Crofelemer, a novel agent for treatment of secretory diarrhea

Clinical Benefits of Octreotide for Managing Persistent Gastrointestinal Fluid Loss in Malignant Small Bowel Obstruction: A Case Report and Literature Review

Malignant small bowel obstruction (mSBO) is a frequent complication in patients with gastrointestinal or gynecologic cancers. For those with inoperable cancers and persistent obstructive symptoms, symptom palliation with a percutaneous gastrostomy tube (PGT) may be required. However, excessive fluid loss from the PGT can lead to significant fluid, electrolyte, and acid-base imbalances. We present a case of a man with metastatic colonic adenocarcinoma who developed mSBO, acute kidney injury, and metabolic alkalosis, all of which were effectively managed with octreotide.

Clinical course and therapeutic trial for a case of congenital secretory diarrhea due to novel GUCY2C variant

Chronic diarrhea presents a significant challenge for managing nutritional and electrolyte deficiencies, especially in children, given the higher stakes of impacting growth and developmental consequence. Congenital secretory diarrhea (CSD) compounds this further, particularly in the case of the activating variants of the guanylate-cyclase 2C (GUCY2C) gene. GUCY2C encodes for the guanylate-cyclase 2C (GC-C) receptor that activates the downstream cystic fibrosis transmembrane receptor (CFTR) that primarily drives the severity of diarrhea with an unclear extent of influence on other intestinal channels. Thus far, management for CSD primarily consists of mitigating nutritional, electrolyte, and volume deficiencies with no known pathophysiology-driven treatments. For activating variants of GUCY2C, experimental compounds have shown efficacy in vitro for direct inhibition of GC-C but are not currently available for clinical use. However, Crofelemer, a CFTR inhibitory modulator with negligible systemic absorption, can theoretically help to treat this type of CSD. Herein, we describe and characterize the clinical course of a premature male infant with a de novo missense variant of GUCY2C not previously reported and highly consistent with CSD. With multi-disciplinary family-directed decision-making, a treatment for CSD was evaluated for the first time to our knowledge with Crofelemer.

Crofelemer for the Management of Neratinib-Associated Diarrhea in Patients With HER2+ Early-Stage Breast Cancer

BACKGROUND

To evaluate the efficacy of crofelemer, a first in class anti-secretory anti-diarrheal agent, to manage neratinib-induced diarrhea in patients with early-stage breast cancer taking adjuvant neratinib.

PATIENTS AND METHODS

This single center, open label trial enrolled patients with Stage 2 to 3 HER2+ breast cancer taking adjuvant neratinib. One cohort took prophylactic crofelemer 125 mg bid and loperamide in the first 2 cycles, and as needed in subsequent cycles. The second cohort took dose-escalated neratinib with loperamide as needed (DE cohort). The primary endpoint was incidence of grade ≥ 3 diarrhea in the first 2 cycles.

RESULTS

Seven patients in the crofelemer cohort and 4 in the DE cohort were enrolled. In the first 2 cycles, 2 patients (29%) in the crofelemer cohort and 2 patients (50%) in the DE cohort experienced grade 3 diarrhea lasting 1 day on average. After cycle 2, no additional patients in either cohort had grade 3 diarrhea. Five of 7 patients controlled diarrhea with crofelemer alone. There were no grade 4 diarrhea events in either cohort. Three patients in the crofelemer cohort dose-reduced neratinib due to diarrhea in the first 2 cycles. Patients in the crofelemer cohort had an average of 0.58 diarrhea episodes/day. 82% experienced constipation, all grade 1.

CONCLUSIONS

This is the first study to investigate crofelemer for neratinib-induced diarrhea and demonstrates crofelemer activity in this setting. Further investigation of crofelemer for diarrhea secondary to cancer treatment is needed.

The International Natural Product Sciences Taskforce (INPST) and the power of Twitter networking exemplified through #INPST hashtag analysis

BACKGROUND

The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled "International Natural Product Sciences Taskforce" (INPST) was established in 2018, to bring together in collaborative environment individuals and organizations interested in natural product scientific research, and to empower their interactions by using digital communication tools.

METHODS

In this work, we present a general overview of INPST activities and showcase the specific use of Twitter as a powerful networking tool that was used to host a one-week "2021 INPST Twitter Networking Event" (spanning from 31st May 2021 to 6th June 2021) based on the application of the Twitter hashtag #INPST.

