Investigational new drugs for the treatment of chronic renal failure: an overview of the literature.

INTRODUCTION: Chronic kidney disease (CKD) is widespread throughout the world, with a high social and health impact. It is considered a 'silent killer' for its sudden onset without symptoms in the early stages of the disease. The main goal of nephrologists is to slow the progression of kidney disease and treat the associated symptoms with a range of new medications. AREAS COVERED: The aim of this systematic review is to analyze the new investigational drugs for the treatment of chronic renal failure. Data were obtained from the available scientific literature and from the ClinicalTrials.gov website. EXPERT OPINION: Among the drugs currently being researched, SGLT2 inhibitors appear to be the most promising drugs for the treatment of CKD, has they have slower progression of CKD and protection of cardiorenal function. An important role in the future of CKD treatment is played by autologous cell-therapy, which appears to be a new frontier in the treatment of CKD. Other therapeutic strategies are currently being investigated and have been shown to slow the progression of CKD. However, further studies are needed to determine whether these approaches may offer benefits in slowing the progression of CKD in the near future.

Investigational drugs for the treatment of dysmenorrhea.

INTRODUCTION: Dysmenorrhea is the most common cause of gynecological pain among women that has considerable impact on quality of life and psychosocial wellbeing. Non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal therapies are most commonly used to treat dysmenorrhea. However, given these drugs are often associated with bothersome side effects and are less effective when there is an underlying cause contributing to dysmenorrhea (e.g. endometriosis), a patient-centered approach to managing dysmenorrhea is important. Various new drugs are currently being investigated for the treatment of primary and secondary dysmenorrhea. AREAS COVERED: This review provides an updated overview on new therapeutic targets and investigational drugs for the treatment of primary and secondary dysmenorrhea. The authors describe the clinical development and implications of these drugs. EXPERT OPINION: Among the investigative drugs discussed in this review, anti-inflammatories show the most promising results for the treatment of dysmenorrhea. However, given some trials have considerable methodological limitations, many drugs cannot be currently recommended. Research focused on understanding the mechanisms involved in menstruation and its associated symptoms will be important to identify new therapeutic targets for dysmenorrhea. Further robust clinical trials are required to better understand the efficacy and safety of investigational drugs for treating primary and secondary dysmenorrhea.

A review of an investigational drug retatrutide, a novel triple agonist agent for the treatment of obesity.

BACKGROUND: Obesity is one of the critical public health problems in our society. It leads to various health conditions, such as type 2 diabetes mellitus, cardiovascular disease, hypertension, dyslipidaemia, and non-alcoholic fatty liver disease. With the rising incidence of obesity, there is a growing demand for new therapies which can effectively manage body weight and improve health. CURRENT EVIDENCE: Currently under development, multi-receptor agonist drugs may offer a promising solution to meet this unmet medical need. Retatrutide is a novel triple receptor agonist peptide that targets the glucagon receptor (GCGR), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon-like peptide-1 receptor (GLP-1R). This novel drug has the potential to treat metabolic abnormalities associated with obesity as well as diseases resulting from it due to its distinct mechanism of action. The Phase III trial of this pipeline drug for treating type 2 diabetes mellitus, non-alcoholic fatty liver disease, and obesity started on August 28, 2023. The results of a Phase II clinical trial have demonstrated significant weight reduction in overweight and obese adults. Specifically, the trial reported an average weight loss of 17.5% and 24.4% at 24 and 48 weeks, respectively. CONCLUSIONS: These findings hold promise for the development of effective weight loss interventions in this population group. There is a need for more phase III studies to provide sufficient clinical evidence for the effectiveness of retatrutide, as current evidence is limited to phase II studies and has yet to prove its worth in a larger population. Here, we aimed to provide an overview of retatrutide's safety and effectiveness in treating obesity.

Drugs of the future for diarrhea-predominant irritable bowel syndrome: an overview of current investigational drugs.

INTRODUCTION: Irritable bowel syndrome (IBS) has a significant impact on society and quality of life. Current treatments are ineffective, and new investigational drugs are necessary. AREAS COVERED: Numerous potential therapies are developing, targeting different areas such as cannabinoid signaling, opioid receptors, tachykinin (NK2) receptors, ß3-adrenergic receptors, intestinal microbiota, inflammation, and 5HT receptors. Clinical trial evidence has shown that loperamide, eluxadoline, alosetron, ramosetron, bile acid sequestrants, and rifaximin can modulate GI alterations and benefit patients with IBS-D. Among the potential therapies, ibodutant, ibudilast, blautix, BOS-589, solabegron, vibegron, olorinab, ebastine, and ORP-101 have demonstrated possible effects but remain confirmed. EXPERT OPINION: Individuals with IBS-D require cost-effective treatment options that do not impede their productivity or that of their caregivers. This is necessary for consistent healthcare and improved quality of life. Therefore, we should focus on developing new, efficient, and affordable medications for IBS-D. The government, insurers, and society must recognize this need and collaborate to ensure its fulfillment.

