Oral Lipid Nanocrystal Amphotericin B for Cryptococcal Meningitis: A Randomized Clinical Trial

Epidemiology, pathogenesis, clinical characteristics, and treatment of mucormycosis: a review

AIM

This review aims to summarize the epidemiology, etiology, pathogenesis, clinical manifestations, and current diagnostic and therapeutic approaches for mucormycosis. The goal is to improve understanding of mucormycosis and promote early diagnosis and treatment to reduce mortality.

METHODS

A comprehensive literature review was conducted, focusing on recent studies and data on mucormycosis. The review includes an analysis of the disease's epidemiology, etiology, and pathogenesis, as well as current diagnostic techniques and therapeutic strategies.

RESULTS

Mucormycosis is increasingly prevalent due to the growing immunocompromised population, the COVID-19 pandemic, and advances in detection methods. The pathogenesis is closely associated with the host immune status, serum-free iron levels, and the virulence of Mucorales. However, the absence of typical clinical manifestations complicates diagnosis, leading to missed or delayed diagnoses and higher mortality.

CONCLUSION

An enhanced understanding of the epidemiology, pathogenesis, and clinical presentation of mucormycosis, along with the adoption of improved diagnostic and therapeutic approaches, is essential for reducing mortality rates associated with this opportunistic fungal infection. Early diagnosis and prompt treatment are critical to improving patient outcomes.

Reassessment of the role of combination antifungal therapy in the current era

PURPOSE OF REVIEW

Given the high mortality and morbidity associated with invasive fungal diseases (IFDs), the use of combination antifungal therapies is often considered despite the dearth of data. This review aims to summarize the current state of literature of combination antifungal therapies, discussing the potential roles of newer antifungal combinations and key considerations for their clinical use.

RECENT FINDINGS

In infections other than cryptococcal meningitis or in the setting of empirical treatment for suspected azole-resistant Aspergillus infections, the utility of the combination antifungal approaches remains controversial given the paucity of well designed randomized controlled trials. Data on potential combined antifungal treatments have been primarily limited to in-vitro studies, animal models, case reports and/or observational studies. With availability of novel antifungal agents (e.g. ibrexafungerp, fosmanogepix), combination therapy to treat mould infections should be re-visited. A phase 2 clinical trial of ibrexafungerp combined with voriconazole to treat invasive pulmonary aspergillosis is on-going.

SUMMARY

There is a need to investigate the use of combination antifungal agents. This includes delineating the indication of these combined antifungal therapies and determining how to use them most appropriately in the clinical setting.

Review of the novel antifungal drug olorofim (F901318)

There is clearly a need for novel antifungal agents, not only concerning spectrum, but also oral bioavailability, tolerability, and drug-drug interactions. There is growing concern for antifungal resistance for current available antifungals, mainly driven by environmental fungicide use or long-term exposure to antifungals, in the setting of mould-active prophylaxis or for chronic antifungal infections, such as chronic pulmonary aspergillosis. Moreover, the incidence of breakthrough infections is increasing, because of the introduction of (mould-active) prophylaxis (1-4). There is emergence of difficult to treat invasive fungal infections, such as those caused by Lomentospora prolificans, cryptic species of Aspergillus, Scedosporium and Coccidioides. Olorofim (F901318) is the first-in class of the orotomides, a novel antifungal class targeting dihydroorotate dehydrogenase (DHODH), a key enzyme in the biosynthesis of pyrimidines. Olorofim shows good in vitro and in vivo activity against Aspergillus species, rare and difficult to treat moulds and endemic dimorphic fungi, including azole- and amphotericin-resistant isolates. It lacks activity against yeasts and the Mucorales species. It is only orally available and shows very promising results in ongoing clinical trials. In this review we will describe the mechanism of action of olorofim, the spectrum of activity in vitro and in vivo, pharmacokinetics, pharmacodynamics, drug-drug interactions, resistance, and clinical outcomes.

