Efficacy of Ibrexafungerp (SCY-078) against Candida auris in an In Vivo Guinea Pig Cutaneous Infection Model

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

Meeting the Therapeutic Challenges of Emergent and Rare Invasive Fungal Diseases Through Novel Clinical Trial Designs

Treatments for emerging and rare invasive fungal diseases (IFDs) represent a critical unmet medical need. For IFDs that occur less frequently than invasive aspergillosis, such as mucormycosis, hyalohyphomycosis, and phaeohyphomycosis, randomized controlled clinical trials are impractical and unlikely to meet urgent public health needs. Understanding regulatory approaches for approval of drugs for rare cancers and rare metabolic diseases could help meet the challenges of studying drugs for rare IFDs. A single-arm, controlled clinical trial with a high-quality external control(s), with confirmatory evidence from nonclinical studies, including pharmacokinetic/pharmacodynamic data in predictive animal models of the disease may support findings of effectiveness of new drugs and biologics. Control populations may include historical controls from published literature, patient registries, and/or contemporaneous external control groups. Continuous engagement among clinicians, industrial sponsors, and regulatory agencies to develop consensus on trial design and innovative development pathways for emergent and rare invasive fungal diseases is important.

Ibrexafungerp: A narrative overview

Ibrexafungerp (IBX) is a new antifungal drug that recently entered the antifungal landscape. It disrupts fungal cell wall synthesis by non-competitive inhibition of the β-(1,3)-D-glucan (BDG) synthase enzyme. It has demonstrated activity against a range of pathogens including Candida and Aspergillus spp., as well as retaining its activity against azole-resistant and echinocandin-resistant strains. It also exhibits anti-biofilm properties. Pharmacokinetic (PK) studies revealed favorable bioavailability, high protein binding, and extensive tissue distribution with a low potential for CYP-mediated drug interactions. It is characterized by the same mechanism of action of echinocandins with limited cross-resistance with other antifungal agents. Resistance to this drug can arise from mutations in the FKS genes, primarily FKS2 mutations in Nakaseomyces glabrata. In vivo, IBX was found to be effective in murine models of invasive candidiasis (IC) and invasive pulmonary aspergillosis (IPA). It also showed promising results in preventing and treating Pneumocystis jirovecii infections. Clinical trials showed that IBX was effective and non-inferior to fluconazole in treating vulvovaginal candidiasis (VVC), including complicated cases, as well as in preventing its recurrence. These trials positioned it as a Food and Drug Administration (FDA)-approved option for the treatment and prophylaxis of VVC. Trials showed comparable responses to standard-of-care in IC, with favorable preliminary results in C. auris infections in terms of efficacy and tolerability as well as in refractory cases of IC. Mild adverse reactions have been reported including gastrointestinal symptoms. Overall, IBX represents a significant addition to the antifungal armamentarium, with its unique action, spectrum of activity, and encouraging clinical trial results warranting further investigation.

Review of treatment options for a multidrug-resistant fungus: Candida auris

Candida auris is a widely distributed, highly lethal, multidrug-resistant fungal pathogen. It was first identified in 2009 when it was isolated from fluid drained from the external ear canal of a patient in Japan. Since then, it has caused infectious outbreaks in over 45 countries, with mortality rates approaching 60%. Drug resistance is common in this species, with a large proportion of isolates displaying fluconazole resistance and nearly half are resistant to two or more antifungal drugs. In this review, we describe the drug resistance mechanism of C. auris and potential small-molecule drugs for treating C. auris infection. Among these antifungal agents, rezafungin was approved by the US Food and Drug Administration (FDA) for the treatment of candidemia and invasive candidiasis on March 22, 2023. Ibrexafungerp and fosmanogepix have entered phase III clinical trials.