The impact of current investigational drugs for acne on future treatment strategies.

INTRODUCTION: Acne vulgaris is one of the most prevalent diseases worldwide with a considerably high cost and a burden on quality of life. There are currently many topical and systemic therapies for acne; however, many are limited by their local adverse event profile. This review provides an update on current, novel Phase I and II trials for acne vulgaris. AREAS COVERED: This review searched the National Institutes of Health US National Library of Medicine online database of clinical trials (ClinicalTrials.gov) for ongoing Phase I and II trials. Only papers discussing novel therapies were discussed, and combinations of previously FDA-approved drugs were excluded. EXPERT OPINION: The current investigational approaches to acne treatment reflect an attempt to mitigate the underlying cause of acne pathogenesis. By targeting key mechanisms involved, studies aim to show long-term improvement with less frequent treatment use. This provides potential for more tolerable treatments with better patient adherence, in turn leading to increased efficacy.

Human neural progenitor cell models to study the antiviral effects and neuroprotective potential of approved and investigational human cytomegalovirus inhibitors.

Human cytomegalovirus (HCMV) is the viral leading cause of congenital defects in newborns worldwide. Many aspects of congenital CMV (cCMV) infection, which currently lacks a specific treatment, as well as the main determinants of neuropathogenesis in the developing brain during HCMV infection are unclear. In this study, we modeled HCMV infection at different stages of neural development. Moreover, we evaluated the effects of both approved and investigational anti-HCMV drugs on viral replication and gene expression in two different neural progenitor cell lines, i.e., human embryonic stem cells-derived neural stem cells (NSCs) and fetus-derived neuroepithelial stem (NES) cells. Ganciclovir, letermovir, nitazoxanide, and the ozonide OZ418 reduced viral DNA synthesis and the production of infectious virus in both lines of neural progenitors. HCMV infection dysregulated the expression of genes that either are markers of neural progenitors, such as SOX2, NESTIN, PAX-6, or play a role in neurogenesis, such as Doublecortin. Treatment with antiviral drugs had different effects on HCMV-induced dysregulation of the genes under investigation. This study contributes to the understanding of the molecular mechanisms of cCMV neuropathogenesis and paves the way for further consideration of anti-HCMV drugs as candidate therapeutic agents for the amelioration of cCMV-associated neurological manifestations.

A win ratio-based framework to combine multiple clinical endpoints in exploratory basket trials.

In contemporary exploratory phase of oncology drug development, there has been an increasing interest in evaluating investigational drug or drug combination in multiple tumor indications in a single basket trial to expedite drug development. There has been extensive research on more efficiently borrowing information across tumor indications in early phase drug development including Bayesian hierarchical modeling and the pruning-and-pooling methods. Despite the fact that the Go/No-Go decision for subsequent Phase 2 or Phase 3 trial initiation is almost always a multi-facet consideration, the statistical literature of basket trial design and analysis has largely been limited to a single binary endpoint. In this paper we explore the application of considering clinical priorities of multiple endpoints based on matched win ratio to the basket trial design and analysis. The control arm data will be simulated for each tumor indication based on the corresponding null assumptions that could be heterogeneous across tumor indications. The matched win ratio matching on the tumor indication can be performed for individual tumor indication, pooled data, or the pooled data after pruning depending on whether an individual evaluation or a simple pooling or a pruning-and-pooling method is used. We conduct the simulation studies to evaluate the performance of proposed win ratio-based framework and the results suggest the proposed framework could provide desirable operating characteristics.

Aggregate IND Safety Reporting for Smaller Companies and Programs.

