Olorofim Susceptibility Testing of 1,423 Danish Mold Isolates Obtained in 2018-2019 Confirms Uniform and Broad-Spectrum Activity

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.

Scedosporiosis and lomentosporiosis: modern perspectives on these difficult-to-treat rare mold infections

SUMMARYAlthough Scedosporium species and Lomentospora prolificans are uncommon causes of invasive fungal diseases (IFDs), these infections are associated with high mortality and are costly to treat with a limited armamentarium of antifungal drugs. In light of recent advances, including in the area of new antifungals, the present review provides a timely and updated overview of these IFDs, with a focus on the taxonomy, clinical epidemiology, pathogenesis and host immune response, disease manifestations, diagnosis, antifungal susceptibility, and treatment. An expansion of hosts at risk for these difficult-to-treat infections has emerged over the last two decades given the increased use of, and broader population treated with, immunomodulatory and targeted molecular agents as well as wider adoption of antifungal prophylaxis. Clinical presentations differ not only between genera but also across the different Scedosporium species. L. prolificans is intrinsically resistant to most currently available antifungal agents, and the prognosis of immunocompromised patients with lomentosporiosis is poor. Development of, and improved access to, diagnostic modalities for early detection of these rare mold infections is paramount for timely targeted antifungal therapy and surgery if indicated. New antifungal agents (e.g., olorofim, fosmanogepix) with novel mechanisms of action and less cross-resistance to existing classes, availability of formulations for oral administration, and fewer drug-drug interactions are now in late-stage clinical trials, and soon, could extend options to treat scedosporiosis/lomentosporiosis. Much work remains to increase our understanding of these infections, especially in the pediatric setting. Knowledge gaps for future research are highlighted in the review.

How do I manage refractory invasive pulmonary aspergillosis

BACKGROUND

Invasive aspergillosis is associated with significant morbidity and mortality in patients with haematologic malignancies and haematopoietic cell transplant recipients. The prognosis is worse among patients who have failed primary antifungal treatment.

OBJECTIVES

We aim to provide guidance on the diagnosis and management of refractory invasive pulmonary aspergillosis.

SOURCES

Using PubMed, we performed a review of original articles, meta-analyses, and systematic reviews.

CONTENT

We discuss the diagnostic criteria for invasive pulmonary aspergillosis and the evidence on the treatment of primary infection. We outline our diagnostic approach to refractory disease. We propose a treatment algorithm for refractory disease and discuss the role of experimental antifungal agents.

IMPLICATIONS

For patients with worsening disease while on antifungal therapy, a thorough diagnostic evaluation is required to confirm the diagnosis of aspergillosis and exclude another concomitant infection. Treatment should be individualized. Current options include switching to another triazole, transitioning to a lipid formulation of amphotericin B, or using combination antifungal therapy.

The Role of Olorofim in the Treatment of Filamentous Fungal Infections: A Review of In Vitro and In Vivo Studies

Invasive fungal infections have recently been recognized by the WHO as a major health, epidemiological, and economic issue. Their high mortality rates and the emergence of drug resistance have driven the development of new molecules, including olorofim, an antifungal belonging to a new family of compounds, the orotomides. A review was conducted on the PubMed database and the ClinicalTrials.gov website to summarize the microbiological profile of olorofim and its role in the treatment of filamentous fungal infections. Twenty-four articles were included from the search and divided into two groups: an "in vitro" group focusing on minimum inhibitory concentration (MIC) results for various fungi and an "in vivo" group evaluating the pharmacokinetics (PK), pharmacodynamics (PD), efficacy, and tolerability of olorofim in animal models of fungal infection and in humans. Olorofim demonstrated in vitro and in vivo activity against numerous filamentous fungi, including azole-resistant Aspergillus fumigatus, various dermatophytes, and endemic and dimorphic fungi. in vitro results showed higher MICs for certain Fusarium species and dematiaceous fungi Alternaria alternata and Exophiala dermatitidis; further in vivo studies are needed. Published PK-PD data in humans are limited. The results of the ongoing phase III clinical trial are eagerly awaited to evaluate olorofim's clinical impact.