Mechanisms of pathogenicity for the emerging fungus Candida auris

Candida auris recently emerged as an urgent public health threat, causing outbreaks of invasive infections in healthcare settings throughout the world. This fungal pathogen persists on the skin of patients and on abiotic surfaces despite antiseptic and decolonization attempts. The heightened capacity for skin colonization and environmental persistence promotes rapid nosocomial spread. Following skin colonization, C. auris can gain entrance to the bloodstream and deeper tissues, often through a wound or an inserted medical device, such as a catheter. C. auris possesses a variety of virulence traits, including the capacity for biofilm formation, production of adhesins and proteases, and evasion of innate immune responses. In this review, we highlight the interactions of C. auris with the host, emphasizing the intersection of laboratory studies and clinical observations.

Public Health Research Priorities for Fungal Diseases: A Multidisciplinary Approach to Save Lives

Fungal infections can cause severe disease and death and impose a substantial economic burden on healthcare systems. Public health research requires a multidisciplinary approach and is essential to help save lives and prevent disability from fungal diseases. In this manuscript, we outline the main public health research priorities for fungal diseases, including the measurement of the fungal disease burden and distribution and the need for improved diagnostics, therapeutics, and vaccines. Characterizing the public health, economic, health system, and individual burden caused by fungal diseases can provide critical insights to promote better prevention and treatment. The development and validation of fungal diagnostic tests that are rapid, accurate, and cost-effective can improve testing practices. Understanding best practices for antifungal prophylaxis can optimize prevention in at-risk populations, while research on antifungal resistance can improve patient outcomes. Investment in vaccines may eliminate certain fungal diseases or lower incidence and mortality. Public health research priorities and approaches may vary by fungal pathogen.

Navigating the New Reality: A Review of the Epidemiological, Clinical, and Microbiological Characteristics of Candida auris, with a Focus on Children

During the past decade, Candida auris emerged across the world, causing nosocomial outbreaks in both pediatric and adult populations, particularly in intensive care settings. We reviewed the epidemiological trends and the clinical and microbiological characteristics of C. auris infection, focusing on the pediatric population. The review is based on 22 studies, which included about 250 pediatric patients with C. auris infection, across multiple countries; neonates and premature babies were the predominant pediatric patient group affected. The most common type of infection reported was bloodstream infection, which was associated with exceptionally high mortality rates. Antifungal treatment varied widely between the patients; this signifies a serious knowledge gap that should be addressed in future research. Advances in molecular diagnostic methods for rapid and accurate identification and for detection of resistance may prove especially valuable in future outbreak situations, as well as the development of investigational antifungals. However, the new reality of a highly resistant and difficult-to-treat pathogen calls for preparedness of all aspects of patient care. This spans from laboratory readiness, to raising awareness among epidemiologists and clinicians for global collaborative efforts to improve patient care and limit the spread of C. auris.

Candida auris in Austria-What Is New and What Is Different

Candida auris is a novel and emerging pathogenic yeast which represents a serious global health threat. Since its first description in Japan 2009, it has been associated with large hospital outbreaks all over the world and is often resistant to more than one antifungal drug class. To date, five C. auris isolates have been detected in Austria. Morphological characterization and antifungal susceptibility profiles against echinocandins, azoles, polyenes and pyrimidines, as well as the new antifungals ibrexafungerp and manogepix, were determined. In order to assess pathogenicity of these isolates, an infection model in Galleria mellonella was performed and whole genome sequencing (WGS) analysis was conducted to determine the phylogeographic origin. We could characterize four isolates as South Asian clade I and one isolate as African clade III. All of them had elevated minimal inhibitory concentrations to at least two different antifungal classes. The new antifungal manogepix showed high in vitro efficacy against all five C. auris isolates. One isolate, belonging to the African clade III, showed an aggregating phenotype, while the other isolates belonging to South Asian clade I were non-aggregating. In the Galleria mellonella infection model, the isolate belonging to African clade III exhibited the lowest in vivo pathogenicity. As the occurrence of C. auris increases globally, it is important to raise awareness to prevent transmission and hospital outbreaks.