RESULTS AND CONCLUSION

The use of this hashtag during the networking event period was analyzed with Symplur Signals (https://www.symplur.com/), revealing a total of 6,036 tweets, shared by 686 users, which generated a total of 65,004,773 impressions (views of the respective tweets). This networking event's achieved high visibility and participation rate showcases a convincing example of how this social media platform can be used as a highly effective tool to host virtual Twitter-based international biomedical research events.

The Effect of Curcuma phaeocaulis Valeton (Zingiberaceae) Extract on Prion Propagation in Cell-Based and Animal Models

Prion diseases are neurodegenerative disorders in humans and animals for which no therapies are currently available. Here, we report that Curcuma phaeocaulis Valeton (Zingiberaceae) (CpV) extract was partly effective in decreasing prion aggregation and propagation in both in vitro and in vivo models. CpV extract inhibited self-aggregation of recombinant prion protein (PrP) in a test tube assay and decreased the accumulation of scrapie PrP (PrP^Sc) in ScN2a cells, a cultured neuroblastoma cell line with chronic prion infection, in a concentration-dependent manner. CpV extract also modified the course of the disease in mice inoculated with mouse-adapted scrapie prions, completely preventing the onset of prion disease in three of eight mice. Biochemical and neuropathological analyses revealed a statistically significant reduction in PrP^Sc accumulation, spongiosis, astrogliosis, and microglia activation in the brains of mice that avoided disease onset. Furthermore, PrP^Sc accumulation in the spleen of mice was also reduced. CpV extract precluded prion infection in cultured cells as demonstrated by the modified standard scrapie cell assay. This study suggests that CpV extract could contribute to investigating the modulation of prion propagation.

Identification of evodiamine and rutecarpine as novel TMEM16A inhibitors and their inhibitory effects on peristalsis in isolated Guinea-pig ileum

The transmembrane member 16A (TMEM16A)-encoded Ca2+-activated Cl- channel (CaCC) is expressed in interstitial cells of Cajal (ICCs) and involved in the generation of the slow-wave currents of gastrointestinal (GI) smooth muscles. TMEM16A modulators have been shown to positively or negatively regulate the contraction of gastrointestinal smooth muscle. Therefore, targeting the pharmacological modulation of TMEM16A may represent a novel treatment approach for gastrointestinal dysfunctions such as constipation and diarrhoea. In this study, evodiamine and rutecarpine were extracted from the traditional Chinese medicine Evodia rutaecarpa and identified as novel TMEM16A inhibitors with comparable inhibitory effects. Their effects on intestinal peristalsis were examined. Whole-cell patch clamp results show that evodiamine and rutecarpine inhibited TMEM16A Cl- currents in CHO cells. The half-maximal inhibition values (IC50) of evodiamine and rutecarpine on TMEM16A Cl- currents were 11.8 ± 1.3 μΜ and 9.2 ± 0.4 μM, and the maximal effect values (Emax) were 95.8 ± 5.1% and 99.1 ± 1.6%, respectively. The Lys384, Thr385, and Met524 in TMEM16A are critical for evodiamine and rutecarpine's inhibitory effects. Further functional studies show that both evodiamine and rutecarpine can significantly suppress the peristalsis in isolated guinea-pig ileum. These findings demonstrate that evodiamine and rutecarpine are new TMEM16A inhibitors and support the regulation effect of TMEM16A modulators on gastrointestinal motility.

Chronic intestinal failure and short bowel syndrome in Crohn's disease

Chronic intestinal failure (CIF) is a rare but feared complication of Crohn's disease. Depending on the remaining length of the small intestine, the affected intestinal segment, and the residual bowel function, CIF can result in a wide spectrum of symptoms, from single micronutrient malabsorption to complete intestinal failure. Management of CIF has improved significantly in recent years. Advances in home-based parenteral nutrition, in particular, have translated into increased survival and improved quality of life. Nevertheless, 60% of patients are permanently reliant on parenteral nutrition. Encouraging results with new drugs such as teduglutide have added a new dimension to CIF therapy. The outcomes of patients with CIF could be greatly improved by more effective prevention, understanding, and treatment. In complex cases, the care of patients with CIF requires a multidisciplinary approach involving not only physicians but also dietitians and nurses to provide optimal intestinal rehabilitation, nutritional support, and an improved quality of life. Here, we summarize current literature on CIF and short bowel syndrome, encompassing epidemiology, pathophysiology, and advances in surgical and medical management, and elucidate advances in the understanding and therapy of CIF-related complications such as catheter-related bloodstream infections and intestinal failure-associated liver disease.

