Therapeutic agent for azole-based antifungal agent-resistant fungal infection caused by candida auris or cryptococcus neoformans

Abstract

Provided are: a novel therapeutic agent for fungal infections caused by Candida auris or Cryptococcus neoformans, which have acquired resistance to an azole-based antifungal agent; and a method for identifying resistant fungal strains, the method being performed prior to treatment with said therapeutic agent.　The therapeutic agent is characterized by combining an azole-based antifungal agent and milbemycin as active ingredients. The identifying method is characterized by using an azole-based antifungal agent-added and milbemycin-added fungal isolation medium and an azole-based antifungal agent-added and milbemycin-free fungal isolation medium.

Description

Treatment for azole antifungal-resistant fungal infections caused by Candida auris or Cryptococcus neoformans

[0001] The present invention relates to a therapeutic agent for treating azole antifungal-resistant mycoses of Candida auris or Cryptococcus neoformans.

[0002] Candida auris and Cryptococcus neoformans are included in the four fungi classified as Critical, the highest priority, out of the three-stage classification (Critical, High, and Medium) of the Fungal Priority Pathogen List (FPPL) first published by the World Health Organization (WHO) in October 2022 (Non-Patent Document 1). Azole antifungal agents are mainly used to treat mycoses caused by Candida auris and Cryptococcus neoformans, but in recent years, the isolation of bacteria resistant to azole antifungal agents has been reported around the world.

[0003] WHO fungal priority pathogens list to guide research, development and public health action. https: / / www.who.int / publications / i / item / 9789240060241.

[0004] An object of the present invention is to provide a novel therapeutic agent for mycosis caused by Candida auris or Cryptococcus neoformans that has acquired resistance to azole antifungal agents, and to provide a method for distinguishing resistant fungal strains that can be carried out prior to treatment with the therapeutic agent.

[0005] The above-mentioned problems can be solved by the present invention as follows: [1] A therapeutic agent for azole antifungal agent-resistant mycosis, which comprises a combination of an azole antifungal agent and a milbemycin as active ingredients, wherein the fungus is selected from the group consisting of Candida auris and Cryptococcus neoformans. [2] A method for distinguishing between azole antifungal agent-resistant fungal strains, which comprises using a fungal isolation medium containing an azole antifungal agent and a milbemycin, and a fungal isolation medium containing an azole antifungal agent but not a milbemycin, wherein the fungus is selected from the group consisting of Candida auris and Cryptococcus neoformans.

[0006] According to the therapeutic agent of the present invention, even azole antifungal agent-resistant mycoses caused by Candida auris or Cryptococcus neoformans that have acquired resistance to azole antifungal agents can be treated with an azole antifungal agent. Furthermore, according to the differentiation method of the present invention, by performing the method prior to the treatment, it is possible to determine whether the fungal strain is resistant to azole antifungal agents, and appropriate treatment can be performed with the therapeutic agent of the present invention.

[0007] (Therapeutic Agent of the Present Invention) The therapeutic agent of the present invention is intended to treat mycoses caused by azole antifungal agent-resistant fungal strains of Candida auris (e.g., candidiasis) or azole antifungal agent-resistant fungal strains of Cryptococcus neoformans (e.g., cryptococcosis).

[0008] The therapeutic agent of the present invention contains an azole antifungal agent and a milbemycin as active ingredients. Examples of the azole antifungal agent include fluconazole, itraconazole, voriconazole, fosravuconazole, efinaconazole, luliconazole, ravuconazole, posaconazole, and isavuconazole. Examples of the milbemycin include milbemycin oxime and its derivatives (e.g., milbemectin, moxidectin, and nemadectin).

[0009] The therapeutic agent of the present invention can be provided as a pharmaceutical composition containing the active ingredients, an azole antifungal agent and a milbemycin in a single preparation, or as a combination of a drug containing an azole antifungal agent and a drug containing a milbemycin (i.e., a two-preparation). Furthermore, the therapeutic agent of the present invention can be administered to a subject (e.g., an animal, preferably a mammal, particularly a human) in an effective amount as the active ingredient alone, or preferably together with a pharmaceutically acceptable carrier or diluent, and can also be provided in the form of a food or drink.

[0010] When the therapeutic agent of the present invention is provided as a pharmaceutical, it can be administered as an oral or parenteral agent, preferably an oral agent. Examples of the oral agent include solid preparations such as tablets, capsules, powders, fine granules, and granules, and liquid preparations such as suspensions, emulsions, syrups, and extracts. Examples of the parenteral agent include injections and topical agents.

[0011] Examples of pharmaceutically acceptable carriers or diluents include excipients, disintegrants, binders, flavoring agents, effervescent agents, sweeteners, flavoring agents, lubricants, buffers, antioxidants, surfactants, and fluidizing agents.

[0012] When the therapeutic agent of the present invention is provided as a pharmaceutical, the dosage of each active ingredient is determined appropriately for each individual case, taking into consideration the symptoms, age, sex, etc. of the subject, but the daily dosage of the azole antifungal agent is usually 10 to 1000 mg, preferably 100 to 400 mg, and the daily dosage of the milbemycins is usually 1 to 50 mg, preferably 10 to 15 mg. These can be administered in a single dose or in 2 to 4 divided doses.