Formulation Strategies to Overcome Amphotericin B Induced Toxicity

Fungal infection poses a major global threat to public health because of its wide prevalence, severe mortality rate, challenges involved in diagnosis and treatment, and the emergence of drug-resistant fungal strains. Millions of people are getting affected by fungal infection, and around 3.8 million people face death per year due to fungal infection, as per the latest report. The polyene antibiotic AmB has an extensive record of use as a therapeutic moiety against systemic fungal infection and leishmaniasis since 1960. AmB has broad-spectrum fungistatic and fungicidal activity. AmB exerts its therapeutic activity at the cellular level by binding to fungal sterol and forming hydrophilic pores, releasing essential cellular components and ions into the extracellular fluid, leading to cell death. Despite using AmB as an antifungal and antileishmanial at a broad scale, its clinical use is limited due to drug-induced nephrotoxicity resulting from binding the aggregated form of the drug to mammalian sterol. To mitigate AmB-induced toxicity and to get better anti-fungal therapeutic outcomes, researchers have developed nanoformulations, self-assembled formulations, prodrugs, cholesterol- and albumin-based AmB formulations, AmB-mAb combination therapy, and AmB cochleates. These formulations have helped to reduce toxicity to a certain extent by controlling the aggregation state of AmB, providing sustained drug release, and altering the physicochemical and pharmacokinetic parameters of AmB. Although the preclinical outcome of AmB formulations is quite satisfactory, its parallel result at the clinical level is insignificant. However, the safety and efficacy of AmB therapy can be improved at the clinical stage by continuous investigation and collaboration among researchers, clinicians, and pharmaceutical companies.

Invasive fungal disease and antifungal prophylaxis in children with acute leukaemia: a multicentre retrospective Australian cohort study

Background

Invasive fungal disease (IFD) is a significant complication for children receiving treatment for leukaemia, contributing to morbidity and mortality. Recent regional paediatric epidemiological IFD data are lacking. Additionally uncertainty remains regarding the optimal prophylactic approach in this context.

Methods

In a multi-centre Australian cohort study of children diagnosed with de novo acute leukaemia between 1st January 2017 and 30th June 2020, we characterised antifungal prophylaxis prescribing and IFD prevalence. Impact of antifungal prophylaxis was assessed using Kaplan Meier curves and Cox-proportional hazards regression adjusting for known IFD risk factors.

Findings

A total of 434 children were included (47.2% female; median age 5.0 years, median follow-up 240 days). This cohort included 351 children with ALL (214 high-risk [HR-ALL]; 137 standard-risk [SR-ALL]), and 73 with AML. The prevalence of proven/probable IFD was 6.8% for AML, 14.0% for HR-ALL and 4.4% for SR-ALL. A mould was implicated as the causative pathogen in almost two thirds of cases. Antifungal prophylaxis was prescribed in 98.7% of chemotherapy cycles for AML, 56.7% for HR-ALL and 14.9% for SR-ALL. A mould-active agent was used in 77.4% of AML cycles and 21.2% of HR-ALL cycles. Mould-active prophylaxis was associated with a lower risk of IFD overall and increased IFD-free survival in AML.

Interpretation

These data demonstrate the persistent high regional burden of IFD in children with HR-ALL, and the potential for mould-active prophylaxis to ameliorate this. Strategies to increase uptake of appropriate prophylaxis are required in this cohort.

Funding

This study was supported by a Perth Children's Hospital Foundation grant (PCHF9973).

Successful Treatment of Refractory Cutaneous Protothecosis With MAT2203, an Oral Lipid Nanocrystal Formulation of Amphotericin B

Prototheca wickerhamii is a rare cause of cutaneous and systemic infection that requires long treatment courses with potentially toxic medications. We describe a patient with cutaneous protothecosis refractory to triazole monotherapy who experienced clinical and radiographic improvement with the novel oral lipid nanocrystal formulation of amphotericin B without experiencing toxicity.