Chemical Stability of the Botanical Drug Substance Crofelemer: A Model System for Comparative Characterization of Complex Mixture Drugs

As the second of a 3-part series of articles in this issue concerning the development of a mathematical model for comparative characterization of complex mixture drugs using crofelemer (CF) as a model compound, this work focuses on the evaluation of the chemical stability profile of CF. CF is a biopolymer containing a mixture of proanthocyanidin oligomers which are primarily composed of gallocatechin with a small contribution from catechin. CF extracted from drug product was subjected to molecular weight-based fractionation and thiolysis. Temperature stress and metal-catalyzed oxidation were selected for accelerated and forced degradation studies. Stressed CF samples were size fractionated, thiolyzed, and analyzed with a combination of negative-ion electrospray ionization mass spectrometry (ESI-MS) and reversed-phase-HPLC with UV absorption and fluorescence detection. We further analyzed the chemical stability data sets for various CF samples generated from reversed-phase-HPLC-UV and ESI-MS using data-mining and machine learning approaches. In particular, calculations based on mutual information of over 800,000 data points in the ESI-MS analytical data set revealed specific CF cleavage and degradation products that were differentially generated under specific storage/degradation conditions, which were not initially identified using traditional analysis of the ESI-MS results.

Antidiarrheal Drug Therapy

INTRODUCTION

Acute diarrhea often runs a self-limited course and little by way of treatment is needed except for oral rehydration therapy. Chronic diarrhea poses a longer-term problem. If not treatable with specific therapy aimed at the underlying pathophysiology, chronic diarrhea often needs long-term symptomatic therapy.

PURPOSE OF REVIEW

This paper aims to examine the options for symptomatic, nonspecific treatment of diarrhea.

RECENT FINDINGS

The most frequently used therapies are opiate antidiarrheal drugs. These drugs are effective for a wide variety of diarrheal conditions and generally can be used safely if monitored closely. They work by slowing motility and allowing more time for absorption. They vary in potency and in addictive liability. In recent years, a variety of other drugs have been developed, which provide more targeted therapy that can mitigate diarrhea in specific situations. These drugs work on other regulatory pathways in the gut or on mucosal absorptive mechanisms. There is evidence for efficacy for both traditional and newer agents used for the symptomatic management of diarrhea. Opiates are used most often for this indication. Other agents may benefit individuals, but further research is needed to establish indications and best practices.

A Perspective on the Phytopharmaceuticals Responsible for the Therapeutic Applications

The word phytopharmaceutical deals with a complex mixture of compounds derived from the plant source that is used as a medicine or drug. Primitive human societies have been depending on plants and plant products for various remedies. Several plants in the different forms have been reported in traditional medicine and to find a rational for the treatment of various diseases than to isolated single compounds. Many of the single compounds isolated from the plant origin are effectively used in the medicine. The search of natural products in drug discovery has been greatly enhanced in the last few years. The impetus to use phytopharmaceutical agents for the treatment of disease, most of the plant based drugs are quite safe and have lesser adverse effects and are claimed that it works as synergistic effects.

Molecular ion index assisted comprehensive profiling of B-type oligomeric proanthocyanidins in rhubarb by high performance liquid chromatography-tandem mass spectrometry

Proanthocyanidins (PAs) are major anti-diarrhea constituents in rhubarb, one of the frequently used traditional medicines. However, the phytochemical investigation of PAs in rhubarb was hampered by their strenuous purification and identification. In the present study, aiming to clarify the distribution of PAs in different rhubarb species, a molecular ion index was priorly established according to the structural features of B-type PAs, which led to a series of targeted discovery of oligomeric PAs in rhubarb by the HPLC-ESI-MS/MS method. Totally, 66 oligomeric PAs including 27 dimers, 29 trimers, and 10 tetramers were tentatively identified on the basis of their MS/MS spectra from 28 rhubarb samples derived from 5 Rheum species as R. palmatum, R. tanguticum, R. officinale, R. coreanum, and R. laciniatum. It is noteworthy that 6 propelargonidins, 14 prodelphinidins, and 10 procyanidin-tetramers were identified from rhubarb for the first time. The profiling comparison of these oligomeric PAs in different rhubarb samples was achieved by visualizing their abundance in a heat map, which indicated the dominant PAs in rhubarb were procyanidin-dimer and its galloylated derivatives.

Crofelemer for the symptomatic relief of non-infectious diarrhea in adult patients with HIV/AIDS on anti-retroviral therapy

Chronic diarrhea remains a common condition that affects people infected with human immunodeficiency virus (HIV) despite the widespread use of potent antiretroviral therapy. It is important that providers control this condition, as the persistence of diarrhea affects the quality of life of patients and may contribute to decreased adherence to antiretroviral therapy. Strategies to control diarrhea in patients with HIV infection include switching to a new antiretroviral regimen and/or the use of specific medications to control the diarrhea. This review aims to provide a concise evaluation of a newly approved medication (crofelemer) that has a novel mechanism of action and has received approval for the symptomatic relief of non-infectious diarrhea in adult patients with HIV on anti-retroviral therapy.