Aspergillus fumigatus strains that evolve resistance to the agrochemical fungicide ipflufenoquin in vitro are also resistant to olorofim

Widespread use of azole antifungals in agriculture has been linked to resistance in the pathogenic fungus Aspergillus fumigatus. We show that exposure of A. fumigatus to the agrochemical fungicide, ipflufenoquin, in vitro can select for strains that are resistant to olorofim, a first-in-class clinical antifungal with the same mechanism of action. Resistance is caused by non-synonymous mutations within the target of ipflufenoquin/olorofim activity, dihydroorotate dehydrogenase (DHODH), and these variants have no overt growth defects.

Invasive Aspergillosis among Lung Transplant Recipients during Time Periods with Universal and Targeted Antifungal Prophylaxis-A Nationwide Cohort Study

The optimal prevention strategy for invasive aspergillosis (IA) in lung transplant recipients (LTXr) is unknown. In 2016, the Danish guidelines were changed from universal to targeted IA prophylaxis. Previously, we found higher rates of adverse events in the universal prophylaxis period. In a Danish nationwide study including LTXr, for 2010-2019, we compared IA rates in time periods with universal vs. targeted prophylaxis and during person-time with vs. person-time without antifungal prophylaxis. IA hazard rates were analyzed in multivariable Cox models with adjustment for time after LTX. Among 295 LTXr, antifungal prophylaxis was initiated in 183/193 and 6/102 during the universal and targeted period, respectively. During the universal period, 62% discontinued prophylaxis prematurely. The median time on prophylaxis was 37 days (IQR 11-84). IA was diagnosed in 27/193 (14%) vs. 15/102 (15%) LTXr in the universal vs. targeted period, with an adjusted hazard ratio (aHR) of 0.94 (95% CI 0.49-1.82). The aHR of IA during person-time with vs. person-time without antifungal prophylaxis was 0.36 (95% CI 0.12-1.02). No difference in IA was found during periods with universal vs. targeted prophylaxis. Prophylaxis was protective of IA when taken. Targeted prophylaxis may be preferred over universal due to comparable IA rates and lower rates of adverse events.

Emerging Diagnostics and Therapeutics for Invasive Fungal Infections

Recently, there have been significant advances in the diagnosis and management of invasive fungal infections. Compared with traditional fungal diagnostics, molecular assays promise improved sensitivity and specificity, the ability to test a range of samples (including noninvasive samples, ie, blood), the detection of genetic mutations associated with antifungal resistance, and the potential for a faster turnaround time. Antifungals in late-stage clinical development include agents with novel mechanisms of action (olorofim and fosmanogepix) and new members of existing classes with distinct advantages over existing antifungals in toxicity, drug-drug interactions, and dosing convenience (oteseconazole, opelconazole, rezafungin, ibrexafungerp, encochleated amphotericin B).

In Vitro Activity of the Novel Antifungal Olorofim against Scedosporium and Lomentospora prolificans

Scedosporium spp. and Lomentospora prolificans are an emerging group of fungi refractory to current antifungal treatments. These species largely affect immunocompromised individuals but can also be lung colonizers in cystic fibrosis patients. Although Scedosporium apiospermum is thought to be the predominant species, the group has been expanded to a species complex. The distribution of species within the S. apiospermum species complex and other closely related species in the United States is largely unknown. Here, we used β-tubulin and ITS sequences to identify 37 Scedosporium isolates to the species level. These Scedosporium isolates as well as 13 L. prolificans isolates were tested against a panel of nine antifungal drugs, including the first in novel class orotimide, olorofim. IMPORTANCE Scedosporium and Lomentospora infections are notoriously hard to treat as these organisms can be resistant to numerous antifungals. The manuscript contributes to our knowledge of the activity of the new antifungal agent olorofim and comparator agents against Lomentospora and against Scedosporium isolates that have been molecularly identified to the species level. The efficacy of olorofim against all species of Scedosporium and Lomentospora was confirmed.