Small molecules for combating multidrug-resistant superbug Candida auris infections

Candida auris is emerging as a major global threat to human health. C. auris infections are associated with high mortality due to intrinsic multi-drug resistance. Currently, therapeutic options for the treatment of C. auris infections are rather limited. We aim to provide a comprehensive review of current strategies, drug candidates, and lead compounds in the discovery and development of novel therapeutic agents against C. auris. The drug resistance profiles and mechanisms are briefly summarized. The structures and activities of clinical candidates, drug combinations, antifungal chemosensitizers, repositioned drugs, new targets, and new types of compounds will be illustrated in detail, and perspectives for guiding future research will be provided. We hope that this review will be helpful to prompting the drug development process to combat this fungal pathogen.

Recent Antifungal Pipeline Developments against Candida auris: A Systematic Review

The alarming spread and impact of multidrug-resistant Candida auris infections alongside the limited therapeutic options have prompted the development of new antifungals. These promising agents are currently in different stages of development, offering novel dosing regimens and mechanisms of action. A systematic search in MEDLINE, EMBASE, Web of Science, and Scopus up to 27 June 2022 was conducted to find relevant articles reporting data of in vitro activity and in vivo efficacy of investigational antifungals against C. auris. These included new additions to existing antifungal classes (rezafungin and opelconazole), first-in-class drugs such as ibrexafungerp, manogepix/fosmanogepix, olorofim and tetrazoles (quilseconazole, oteseconazole and VT-1598), as well as other innovative agents like ATI-2307, MGCD290 and VL-2397. From 592 articles retrieved in the primary search, 27 met the eligibility criteria. The most studied agent was manogepix/fosmanogepix (overall MIC₉₀: 0.03 mg/L), followed by ibrexafungerp (overall MIC₉₀: 1 mg/L) and rezafungin (overall MIC mode: 0.25 mg/L), while VT-1598 and ATI-2307 were the least explored drugs against C. auris. All these compounds demonstrated significant improvements in survival and reduction in tissue fungal burden on neutropenic animal models of candidemia due to C. auris. Continual efforts towards the discovery of new treatments against this multidrug-resistant fungus are essential.

Update on the Pathogenesis, Virulence, and Treatment of Candida auris

Candida auris is an emerging, multi-drug resistant fungal pathogen that causes considerable morbidity and mortality. First identified in Japan in 2009, it has since been reported in more than 40 countries. C. auris can persist for long periods on different environmental surfaces as well as the skin. Clinical isolates are typically resistant to commonly prescribed antifungal drugs. Increasingly recognized as a cause of infections and outbreaks in nosocomial settings, C. auris is difficult to identify using traditional microbiological methods. One of the main reasons for the ongoing spread of C. auris is the multitude of virulence factors it possesses and uses against its human host that enables fungal persistence on the skin surface. Yet, many of the virulence mechanisms are unknown or remain incompletely understood. In this review, we summarize the evolution of virulence of C. auris, offer recommendations for combating this important human pathogen, and suggest directions for further research.

Candida auris, a singular emergent pathogenic yeast: its resistance and new therapeutic alternatives

Nowadays, fungal infections affect millions of people across the world. Candida auris, a new emergent yeast, is a worrisome pathogen because it associates with a high rate of incidence and prevalence, including in the nosocomial environment. The hard identification, the phenotypic plasticity, and the easy adaptation to stressful conditions are some of the C. auris traits that render this latest yeast singular challenging. C. auris infections have already been reported from more than 30 countries and are associated with high mortality rates. This is the result from rapid transmission and the difficulty of prevention, control, and eradication. There are several factors related to the high virulence of C. auris, such as the multidrug resistance, biofilm development, and the ability to escape the response of the innate immune system. So, C. auris infections are a serious and alarming problem, not only because of the high pathogenicity of the fungal agent but also because of the low effectiveness of the treatments available. Although new formulations have been developed against C. auris strains, a better understanding is essential to efficiently treat, prevent, and control C. auris infections.

