RESUMO
VT-1598 is a novel fungal CYP51 inhibitor and 1-tetrazole-based antifungal drug candidate with improved selectivity minimizing off-target binding to and inhibition of human CYP450 enzymes. Data are presented from this first clinical study in the evaluation of the safety and pharmacokinetic (PK) of single ascending doses of 40, 80, 160, 320, and 640 mg VT-1598, comprising a 160 mg cohort in both fasting and fed states. Eight healthy adults per dose were randomized to receive either oral VT-1598 or placebo (3:1). Over the dose range, exposures were with relatively high variation. The maximum plasma concentrations (Cmax) for VT-1598 were 31.00-279.4 ng/ml and for its primary metabolite, VT-11134, were 27.80-108.8 ng/ml. The plasma area under the concentration-time curve to the last measurable concentration (AUC0-last) for VT-1598 were 116.1-4507 ng*h/ml, and for VT-11134 were 1140-7156 ng*h/ml. The dose proportionality was inconclusive based on the results of the power model. The peak concentration time (Tmax) was 4-5 h for VT-1598 and for VT-11134. Half-life was 103-126 h for VT-11134. After food intake, Cmax of VT-1598 increased by 44% (geometric mean ratio (GMR), 1.44; 90%CI [0.691, 2.19]) and AUC0-last by 126% (GMR, 2.26; 90%CI [1.09, 3.44]), while exposure of VT-11134 was decreased 23% for Cmax (GMR, 0.77; 90%CI [0.239, 1.31]) and unchanged for AUC0-last (GMR, 1.02; 90%CI [0.701, 1.33]). Neither VT-1598 nor VT-11134 were detected in urine. No serious adverse events (AEs) or AEs leading to early termination were observed. The safety and PK profiles of VT-1598 support its further clinical development.
VT-1598 is a tetrazole antifungal with improved selectivity and demonstrated a high survival rate when murine infected with invasive aspergillosis, coccidiodomycosis, cryptococcosis, and candidiasis. We report a first-in-human study to evaluate safety and pharmacokinetics after an oral dose of VT-1598.
RESUMO
VT-1161 and VT-1598 are promising investigational tetrazole antifungals that have shown in vitro and in vivo activity against Candida and other fungi. Candida glabrata is a problematic opportunistic pathogen that is associated with high mortality in invasive infection, as well as both intrinsic and rapidly acquired antifungal resistance. The MICs of VT-1161 and VT-1598 were determined by CLSI methodology to evaluate their in vitro activities against clinical C. glabrata isolates and strains containing individual deletions of the zinc cluster transcription factor genes PDR1 and UPC2A as well as the efflux transporter genes CDR1, PDH1, and SNQ2 Overall, both tetrazoles demonstrated relative activities comparable to those of the tested triazole antifungals against clinical C. glabrata isolates (MIC range, 0.25 to 2 mg/liter and 0.5 to 2 µg/ml for VT-1161 and VT-1598, respectively). Deletion of the PDR1 gene in fluconazole-resistant matched clinical isolate SM3 abolished the decreased susceptibility phenotype completely for both VT-1161 and VT-1598, similarly to the triazoles. UPC2A deletion also increased susceptibility to both triazoles and tetrazoles but to a lesser extent than PDR1 deletion. Of the three major transporter genes regulated by Pdr1, CDR1 deletion resulted in the largest MIC reductions for all agents tested, while PDH1 and SNQ2 deletion individually impacted MICs very little. Overall, both VT-1161 and VT-1598 have comparable activities to those of the available triazoles, and decreased susceptibility to these tetrazoles in C. glabrata is driven by many of the same known resistance mechanisms.
