Regulatory decisions pertaining to aprotinin may be putting patients at risk

Consensus of the Brazilian association of hematology, hemotherapy and cellular therapy on patient blood management: Antifibrinolytics

The use of strategies to reduce blood loss and transfusions is essential in the treatment of surgical patients, including in complex cardiac surgeries and those that use cardiopulmonary bypass. Antifibrinolytics, such as epsilon-aminocaproic acid (EACA) and tranexamic acid (TXA), are widely used in these procedures, as well as in other types of surgeries. These medicines are included in the World Health Organization (WHO) list of 'essential medicines'. Scientific evidence demonstrates the effectiveness of EACA in reducing bleeding and the need for transfusions in heart surgery. EACA is highly recommended for use in heart surgery by the American Society of Anesthesiology Task Force on Perioperative Blood Management. Regarding the safety of EACA, there is no robust evidence of any significant thrombotic potential. TXA has also been shown to be effective in reducing the use of blood transfusions in cardiac and non-cardiac surgeries and is considered safer than other antifibrinolytic agents. There is no evidence of any increased risk of thromboembolic events with TXA, but doses greater than 2 g per day have been associated with an increased risk of seizures. It is also important to adjust the dose in patients with renal impairment. In conclusion, antifibrinolytics, such as EACA and TXA, are effective in reducing blood loss and transfusion use in cardiac and non-cardiac surgeries, without causing serious adverse effects.

Peptide-Based Agents for Cancer Treatment: Current Applications and Future Directions

Peptide-based strategies have received an enormous amount of attention because of their specificity and applicability. Their specificity and tumor-targeting ability are applied to diagnosis and treatment for cancer patients. In this review, we will summarize recent advancements and future perspectives on peptide-based strategies for cancer treatment. The literature search was conducted to identify relevant articles for peptide-based strategies for cancer treatment. It was performed using PubMed for articles in English until June 2023. Information on clinical trials was also obtained from ClinicalTrial.gov. Given that peptide-based strategies have several advantages such as targeted delivery to the diseased area, personalized designs, relatively small sizes, and simple production process, bioactive peptides having anti-cancer activities (anti-cancer peptides or ACPs) have been tested in pre-clinical settings and clinical trials. The capability of peptides for tumor targeting is essentially useful for peptide-drug conjugates (PDCs), diagnosis, and image-guided surgery. Immunomodulation with peptide vaccines has been extensively tested in clinical trials. Despite such advantages, FDA-approved peptide agents for solid cancer are still limited. This review will provide a detailed overview of current approaches, design strategies, routes of administration, and new technological advancements. We will highlight the success and limitations of peptide-based therapies for cancer treatment.

Synthesis and Structural Characterization of Macrocyclic Plasmin Inhibitors

Two series of macrocyclic plasmin inhibitors with a C-terminal benzylamine group were synthesized. The substitution of the N-terminal phenylsulfonyl group of a previously described inhibitor provided two analogues with sub-nanomolar inhibition constants. Both compounds possess a high selectivity against all other tested trypsin-like serine proteases. Furthermore, a new approach was used to selectively introduce asymmetric linker segments. Two of these compounds inhibit plasmin with K_i values close to 2 nM. For the first time, four crystal structures of these macrocyclic inhibitors could be determined in complex with a Ser195Ala microplasmin mutant. The macrocyclic core segment of the inhibitors binds to the open active site of plasmin without any steric hindrance. This binding mode is incompatible with other trypsin-like serine proteases containing a sterically demanding 99-hairpin loop. The crystal structures obtained experimentally explain the excellent selectivity of this inhibitor type as previously hypothesized.

