C. diffに対する新抗生物質「イベザポルスタット」が臨床試験で有効性を示す(New Antibiotic to Fight Superbug C. Diff Proves Effective in Clinical Trial)

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2025-09-04 ヒューストン大学(UH)

ヒューストン大学の研究によると、新抗菌薬「ibezapolstat」が重篤な院内感染症クロストリジオイデス・ディフィシル(C. diff)に対して有望な成果を示した。米国では年間約45万件の感染と約3万人の死亡が報告され、既存薬バンコマイシンやフィダキソマイシンでは治癒率や再発率に限界がある。ibezapolstatはC. diffを選択的に抑制しつつ善玉菌群や胆汁酸代謝を保持する特徴があり、腸内フローラを保護する利点がある。ランセット・マイクローブ誌に掲載された第2b相試験では治療1か月後の治癒率94%、再発ゼロという結果を達成し、これまでの第2相全試験25例で再発が見られなかった。安全性も高く、耐性菌感染症対策における次世代治療薬として期待され、第3相試験への移行が見込まれている。

<関連情報>

クロストリジオイデス・ディフィシル感染症成人患者におけるイベザポルスタットとバンコマイシンの有効性、安全性、薬物動態および関連するマイクロバイオーム変化の比較:第II相b、無作為化、二重盲検、活性対照、多施設共同試験 Efficacy, safety, pharmacokinetics, and associated microbiome changes of ibezapolstat compared with vancomycin in adults with Clostridioides difficile infection: a phase 2b, randomised, double-blind, active-controlled, multicentre study

Taryn A Eubank PharmD, Jinhee Jo PharmD, M Jahangir Alam PhD, Khurshida Begum PhD, Jacob K McPherson PharmD, ThanhPhuong M Le PharmD, Thomas D Horvath PhD, Sigmund J Haidacher BS, Eugene C Poggio PhD, Rong Lin MD, Corinne Seng Yue PhD, Murray P Ducharme PharmD, Georges Koudssi BS, Julie Mercier BS, Jeffrey D Alder PhD, Michael H Silverman MD, Prof Kevin W Garey PharmD,Ibezapolstat Phase 2 Investigator Group
The Lancet Microbe  Available online: 11 June 2025
DOI:https://doi.org/10.1016/j.lanmic.2025.101126

C. diffに対する新抗生物質「イベザポルスタット」が臨床試験で有効性を示す(New Antibiotic to Fight Superbug C. Diff Proves Effective in Clinical Trial)

Summary

Background

Clostridioides difficile infection is a common health-care-associated and community-acquired disease with few antibiotic treatment options. We aimed to assess the safety, efficacy, pharmacokinetics, and associated microbiome changes of ibezapolstat, an antibiotic that inhibits the PolC-type DNA polymerase III α subunit C, versus vancomycin for the treatment of C difficile infection in adults.

Methods

This was a phase 2b, randomised, double-blind, active-controlled study conducted at 15 centres, primarily outpatient clinics and hospitals, in the USA. Adults aged 18–90 years, with signs and symptoms of C difficile infection and a positive toxin stool test were recruited. Participants were randomly assigned (1:1) with block assignment by study site using an interactive web response system to receive oral ibezapolstat (450 mg twice daily) or oral vancomycin (125 mg every 6 h) for 10 days. Masking was achieved by over-encapsulation of both study drugs (ibezapolstat and vancomycin) and placebo into identically sized capsules. Participants were excluded if they had received more than 24 h of treatment with oral vancomycin, fidaxomicin, or metronidazole for the current episode of C difficile infection before the first dose of study drug or any other antibacterial therapy within 48 h, had had more than three episodes of C difficile infection in the previous 12 months, or had had more than one previous episode in the past 3 months (excluding the current episode). The primary efficacy endpoint was initial clinical cure maintained for at least 48 h after the end of treatment. All individuals with C difficile infection who met inclusion and exclusion criteria, were randomly assigned, and were administered at least one dose of study drug were included in the efficacy analysis. The safety and tolerability of ibezapolstat was assessed in all individuals who were administered at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT04247542.

Findings

Between March 12, 2021, and Oct 27, 2023, 39 individuals were assessed for eligibility, 32 of whom were recruited and randomly assigned to ibezapolstat (n=18) or vancomycin (n=14). Two participants were excluded from the efficacy analysis: one participant in the ibezapolstat group withdrew consent before receiving the study drug and another was identified after random assignment as having an exclusion criterion. The primary efficacy analysis included 16 participants in the ibezapolstat group and 14 in the vancomycin group; 24 (80%) participants were female and six (20%) were male. 15 (94%) of 16 participants in the ibezapolstat group had initial clinical cure compared with 14 (100%) of 14 participants in the vancomycin group (treatment difference -6·3% [95% CI -30·7 to 19·4]; p=1·0). Ibezapolstat was well tolerated with a safety profile similar to vancomycin. No drug-related serious adverse events, drug-related treatment withdrawal, or treatment-related deaths occurred in either group.

Interpretation

Ibezapolstat is a Gram-positive selective spectrum antibiotic that shows potential in the treatment of initial C difficile infection and prevention of recurrence. Further clinical development is warranted.

Funding

Acurx Pharmaceuticals.

医療・健康
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