Assuntos
Antifúngicos/farmacologia , Candida glabrata/efeitos dos fármacos , Piridinas/farmacologia , Tetrazóis/farmacologia , Candida glabrata/genética , Candida glabrata/metabolismo , Farmacorresistência Fúngica/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Testes de Sensibilidade Microbiana , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The fungal Cyp51-specific inhibitors VT-1161 and VT-1598 have emerged as promising new therapies to combat fungal infections, including Candida spp. To evaluate their in vitro activities compared to other azoles, MICs were determined by Clinical and Laboratory Standards Institute (CLSI) method for VT-1161, VT-1598, fluconazole, voriconazole, itraconazole, and posaconazole against 68 C. albicans clinical isolates well characterized for azole resistance mechanisms and mutant strains representing individual azole resistance mechanisms. VT-1161 and VT-1598 demonstrated potent activity (geometric mean MICs ≤0.15 µg/ml) against predominantly fluconazole-resistant (≥8 µg/ml) isolates. However, five of 68 isolates exhibited MICs greater than six dilutions (>2 µg/ml) to both tetrazoles compared to fluconazole-susceptible isolates. Four of these isolates likewise exhibited high MICs beyond the upper limit of the assay for all triazoles tested. A premature stop codon in ERG3 likely explained the high-level resistance in one isolate. VT-1598 was effective against strains with hyperactive Tac1, Mrr1, and Upc2 transcription factors and against most ERG11 mutant strains. VT-1161 MICs were elevated compared to the control strain SC5314 for hyperactive Tac1 strains and two strains with Erg11 substitutions (Y132F and Y132F&K143R) but showed activity against hyperactive Mrr1 and Upc2 strains. While mutations affecting Erg3 activity appear to greatly reduce susceptibility to VT-1161 and VT-1598, the elevated MICs of both tetrazoles for four isolates could not be explained by known azole resistance mechanisms, suggesting the presence of undescribed resistance mechanisms to triazole- and tetrazole-based sterol demethylase inhibitors.
Assuntos
Antifúngicos/farmacologia , Azóis/farmacologia , Candida albicans/efeitos dos fármacos , Farmacorresistência Fúngica/efeitos dos fármacos , Piridinas/farmacologia , Tetrazóis/farmacologia , Candida albicans/genética , Farmacorresistência Fúngica/genética , Fluconazol/farmacologia , Proteínas Fúngicas/genética , Humanos , Testes de Sensibilidade Microbiana/métodos , Mutação/genética , Fatores de Transcrição/genéticaRESUMO
Candida auris is an emerging pathogen associated with significant mortality and often multidrug resistance. VT-1598, a tetrazole-based fungal CYP51-specific inhibitor, was evaluated in vitro and in vivo against C. auris Susceptibility testing was performed against 100 clinical isolates of C. auris by broth microdilution. Neutropenic mice were infected intravenously with C. auris, and treatment began 24 h postinoculation with a vehicle control, oral VT-1598 (5, 15, and 50 mg/kg of body weight once daily), oral fluconazole (20 mg/kg once daily), or intraperitoneal caspofungin (10 mg/kg once daily), which continued for 7 days. Fungal burden was assessed in the kidneys and brains on day 8 in the fungal burden arm and on the days the mice succumbed to infection or on day 21 in the survival arm. VT-1598 plasma trough concentrations were also assessed on day 8. VT-1598 demonstrated in vitro activity against C. auris, with a mode MIC of 0.25 µg/ml and MICs ranging from 0.03 to 8 µg/ml. Treatment with VT-1598 resulted in significant and dose-dependent improvements in survival (median survival, 15 and >21 days for VT-1598 at 15 and 50 mg/kg, respectively) and reductions in kidney and brain fungal burden (reductions of 1.88 to 3.61 log10 CFU/g) compared to the control (5 days). The reductions in fungal burden correlated with plasma trough concentrations. Treatment with caspofungin, but not fluconazole, also resulted in significant improvements in survival and reductions in fungal burden compared to those with the control. These results suggest that VT-1598 may be a future option for the treatment of invasive infections caused by C. auris.
