complications and decreased patient survival. Recent studies have suggested that perioperative thrombocytopenia is associated with poor graft regeneration and postoperative morbidity in the short and long term after LDLT. Although it is not fully understood whether thrombocytopenia is the cause or result, increasing platelet counts are frequently suggested to improve posttransplant outcomes in clinical studies. Based on rodent experiments, previous studies have identified that platelets stimulate liver regeneration after partial hepatectomy. However, the role of platelets in LDLT is controversial, as platelets are supposed to aggravate I/R injury in the liver. Recently, a rat model of partial liver transplantation (LT) was used to demonstrate that thrombopoietin-induced thrombocytosis prior to surgery accelerated graft regeneration and improved the survival rate after transplantation. It was clarified that platelet-derived liver regeneration outweighed the associated risk of I/R injury after partial LT. Clinical strategies to increase perioperative platelet counts, such as thrombopoietin, thrombopoietin receptor agonist and platelet transfusion, may improve graft regeneration and survival after LDLT.

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.

Pharmacokinetics of Lusutrombopag, a Novel Thrombopoietin Receptor Agonist, in Rats by UPLC-MS/MS

Lusutrombopag is a second oral thrombopoietin (TPO) receptor agonist that selectively acts on human TPO receptors. In the study, UPLC-MS/MS was used to establish a selective and sensitive method to determine lusutrombopag with poziotinib as IS (internal standard) in rat plasma. Samples were prepared by precipitating protein with acetonitrile as a precipitant. Separation of lusutrombopag and poziotinib was performed on a CORTECS UPLC C18 column (2.1 ∗ 50 mm, 1.6 μm). The mobile phase (acetonitrile and water containing 0.1% formic acid) with gradient elution was set at a flow rate of 0.4 ml/min. The mass spectrometric measurement was conducted under positive ion mode using multiple reaction monitoring (MRM) of m/z 592.97 ⟶ 491.02 for lusutrombopag and m/z for poziotinib (IS) 492.06 ⟶ 354.55. The linear calibration curve of the concentration range was 2–2000 ng/ml for lusutrombopag, with a lower limit of quantification (LLOQ) of 2 ng/ml. RSD of interday and intraday precision were both no more than 9.66% with the accuracy ranging from 105.82% to 108.27%. The extraction recovery of lusutrombopag was between 82.15% and 90.34%. The developed and validated method was perfectly used in the pharmacokinetic study of lusutrombopag after oral administration in rats.

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.

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.

New Small Molecule Drugs for Thrombocytopenia: Chemical, Pharmacological, and Therapeutic Use Considerations

This review provides details about three small molecules that were recently approved by the FDA for the treatment of thrombocytopenia. The new treatments include lusutrombopag, avatrombopag, and fostamatinib. The first two drugs are orally active thrombopoietin receptor (TPO-R) agonists which are FDA-approved for the treatment of thrombocytopenia in adult patients with chronic liver disease who are scheduled to undergo a procedure. Fostamatinib is orally active prodrug that, after activation, becomes spleen tyrosine kinase (SYK) inhibitor. Fostamatinib is currently used to treat chronic and refractory immune thrombocytopenia in patients who have had insufficient response to previous treatment. Chemical structures, available dosage forms, recommended dosing, pharmacokinetics, results of toxicity studies in animals, most frequent adverse effects, significant outcomes of the corresponding clinical trials, and their use in specific patient populations are thoroughly described. Described also is a comparative summary of the different aspects of five currently available therapies targeting TPO-R or SYK for the treatment of thrombocytopenia.

Immunological consequences following splenectomy in patients with liver cirrhosis

The immune status in patients with liver cirrhosis is generally impaired due to concomitant hypersplenism. As the spleen is the largest lymphoid organ, deleterious events resulting from splenectomy are of concern in these patients. However, the immunological consequences after splenectomy have not yet been fully elucidated. In the present study, the immune status after splenectomy was comprehensively examined. Splenectomy was performed in 11 patients with liver cirrhosis and hypersplenism, and the immune status in peripheral blood was examined and compared before and at 1, 3 and 6 months after splenectomy. Splenectomy significantly lowered the neutrophil-to-lymphocyte ratio, due to a surge in lymphocytes in the peripheral circulation at 3 and 6 months after splenectomy. The frequency of cluster of differentiation (CD)4⁺ T cells decreased after splenectomy, whereas the frequency of CD8⁺ T cells increased. Notably, the frequencies of the naïve and central memory subsets of CD4⁺ and CD8⁺ T cells decreased, whereas those of the effector memory subset trended upward. In addition, the frequencies of other immune cells such as γδ T cells, natural killer T cells and natural killer cells transiently increased, while inhibitory cells such as regulatory T cells and myeloid-derived suppressor cells significantly decreased. T-cell responses to viral- and tumor-associated antigens increased after splenectomy in five of eight and two of five patients, respectively. To the best of our knowledge, this is the first study to precisely examine the drastic changes of immunological phenotypes in peripheral blood after splenectomy in patients with cirrhosis. Our findings suggested that splenectomy in patients with cirrhosis may ameliorate the impaired immune status, possibly by reducing suppressive cells and enhancing the effector cell population and function, which could, at least in part, explain the mechanisms responsible for the clinical benefits of splenectomy.

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.

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.