Aprotinin does not Impair Vascular Function in Patients Undergoing Coronary Artery Bypass Graft Surgery

Bleeding is a major complication in coronary artery bypass graft surgery. Antifibrinolytic agents like serine protease inhibitor aprotinin can decrease postoperative bleeding and complications of cardiac surgery. However, the effects of aprotinin on vascular function are not completely elucidated. We compared the ex vivo vascular function of left internal mammary arteries from patients undergoing coronary artery bypass graft surgery with and without intraoperative application of aprotinin using a Mulvany Myograph. Human internal mammary arteries were treated with aprotinin ex vivo and tested for changes in vascular function. We analyzed the impact of aprotinin on vascular function in rat aortic rings. Finally, impact of aprotinin on expression and activity of endothelial nitric oxide synthase was tested in human endothelial cells. Intraoperative application of aprotinin did not impair ex vivo vascular function of internal mammary arteries of patients undergoing coronary artery bypass graft surgery. Endothelium-dependent and -independent relaxations were not different in patients with or without aprotinin after nitric oxide synthase blockade. A maximum vasorelaxation of 94.5%±11.4vs. 96.1%±5.5% indicated a similar vascular smooth muscle function in both patient groups (n=13 each). Long-term application of aprotinin under physiological condition preserved vascular function of the rat aorta. In vitro application of increasing concentrations of aprotinin on human endothelial cells resulted in a similar expression and activity of endothelial nitric oxide synthase. In conclusion, intraoperative and ex vivo application of aprotinin does not impair the endothelial function in human internal mammary arteries and experimental models.

Tranexamic acid for the prevention and treatment of bleeding in surgery, trauma and bleeding disorders: a narrative review

OBJECTIVES

We review the evidence for tranexamic acid (TXA) for the treatment and prevention of bleeding caused by surgery, trauma and bleeding disorders. We highlight therapeutic areas where evidence is lacking and discuss safety issues, particularly the concern regarding thrombotic complications.

METHODS

An electronic search was performed in PubMed and the Cochrane Library to identify clinical trials, safety reports and review articles.

FINDINGS

TXA reduces bleeding in patients with menorrhagia, and in patients undergoing caesarian section, myomectomy, hysterectomy, orthopedic surgery, cardiac surgery, orthognathic surgery, rhinoplasty, and prostate surgery. For dental extractions in patients with bleeding disorders or taking antithrombotic drugs, as well as in cases of idiopathic epistaxis, tonsillectomy, liver transplantation and resection, nephrolithotomy, skin cancer surgery, burn wounds and skin grafting, there is moderate evidence that TXA is effective for reducing bleeding. TXA was not effective in reducing bleeding in traumatic brain injury and upper and lower gastrointestinal bleeding. TXA reduces mortality in patients suffering from trauma and postpartum hemorrhage. For many of these indications, there is no consensus about the optimal TXA dose. With certain dosages and with certain indications TXA can cause harm, such as an increased risk of seizures after high TXA doses with brain injury and cardiac surgery, and an increased mortality after delayed administration of TXA for trauma events or postpartum hemorrhage. Whereas most trials did not signal an increased risk for thrombotic events, some trials reported an increased rate of thrombotic complications with the use of TXA for gastro-intestinal bleeding and trauma.

CONCLUSIONS

TXA has well-documented beneficial effects in many clinical indications. Identifying these indications and the optimal dose and timing to minimize risk of seizures or thromboembolic events is work in progress.

Trypsin-Like Proteases and Their Role in Muco-Obstructive Lung Diseases

Trypsin-like proteases (TLPs) belong to a family of serine enzymes with primary substrate specificities for the basic residues, lysine and arginine, in the P1 position. Whilst initially perceived as soluble enzymes that are extracellularly secreted, a number of novel TLPs that are anchored in the cell membrane have since been discovered. Muco-obstructive lung diseases (MucOLDs) are characterised by the accumulation of hyper-concentrated mucus in the small airways, leading to persistent inflammation, infection and dysregulated protease activity. Although neutrophilic serine proteases, particularly neutrophil elastase, have been implicated in the propagation of inflammation and local tissue destruction, it is likely that the serine TLPs also contribute to various disease-relevant processes given the roles that a number of these enzymes play in the activation of both the epithelial sodium channel (ENaC) and protease-activated receptor 2 (PAR2). More recently, significant attention has focused on the activation of viruses such as SARS-CoV-2 by host TLPs. The purpose of this review was to highlight key TLPs linked to the activation of ENaC and PAR2 and their association with airway dehydration and inflammatory signalling pathways, respectively. The role of TLPs in viral infectivity will also be discussed in the context of the inhibition of TLP activities and the potential of these proteases as therapeutic targets.