New Technologies to Diagnose and Treat a Multidrug-Resistant Candida auris: A Patent Review

Candida auris is responsible for hospital outbreaks worldwide. Some C. auris isolates may show concomitant resistance to azoles, echinocandins, and polyenes, thereby possibly leaving clinicians with few therapeutic options. In addition, this multi-drug-resistant yeast is difficult to identify with conventional methods and has the ability to persist on environmental surfaces causing hospital-acquired infections. The development of new treatment options and tools for identification is critical to control, prevent, and establish an early diagnosis of this emerging pathogen. The aim of this study was to perform a critical patent review to explore and identify the latest advances in therapeutic strategies as well as diagnostic methods for C. auris. A total of 19 patents were identified for a preliminary assessment from the Espacenet database. Three patents were excluded as they were out of focus for this review according to their abstract and/or description. The final selection covered 16 patents, which were surveyed by country, year and classified as treatment or diagnostic methods for C. auris. As noted in the patent reading, in recent years, the interest of academic, government and industry sectors have shown an increasing tendency focused on research and development of new therapeutic molecules and diagnostic methods to combat this emerging pathogen.

In Vivo Skin Colonization and Decolonization Models for Candida auris

Candida auris infections present a critical problem to the healthcare system in many parts of the world. This yeast clinically manifests as a disseminated candidiasis which can be life-threating for susceptible individuals, as well as cutaneous and wound infections. Moreover, C. auris can colonize the skin and act as a nidus of infection. Importantly, this emerging yeast unlike other Candida spp. has demonstrated multidrug resistance; thus its eradication can be challenging. Animal models are important to gain insight into the pathogenesis of this infection, as well as play a significant role in drug development. In this chapter, we describe two C. auris animal models: a cutaneous infection guinea pig model and a skin decolonization mouse model.

OUP accepted manuscript

Candida auris is an emerging, multi drug resistant fungal pathogen that has caused infectious outbreaks in over 45 countries since its first isolation over a decade ago, leading to in-hospital crude mortality rates as high as 72%. The fungus is also acclimated to disinfection procedures and persists for weeks in nosocomial ecosystems. Alarmingly, the outbreaks of C. auris infections in Coronavirus Disease-2019 (COVID-19) patients have also been reported. The pathogenicity, drug resistance and global spread of C. auris have led to an urgent exploration of novel, candidate antifungal agents for C. auris therapeutics. This narrative review codifies the emerging data on the following new/emerging antifungal compounds and strategies: antimicrobial peptides, combinational therapy, immunotherapy, metals and nano particles, natural compounds, and repurposed drugs. Encouragingly, a vast majority of these exhibit excellent anti- C. auris properties, with promising drugs now in the pipeline in various stages of development. Nevertheless, further research on the modes of action, toxicity, and the dosage of the new formulations are warranted. Studies are needed with representation from all five C. auris clades, so as to produce data of grater relevance, and broader significance and validity.

Current scenario of the search for new antifungal agents to treat Candida auris infections: An integrative review

Candida auris emerges as an important causative agent of fungal infections, with worrisome mortality rates, mainly in immunocompromised individuals. This scenario is worsened by the limited availability of antifungal drugs and the increasing development of resistance to them. Due to the relevance of C. auris infections to public health, several studies aimed to discover new antifungal compounds capable of overcoming this fungus. Nonetheless, these information are decentralized, precluding the understandment of the current status of the search for new anti-C. auris compounds. Thus, this integrative review aimed to summarize information regarding anti-C. auris compounds reported in literature. After using predefined selection criteria, 71 articles were included in this review, and data from a total of 101 substances were extracted. Most of the studies tested synthetic substances, including several azoles. Moreover, drug repurposing emerges as a suitable strategy to discover new anti-C. auris agents. Few studies, however, assessed the mechanism of action and the in vivo antifungal activity of the compounds. Therefore, more studies must be performed to evaluate the usefulness of these substances as anti-C. auris therapies.

