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

Avatrombopag, a promising novel thrombopoietin receptor agonist for refractory/relapsed/intolerant non-severe aplastic anemia: a phase 2 single-arm clinical trial

INTRODUCTION

The therapeutic options for thrombocytopenia in non-severe aplastic anaemia (NSAA) are limited. Avatrombopag (AVA) is prescribed for thrombocytopenic diseases but not for NSAA.

METHODS

Herein, we conducted a phase 2, non-randomized, single-arm trial to explore the efficacy and safety of AVA in refractory/relapsed/intolerant NSAA. AVA dose was initiated at 20 mg/d and titrated to a maximum of 60 mg/d. The primary endpoint was the haematological response at 3 months.

RESULTS

Twenty-five patients were analyzed. The overall response rate (ORR) at 3 months was 56% (14/25), with 12% (3/25) achieving a complete response (CR). At a median follow-up of 7 (3-10) months, the OR and CR rates were 52% and 20%, respectively. Responders had a shorter duration of diagnosis of AVA administration than non-responders (10 (6-80) vs 37 (6-480) months, p = 0.027) and belonged to the relapsed/intolerant NSAA type (71% vs 27%, p = 0.047); 44% (8/18) patients previously treated with eltrombopag before enrollment responded at 3 months, with an average prior eltrombopag dose of median 72.5 (50-100) mg/d and an average AVA dose for a response of median 43.5 (20-60) mg/d. 3-month ORR had no significant correlation with eltrombopag exposure (p = 0.09), prior eltrombopag length (R²=0.11), or cumulative eltrombopag dose (R²=0.30). Only one patient relapsed after stopping AVA for 1 month. No serious AVA-related side effects or clone evolution were detected.

CONCLUSION

AVA is effective and well-tolerated in NSAA patients who are refractory, relapsed, or intolerant to CsA/tacrolimus ± eltrombopag. Earlier treatment and relapsed/intolerant AA may show a better short-term response rate. More studies are needed to define the optimal dose and the long-term efficacy (NCT04728789).

Brønsted acid-promoted ring-opening and annulation of thioamides and 2H-azirines to synthesize 2,4,5-trisubstituted thiazoles

In this study, a metal-free synthesis of 2,4,5-trisubstituted thiazoles using 2H-azirines and thioamides is disclosed. Under the catalysis of HClO₄, the protocol was realized through a novel chemical bond breaking of 2H-azirine, which is usually achieved using a metal catalyst. It provides an efficient and green route for the synthesis of substituted thiazoles with a broad substrate scope. Preliminary mechanistic studies show that such a reaction may involve a ring-opening reaction, annulation, and a hydrogen atom rearrangement process.

Application and synthesis of thiazole ring in clinically approved drugs

The development of heterocyclic derivatives has progressed considerably over the past few decades, and many new agents of synthetic and natural origin have been produced. Among heterocyclic compounds, thiazole is a unique five-membered heterocyclic motif characterized by nitrogen and sulfur atoms, which is widely used as an important core skeleton in a variety of pharmaceutically important compounds due to their diverse biological activities, such as antibacterial, antivirus, and antifungal. To the best of our knowledge, more than 90 thiazole-containing derivatives have been currently under clinical investigation, and some thiazole analogs have been approved to treat various diseases. As the potentially privileged scaffolds, thiazole derivatives can be further extensively explored to search for new drugs characterized by improved therapeutic efficacy and similar biological targets. This review aims to outline the applications and synthetic routes of some representative thiazole-containing drugs approved in the clinic, which may guide medicinal researchers to rationally design more effective thiazole-containing drug candidates.

Avatrombopag for the treatment of thrombocytopenia in children's patients following allogeneic hematopoietic stem-cell transplantation: A pilot study

Thrombocytopenia following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a common and life-threatening complication. Thus, new prevention and treatment strategies for post-HSCT thrombocytopenia are urgently required. In recent studies, thrombopoietin receptor agonists (TPO-RA) for treating post-HSCT thrombocytopenia indicated efficiency and safety. The improved effect of post-HSCT thrombocytopenia in adults was found in the administration of avatrombopag which was a new TPO-RA. However, there was no relevant study in the children's cohort. Herein, we retrospectively analyzed the effect of avatrombopag in post-HSCT thrombocytopenia in children. As a result, the overall response rate (ORR) and complete response rate (CRR) were 91% and 78%, respectively. Furthermore, both cumulative ORR and CRR were significantly lower in the poor graft function (PGF)/secondary failure of platelet recovery (SFPR) group compared to the engraftment-promotion group (86.7% vs. 100%, p = 0.002 and 65.0% vs. 100%, p < 0.001, respectively). Achieving OR required a median of 16 days in the PGF/SFPR group while 7 days in the engraftment-promotion group (p = 0.003). Grade III-IV acute graft vs. host disease and inadequate megakaryocytes were identified as risk factors of CRR only in univariate analysis (p = 0.03 and p = 0.01, respectively). No severe adverse events were documented. Conclusively, avatrombopag is an alternatively efficient and safe agent for treating post-HSCT thrombocytopenia in children.