Assuntos
Inibidores de 14-alfa Desmetilase/uso terapêutico , Antifúngicos/uso terapêutico , Candida/efeitos dos fármacos , Candidíase Invasiva/tratamento farmacológico , Piridinas/uso terapêutico , Tetrazóis/uso terapêutico , Animais , Candidíase Invasiva/microbiologia , Caspofungina/uso terapêutico , Modelos Animais de Doenças , Fluconazol/uso terapêutico , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Esterol 14-Desmetilase/metabolismoRESUMO
Synthetic neamine mimetics have been evaluated for binding to the HIV-1 Rev response element. Modified neamine derivatives, obtained from reductive amination of neamine, led to identification of new 6-amino modified neamine-type ligands with HIV-1 RRE binding affinity up to 20× that of neamine and up to 6× that of the more complex neomycin itself. This provides a noteworthy structure-activity increase and a useful lead to simplified, chemically accessible mimetics.
Assuntos
Fármacos Anti-HIV/farmacologia , Framicetina/farmacologia , HIV-1/efeitos dos fármacos , Neomicina/farmacologia , RNA Viral/efeitos dos fármacos , Elementos de Resposta/efeitos dos fármacos , Fármacos Anti-HIV/síntese química , Fármacos Anti-HIV/química , Relação Dose-Resposta a Droga , Framicetina/síntese química , Framicetina/química , Estrutura Molecular , Neomicina/análogos & derivados , Neomicina/química , Relação Estrutura-AtividadeRESUMO
VT-1129 is a novel fungal enzyme-specific Cyp51 inhibitor with potent cryptococcal activity. Because of its long half-life (>6 days in mice) and our desire to quickly reach potent efficacy, we evaluated a VT-1129 loading dose-maintenance dose strategy against cryptococcal meningitis. VT-1129 plasma and brain pharmacokinetics were first studied in healthy mice, and these data were used to model loading dose-maintenance dose regimens to generate different steady-state concentrations. Mice were inoculated intracranially with Cryptococcus neoformans, and oral treatment began 1 day later. Treatment consisted of placebo or one of three VT-1129 loading dose-maintenance dose regimens, i.e., loading dose of 1, 3, or 30 mg/kg on day 1, followed by once-daily maintenance doses of 0.15, 0.5, or 5 mg/kg, respectively. In the fungal burden arm, therapy continued for 14 days and brains were collected on day 15 for fungal burden assessments. In the survival arm, treatment continued for 10 days, after which mice were monitored without therapy until day 30. VT-1129 plasma and brain concentrations were also measured. All VT-1129 doses significantly improved survival and reduced fungal burdens, compared to placebo. VT-1129 plasma and brain levels correlated with fungal burden reductions (R2 = 0.72 and R2 = 0.67, respectively), with a plasma concentration of 1 µg/ml yielding a reduction of â¼5 log10 CFU/g. With the highest loading dose-maintenance dose regimen, fungal burdens were undetectable in one-half of the mice in the fungal burden arm and in one-fourth of the mice in the survival arm, 20 days after the final dose. These data support a loading dose-maintenance dose strategy for quickly reaching highly efficacious VT-1129 concentrations for treating cryptococcal meningitis.
Assuntos
Antifúngicos/farmacologia , Meningite Criptocócica/tratamento farmacológico , Piridinas/farmacologia , Tetrazóis/farmacologia , Animais , Encéfalo/microbiologia , Cryptococcus neoformans/efeitos dos fármacos , Masculino , Meningite Criptocócica/microbiologia , Camundongos , Camundongos Endogâmicos ICR , Testes de Sensibilidade Microbiana/métodosRESUMO
Cryptococcal meningitis is a significant cause of morbidity and mortality in immunocompromised patients. VT-1129 is a novel fungus-specific Cyp51 inhibitor with potent in vitro activity against Cryptococcus species. Our objective was to evaluate the in vivo efficacy of VT-1129 against cryptococcal meningitis. Mice were inoculated intracranially with Cryptococcus neoformans Oral treatment with VT-1129, fluconazole, or placebo began 1 day later and continued for either 7 or 14 days, and brains and plasma were collected on day 8 or 15, 1 day after therapy ended, and the fungal burden was assessed. In the survival study, treatment continued until day 10 or day 28, after which mice were monitored off therapy until day 30 or day 60, respectively, to assess survival. The fungal burden was also assessed in the survival arm. VT-1129 plasma and brain concentrations were also measured. VT-1129 reached a significant maximal survival benefit (100%) at a dose of 20 mg/kg of body weight once daily. VT-1129 at doses of ≥0.3 mg/kg/day and each dose of fluconazole significantly reduced the brain tissue fungal burden compared to that in the control after both 7 and 14 days of dosing. The fungal burden was also undetectable in most mice treated with a dose of ≥3 mg/kg/day, even ≥20 days after dosing had stopped, in the survival arm. In contrast, rebounds in fungal burden were observed with fluconazole. These results are consistent with the VT-1129 concentrations, which remained elevated long after dosing had stopped. These data demonstrate the potential utility of VT-1129 to have a marked impact in the treatment of cryptococcal meningitis.