EUCAST-Obtained Olorofim MICs against Aspergillus and Scedosporium Species and Lomentospora prolificans Showed High Agreements between Visual Inspection and Spectrophotometric Readings

Previous studies show high agreement between MIC spectrophotometric readings and visual inspection of azoles and amphotericin B against Aspergillus fumigatus isolates. Here, we tested and compared the in vitro activity of a novel antifungal, olorofim, against Aspergillus spp., Scedosporium spp., and Lomentospora prolificans by visual inspection and spectrophotometric readings. Clinical isolates of Aspergillus (n = 686) and Scedosporium (n = 36) spp. and L. prolificans (n = 13) were tested. Olorofim MICs were evaluated-following the EUCAST E.Def 9.4 procedure-by visual inspection or spectrophotometric readings (combinations of either ≥90% or ≥95% fungal growth inhibition endpoints compared to drug-free control endpoints and different wavelengths [405 nm, 450 nm, 492 nm, 540 nm, and 620 nm]). We observed high in vitro activity of olorofim against all tested Aspergillus spp. (MICs up to 0.06 mg/L), except for A. calidoustus, and against L. prolificans and Scedosporium spp. (MICs up to 0.125 mg/L). The combination of ≥90% fungal growth inhibition endpoints at wavelengths of ≥492 nm resulted in high essential agreements with A. fumigatus and lesser agreement with non-fumigatus Aspergillus, Scedosporium spp., and L. prolificans, although the number of isolates studied was low. This single-center study shows high agreement among olorofim MICs against A. fumigatus by visual inspection and spectrophotometric readings (≥90% fungal growth inhibition endpoints and wavelengths of ≥492 nm) and encouraging results against non-fumigatus Aspergillus spp., Scedosporium spp., and L. prolificans.

Novel agents in the treatment of invasive fungal infections in solid organ transplant recipients

PURPOSE OF REVIEW

Recipients of solid organ transplants (SOTs) suffer a significant burden of invasive fungal infections (IFIs). The emergence of drug-resistant fungi and toxicities of currently used antifungal agents as well as drug-drug interactions with immunosuppressants make their treatment challenging. This review discusses selected novel antifungal agents in the development pipeline that can currently be used through clinical trials or may be commercially available in the near future.

RECENT FINDINGS

These agents in development have novel pharmacokinetics and pharmacodynamics, expanded spectra of activity and excellent safety profiles.

SUMMARY

The properties of novel antifungal agents have the potential to expand the therapeutic options for IFIs in recipients of SOTs.

In vitro activity of olorofim against Aspergillus fumigatus sensu lato clinical isolates: activity is retained against isolates showing resistance to azoles and/or amphotericin B

OBJECTIVES

New antifungal drugs, such as olorofim, may overcome the problem of resistance in Aspergillus fumigatus. We here report the activity of olorofim against a set of A. fumigatus sensu lato recently collected in Spain.

METHODS

A total of 332 A. fumigatus sensu lato clinical isolates collected in a multicentre study conducted in Spain in 2019 and comprising susceptible and resistant isolates to azoles and/or amphotericin B were tested. Isolates distributed among the following species: A. fumigatus sensu stricto (n = 312), Aspergillus lentulus (n = 6), Aspergillus fumigatiaffinis (n = 5), Neosartorya tsurutae (n = 3), Neosartorya udagawae (n = 3), Aspergillus novofumigatus (n = 2), and Aspergillus thermomutatus (n = 1). Azole resistance was found in 44 A. fumigatus sensu stricto isolates that harboured the following cyp51A gene substitutions: TR₃₄-L98H (n = 24), G54 (n = 5), TR₄₆/Y121F/T289A (n = 1), other mutations (n = 4), and gene wild type (n = 10). Isolates were tested for antifungal susceptibility to olorofim using European Committee on Antimicrobial Susceptibility Testing (EUCAST) E.Def. 9.4 methodology.