Avatrombopag for the treatment of thrombocytopenia induced by chemotherapy in patients with solid tumors: A multicenter, open-label, single-arm trial

Objective: To explore the effect and safety of avatrombopag for chemotherapy-induced thrombocytopenia (CIT).

Methods: This multicenter, open-label, single-arm trial enrolled CIT patients in eight centers from October 2020 to April 2021. The participants received avatrombopag tablets 60 mg once a day for 5–10 days. The main endpoint was the proportion of patients with platelet count ≥100×10⁹/L or increased by ≥ 50×10⁹/L or increased by ≥ 100% in the cycle after the start of treatment.

Results: Seventy-four participants were enrolled with a mean age of 59.8 ± 11.62.2% were males. The cumulative effective rate (any criteria) was 70.3% at 4 weeks. 42 (56.8%) achieved platelet count ≥100×10⁹/L, 44 (59.5%) increased by ≥ 50×10⁹/L, and 27 (36.5%) increase by ≥ 100% from baseline. The duration of grade III and IV platelet reduction was 4.2 ± 5.3 days. The time of PLT recovery to ≥75×10⁹/L was 9.4 ± 6.6 days. The time of PLT recovery to ≥100×10⁹/L was 10.2 ± 6.4 days. The platelet count nadir was 57.9 ± 45.3×10⁹/L. The most common adverse events were nausea (8.1%), fatigue (5.4%), and abdominal pain (1.4%). There were no cases of fever, headache, or peripheral edema.

Conclusion: Although it was a single-arm trial without a control group, the application of avatrombopag in patients with CIT can increase the platelet count of the patients compared with baseline. Avatrombopag is safe and tolerable.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT04609891?term=04609891&draw=2&rank=1, identifier [NCT04609891]

Thrombopoietin from hepatocytes promotes hematopoietic stem cell regeneration after myeloablation

The bone marrow niche plays critical roles in hematopoietic recovery and hematopoietic stem cell (HSC) regeneration after myeloablative stress. However, it is not clear whether systemic factors beyond the local niche are required for these essential processes in vivo. Thrombopoietin (THPO) is a key cytokine promoting hematopoietic rebound after myeloablation and its transcripts are expressed by multiple cellular sources. The upregulation of bone marrow-derived THPO has been proposed to be crucial for hematopoietic recovery and HSC regeneration after stress. Nonetheless, the cellular source of THPO in myeloablative stress has never been investigated genetically. We assessed the functional sources of THPO following two common myeloablative perturbations: 5-fluorouracil (5-FU) administration and irradiation. Using a Thpo translational reporter, we found that the liver but not the bone marrow is the major source of THPO protein after myeloablation. Mice with conditional Thpo deletion from osteoblasts and/or bone marrow stromal cells showed normal recovery of HSCs and hematopoiesis after myeloablation. In contrast, mice with conditional Thpo deletion from hepatocytes showed significant defects in HSC regeneration and hematopoietic rebound after myeloablation. Thus, systemic THPO from the liver is necessary for HSC regeneration and hematopoietic recovery in myeloablative stress conditions.

Repurposing Pharmaceuticals Previously Approved by Regulatory Agencies to Medically Counter Injuries Arising Either Early or Late Following Radiation Exposure

The increasing risks of radiological or nuclear attacks or associated accidents have served to renew interest in developing radiation medical countermeasures. The development of prospective countermeasures and the subsequent gain of Food and Drug Administration (FDA) approval are invariably time consuming and expensive processes, especially in terms of generating essential human data. Due to the limited resources for drug development and the need for expedited drug approval, drug developers have turned, in part, to the strategy of repurposing agents for which safety and clinical data are already available. Approval of drugs that are already in clinical use for one indication and are being repurposed for another indication is inherently faster and more cost effective than for new agents that lack regulatory approval of any sort. There are four known growth factors which have been repurposed in the recent past as radiomitigators following the FDA Animal Rule: Neupogen, Neulasta, Leukine, and Nplate. These four drugs were in clinic for several decades for other indications and were repurposed. A large number of additional agents approved by various regulatory authorities for given indications are currently under investigation for dual use for acute radiation syndrome or for delayed pathological effects of acute radiation exposure. The process of drug repurposing, however, is not without its own set of challenges and limitations.