Potential Causes and Present Pharmacotherapy of Irritable Bowel Syndrome: An Overview

BACKGROUND

Irritable bowel syndrome (IBS) is currently one of the most common disorders of the digestive system in the Western society. Almost 2 out of 10 people suffer from IBS with women being more affected than men. IBS is associated with abdominal pain, bloating and altered stool consistency and imposes a heavy burden for the affected patients.

SUMMARY

The pathophysiology of IBS remains elusive although potential causes have been suggested, such as a deranged brain-gut signaling, hypersensitivity of visceral sensory afferent fibers, bacterial gastroenteritis, small intestinal bacterial overgrowth (SIBO), genetic alterations and food sensitivity. Targets for the pharmacotherapy of IBS include the serotonergic and opioidergic system, and the microbial population of the gut. Alternative therapies like traditional Chinese medicine have shown some success in the combat against IBS. Key Messages: Many therapeutics for the treatment of IBS have emerged in the past; however, only a few have met up with the expectations in larger clinical trials. Additionally, the multifactorial etiology of IBS and its variety of cardinal symptoms requires an individual set of therapeutics. This review provides a short overview of potential causes and current pharmacological therapeutics and of additional and alternative therapies for IBS.

ErbB small molecule tyrosine kinase inhibitor (TKI) induced diarrhoea: Chloride secretion as a mechanistic hypothesis

Diarrhoea is a common, debilitating and potentially life threatening toxicity of many cancer therapies. While the mechanisms of diarrhoea induced by traditional chemotherapy have been the focus of much research, the mechanism(s) of diarrhoea induced by small molecule ErbB TKI, have received relatively little attention. Given the increasing use of small molecule ErbB TKIs, identifying this mechanism is key to optimal cancer care. This paper critically reviews the literature and forms a hypothesis that diarrhoea induced by small molecule ErbB TKIs is driven by intestinal chloride secretion based on the negative regulation of chloride secretion by ErbB receptors being disrupted by tyrosine kinase inhibition.

Crofelemer: a review of its use in the management of non-infectious diarrhoea in adult patients with HIV/AIDS on antiretroviral therapy

Crofelemer (Fulyzaq) is a botanical drug substance (oligomeric proanthocyanidin) extracted from the stem bark latex of the Croton lechleri tree. Crofelemer undergoes minimal systemic absorption following oral administration; it acts locally within the gastrointestinal (GI) tract by inhibiting the two principal chloride ion channels in the luminal membrane of enterocytes. Crofelemer is the first (and so far only) agent to be approved by the US FDA specifically for the symptomatic relief of non-infectious (i.e. secretory) diarrhoea in adult patients with HIV/AIDS on antiretroviral therapy (ART). This approval was based on findings from the ADVENT study, a large (n = 376 randomized patients), multicentre, phase III trial in which the recommended dosage of oral crofelemer (125 mg twice daily) significantly reduced secretory diarrhoea in HIV-positive individuals on ART compared with placebo, as assessed over a 4-week period. Crofelemer was generally well tolerated in ADVENT (which included a 5-month placebo-free extension phase) and a 48-week, open-label, phase III safety study; infections and GI disorders were the most frequently reported treatment-emergent adverse events (TEAEs) in patients receiving the drug. Of note, the overall incidence of TEAEs was similar in the crofelemer and placebo groups during the 4-week placebo-controlled phase of ADVENT. Treatment with crofelemer had no appreciable effect on immune parameters, such as HIV viral load and CD4+ cell counts.

Crofelemer, a novel agent for treatment of non-infectious diarrhea in HIV-infected persons

Crofelemer is the first US FDA-approved drug for symptomatic relief in HIV-infected persons on antiretroviral therapy (ART) who have non-infectious diarrhea. With the availability of ART, there is increased survival and decrease in gastrointestinal opportunistic infections. However, diarrhea secondary to ART and HIV enteropathy is common in HIV-infected persons. Crofelemer is manufactured from the red latex sap of the Croton lechleri tree in South America. It has a unique mechanism leading to inhibition of chloride ion secretion by blocking chloride channels in the gastrointestinal lumen. This reduces efflux of sodium and water, which in turn reduces the frequency and consistency of diarrhea. Crofelemer is well tolerated due to minimal systemic absorption and has a good safety profile. The availability of crofelemer will likely have a positive impact on the quality of life in HIV-infected persons and also increase compliance to ART.