Assuntos
Inibidores de 14-alfa Desmetilase/farmacologia , Cryptococcus neoformans/efeitos dos fármacos , Meningite Criptocócica/tratamento farmacológico , Piridinas/farmacologia , Esterol 14-Desmetilase/metabolismo , Tetrazóis/farmacologia , Animais , Antifúngicos/farmacologia , Criptococose/tratamento farmacológico , Fluconazol/farmacologia , Camundongos , Testes de Sensibilidade Microbiana/métodos , Modelos TeóricosRESUMO
Coccidioidal meningitis can cause significant morbidity, and lifelong antifungal therapy is often required. VT-1598 is a fungus-specific Cyp51 inhibitor that has potent in vitro activity against Coccidioides species. We evaluated the in vivo efficacy of VT-1598 in murine models of central nervous system coccidioidomycosis caused by C. posadasii and C. immitis Infection was introduced via intracranial inoculation, and therapy began 48 h postinoculation. Oral treatments consisted of vehicle control, VT-1598, and positive controls of fluconazole in the C. immitis study and VT-1161 in the C. posadasii study. Treatment continued for 7 and 14 days in the fungal-burden and survival studies, respectively. Fungal burden was assessed in brain tissue collected 24 to 48 h posttreatment in the fungal-burden studies, on the days the mice succumbed to infection, or at prespecified endpoints in the survival studies. VT-1598 plasma concentrations were also measured in the C. posadasii study. VT-1598 resulted in significant improvements in survival in mice infected with either species. In addition, the fungal burden was significantly reduced in the fungal-burden studies. Plasma concentrations 48 h after dosing stopped remained above the VT-1598 MIC against the C. posadasii isolate, although levels were undetectable in the survival study after a 4-week washout. Whereas fungal burden remained suppressed after a 2-week washout in the C. immitis model, a higher fungal burden was observed in the survival arm of the C. posadasii model. This in vivo efficacy supports human studies to establish the utility of VT-1598 for the treatment of coccidioidomycosis.
Assuntos
Inibidores de 14-alfa Desmetilase/uso terapêutico , Coccidioides/efeitos dos fármacos , Coccidioides/patogenicidade , Coccidioidomicose/tratamento farmacológico , Animais , Fluconazol/uso terapêutico , Masculino , Camundongos , Camundongos Endogâmicos ICR , Testes de Sensibilidade Microbiana , Modelos TeóricosRESUMO
Background: Invasive fungal infections, including those caused by yeasts, moulds and endemic organisms, can be significant causes of morbidity and mortality in immunocompromised hosts, those with multiple comorbidities and occasionally immunocompetent hosts. Current antifungal agents are often limited by drug toxicities, drug interactions or the development of resistance. VT-1598 is a novel tetrazole that has greater specificity for fungal Cyp51 than currently available triazoles and thus the potential for clinically significant drug interactions is reduced. We measured the in vitro activity of VT-1598 against clinical isolates of Candida and Cryptococcus species, endemic fungi, including Coccidioides, Blastomyces and Histoplasma, Aspergillus species and Rhizopus arrhizus. Methods: Antifungal susceptibility testing was performed by broth microdilution or macrodilution methods per CLSI standards. Clinical isolates of each species were used and clinically available antifungal agents were tested against each isolate. Results: VT-1598 demonstrated in vitro activity against yeasts and moulds that was similar to or greater than that of clinically available antifungal agents, including amphotericin B, fluconazole, caspofungin, voriconazole and posaconazole. The in vitro activity of VT-1598 was also maintained against resistant isolates, including fluconazole-resistant Candida isolates. In vitro activity was also observed against endemic fungi, including Blastomyces, Histoplasma and both Coccidioides immitis and Coccidioides posadasii. Conclusions: VT-1598 demonstrated in vitro activity against yeasts, moulds and endemic fungi, which was maintained against isolates that had reduced susceptibility to other antifungals. Further studies are warranted to evaluate the in vivo efficacy of VT-1598 against various fungal pathogens.