Update on diagnosis and treatment of immune thrombocytopenia

BACKGROUND

Immune thrombocytopenia (ITP) is a heterogeneous acquired disorder characterized by isolated thrombocytopenia whose exact pathogenesis is not yet clear. Depending upon the presence or absence of an underlying treatable cause, ITP can be categorized as primary or secondary. Primary ITP is a diagnosis of exclusion and there is no gold standard test for its confirmation. Recent drug intake, infections, lymphoproliferative disorders, and connective tissue disorders should be ruled out before labeling a patient as primary ITP.

AREA COVERED

This review summarizes a comprehensive update on the diagnostic and therapeutic modalities for ITP. We reviewed the literature using GOOGLE SCHOLAR, PUBMED and ClinicalTrial.gov databases as needed to support the evidence. We searched the literature using the following keywords: 'immune thrombocytopenia,' 'idiopathic thrombocytopenic purpura,' 'thrombocytopenia,' 'immune thrombocytopenic purpura,' and 'isolated thrombocytopenia'.

EXPERT OPINION

We believe that more detailed studies are required to understand the exact pathophysiology behind ITP. The first-line drugs like corticosteroids have both short-term and long-term adverse effects. This brings the need to explore effective alternative medications and to reconsider their role in ITP treatment algorithm if guidelines can be modified based on new studies.

Occurrence and Management of Thrombocytopenia in Metastatic Colorectal Cancer Patients Receiving Chemotherapy: Secondary Analysis of Data From Prospective Clinical Trials

INTRODUCTION

Chemotherapy-induced thrombocytopenia (CIT) contributes to treatment dose delay and/or modification, often resulting in poorer survival and disease progression. We explored the incidence and clinical consequences of CIT among metastatic colorectal cancer (mCRC) patients.

MATERIALS AND METHODS

Data from two prospective randomized phase 3 trials of mCRC patients receiving either first-line FOLFOX4 (fluorouracil, leucovorin, oxaliplatin) or second-line FOLFIRI (fluorouracil, leucovorin, irinotecan) were analyzed. Thrombocytopenia was defined by platelet count < 100 × 10⁹/L (further categorized by grade) and by recorded adverse events (AEs). Co-occurrence of anemia (hemoglobin < 12 g/dL) and neutropenia (neutrophil count < 2 × 10⁹/L) and clinical consequences of CIT were also evaluated.

RESULTS

Among 1078 mCRC patients in the FOLFOX4 study, cumulative incidence of CIT based on platelet count was 37% (grade 3, 2%; grade 4, 1%) during an average 8 months' follow-up. Neutropenia or anemia were absent in 44% of CIT episodes; 62% of CIT AEs led to chemotherapy dose delay, change, and/or discontinuation. Among 1067 mCRC patients in the FOLFIRI study, cumulative incidence of CIT based on platelet count was 4% (grade 3, < 1%; grade 4, 0) during an average 4 months' follow-up. Neutropenia or anemia were absent in 22% of CIT episodes; 32% of CIT AEs led to chemotherapy dose delay, change, and/or discontinuation. With both regimens, transfusions and hospitalizations after CIT AEs were rare (< 3%).

CONCLUSION

CIT was common among mCRC patients receiving the FOLFOX4 regimen. The most frequent consequence of CIT was a delay in chemotherapy, highlighting the unmet need in CIT management.

Hemostatic Alterations in Patients With Cirrhosis: From Primary Hemostasis to Fibrinolysis

In the setting of liver cirrhosis (LC), profound hemostatic changes occur, which affect primary hemostasis, coagulation, and fibrinolysis. They involve prohemorrhagic and prothrombotic alterations at each of these steps. Patients with cirrhosis exhibit multifactorial thrombocytopenia and in vitro thrombocytopathy, counterbalanced by increased von Willebrand factor. The resultant shift is difficult to assess, but overall these changes probably result in a rebalanced primary hemostasis. Concerning coagulation, the reduced activity of coagulation factors is counterbalanced by an increase in factor VIII (produced by liver sinusoidal endothelial cells), a decrease of the natural anticoagulants, and complex changes, including changes in circulating microparticles, cell-free DNA, and neutrophil extracellular traps. Overall, these alterations result in a procoagulant state. As for fibrinolysis, increased tissue-type and urokinase-type plasminogen activators, a relatively decreased plasminogen activator inhibitor 1, and decreased levels of thrombin-activatable fibrinolysis inhibitor and α2-antiplasmin are counterbalanced by decreased plasminogen and a decreased fibrin clot permeability. Whether and how these changes shift fibrinolysis remains to be determined. Overall, the current consensus is that in patients with cirrhosis, the hemostasis is shifted toward a procoagulant state. We review the published evidence for the concept of LC as a prothrombotic state, discuss discordant data, and highlight the impact of the underlying cause of LC on the resultant imbalance.