The United States (US) Food and Drug Administration (FDA) Investigational New Drug (IND) Final Rule (US FDA, Final rule: Investigational new drug safety reporting requirements for human drug and biological products and safety reporting requirements for bioavailability and bioequivalence studies in humans, 2010) applies to all human drugs and biological products being studied under an IND. The Final Rule specifies that a sponsor must file an IND safety report for any Suspected Unexpected Serious Adverse Reaction (SUSAR) of a medicinal product being investigated. To make a proper SUSAR classification, sponsors need to go beyond conventional Data Monitoring Committees (DMCs) with an interdisciplinary effort, using all relevant data (including data outside clinical trials), to make judgments on the possibility of serious adverse events being caused by the study drug-rather than the underlying condition of the patient or a concomitant therapy. Ball et al. (Ball et al. in Ther Innov Regul Sci 55:705-716, 2021) have reported on how the Final Rule has been implemented by large pharmaceutical companies. This paper explores the experiences of small sponsor companies regarding the Final Rule, to understand the current challenges that they have been facing to meet aggregate IND safety reporting requirements.

Progress in the treatment of anal cancer: an overview of the latest investigational drugs.

INTRODUCTION: Anal cancer, a rare malignancy accounting for 2.5-3.0% of gastrointestinal cancers, primarily manifests as squamous cell carcinoma associated with HPV. Recent years have witnessed significant advancements in managing squamous cell carcinoma of the anus (SCCA), particularly with the introduction of immune checkpoint inhibitors (ICIs) and randomized data on front-line chemotherapy. AREAS COVERED: This review discusses the current standard treatments for both early and advanced SCCA, based on published data. The authors then describe the new approaches, focusing on ICI combinations, targeted agents, T-cell adoptive therapy, and HPV-therapeutic vaccines. EXPERT OPINION: The current standard treatment for SCCA includes front-line carboplatin and paclitaxel, with pembrolizumab and nivolumab as later-line options. While modified DCF has shown promise in single-arm studies, its role as a front-line therapy requires confirmation through randomized data. We eagerly anticipate the results of phase 3 trials investigating the front-line chemo-immunotherapy for metastatic SCCA and ICI consolidation following chemoradiation for early-stage SCCA. Novel approaches like T-cell adoptive therapy, HPV-therapeutic vaccines, and bifunctional antibodies combined with HPV vaccines are in early-stage trials for HPV-mediated tumors, including HPV-positive SCCA. These approaches targeting HPV epitopes may eventually gain tumor-agnostic approval, although their role in SCCA may take time to establish.

New investigational drugs to treat Sjogren's syndrome: lessons learnt from immunology.

INTRODUCTION: Sjögren's syndrome is a heterogeneous autoimmune condition that impairs quality of life because of dryness, fatigue, pain, and systemic involvements. Current treatment largely depends on empirical evidence, with no effective therapy approved. Clinical trials on targeted drugs often fail to report efficacy due to common factors. AREAS COVERED: This review summarizes the pathogenesis and what caused the failure of new investigational drugs in clinical trials, highlighting solutions for more effective investigations, with greater consistency between research outcomes, clinical use, and patient needs. EXPERT OPINION: Unlinked pathobiology with symptoms resulted in misidentified targets and disappointing trials. Useful stratification tools are necessary for the heterogeneous SS patients. Composite endpoints or improvements in ESSDAI scores are needed, considering the high placebo response, and the unbalance between symptom burden and disease activity. Compared to classic biologics, targeted cell therapy will be a more promising field of investigation in the coming years.

Physiological Indirect Response Model to Omics-Powered Quantitative Systems Pharmacology Model.

Over the past several decades, mathematical modeling has been applied to increasingly wider scopes of questions in drug development. Accordingly, the range of modeling tools has also been evolving, as showcased by contributions of Jusko and colleagues: from basic pharmacokinetics/pharmacodynamics (PK/PD) modeling to today's platform-based approach of quantitative systems pharmacology (QSP) modeling. Aimed at understanding the mechanism of action of investigational drugs, QSP models characterize systemic effects by incorporating information about cellular signaling networks, which is often represented by omics data. In this perspective, we share a few examples illustrating approaches for the integration of omics into mechanistic QSP modeling. We briefly overview how the evolution of PK/PD modeling into QSP has been accompanied by an increase in available data and the complexity of mathematical methods that integrate it. We discuss current gaps and challenges of integrating omics data into QSP models and propose several potential areas where integrated QSP and omics modeling may benefit drug development.

In vitro and in vivo pharmacokinetics, disposition, and drug-drug interaction potential of tinengotinib (TT-00420), a promising investigational drug for treatment of cholangiocarcinoma and other solid tumors.

