Metabolism, Excretion, and Mass Balance of [14C]-Rezafungin in Animals and Humans

Formulary Drug Review: Rezafungin

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are available online to subscribers. Monographs can be customized to meet the needs of a facility. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, contact Wolters Kluwer customer service at 866-397-3433.

Small molecule drug metabolite synthesis and identification: why, when and how?

The drug discovery and development process encompasses the interrogation of metabolites arising from the biotransformation of drugs. Here we look at why, when and how metabolites of small-molecule drugs are synthesised from the perspective of a specialist contract research organisation, with particular attention paid to projects for which regulatory oversight is relevant during this journey. To illustrate important aspects, we look at recent case studies, trends and learnings from our experience of making and identifying metabolites over the past ten years, along with with selected examples from the literature.

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 and safety of rezafungin and caspofungin in candidaemia and invasive candidiasis: pooled data from two prospective randomised controlled trials

BACKGROUND

Rezafungin, a new US Food and Drug Administration-approved, long-acting echinocandin to treat candidaemia and invasive candidiasis, was efficacious with a similar safety profile to caspofungin in clinical trials. We conducted pooled analyses of the phase 2 STRIVE and phase 3 ReSTORE rezafungin trials.

METHODS

ReSTORE was a multicentre, double-blind, double-dummy, randomised phase 3 trial conducted at 66 tertiary care centres in 15 countries. STRIVE was a multicentre, double-blind, double-dummy, randomised phase 2 trial conducted at 44 centres in 10 countries. Adults (≥18 years) with candidaemia or invasive candidiasis were treated with once-a-week intravenous rezafungin (400 mg and 200 mg) or once-a-day intravenous caspofungin (70 mg and 50 mg). Efficacy was evaluated in a pooled modified intent-to-treat (mITT) population. Primary efficacy endpoint was day 30 all-cause mortality (tested for non-inferiority with a pre-specified margin of 20%). Secondary efficacy endpoint was mycological response. Safety was also evaluated. The STRIVE and ReSTORE trials are registered with ClinicalTrials.gov, NCT02734862 and NCT03667690, and both studies are complete.

FINDINGS

ReSTORE was conducted from Oct 12, 2018, to Oct 11, 2021, and STRIVE from July 26, 2016, to April 18, 2019. The mITT population, pooling the data from the two trials, comprised 139 patients for rezafungin and 155 patients for caspofungin. Day 30 all-cause mortality rates were comparable between groups (19% [26 of 139] for the rezafungin group and 19% [30 of 155] for the caspofungin group) and the upper bound of the 95% CI for the weighted treatment difference was below 10% (-1·5% [95% CI -10·7 to 7·7]). Mycological eradication occurred by day 5 in 102 (73%) of 139 rezafungin patients and 100 (65%) of 155 caspofungin patients (weighted treatment difference 10·0% [95% CI -0·3 to 20·4]). Safety profiles were similar across groups.

INTERPRETATION

Rezafungin was non-inferior to caspofungin for all-cause mortality, with a potential early treatment benefit, possibly reflecting rezafungin's front-loaded dosing regimen. These findings are of clinical importance in fighting active and aggressive infections and reducing the morbidity and mortality caused by candidaemia and invasive candidiasis.

FUNDING

Melinta Therapeutics and Cidara Therapeutics.

Pipeline of Novel Antifungals for Invasive Fungal Disease in Transplant Recipients: A Pediatric Perspective

Invasive fungal disease (IFD) remains a significant cause of morbidity and mortality in children undergoing transplantation. There is a growing armamentarium of novel antifungal agents recently approved for use or in late stages of clinical development. The overarching goal of this review is to discuss the mechanisms of action, spectrum of activity, stage of development, and pediatric-specific data for the following agents: encochleated amphotericin B deoxycholate, fosmanogepix, ibrexafungerp, isavuconazole, olorofim, opelconazole, oteseconazole, and rezafungin. Additionally, key drug attributes of these novel agents and their potential future therapeutic roles in pediatric transplant recipients are discussed.