Assuntos
Inibidores de 14-alfa Desmetilase/farmacologia , Antifúngicos/farmacologia , Fungos/efeitos dos fármacos , Tetrazóis/farmacologia , Fungos/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana , Micoses/microbiologiaRESUMO
BACKGROUND: Candida albicans, the most common human fungal pathogen, causes chronic mucosal infections in patients with inborn errors of IL-17 immunity that rely heavily on chronic, often lifelong, azole antifungal agents for treatment. However, a rise in azole resistance has predicated a need for developing new antifungal drugs. OBJECTIVES: To test the in vitro and in vivo efficacy of VT-1161 and VT-1129 in the treatment of oropharyngeal candidiasis with azole-susceptible or -resistant C. albicans strains. METHODS: MICs of VT-1161, VT-1129 and nine licensed antifungal drugs were determined for 31 Candida clinical isolates. The drug concentrations in mouse serum and tongues were measured following oral administration. IL-17-signalling-deficient Act1-/- mice were infected with fluconazole-susceptible or fluconazole-resistant C. albicans strains, and the amount of mucosal fungal burden was determined after fluconazole or VT-1161 treatment. RESULTS: Fourteen isolates (45%) were not fluconazole susceptible (MIC ≥4 mg/L). VT-1161 and VT-1129 showed significant in vitro activity against the majority of the 31 mucosal clinical isolates (MIC50 0.03 and 0.06 mg/L, respectively), including Candida glabrata (MIC50, 0.125 and 0.25 mg/L, respectively). After oral doses, VT-1161 and VT-1129 concentrations in mouse serum and tongues were well above their MIC50 values. VT-1161 was highly effective as treatment of both fluconazole-susceptible and -resistant oropharyngeal candidiasis in Act1-/- mice. CONCLUSIONS: VT-1129 and VT-1161 exhibit significant in vitro activity against Candida strains, including fluconazole-resistant C. albicans and C. glabrata. VT-1161 administration in mice results in significant mucosal drug accumulation and eradicates infection caused by fluconazole-susceptible and -resistant Candida strains.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Candida glabrata/efeitos dos fármacos , Candidíase Bucal/tratamento farmacológico , Candidíase Bucal/prevenção & controle , Piridinas/farmacologia , Tetrazóis/farmacologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Candida albicans/isolamento & purificação , Candida glabrata/isolamento & purificação , Candidíase Bucal/microbiologia , Farmacorresistência Fúngica , Fluconazol/farmacologia , Humanos , Camundongos , Camundongos Knockout , Testes de Sensibilidade MicrobianaRESUMO
Background: Chronic mucocutaneous candidiasis (CMC) treatment often induces drug resistance, posing long-term challenges. A novel broad-spectrum fungal CYP51 inhibitor, VT-1598, specifically targets fungal CYP51, but not human CYP enzymes. Objectives: To determine the efficacy of VT-1598 in the treatment of oral Candida infection caused by fluconazole-susceptible and -resistant clinical isolates. Methods: The MICs of VT-1598 and fluconazole for 28 Candida isolates recovered from patients with inherited CMC were determined using CLSI M27-A3 and M27-S4 guidelines. Plasma and tongue VT-1598 or fluconazole concentrations were measured in mice following oral administration to determine tissue distribution. Tongue fungal load was determined in IL-17 signalling-deficient Act1-/- mice following sublingual Candida albicans infection and oral treatment with fluconazole or VT-1598. Results: Among the 28 Candida isolates, 10 (36%) had fluconazole MICs of ≥4 mg/L, whereas VT-1598 demonstrated potent in vitro activity against all isolates (MIC90, 0.125 mg/L). After oral administration, VT-1598 levels in mouse plasma and tongue were significantly greater than those of fluconazole. In vivo, VT-1598 exhibited significant efficacy against fluconazole-susceptible and -resistant C. albicans, even at low drug doses. Furthermore, after a 10 day washout period, tongue fungal burdens in fluconazole-treated mice returned to vehicle control levels, whereas, in contrast, they were undetectable in mice treated with VT-1598. Conclusions: VT-1598 effectively controls in vitro growth of mucosally derived Candida clinical isolates, including fluconazole-resistant strains. In vivo, VT-1598 eliminates C. albicans, even after a long washout period or at low doses. Therefore, VT-1598 is a promising drug candidate that may significantly improve treatment options for CMC patients.