[0013] (Discrimination method of the present invention) According to the discrimination method of the present invention, it is possible to distinguish between azole antifungal agent-resistant fungal strains that can be treated with the therapeutic agent of the present invention and fungi that cannot be treated with the therapeutic agent of the present invention. The fungi are Candida auris or Cryptococcus neoformans.

[0014] The differentiation method of the present invention uses a fungal isolation medium containing an azole antifungal agent but not milbemycins (hereinafter referred to as "M-free medium") and a fungal isolation medium containing an azole antifungal agent but not milbemycins (hereinafter referred to as "M-added medium"). As the fungal classification medium, a conventionally known medium for Candida auris or Cryptococcus neoformans can be used, such as RPMI (Roswell Park Memorial Institute) 1640 medium. As the azole antifungal agent and milbemycins, those previously described in the description of the therapeutic agent of the present invention can be used. The milbemycins can be added to the medium at a concentration that does not inhibit fungal growth, for example, 1 μg / mL.

[0015] In the differentiation method of the present invention, the minimum inhibitory concentration (MIC) for an azole antifungal agent is calculated by a conventional method, for example, the broth microdilution method. If a fungus that is resistant to an azole antifungal agent in an M-free medium (showing a higher minimum inhibitory concentration than an azole antifungal agent-susceptible strain) is susceptible to an azole antifungal agent in an M-added medium (showing a lower minimum inhibitory concentration than an M-free medium), it can be determined that the fungal strain is resistant to an azole antifungal agent and that mycosis caused by this fungal strain can be treated with the therapeutic agent of the present invention. Instead of calculating the minimum inhibitory concentration (MIC), sensitivity can also be determined by visually comparing the growth of the fungus.

[0016] By using the differentiation method of the present invention prior to treatment of a fungal infection, it is possible to determine whether the fungal infection can be expected to be treated effectively with the therapeutic drug of the present invention or whether it cannot be treated with the therapeutic drug of the present invention, and a more appropriate treatment can be selected before treatment is initiated.

[0017] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0018] Example 1 In this example, azole antifungal drug-resistant strains of Candida auris and Cryptococcus neoformans listed in Table 1 were used, and their susceptibility to azole antifungals was evaluated by calculating the minimum inhibitory concentration (MIC) using a broth microdilution assay based on the Clinical and Laboratory Standards Institute (CLSI) M27 and M38 guidelines (Non-Patent Documents 2 and 3). RPMI (Roswell Park Memorial Institute) 1640 medium (Cytiva, Tokyo, Japan) containing 1 μg / mL milbemycin oxime (FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan) was used as the culture medium, and fluconazole (FLCZ), itraconazole (ITCZ), and voriconazole (VRCZ) were used as the azole antifungals.

[0019] (Non-patent document 2) Clinical Laboratory Standards Institute. 2017. Reference method for broth dilution antifungal susceptibility testing of yeasts: 4th edn. CLSI document M27. 2017. Clinical and Laboratory Standards Institute, Wayne, PA. (Non-patent document 3) Clinical Laboratory Standards Institute. 2017. Reference method for broth dilution antifungal susceptibility testing of filamentous fungi, 3rd Edition: 3rd edn. CLSI document M38. 2017. Clinical and Laboratory Standards Institute, Wayne, PA.

[0020] The results are shown in Table 1. In Table 1, "+M" indicates that the medium was supplemented with milbemycin oxime. The sensitivity of strains resistant to azole antifungal agents, both Candida auris and Cryptococcus neoformans, increased with the addition of milbemycin oxime. The sensitivity of strains to antifungal agents to which resistance had not been acquired (for example, Candida auris JCM15448) was not increased with the addition of milbemycin oxime. Ｔ There was no tendency for changes in sensitivity to the strains of genotype 1 to be observed with or without the addition of itraconazole, voriconazole, or milbemycin oxime.

[0021]

[0022] Reference Example 1 In this Reference Example, the effect of milbemycin oxime on azole antifungal agent-resistant strains of Aspergillus fumigatus listed in Table 2 was investigated according to the method described in Example 1. Aspergillus fumigatus is one of four fungi classified as "Critical," the highest priority, in the Fungal Priority Pathogen List (FPPL) first published by the World Health Organization (WHO) (Non-Patent Document 1).

[0023] The results are shown in Table 2. In Aspergillus fumigatus, no change in sensitivity was observed regardless of whether milbemycin oxime was added or not.

[0024]

[0025] The therapeutic agent of the present invention can be used to treat azole antifungal agent-resistant mycosis caused by Candida auris or Cryptococcus neoformans. Furthermore, by performing the differentiation method of the present invention prior to the treatment, appropriate treatment can be performed.

Claims

1. A therapeutic agent for azole antifungal agent-resistant mycosis, characterized by a combination of an azole antifungal agent and a milbemycin as active ingredients, wherein the fungus is selected from the group consisting of Candida auris and Cryptococcus neoformans.

2. A method for distinguishing between fungal strains resistant to azole antifungal agents, comprising using a fungal isolation medium containing an azole antifungal agent but not containing milbemycins, and a fungal isolation medium containing an azole antifungal agent and containing milbemycins, wherein the fungus is selected from the group consisting of Candida auris and Cryptococcus neoformans.

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