RESULTS

Olorofim minimum inhibitory concentrations against A. fumigatus sensu stricto isolates ranged from 0.008 to 0.125 mg/L and in vitro activity of the drug was not impacted by the presence of azole/amphotericin B resistance. Azole resistance and amphotericin B resistance was found in 18 and 13 cryptic species isolates, respectively. Olorofim showed high in vitro activity against cryptic species isolates and minimum inhibitory concentrations ranged from 0.004 to 0.016 mg/L, regardless of the presence of resistance to other drugs.

DISCUSSION

Olorofim showed in vitro activity against both A. fumigatus sensu stricto and cryptic species clinical isolates and was active against isolates showing resistance to azoles and/or amphotericin B.

Resistance profiling of Aspergillus fumigatus to olorofim indicates absence of intrinsic resistance and unveils the molecular mechanisms of acquired olorofim resistance

Olorofim (F901318) is a new antifungal currently under clinical development that shows both in vitro and in vivo activity against a number of filamentous fungi including Aspergillus fumigatus. In this study, we screened A. fumigatus isolates for intrinsic olorofim-resistant A. fumigatus and evaluated the ability of A. fumigatus to acquire an olorofim-resistant phenotype. No intrinsic resistance was found in 975 clinical A. fumigatus isolates. However, we found that isolates with increased olorofim MICs (> 8 mg/L) could be selected using a high number of conidia and olorofim exposure under laboratory conditions. Assessment of the frequency of acquired olorofim resistance development of A. fumigatus was shown to be higher than for voriconazole but lower than for itraconazole. Sequencing the PyrE gene of isogenic isolates with olorofim MICs of >8 mg/L identified various amino acid substitutions with a hotspot at locus G119. Olorofim was shown to have reduced affinity to mutated target protein dihydroorotate dehydrogenase (DHODH) and the effect of these mutations was proven by introducing the mutations directly in A. fumigatus. We then investigated whether G119 mutations were associated with a fitness cost in A. fumigatus. These experiments showed a small but significant reduction in growth rate for strains with a G119V substitution, while strains with a G119C substitution did not exhibit a reduction in growth rate. These in vitro findings were confirmed in an in vivo pathogenicity model.

Olorofim Effectively Eradicates Dermatophytes In Vitro and In Vivo

Superficial fungal infections are prevalent worldwide, with dermatophytes as the most common cause. Various antifungal agents including azoles and allylamines are commonly used to treat dermatophytosis. However, their overuse has yielded drug-resistant strains, calling for the development of novel antimycotic compounds. Olorofim is a newly developed antifungal compound that targets pyrimidine biosynthesis in molds. The purpose of this study was to determine the in vitro and in vivo antifungal effects of olorofim against common dermatophytes. The in vitro activity of olorofim against dermatophytes was assessed by microtiter broth dilution method. Bioinformatic analysis of olorofim binding to dihydroorotate dehydrogenase (DHODH) of dermatophytes was also performed, using Aspergillus fumigatus DHODH as a template. The in vivo efficacy of the drug was investigated, using a guinea pig model, experimentally infected with Microsporum gypseum. Microtiter assays confirmed the high in vitro sensitivity of dermatophytes to olorofim (MIC = 0.015-0.06 mg/liter). Amino acid sequence analysis indicated that DHODH is highly conserved among dermatophytes. The critical residues, in dermatophytes, involved in olorofim binding were similar to their counterparts in A. fumigatus DHODH, which explains their susceptibility to olorofim. Typical skin lesions of dermatophyte infection were observed in the guinea pig model at 7 days postinoculation. Following 1 week of daily topical administration of olorofim, similar to the clotrimazole group, the skin lesions were resolved and normal hair growth patterns appeared. In light of the in vitro and in vivo activity of olorofim against dermatophytes, this novel agent may be considered as a treatment of choice against dermatophytosis.