Clinical Mycology Today: Emerging Challenges and Opportunities

The Mycoses Study Group Education and Research Consortium is a collective of clinicians, researchers, and educators with the common goal to advance awareness, diagnosis, and management of invasive fungal diseases. Clinical Mycology Today, the Mycoses Study Group Education and Research Consortium's biennial meeting, is dedicated to discussing the most pressing contemporary issues facing the field of clinical mycology, promoting clinical, translational, and basic science collaborations, and mentoring the next generation of clinical mycologists. Here, we review the current opportunities and challenges facing the field of mycology that arose from discussions at the 2022 meeting, with emphasis on novel host risk factors, emerging resistant fungal pathogens, the evolving antifungal pipeline, and critical issues affecting the advancement of mycology research.

Oral Lipid Nanocrystal Amphotericin B (MAT2203) for the Treatment of Invasive Fungal Infections

Amphotericin B (AmB) has broad fungicidal activity against many fungi, but the high incidence of adverse events, particularly nephrotoxicity, and the need for intravenous administration restrict its use for many patients. MAT2203, an investigational oral AmB formulation available under a compassionate use program, uses a lipid nanocrystal bilayer structure to deliver AmB with lower toxicity. We present a synopsis of clinical characteristics, treatment course, and outcomes for 5 patients who were treated with MAT2203. Outcomes were positive, with cure of infection noted in 4 patients and improvement in 1 patient who remains on therapy. MAT2203 was well tolerated with only modest gastrointestinal adverse effects. This new oral formulation might provide a safer treatment option for patients requiring extended courses of AmB.

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.

Efficacy of an oral lipid nanocrystal formulation of amphotericin B (MAT2203) in the neutropenic mouse model of pulmonary mucormycosis

Invasive mucormycosis (IM) is associated with high mortality and morbidity. MAT2203 is an orally administered lipid nanocrystal formulation of amphotericin B, which has been shown to be safe and effective against other fungal infections. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM due to Rhizopus arrhizus var. delemar or Mucor circinelloides f. jenssenii DI15-131. In R. arrhizus var. delemar-infected mice, 15 mg/kg of MAT2203 qd was as effective as 10 mg/kg of LAMB in prolonging median survival time vs placebo (13.5 and 16.5 days for MAT2203 and LAMB, respectively, vs 9 days for placebo) and enhancing overall survival vs placebo-treated mice (40% and 45% for MAT2203 and LAMB, respectively, vs 0% for placebo). A higher dose of 45 mg/kg of MAT2203 was not well tolerated by mice and showed no benefit over placebo. Similar results were obtained with mice infected with M. circinelloides. Furthermore, while both MAT2203 and LAMB treatment resulted in a significant reduction of ~1.0-2.0log and ~2.0-2.5log in Rhizopus delemar or M. circinelloides lung and brain burden vs placebo mice, respectively, LAMB significantly reduced tissue fungal burden in mice infected with R. delemar vs tissues of mice treated with MAT2203. These results support continued investigation and development of MAT2203 as a novel and oral formulation of amphotericin for the treatment of mucormycosis.

New treatment options for critically important WHO fungal priority pathogens

BACKGROUND

Yet often overlooked in public health discourse, fungal infections pose a crucial global disease burden associated with annual mortality rates approximately equal to tuberculosis and HIV. In response, the WHO published its first global priority list of fungal pathogens in 2022 assigning Aspergillus fumigatus, Candida albicans, Candida auris, and Cryptococcus neoformans to the critical group.

OBJECTIVES

This review provides succinct insights into novel antifungals in development, aiming to contribute valuable information and perspectives with a focus on recent clinical findings and new treatment approaches for critical members of the WHO fungal pathogen priority list.

SOURCES

PubMed literature search using 'Aspergillus fumigatus', 'Cryptococcus neoformans', 'Candida auris', and 'Candida albicans', along with the names of novel antifungal substances, including 'fosmanogepix', 'ibrexafungerp', 'opelconazole', 'oteseconazole', 'MAT2203', 'olorofim', and 'rezafungin' was conducted.