Recent advances and new perspectives in targeting CFTR for therapy of cystic fibrosis and enterotoxin-induced secretory diarrheas

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated chloride channel localized primarily at the apical surfaces of epithelial cells lining airway, gut and exocrine glands, where it is responsible for transepithelial salt and water transport. Several human diseases are associated with an altered channel function of CFTR. Cystic fibrosis (CF) is caused by the loss or dysfunction of CFTR-channel activity resulting from the mutations on the gene; whereas enterotoxin-induced secretory diarrheas are caused by the hyperactivation of CFTR channel function. CFTR is a validated target for drug development to treat these diseases. Significant progress has been made in developing CFTR modulator therapy by means of high-throughput screening followed by hit-to-lead optimization. Several oral administrated investigational drugs are currently being evaluated in clinical trials for CF. Also importantly, new ideas and methodologies are emerging. Targeting CFTR-containing macromolecular complexes is one such novel approach.

Etiology and pharmacologic management of noninfectious diarrhea in HIV-infected individuals in the highly active antiretroviral therapy era

Diarrhea remains a common problem for patients with human immunodeficiency virus (HIV) infection despite highly active antiretroviral therapies (HAART) and can negatively affect patient quality of life and lead to discontinuation or switching of HAART regimens. In the era of HAART, diarrhea from opportunistic infections is uncommon, and HIV-associated diarrhea often has noninfectious causes, including HAART-related adverse events and HIV enteropathy. Diarrhea associated with HAART is typically caused by protease inhibitors (eg, ritonavir), which may damage the intestinal epithelial barrier (leaky-flux diarrhea) and/or alter chloride ion secretion (secretory diarrhea). HIV enteropathy may result from direct effects of HIV on gastrointestinal tract cells and on the gastrointestinal immune system and gut-associated lymphoid tissue, which may be active sites of HIV infection and ongoing inflammation and mucosal damage. New therapies targeting the pathogenic mechanisms of noninfectious diarrheas are needed.

Developing novel antisecretory drugs to treat infectious diarrhea

Diarrhea, a disease of poverty and poor sanitation, kills an estimated two million children each year. Oral rehydration therapy is a very simple and inexpensive treatment that has significantly reduced mortality from secretory diarrhea caused by rotavirus, cholera and enterotoxigenic Escherichia coli. The efficacy and adoption of oral rehydration therapy would be enhanced by a drug that reduces fluid loss associated with these diseases and alleviates disease symptoms. Secretion and absorption by the intestine offer a number of potential drug targets to reduce fluid loss. Among these, the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is the most attractive because it is the primary driver of secretion in cases of diarrhea caused by enterotoxigenic bacteria. CFTR can be inhibited by both natural products and synthetic small molecules. iOWH032 is a synthetic CFTR inhibitor that has recently entered clinical trials for this indication.

Interleukin-13 (IL-13)/IL-13 receptor alpha1 (IL-13Ralpha1) signaling regulates intestinal epithelial cystic fibrosis transmembrane conductance regulator channel-dependent Cl- secretion

Interleukin-13 (IL-13) has been linked to the pathogenesis of inflammatory diseases of the gastrointestinal tract. It is postulated that IL-13 drives inflammatory lesions through the modulation of both hematopoietic and nonhematopoietic cell function in the intestine. To delineate the relevant contribution of elevated levels of intestinal IL-13 to intestinal structure and function, we generated an intestinal IL-13 transgenic mouse (iIL-13Tg). We show that constitutive overexpression of IL-13 in the small bowel induces modification of intestinal epithelial architecture (villus blunting, goblet cell hyperplasia, and increased epithelial proliferation) and epithelial function (altered basolateral → apical Cl(-) ion conductance). Pharmacological analyses in vitro and in vivo determined that elevated Cl(-) conductance is mediated by altered cystic fibrosis transmembrane conductance regulator expression and activity. Generation of iIL-13Tg/Il13rα1(-/-), iIL-13Tg/Il13rα2(-/-), and iIL-13Tg/Stat6(-/-) mice revealed that IL-13-mediated dysregulation of epithelial architecture and Cl(-) conductance is dependent on IL-13Rα1 and STAT-6. These observations demonstrate a central role for the IL-13/IL-13Rα1 pathway in the regulation of intestinal epithelial cell Cl(-) secretion via up-regulation of cystic fibrosis transmembrane conductance regulator, suggesting an important role for this pathway in secretory diarrhea.