Antifibrinolytics and cardiac surgery: The past, the present, and the future

Cardiac surgery is usually associated with significant blood loss, which often necessitates blood transfusion. In order to decrease the risks associated with the latter, pharmacological as well as nonpharmacological strategies have been used to reduce blood loss. Among the pharmacological approaches, antifibrinolytic drugs are the mainstay. Aprotinin, which was the first ubiquitously used drug, fell into disrepute only to re-emerge after much debate. The decline of aprotinin paved the way for the lysine analogs. However, we must be aware with the side effects of these drugs as well as the dose modification required in special situations. Nonsaccharide glycosaminoglycans have been under investigation to overcome the drawbacks of the lysine analogs. It remains to be seen whether these drugs can replace the traditional antifibrinolytics.

Exclusion criteria and adverse events in perioperative trials of tranexamic acid: a systematic review and meta-analysis

BACKGROUND

Tranexamic acid (TXA) is an inexpensive therapy effective at minimizing perioperative blood loss and transfusion. However, it remains underutilized due to safety concerns. To date, no evidence-based guidelines exist identifying which patients should not receive TXA therapy. This study determined patient groups for whom safety information regarding TXA is lacking due to common exclusion from perioperative TXA trials.

STUDY DESIGN AND METHODS

A systematic review searching the databases Medline, EMBASE, CENTRAL, and Clinicaltrials.gov was performed. Randomized controlled trials (RCTs) administering systemic TXA perioperatively to elective or emergent surgery patients were eligible. Our primary outcome was to describe exclusion criteria of RCTs, and the secondary outcome was TXA safety. A descriptive synthesis of exclusion criteria was performed, and TXA safety was assessed by meta-analysis.

RESULTS

A total of 268 eligible RCTs were included. Meta-analysis showed that systemic TXA did not increase risk of adverse events compared to placebo or no intervention (relative risk, 1.05; 95% confidence interval, 0.99-1.12). Patient groups commonly excluded from perioperative TXA trials, and thus potentially lacking TXA safety data, were those with major comorbidities, a history of thromboembolism, medication use affecting coagulation, TXA allergy, and coagulopathy. Exclusion of patients with major comorbidities may not be necessary; we showed that the risk of adverse events was similar in studies that excluded patients with major comorbidities and those that did not.

CONCLUSION

Sufficient evidence exists to develop perioperative guidelines for TXA use in many populations. Further studies evaluating perioperative TXA use in patients with a history of thromboembolism are warranted.

Antifibrinolytic Therapy for Cardiac Surgery

Antifibrinolytic therapy reduces bleeding and chest tube drainage output in cardiac surgical patients but is associated with potential side effects. Two phase-II studies with new compounds were terminated prematurely. There is increasing evidence of adverse side effects with tranexamic acid.

Issues in assessing products for the treatment of hemophilia - the intersection between efficacy, economics, and ethics

Following the obviation of the pathogen safety threats posed by previous generations of clotting factor concentrates for the treatment of hemophilia, the principal issue facing the patient community is timely access to adequate supplies of continuously improving therapies. The application of evidence-based medicine has enhanced the basis of hemophilia therapy, while resulting in some challenges to patient care. Increasingly, the criteria used for the approval and payment of treatment products by regulatory and reimbursement agencies, respectively, are becoming inflexible and unrealistic. This is occurring particularly in the requirements for demonstrating product efficacy. Concurrently, emerging evidence of the interpatient variability in the clinical response to therapy has led to the proposed personalization of therapeutic regimens. Possible impediments to optimal care include competitive tensions among suppliers who seek to gain label claims for reimbursement purposes, which result in clinical trial designs of, arguably, unethical design, carried out in poor countries. We synthesize these converging developments to suggest some changes to the current hemophilia treatment paradigm, which should make it more patient-centric and enable speedier access to new therapies.