Invasive Candida infection: epidemiology, clinical and therapeutic aspects of an evolving disease and the role of rezafungin

INTRODUCTION

Invasive Candida Infections (ICIs) have undergone a series of significant epidemiological, pathophysiological, and clinical changes during the last decades, with a shift toward non-albicans species, an increase in the rate of exogenous infections and clinical manifestations ranging from candidemia to an array of highly invasive and life-threatening clinical syndromes. The long-acting echinocandin rezafungin exhibits potent in-vitro activity against most wild-type and azole-resistant Candida spp. including C.auris.

AREAS COVERED

The following topics regarding candidemia only and ICIs were reviewed and addressed: i) pathogenesis; ii) epidemiology and temporal evolution of Candida species; iii) clinical approach; iv) potential role of the novel long-acting rezafungin in the treatment of ICIs.

EXPERT OPINION

Authors' expert opinion focused on considering the potential role of rezafungin in the evolving context of ICIs. Rezafungin, which combines a potent in-vitro activity against Candida species, including azole-resistant strains and C.auris, with a low likelihood of drug-drug interactions and a good safety profile, may revolutionize the treatment of candidemia/ICI. Indeed, it may shorten the length of hospital stays when clinical conditions allow and extend outpatient access to treatment of invasive candidiasis, especially when prolonged treatment duration is expected.

Therapeutic Approaches for Combating Aspergillus Associated Infection

Now-a-days fungal infection emerges as a significant problem to healthcare management systems due to high frequency of associated morbidity, mortality toxicity, drug-drug interactions, and resistance of the antifungal agents. Aspergillus is the most common mold that cause infection in immunocompromised hosts. It's a hyaline mold that is cosmopolitan and ubiquitous in nature. Aspergillus infects around 10 million population each year with a mortality rate of 30-90%. Clinically available antifungal formulations are restricted to four classes (i.e., polyene, triazole, echinocandin, and allylamine), and each of them have their own limitations associated with the activity spectrum, the emergence of resistance, and toxicity. Consequently, novel antifungal agents with modified and altered chemical structures are required to combat these invasive fungal infections. To overcome these limitations, there is an urgent need for new antifungal agents that can act as potent drugs in near future. Currently, some compounds have shown effective antifungal activity. In this review article, we have discussed all potential antifungal therapies that contain old antifungal drugs, combination therapies, and recent novel antifungal formulations, with a focus on the Aspergillus associated infections.

Anti-inflammatory and anticancer p-terphenyl derivatives from fungi of the genus Thelephora

Fungi from the genus Thelephora have been exploited to identify bioactive compounds. The main natural products characterized are para-terphenyl derivatives, chiefly represented by the lead anti-inflammatory compound vialinin A isolated from species T. vialis and T. terrestris. Different series of p-terphenyls have been identified, including vialinins, ganbajunins, terrestrins, telephantins and other products. Their mechanism of action is not always clearly identified, and different potential molecule targets have been proposed. The lead vialinin A functions as a protease inhibitor, efficiently targeting ubiquitin-specific peptidases USP4/5 and sentrin-specific protease SENP1 which are prominent anti-inflammatory and anticancer targets. Protease inhibition is coupled with a powerful inhibition of the cellular production of tumor necrosis factor TNFα. Other mechanisms contributing to the anti-inflammatory or anti-proliferative action of these p-terphenyl compounds have been invoked, including the formation of cytotoxic copper complexes for derivatives bearing a catechol central unit such vialinin A, terrestrin B and telephantin O. These p-terphenyl compounds could be further exploited to design novel anticancer agents, as evidenced with the parent compound terphenyllin (essentially found in Aspergillus species) which has revealed marked antitumor and anti-metastatic effects in xenograft models of gastric and pancreatic cancer. This review shed light on the structural and functional diversity of p-terphenyls compounds isolated from Thelephora species, their molecular targets and pharmacological properties.