Early-stage clinical evaluation of tinengotinib (TT-00420) demonstrated encouraging preliminary efficacies in multiple types of refractory cancers, including fibroblast growth factor receptors (FGFR) inhibitors relapsed cholangiocarcinoma (CCA), castrate-resistant prostate cancer (CRPC), and HR+/HER2- breast cancer and triple negative breast cancer (TNBC). To further evaluate drug-like properties of the drug candidate, it is imperative to understand its metabolism and pharmacokinetic properties. This manuscript presented the investigation results of in vitro permeability, plasma protein binding, metabolic stability, metabolite identification, and drug-drug interaction of tinengotinib. Preclinical ADME (absorption, distribution, excretion, and metabolism) studies in rats and dogs was also conducted using a radioactive labeled tinengotinib, [14C]tinengotinib. Tinengotinib was found to have high permeability and high plasma protein binding and equally distributed between blood and plasma. There were no unique metabolites in human liver microsomes and tinengotinib showed moderate hepatic clearance. Tinengotinib is neither a potential inhibitor nor an inducer of P450 enzymes at clinically relevant concentrations, and unlikely to cause drug-drug interactions when used in combination with other drugs mediated by a key transporter, either as victim or perpetrator. Taken together, tinengotinib demonstrated a minimal risk of clinically relevant drug-drug interactions. Tinengotinib showed good oral bioavailability and dose-dependent exposures in both rat and dog after oral administration. The total radioactivity was largely distributed in the gastrointestinal system and liver, and tinengotinib could not easily pass through the blood-brain barrier. The major drug-related component in rat and dog plasma was unchanged drug (>89 %) with primary route of elimination via feces (>93 % of the dose) and minor via renal excretion (<4 % of the dose). Tinengotinib metabolism is mediated largely by CYP3A4, with minor contributions from CYP2D6 and CYP2C8. Major metabolic pathways include oxidation, oxidative cleavage of the morpholine ring, glucuronide and glutathione conjugations. The overall preclinical pharmacokinetics profile supported the selection and development of tinengotinib as a clinical candidate.

Decisions on Non-oncology Breakthrough Therapy Designation Requests in 2017-2019.

BACKGROUND: The US Food and Drug Administration's Breakthrough Therapy Designation (BTD) program is intended to facilitate and expedite development of investigational drugs to address unmet medical needs. The objective of this study is to provide an update on FDA's process for review of BTD requests. METHODS: We reviewed Center for Drug Evaluation and Research (CDER) decisions to grant or deny breakthrough therapy designation requests for non-oncology drugs or biological products ("drugs") from January 1, 2017, through December 31, 2019. Data collection included characteristics of the corresponding drug and condition, reasons for granting or denying breakthrough therapy status, reasons for rescinding or withdrawing breakthrough therapy status after a request was granted (if applicable), and subsequent marketing approval status through 2022. RESULTS: Among 240 requests, 93 (39%) requests were granted and 147 (61%) requests were denied. Granting of requests was more common for conditions where no therapy was available or for orphan diseases. Common reasons for denial included data-related issues, insufficient treatment effect, inadequate study design, endpoint attributes, safety issues, and reliance on post hoc analyses. Among 28 drugs receiving marketing approval as of the end of 2022 for the indication for which BTD was previously granted, 21 (75%) involved a first-in-class mechanism of action. CONCLUSIONS: This analysis describes CDER's decision-making process related to review of requests for breakthrough therapy designations and enhances public awareness regarding efforts to expedite drug development.

Post-trial access to investigational drugs in India: addressing challenges in the regulatory framework.

Through the New Drugs and Clinical Trials Rules, 2019 (2019 Rules), India has developed the rules governing post-trial access (PTA) to new drugs or investigational new drugs. However, inconsistencies and interpretational challenges exist in the application of the 2019 Rules and the Indian Council of Medical Research Guidelines 2017. This conflation poses a real harm to the trial participants, specifically the ones with limited access to healthcare facilities. Since drug laws in India do not expressly deal with other forms of access like the 'Compassionate Use' or 'Expanded Access' mechanism, demarcating the scope and describing the strategies for PTA are the need of the hour. We propose possible strategies to address inadequacies in the regulatory regime and establish 'win-win' situations among all stakeholders. We further argue that India is well positioned to provide leadership by developing detailed PTA provisions and may set a potential path for the other clinical trial host countries.

The Importance of Assessing Drug Exposure and Medication Adherence in Evaluating Investigational Medications: Ensuring Validity and Reliability of Clinical Trial Results.