Efficacy of Voriconazole, Isavuconazole, Fluconazole, and Anidulafungin in the Treatment of Emerging Candida auris Using an Immunocompromised Murine Model of Disseminated Candidiasis

Antifungal activity of anidulafungin, voriconazole, isavuconazole, and fluconazole in the treatment of Candida auris was determined in vitro and in vivo. MICs for anidulafungin, voriconazole, isavuconazole, fluconazole, and amphotericin B were 0.5, 1, >64, 0.25, and 4 μg/ml, respectively. Significant in vivo efficacy was observed in the anidulafungin- and voriconazole-treated groups in survival and reduction in kidney tissue fungal burden compared to that in the untreated group (P values of <0.001 and 0.044, respectively). Our data showed that anidulafungin and voriconazole had comparable efficacies against C. auris, whereas isavuconazole did not show significant in vivo activity.

Ibrexafungerp: First Approval

Ibrexafungerp (BREXAFEMME^®) is an orally active triterpenoid antifungal drug being developed by SCYNEXIS, Inc. for the treatment of fungal infections. The inhibition of β-1,3-D glucan synthetase by ibrexafungerp compromises the integrity of fungal cell walls. Ibrexafungerp has been recently approved for the treatment of vulvovaginal candidiasis (VVC), and it is the first novel antifungal drug class to be approved in more than 20 years. Development for the treatment of recurrent VVC and invasive fungal infections is ongoing. This article summarizes the milestones in the development of ibrexafungerp leading to this first approval for the treatment of VVC in adult and postmenarchal paediatric females.

Advances in anti-fungal therapies

Anti-fungal therapies remain sub-optimal, and resistant pathogens are increasing. New therapies are desperately needed, especially options that are less toxic than most of the currently available selection. In this review, I will discuss anti-fungal therapies that are in at least phase I human trials. These include VT-1161 and VT-1598, modified azoles with a tetrazole metal-binding group; the echinocandin rezafugin; the novel β-1,3-d-glucan synthase inhibitor ibrexafungerp; fosmanogepix, a novel anti-fungal targeting Gwt1; the arylamidine T-2307; the dihydroorotate inhibitor olorofim; and the cyclic hexapeptide ASP2397. The available data including spectrum of activity, toxicity and stage of clinical development will be discussed for each of these so clinicians are aware of promising anti-fungal agents with a strong likelihood of clinical availability in the next 5–7 years.

How urgent is the need for new antifungals?

Introduction: Invasive fungal infection carries a high morbidity, mortality and economic cost. In recent times, a rising incidence of fungal infection and antifungal resistance is occurring which has prompted the development of novel antifungal agents.Areas covered:In this perspective, the authors describe the current status of registered antifungals and their limitations in the treatment of invasive fungal infection. They also go on to describe the new antifungal agents that are in the clinical stage of development and how they might be best utilized in patient care in the future.Expert opinion: The antifungal drug development pipeline has responded to a growing need for new agents to effectively treat fungal disease without concomitant toxicity or issues with drug tolerance. Olorofim (F901318), ibrexafungerp (SCY-078), fosmanogepix (APX001), rezafungin (CD101), oteseconazole (VT-1161), encochleated amphotericin B (MAT2203), nikkomycin Z (NikZ) and ATI-2307 are all in the clinical stage of development and offer great promise in offering clinicians better agents to treat these difficult infections.