A Phase 1 Randomized, Double-Blind, Single Subcutaneous Dose Escalation Study to Determine the Safety, Tolerability, and Pharmacokinetics of Rezafungin in Healthy Adult Subjects

Rezafungin is a novel echinocandin being developed for the treatment and prevention of invasive fungal infections. The objectives of this randomized, double‐blind study in healthy adults were to determine the safety, tolerability, and pharmacokinetics of rezafungin after subcutaneous (s.c.) administration. The study design consisted of six sequential cohorts of eight subjects, except for the first cohort with four subjects. The subjects were randomized in a 3:1 ratio of rezafungin to placebo and were to receive a single dose of 1, 10, 30, 60, 100, or 200 mg. The most common adverse events (AEs) were increased alanine aminotransferase and sinus bradycardia (unsolicited) and erythema at the injection site (solicited). Unsolicited AEs were generally mild to moderate and not rezafungin‐related. Although the study was terminated after the 10 mg dose cohort due to concerns of potential increased severity of injection site reactions, no predetermined dose escalation halting criteria were met. Following the 10 mg single s.c. dose of rezafungin (n = 6), the geometric mean (GM) maximum concentration (C_max) was 105.0 ng/ml and the median time to C_max was 144 h. The GM area under the concentration‐time curve was 32,770 ng*h/ml. The median estimated terminal half‐life was 193 h. The GM apparent oral clearance was 0.255 L/h and the GM apparent volume of distribution was 68.5 L. This study demonstrates that a single s.c. dose of rezafungin in healthy adult subjects: (1) did not result in serious AEs, death, or withdrawal from the study due to an AE; and (2) produced a pharmacokinetic profile with long exposure period postadministration. In an effort to reduce the occurrence of injection site reactions, a re‐evaluation of the rezafungin s.c. formulation could be considered in the future.

Evaluation of Rezafungin Provisional CLSI Clinical Breakpoints and Epidemiological Cutoff Values Tested against a Worldwide Collection of Contemporaneous Invasive Fungal Isolates (2019 to 2020)

Rezafungin is a new echinocandin under development for the treatment of candidemia and invasive candidiasis. CLSI recently approved provisional susceptible-only breakpoints and epidemiological cutoff values for Candida spp. and rezafungin. The activities of rezafungin and comparators against 2019 to 2020 invasive fungal isolates was evaluated by applying the new CLSI breakpoints. Rezafungin demonstrated potent activity against Candida albicans (MIC 50 /MIC 90 , 0.03/0.06 mg/L; 100.0% susceptible), Candida tropicalis (MIC 50 /MIC 90 , 0.03/0.06 mg/L; 100% susceptible), Candida glabrata (MIC 50 /MIC 90 , 0.06/0.06 mg/L; 98.3% susceptible), Candida krusei (MIC 50 /MIC 90 , 0.03/0.03 mg/L; 100% susceptible), and Candida dubliniensis (MIC 50 /MIC 90 , 0.06/0.12 mg/L; 100% susceptible) when tested by the CLSI broth microdilution method. Rezafungin inhibited 99.6% of Candida parapsilosis isolates (MIC 50 /MIC 90 , 1/2 mg/L) at the susceptible breakpoint of ≤2 mg/L. All C. albicans , C. tropicalis , and C. krusei isolates, as well as most C. glabrata (96.2% to 97.9%) and C. parapsilosis (86.2% to 100%) isolates, were susceptible to comparator echinocandins. Fluconazole resistance was detected among 0.5%, 4.5%, 10.5%, and 1.2% of C. albicans , C. glabrata , C. parapsilosis , and C. tropicalis isolates, respectively. All echinocandins displayed limited activity against Cryptococcus neoformans . Rezafungin and other echinocandins were active against Aspergillus fumigatus (minimum effective concentration for 90% of isolates tested [MEC 90 ] range, 0.015 to 0.06 mg/L) and Aspergillus section Flavi (MEC 90 range, 0.015 to 0.03 mg/L). All but 16 (8.6%) A. fumigatus isolates were susceptible to voriconazole, and 100% of Aspergillus section Flavi isolates were WT to mold-active azoles. When applying the CLSI clinical breakpoints, rezafungin displayed high susceptibility rates (>98.0%) against Candida isolates from invasive fungal infections and showed potent activity against Aspergillus isolates.