Future Directions for Clinical Respiratory Fungal Research

There has been a growing appreciation of the importance of respiratory fungal diseases in recent years, with better understanding of their prevalence as well as their global distribution. In step with the greater awareness of these complex infections, we are currently poised to make major advances in the characterization and treatment of these fungal diseases, which in itself is largely a consequence of post-genomic technologies which have enabled rational drug development and a path towards personalized medicines. These advances are set against a backdrop of globalization and anthropogenic change, which have impacted the world-wide distribution of fungi and antifungal resistance, as well as our built environment. The current revolution in immunomodulatory therapies has led to a rapidly evolving population at-risk for respiratory fungal disease. Whilst challenges are considerable, perhaps the tools we now have to manage these infections are up to this challenge. There has been a welcome acceleration of the antifungal pipeline in recent years, with a number of new drug classes in clinical or pre-clinical development, as well as new focus on inhaled antifungal drug delivery. The "post-genomic" revolution has opened up metagenomic diagnostic approaches spanning host immunogenetics to the fungal mycobiome that have allowed better characterization of respiratory fungal disease endotypes. When these advances are considered together the key challenge is clear: to develop a personalized medicine framework to enable a rational therapeutic approach.

The Antifungal Pipeline: Fosmanogepix, Ibrexafungerp, Olorofim, Opelconazole, and Rezafungin

The epidemiology of invasive fungal infections is changing, with new populations at risk and the emergence of resistance caused by the selective pressure from increased usage of antifungal agents in prophylaxis, empiric therapy, and agriculture. Limited antifungal therapeutic options are further challenged by drug-drug interactions, toxicity, and constraints in administration routes. Despite the need for more antifungal drug options, no new classes of antifungal drugs have become available over the last 2 decades, and only one single new agent from a known antifungal class has been approved in the last decade. Nevertheless, there is hope on the horizon, with a number of new antifungal classes in late-stage clinical development. In this review, we describe the mechanisms of drug resistance employed by fungi and extensively discuss the most promising drugs in development, including fosmanogepix (a novel Gwt1 enzyme inhibitor), ibrexafungerp (a first-in-class triterpenoid), olorofim (a novel dihyroorotate dehydrogenase enzyme inhibitor), opelconazole (a novel triazole optimized for inhalation), and rezafungin (an echinocandin designed to be dosed once weekly). We focus on the mechanism of action and pharmacokinetics, as well as the spectrum of activity and stages of clinical development. We also highlight the potential future role of these drugs and unmet needs.

In vitro activity of the novel antifungal olorofim against dermatophytes and opportunistic moulds including Penicillium and Talaromyces species

Objectives

Olorofim is a novel antifungal agent with in vitro activity against Aspergillus and other opportunistic moulds. We investigated the in vitro activity of olorofim against a range of filamentous fungi comprising isolates of Aspergillus species, Scedosporium species, Alternaria alternata, dermatophytes, including terbinafine- and multidrug-resistant Trichophyton species, and Penicillium/Talaromyces species originating from patients in North India.

Methods

Antifungal susceptibility of olorofim was tested against 241 mould isolates of Penicillium/Talaromyces species, Trichophyton species, A. fumigatus and cryptic Aspergillus species, Scedosporium species, and Alternaria alternata using CLSI broth microdilution. The comparators were five systemic azoles, amphotericin B, terbinafine, and luliconazole.

Results

Overall, olorofim showed highly potent in vitro activity against dermatophytes and opportunistic moulds (MIC range of 0.004–0.125 mg/L) except for Alternaria alternata. Penicillium, and Talaromyces species and Trichophyton species exhibited a low geometric mean (GM) MIC (GM 0.027 mg/L and 0.015 mg/L, respectively) of olorofim. Importantly, a 2–12 dilution step decrease in in vitro activity of olorofim as compared with azoles was observed against Penicillium and Talaromyces. Notably, olorofim displayed potent in vitro activity against Trichophyton isolates including terbinafine-resistant and azole-resistant Trichophyton mentagrophytes/interdigitale with a modal MIC value of 0.008 mg/L. Further, azole-resistant A. fumigatus isolates harbouring mutations in azole target Cyp51A genes and several cryptic aspergilli displayed low MICs (range 0.004–0.03 mg/L) of olorofim. However, no in vitro activity of olorofim against Alternaria alternata was observed.