The objective of this current opinion paper is to draw global attention to medication adherence, emphasizing its crucial role in drug trials. Frequently, trialists lean on traditional approaches to assess medication adherence, which, while comfortable, may only reveal what trialists desire rather than offering the essential insights needed for informed decision making in drug development. Understanding drug exposure and medication adherence is paramount when evaluating the effectiveness and safety of investigational medications. Without a comprehensive understanding of how patients adhere to their prescribed treatment regimens, the integrity and dependability of clinical trial results can be compromised. This paper emphasizes the need for measures that accurately and reliably assess medication intake behaviors, enabling the differentiation between minor dosing errors and significant deviations that may impact the drug's efficacy and safety. Accurate knowledge of drug exposure empowers researchers to make informed decisions, identify potential confounding factors, and appropriately interpret study outcomes, ultimately ensuring the validity and reliability of the research findings. By prioritizing drug exposure assessment and medication adherence measurement, clinical trials can enhance their scientific rigor, contribute to more accurate evaluations of investigational medications, and ultimately speed up the development process.

Use of suboptimal control arms in randomized clinical trials of investigational cancer drugs in China, 2016-2021: An observational study.

BACKGROUND: The use of suboptimal controls in randomized trials of new cancer drugs can produce potentially unreliable clinical efficacy results over the current standard of care and expose patients to substandard therapy. We aim to investigate the proportion of randomized trials of investigational cancer drugs that used a suboptimal control arm and the number of trial participants at risk of exposure to suboptimal treatments in China. The association between the use of a suboptimal control and concluding statistical significance on the primary endpoint was also examined. METHODS AND FINDINGS: This observational study included randomized controlled trials (RCTs) of cancer drugs that were authorized by specific Chinese institutional review boards between 2016 and 2021, supporting investigational new drug applications of these drugs in China. The proportion of trials that used a suboptimal control arm and the total number of trial participants at risk of exposure to suboptimal treatments were calculated. In a randomized trial for a specific condition, a comparator was deemed suboptimal if it was not recommended by clinical guidelines published in priori or if there existed a regimen with a higher level of recommendation for the indication. The final sample included 453 Phase II/III and Phase III randomized oncology trials. Overall, 60 trials (13.2%) adopted a suboptimal control arm. Among them, 58.3% (35/60) used comparators that were not recommended by a prior guideline for the indication. The cumulative number of trial participants at risk of exposure to suboptimal treatments totaled 18,610 by the end of 2021, contributing 15.1% to the total number of enrollees of all sampled RCTs in this study. After adjusting for the year of ethical approval, region of participant recruitment, line of therapy, and cancer site, second-line therapies (adjusted odds ratio [aOR] = 2.7, 95%CI [1.2, 5.9]), adjuvant therapies (aOR = 8.9, 95% CI [3.4, 23.1]), maintenance therapies (aOR = 5.2, 95% CI [1.6, 17.0]), and trials recruiting participants in China only (aOR = 4.1, 95% CI [2.1, 8.0]) were more likely to adopt a suboptimal control. For the 105 trials with publicly available results, no statistically significant difference was observed between the use of a suboptimal control and concluding positive on the primary endpoint (100.0% [12/12] versus 83.9% [78/93], p = 0.208). The main limitation of this study is its reliance on clinical guidelines that could vary across cancer types and time in assessing the quality of the control groups. CONCLUSIONS: In this study, over one-eighth of randomized trials of cancer drugs registered to apply for regulatory approval in China used a suboptimal comparator. Our results highlight the necessity to refine the design of randomized trials to generate optimal clinical evidence for new cancer therapies.

Efficacy and safety of compassionate use for rare diseases: a scoping review from 1991 to 2022.