Ibrexafungerp Demonstrates In Vitro Activity against Fluconazole-Resistant Candida auris and In Vivo Efficacy with Delayed Initiation of Therapy in an Experimental Model of Invasive Candidiasis

Candida auris is an emerging pathogen that has rapidly spread to many countries on multiple continents. Invasive infections caused by this species are associated with significant mortality, and treatment options are limited due to antifungal resistance. Ibrexafungerp is the first-in-class member of the triterpenoids, which inhibit the production of (1,3)-β-d-glucan and can be administered orally. We evaluated the in vitro activity and in vivo efficacy of ibrexafungerp against C. auris Antifungal susceptibility was tested by broth microdilution against 54 C. auris isolates. Neutropenic mice were intravenously infected with a clinical isolate, and a 7-day treatment course was begun 24 h postinoculation with vehicle control, ibrexafungerp (20, 30, and 40 mg/kg orally twice daily), fluconazole (20 mg/kg orally once daily), or caspofungin (10 mg/kg intraperitoneally once daily). Fungal burden was assessed by colony counts in the kidneys on day 8 and on day 21 or as mice became moribund in the survival arm. Ibrexafungerp demonstrated consistent activity, with MICs ranging between 0.25 and 2 μg/ml against all isolates. Marked improvements in survival were observed in mice treated with the higher doses of ibrexafungerp and caspofungin. Similarly, reductions in kidney fungal burden were also observed in these groups. No improvements in survival or reductions in fungal burden were observed with fluconazole, consistent with the in vitro resistance of the isolate used to establish infection to this azole. These results demonstrate that ibrexafungerp is effective in vivo against C. auris even when the start of therapy is delayed.

A Novel Transdermal Application for Clearing Skin Colonization by Candida auris

BACKGROUND. Candida auris has demonstrated the ability to colonize the skin of hospitalized patients, possibly contributing to nosocomial spread. OBJECTIVE. The objective was to determine whether two novel transdermal agents could clear skin colonization established by C. auris METHODS. A murine skin colonization model was first optimized and then used to test fungal burden reduction following treatment with 1% terbinafine or 1% clotrimazole in a proprietary Advanced Penetration Technology formulation (APT™). RESULTS. Both treatments significantly reduced fungal burden compared to control groups. CONCLUSION. These novel agents show promise as a topical means of preventing skin colonization by C. auris.

Promising Drug Candidates and New Strategies for Fighting against the Emerging Superbug Candida auris

Invasive fungal infections represent an expanding threat to public health. During the past decade, a paradigm shift of candidiasis from Candida albicans to non-albicans Candida species has fundamentally increased with the advent of Candida auris. C. auris was identified in 2009 and is now recognized as an emerging species of concern and underscores the urgent need for novel drug development strategies. In this review, we discuss the genomic epidemiology and the main virulence factors of C. auris. We also focus on the different new strategies and results obtained during the past decade in the field of antifungal design against this emerging C. auris pathogen yeast, based on a medicinal chemist point of view. Critical analyses of chemical features and physicochemical descriptors will be carried out along with the description of reported strategies.

Ibrexafungerp, a Novel Oral Triterpenoid Antifungal in Development: Overview of Antifungal Activity Against Candida glabrata

Systemic infections caused by Candida species are an important cause of morbidity and mortality among immunocompromised and non-immunocompromised patients. In particular, Candida glabrata is an emerging species within the Candida family that causes infections ranging from superficial to life-threatening systemic disease. Echinocandins and azoles are typically the first-line therapies used to treat infections caused by C. glabrata, however, there is an increasing prevalence of resistance to these antifungal agents in patients. Thus, a need exists for novel therapies that demonstrate high efficacy against C. glabrata. Ibrexafungerp is a first-in-class glucan synthase inhibitor with oral availability developed to address this increasing antifungal resistance. Ibrexafungerp demonstrates broad in vitro activity against wild-type, azole-resistant, and echinocandin-resistant C. glabrata species. Furthermore, ibrexafungerp has shown efficacy in low pH environments, which suggests its potential effectiveness in treating vulvovaginal candidiasis. Additional preclinical and clinical studies are needed to further examine the mechanism(s) of ibrexafungerp, including acting as a promising new agent for treating C. glabrata infections.