Conclusions

The potent in vitro activity of olorofim against drug-resistant dermatophytes and opportunistic moulds is promising, warranting evaluation of the clinical utility of olorofim.

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.

Invasive infections with Purpureocillium lilacinum: clinical characteristics and outcome of 101 cases from FungiScope® and the literature

OBJECTIVES

To provide a basis for clinical management decisions in Purpureocillium lilacinum infection.

METHODS

Unpublished cases of invasive P. lilacinum infection from the FungiScope® registry and all cases reported in the literature were analysed.

RESULTS

We identified 101 cases with invasive P. lilacinum infection. Main predisposing factors were haematological and oncological diseases in 31 cases (30.7%), steroid treatment in 27 cases (26.7%), solid organ transplant in 26 cases (25.7%), and diabetes mellitus in 19 cases (18.8%). The most prevalent infection sites were skin (n = 37/101, 36.6%) and lungs (n = 26/101, 25.7%). Dissemination occurred in 22 cases (21.8%). Pain and fever were the most frequent symptoms (n = 40/101, 39.6% and n = 34/101, 33.7%, respectively). Diagnosis was established by culture in 98 cases (97.0%). P. lilacinum caused breakthrough infection in 10 patients (9.9%). Clinical isolates were frequently resistant to amphotericin B, whereas posaconazole and voriconazole showed good in vitro activity. Susceptibility to echinocandins varied considerably. Systemic antifungal treatment was administered in 90 patients (89.1%). Frequently employed antifungals were voriconazole in 51 (56.7%) and itraconazole in 26 patients (28.9%). Amphotericin B treatment was significantly associated with high mortality rates (n = 13/33, 39.4%, P = <0.001). Overall mortality was 21.8% (n = 22/101) and death was attributed to P. lilacinum infection in 45.5% (n = 10/22).

CONCLUSIONS

P. lilacinum mainly presents as soft-tissue, pulmonary or disseminated infection in immunocompromised patients. Owing to intrinsic resistance, accurate species identification and susceptibility testing are vital. Outcome is better in patients treated with triazoles compared with amphotericin B formulations.

In vitro activity of olorofim against clinical isolates of the Fusarium oxysporum and Fusarium solani species complexes

BACKGROUND

Invasive fusariosis is associated with marked morbidity and mortality in immunocompromised hosts, and clinical outcomes are poor with conventional therapy. Olorofim (F901318) is an investigational antifungal in the orotomide class that selectively targets fungal dihydroorotate dehydrogenase (DHODH) causing inhibition of pyrimidine biosynthesis.

OBJECTIVE

We evaluated the in vitro activity of olorofim against 61 clinical isolates of the Fusarium oxysporum and F solani species complexes (FOSC and FSSC, respectively), the most prevalent causes of invasive fusariosis.

METHODS

Clinical isolates of FOSC (n = 45) and FSSC (n = 16) were identified using DNA sequence analysis of the translation elongation factor 1-alpha (TEF1α) and RNA polymerase II second largest subunit (RPB2). Antifungal susceptibility testing was performed by CLSI M38 broth microdilution for olorofim, amphotericin B, isavuconazole, posaconazole, voriconazole and micafungin.

RESULTS

Olorofim demonstrated good in vitro activity against both FOSC and FSSC. Against the 45 FOSC isolates, olorofim MICs ranged between 0.03-0.5 mg/L and 0.06->4 mg/L at the 50% and 100% inhibition endpoints, respectively. Against FSSC isolates, olorofim MIC ranged between 0.25-1 mg/L and 1->4 mg/L at 50% and 100% inhibition, respectively. While amphotericin B also demonstrated similar in vitro activity (MIC ranges 1-4 and 0.25-4 mg/L against FOSC and FSSC, respectively), neither the triazoles nor micafungin demonstrated consistent in vitro activity against Fusarium isolates at clinically relevant concentrations.

CONCLUSIONS

The investigational agent olorofim demonstrated good in vitro activity against FOSC and FSSC clinical isolates. Further studies are warranted to determine how well this in vitro activity translates into in vivo efficacy.