CONTENT

For each critical pathogen, current issues and global clinical data from recent trials are covered. The remarkable development of three new antifungal therapeutics recently receiving Food and Drug Administration approval (ibrexafungerp-June 2021, oteseconazole -April 2022, and rezafungin-March 2023) is outlined, with two more exciting new antifungal substances, namely, olorofim and fosmanogepix expecting approval within the next years. Ibrexafungerp, fosmanogepix, and rezafungin have additionally been granted orphan drug status by the European Medicines Agency in Europe (ibrexafungerp-November 2021, fosmanogepix-July 2022, and rezafungin-January 2024).

IMPLICATIONS

Although the limited number of targets and the emergence of resistance have posed challenges to antifungal treatment, new drugs such as ibrexafungerp, rezafungin, fosmanogepix, or olorofim have shown promising clinical efficacy. These drugs not only provide alternative options for invasive fungal infections but also alleviate treatment in outpatient settings. More clinical data, implementation of stewardship programmes, and surveillance, including utilization of drugs in agriculture, are necessary to prevent resistance development and to ensure the safety and efficacy of these new agents.

Histoplasmosis in Solid Organ Transplantation

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. It has a broad global distribution with shifting epidemiology during recent decades. While in immunocompetent individuals infection is usually self-resolving, solid organ transplant recipients are at increased risk of symptomatic disease with dissemination to extrapulmonary tissue. Diagnosis of histoplasmosis relies on direct observation of the pathogen (histopathology, cytopathology, and culture) or detection of antigens, antibodies, or nucleic acids. All transplant recipients with histoplasmosis warrant therapy, though the agent of choice and duration of therapy depends on the severity of disease. In the present article, we describe the pathogenesis, epidemiology, clinical manifestations and management of histoplasmosis in solid organ transplant recipients.

Antifungal Therapies for Aspergillus spp.: Present and Future

Currently available and recommended options for the treatment of pulmonary aspergillosis include the triazoles, echinocandins, and amphotericin B products. These therapies have significant limitations. Only the azoles are available orally, but their use is often limited by toxicities, drug-drug interactions, pharmacokinetic variability, and emerging resistance. While the echinocandins are safe agents and may have a role in combination therapy, they are unproven as monotherapy. Amphotericin B preparations are toxic and require intensive monitoring. Finally, aspergillosis continues to be a disease conferring substantial morbidity and mortality, and clinical trials have not identified a therapeutic approach clearly associated with improved outcomes. As a result, there is a great need for new options in the treatment of invasive aspergillosis. Ideally, such options would be safe, have high oral bioavailability, have favorable pharmacokinetics to sequestered sites and retain activity against azole-resistant isolates. Reassuringly, there is a robust pipeline of novel therapies in development. Rezafungin (a once-weekly dosed echinocandin) and ibrexafungerp (oral agent with same mechanism of action as echinocandins) will likely be reserved for combination therapy or refractory/intolerance scenarios with no other options. Inhaled opelconazole is an attractive option for combination therapy and prophylaxis of pulmonary aspergillosis. Development of an oral form of amphotericin B that avoids nephrotoxicity and electrolyte disturbances is an exciting development. Finally, olorofim and fosmanogepix, two agents with novel mechanisms of action and oral formulations, hold significant potential to challenge the triazole antifungals place as preferred therapies. However, many questions remain regarding these novel agents, and at the time of this writing, none of these agents have been robustly studied in Phase III studies of aspergillosis, and so their promise remains investigational.

Nanotechnology in the Diagnosis and Treatment of Antibiotic-Resistant Infections

The development of antimicrobial resistance (AMR), along with the relative reduction in the production of new antimicrobials, significantly limits the therapeutic options in infectious diseases. Thus, novel treatments, especially in the current era, where AMR is increasing, are urgently needed. There are several ongoing studies on non-classical therapies for infectious diseases, such as bacteriophages, antimicrobial peptides, and nanotechnology, among others. Nanomaterials involve materials on the nanoscale that could be used in the diagnosis, treatment, and prevention of infectious diseases. This review provides an overview of the applications of nanotechnology in the diagnosis and treatment of infectious diseases from a clinician's perspective, with a focus on pathogens with AMR. Applications of nanomaterials in diagnosis, by taking advantage of their electrochemical, optic, magnetic, and fluorescent properties, are described. Moreover, the potential of metallic or organic nanoparticles (NPs) in the treatment of infections is also addressed. Finally, the potential use of NPs in the development of safe and efficient vaccines is also reviewed. Further studies are needed to prove the safety and efficacy of NPs that would facilitate their approval by regulatory authorities for clinical use.