Ibrexafungerp: A First-in-Class Oral Triterpenoid Glucan Synthase Inhibitor

Ibrexafungerp (formerly SCY-078 or MK-3118) is a first-in-class triterpenoid antifungal or “fungerp” that inhibits biosynthesis of β-(1,3)-D-glucan in the fungal cell wall, a mechanism of action similar to that of echinocandins. Distinguishing characteristics of ibrexafungerp include oral bioavailability, a favourable safety profile, few drug–drug interactions, good tissue penetration, increased activity at low pH and activity against multi-drug resistant isolates including C. auris and C. glabrata. In vitro data has demonstrated broad and potent activity against Candida and Aspergillus species. Importantly, ibrexafungerp also has potent activity against azole-resistant isolates, including biofilm-forming Candida spp., and echinocandin-resistant isolates. It also has activity against the asci form of Pneumocystis spp., and other pathogenic fungi including some non-Candida yeasts and non-Aspergillus moulds. In vivo data have shown IBX to be effective for treatment of candidiasis and aspergillosis. Ibrexafungerp is effective for the treatment of acute vulvovaginal candidiasis in completed phase 3 clinical trials.

The Neosartorya fischeri Antifungal Protein 2 (NFAP2): A New Potential Weapon against Multidrug-Resistant Candida auris Biofilms

Candida auris is a potential multidrug-resistant pathogen able to persist on indwelling devices as a biofilm, which serve as a source of catheter-associated infections. Neosartorya fischeri antifungal protein 2 (NFAP2) is a cysteine-rich, cationic protein with potent anti-Candida activity. We studied the in vitro activity of NFAP2 alone and in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin against C. auris biofilms. The nature of interactions was assessed utilizing the fractional inhibitory concentration index (FICI), a Bliss independence model, and LIVE/DEAD viability assay. NFAP2 exerted synergy with all tested antifungals with FICIs ranging between 0.312-0.5, 0.155-0.5, 0.037-0.375, 0.064-0.375, and 0.064-0.375 for fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. These results were confirmed using a Bliss model, where NFAP2 produced 17.54 μM²%, 2.16 μM²%, 33.31 μM²%, 10.72 μM²%, and 111.19 μM²% cumulative synergy log volume in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. In addition, biofilms exposed to echinocandins (32 mg/L) showed significant cell death in the presence of NFAP2 (128 mg/L). Our study shows that NFAP2 displays strong potential as a novel antifungal compound in alternative therapies to combat C. auris biofilms.

Ibrexafungerp: A Novel Oral Triterpenoid Antifungal in Development for the Treatment of Candida auris Infections

Candida auris is an emerging multidrug-resistant fungal pathogen reported worldwide. Infections due to C. auris are usually nosocomial and associated with high rates of fluconazole resistance and mortality. Echinocandins are utilized as the first-line treatment. However, echinocandins are only available intravenously and are associated with increasingly higher rates of resistance by C. auris. Thus, a need exists for novel treatments that demonstrate potent activity against C. auris. Ibrexafungerp is a first-in-class triterpenoid antifungal agent. Similar to echinocandins, ibrexafungerp inhibits (1→3)-β-D-glucan synthase, a key component of the fungal cell wall, resulting in fungicidal activity against Candida spp. Ibrexafungerp demonstrates broad in vitro activity against various Candida spp. including C. auris and C. auris isolates with fks mutations. Minimum inhibitory concentration (MIC₅₀ and MIC₉₀) values in >400 C. auris isolates were 0.5 μg/mL and 1.0 μg/mL, respectively. Clinical results were reported for two patients with invasive candidiasis or candidemia due to C. auris treated during the CARES (Candidiasis Caused by Candida Auris) trial, an ongoing open-label study. These patients experienced a complete response after treatment with ibrexafungerp. Thus, ibrexafungerp represents a promising new antifungal agent for treating C. auris infections.