BACKGROUND: Compassionate use is a system that provides patients with expedited access to drugs which has not yet been approved, but currently in clinical trials. The investigational drugs have been authorized for compassionate use in cases involving patients suffered from life-threatening diseases and with no alternative treatments. For instance, patients afflicted with highly heterogeneous rare diseases are eligible for treatment assistance through the compassionate use program. This study aims to investigate the characteristics of compassionate use in the context of rare diseases, evaluate the efficacy and safety of compassionate use for rare diseases, and analyze the marketing approval of investigational drugs. METHODS: The case reports/case series of compassionate use were collected by conducting searches on Embase, PubMed, Web of Science, CNKI and SinoMed, spanning from January 1991 to December 2022. Subsequently, two independent reviewers evaluated these reports. Case reports/case series that met the inclusion criteria and exclusion criteria were enrolled. Information extracted from these reports and series included patients' basic information, the investigational drug's name, its indication, adverse events, treatment outcomes, and other relevant data. RESULTS: A total of forty-six studies were included, encompassing 2079 patients with an average age of 38.1 years. Thirty-nine different drugs were involved in 46 studies. Furthermore, neoplasms emerged as the most common therapeutic area for compassionate use in rare disease management (23/46, 50.0%). Regarding the treatment efficacy, four studies reported successful disease resolution, while 35 studies observed symptom improvement among patients. Conversely, four studies documented no significant effects on patients' diseases. Moreover, one study reported worsened results following compassionate use, while the efficacy was not described in 2 studies. Adverse events were reported in 31 studies (67.4%) because of the compassionate use, while no adverse events occurred in 13 studies (28.3%). In other 2 studies, there was no description about whether treatment-emergent adverse events (TEAEs) were happened. 136 patients (6.5%) had Grade 5 adverse events (death), of which 19 deaths (0.9%) were considered to be related to compassionate use. Furthermore, the investigational drugs in 33 studies (33/46, 71.7%) received new drug approval at the end of January 31, 2023.The time lag from the start of the compassionate use to the formal approval of the investigational drug was 790.5 (IQR 359-2199.3) days. We found that in 11 studies, encompassing 9 different drugs, some compassionate use indications had not received regulatory authorities at the end of January 31, 2023. CONCLUSION: The current status of compassionate use for rare diseases was clarified systematically in this study. Compassionate use of investigational drug is a significant treatment option for rare disease. In general, compassionate use appears to demonstrate favorable efficacy in the context of rare diseases, with a significant proportion of compassionate use drugs subsequently receiving marketing approval. However, the safety of drugs for compassionate use cannot be fully evaluated due to the safety data were not covered in some enrolled studies. Therefore, the establishment of an adverse event reporting system specific to compassionate use is warranted.

Experimental drugs for the treatment of idiopathic intracranial hypertension (IIH): shedding light on phase I and II trials.

INTRODUCTION: Idiopathic intracranial hypertension is a neurological condition characterized by a raised intracranial pressure and papilledema that causes debilitating headaches. While the extent of the pathophysiology is being discovered, the condition is emerging as a systemic metabolic disease distinct to people living with obesity alone. Idiopathic intracranial hypertension is becoming more common and therefore establishing licensed therapeutics is a key priority. AREA COVERED: The translation of preclinical work in idiopathic intracranial hypertension is evident by the two early phase trials evaluating 11-ß-hydroxysteroid dehydrogenase inhibitor, AZD4017, and a glucagon like peptide-1 receptor agonist, Exenatide. This review summarizes these two early phase trials evaluating targeted medicines for the treatment of intracranial pressure. The modulation of these two distinct mechanisms have potential for therapeutic intervention in people living with idiopathic intracranial hypertension. EXPERT OPINION: The clinical trial landscape in idiopathic intracranial hypertension is a challenge due to the rarity of the disease and the lack of agreed meaningful trial outcomes. Further preclinical work to fully understand the pathogenesis is required to enable personalized targeted drug treatment.

Hepatic encephalopathy: investigational drugs in preclinical and early phase development.

INTRODUCTION: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, in patients with liver disease, which affects life quality and span. Current treatments are lactulose or rifaximin, acting on gut microbiota. Treatments aiming ammonia levels reduction have been tested with little success. AREAS COVERED: Pre-clinical research shows that the process inducing HE involves sequentially: liver failure, altered microbiome, hyperammonemia, peripheral inflammation, changes in immunophenotype and extracellular vesicles and neuroinflammation, which alters neurotransmission impairing cognitive and motor function. HE may be reversed using drugs acting at any step: modulating microbiota with probiotics or fecal transplantation; reducing peripheral inflammation with anti-TNFα, autotaxin inhibitors or silymarin; reducing neuroinflammation with sulforaphane, p38 MAP kinase or phosphodiesteras 5 inhibitors, antagonists of sphingosine-1-phosphate receptor 2, enhancing meningeal lymphatic drainage or with extracellular vesicles from mesenchymal stem cells; reducing GABAergic neurotransmission with indomethacin or golexanolone. EXPERT OPINION: A factor limiting the progress of HE treatment is the lack of translation of research advances into clinical trials. Only drugs acting on microbiota or ammonia reduction have been tested in patients. It is urgent to change the mentality on how to approach HE treatment to develop clinical trials to assess drugs acting on the immune system/peripheral inflammation, neuroinflammation or neurotransmission to improve HE.