Re-estimation of the burden of serious fungal diseases in Uganda

Background

It is of utmost importance to monitor any change in the epidemiology of fungal diseases that may arise from a change in the number of the at-risk population or the availability of local data.

Objective

We sought to update the 2015 publication on the incidence and prevalence of serious fungal diseases in Uganda.

Methods

Using the Leading International Fungal Education methodology, we reviewed published data on fungal diseases and drivers of fungal diseases in Uganda. Regional or global data were used where there were no Ugandan data.

Results

With a population of ~45 million, we estimate the annual burden of serious fungal diseases at 4,099,357 cases (about 9%). We estimated the burden of candidiasis as follows: recurrent Candida vaginitis (656,340 cases), oral candidiasis (29,057 cases), and esophageal candidiasis (74,686 cases) in HIV-infected people. Cryptococcal meningitis annual incidence is estimated at 5553 cases, Pneumocystis pneumonia at 4604 cases in adults and 2100 cases in children. For aspergillosis syndromes, invasive aspergillosis annual incidence (3607 cases), chronic pulmonary aspergillosis (26,765 annual cases and 63,574 5-year-period prevalent cases), and prevalence of allergic bronchopulmonary aspergillosis at 75,931 cases, and severe asthma with fungal sensitization at 100,228 cases. Tinea capitis is common with 3,047,989 prevalent cases. For other mycoses, we estimate the annual incidence of histoplasmosis to be 646 cases and mucormycosis at 9 cases.

Conclusion

Serious fungal diseases affect nearly 9% of Ugandans every year. Tuberculosis and HIV remain the most important predisposition to acute fungal infection necessitating accelerated preventive, diagnostic, and therapeutic interventions for the management of these diseases.

Diagnosis and management of cryptococcal meningitis in HIV-infected adults

Cryptococcal meningitis is a leading cause of morbidity and mortality globally, especially in people with advanced HIV disease. Cryptococcal meningitis is responsible for nearly 20% of all deaths related to advanced HIV disease, with the burden of disease predominantly experienced by people in resource-limited countries. Major advancements in diagnostics have introduced low-cost, easy-to-use antigen tests with remarkably high sensitivity and specificity. These tests have led to improved diagnostic accuracy and are essential for screening campaigns to reduce the burden of cryptococcosis. In the last 5 years, several high-quality, multisite clinical trials have led to innovations in therapeutics that have allowed for simplified regimens, which are better tolerated and result in less intensive monitoring and management of medication adverse effects. One trial found that a shorter, 7-day course of deoxycholate amphotericin B is as effective as the longer 14-day course and that flucytosine is an essential partner drug for reducing mortality in the acute phase of disease. Single-dose liposomal amphotericin B has also been found to be as effective as a 7-day course of deoxycholate amphotericin B. These findings have allowed for simpler and safer treatment regimens that also reduce the burden on the healthcare system. This review provides a detailed discussion of the latest evidence guiding the clinical management and special circumstances that make cryptococcal meningitis uniquely difficult to treat.

5-Flucytosine Longitudinal Antifungal Susceptibility Testing of Cryptococcus neoformans: A Substudy of the EnACT Trial Testing Oral Amphotericin

Background

The EnACT trial was a phase 2 randomized clinical trial conducted in Uganda, which evaluated a novel orally delivered lipid nanocrystal (LNC) amphotericin B in combination with flucytosine for the treatment of cryptococcal meningitis. When flucytosine (5FC) is used as monotherapy in cryptococcosis, 5FC can induce resistant Cryptococcus mutants. Oral amphotericin B uses a novel drug delivery mechanism, and we assessed whether resistance to 5FC develops during oral LNC-amphotericin B therapy.

Methods

We enrolled Ugandans with HIV diagnosed with cryptococcal meningitis and who were randomized to receive 5FC and either standard intravenous (IV) amphotericin B or oral LNC-amphotericin B. We used broth microdilution to measure the minimum inhibitory concentration (MIC) of the first and last cryptococcal isolates in each participant. Breakpoints are inferred from 5FC in Candida albicans. We measured cerebral spinal fluid (CSF) 5FC concentrations by liquid chromatography and tandem mass spectrometry.

Results

Cryptococcus 5FC MIC50 was 4 µg/mL, and MIC90 was 8 µg/mL. After 2 weeks of therapy, there was no evidence of 5FC resistance developing, defined as a >4-fold change in susceptibility in any Cryptococcus isolate tested. The median CSF 5FC concentration to MIC ratio (interquartile range) was 3.0 (1.7-5.5) µg/mL. There was no association between 5FC/MIC ratio and early fungicidal activity of the quantitative rate of CSF yeast clearance (R2 = 0.004; P = .63).

Conclusions

There is no evidence of baseline resistance to 5FC or incident resistance during combination therapy with oral or IV amphotericin B in Uganda. Oral amphotericin B can safely be used in combination with 5FC.

Efficacy of an oral lipid nanocrystal (LNC) formulation of amphotericin B (MAT2203) in the neutropenic mouse model of pulmonary mucormycosis

Invasive mucormycosis (IM) is associated with high mortality and morbidity and commonly afflicts patients with weakened immune systems. MAT2203 is an orally administered lipid nanocrystal (LNC) formulation of amphotericin B, which has been shown to be safe and effective against other fungal infections. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM due to R. arrhizus var. delemar or Mucor circinelloides f. jenssenii DI15-131. Treatment with placebo (diluent control), oral MAT2203 administered as BID and QD or intravenous LAMB for 4 days, began 16 h post infection and continued for 7 and 4 days, respectively. Survival through Day +21 and tissue fungal burden of lung or brain in animals euthanized on Day +4 served as a primary and secondary endpoint, respectively. In both infection types, MAT2203 was as effective as LAMB in prolonging median survival time (MST) and enhancing overall survival vs. placebo-treated mice ( P <0.05 by Log-Rank). Furthermore, both MAT2203 and LAMB treatment resulted in significant ∼1.0-1.5-log reduction and ∼2.0-2.2-log in R. delemar or M. circinelloides lung and brain burden, vs. placebo mice, respectively. These results support the potential efficacy of oral MAT2203 as an alternative to LAMB. Continued investigation and development of this novel oral formulation of the amphotericin B for the treatment of mucormycosis is warranted.

Cryptococcal meningitis

Cryptococcus neoformans and Cryptococcus gattii species complexes cause meningoencephalitis with high fatality rates and considerable morbidity, particularly in persons with deficient T cell-mediated immunity, most commonly affecting people living with HIV. Whereas the global incidence of HIV-associated cryptococcal meningitis (HIV-CM) has decreased over the past decade, cryptococcosis still accounts for one in five AIDS-related deaths globally due to the persistent burden of advanced HIV disease. Moreover, mortality remains high (~50%) in low-resource settings. The armamentarium to decrease cryptococcosis-associated mortality is expanding: cryptococcal antigen screening in the serum and pre-emptive azole therapy for cryptococcal antigenaemia are well established, whereas enhanced pre-emptive combination treatment regimens to improve survival of persons with cryptococcal antigenaemia are in clinical trials. Short courses (≤7 days) of amphotericin-based therapy combined with flucytosine are currently the preferred options for induction therapy of cryptococcal meningitis. Whether short-course induction regimens improve long-term morbidity such as depression, reduced neurocognitive performance and physical disability among survivors is the subject of further study. Here, we discuss underlying immunology, changing epidemiology, and updates on the management of cryptococcal meningitis with emphasis on HIV-associated disease.