Assuntos
Antifúngicos/farmacologia , Candida/efeitos dos fármacos , Candidíase Bucal/tratamento farmacológico , Fluconazol/farmacologia , Piridinas/farmacologia , Tetrazóis/farmacologia , Administração Oral , Animais , Farmacorresistência Fúngica , Humanos , Interleucina-17/genética , Camundongos , Camundongos Knockout , Testes de Sensibilidade Microbiana , Língua/microbiologiaRESUMO
Coccidioidomycosis can be a chronic, systemic fungal infection requiring long-term to lifetime medication. Thus, there is a need for improved antifungal agents with greater efficacy and reduced toxicity. VT-1161 has a low affinity for mammalian cytochromes and potently inhibits fungal CYP51 with proven efficacy in murine models of central nervous system (CNS) and respiratory coccidioidomycosis. Dogs experience coccidioidomycosis similar to humans and are a useful preclinical model for naturally occurring disease. Twenty-four client-owned dogs diagnosed with respiratory coccidioidomycosis based on radiography, serology, clinical signs, and clinicopathologic abnormalities were treated with a loading dose of VT-1161 for 14 days, followed by 46 days of a lower maintenance dose. Twelve dogs received a high dose (29 mg/kg loading, 6 mg/kg maintenance) and 12 received a low dose (10 mg/kg loading, 1.6 mg/kg maintenance). Response to treatment was assessed by calculating the reduction in disease scores at exit compared to disease scores at enrollment. Overall, 20 of 24 (83%) dogs had ≥50% reduction in enrollment disease scores at exit (P < 0.001), with no difference between the high- and low-dose groups (P = 0.66). Time-weighted average plasma concentrations for the high- and low-dose groups were 39 ± 5 µg/ml and 19 ± 2 µg/ml, respectively. In this open-label study, VT-1161 was efficacious for the treatment of respiratory coccidioidomycosis in naturally infected dogs. Combined with previously reported murine data, this finding supports the further development of VT-1161 for the treatment of coccidioidomycosis in humans.
Assuntos
Inibidores de 14-alfa Desmetilase/uso terapêutico , Antifúngicos/uso terapêutico , Coccidioides/efeitos dos fármacos , Coccidioidomicose/tratamento farmacológico , Coccidioidomicose/veterinária , Doenças do Cão/tratamento farmacológico , Piridinas/uso terapêutico , Tetrazóis/uso terapêutico , Animais , Antifúngicos/farmacocinética , Coccidioidomicose/microbiologia , Modelos Animais de Doenças , Doenças do Cão/microbiologia , Cães , Feminino , Masculino , Piridinas/farmacocinética , Esterol 14-Desmetilase/metabolismo , Tetrazóis/farmacocinéticaRESUMO
We compared prophylactic or continuous therapy with the investigational drug VT-1161 to that with posaconazole in treating murine mucormycosis due to Rhizopus arrhizus var. arrhizus In the prophylaxis studies, only VT-1161 resulted in improved survival and lowered tissue fungal burden of immunosuppressed infected mice. In the continuous therapy, VT-1161 outperformed posaconazole in prolonging mouse survival time despite its comparable effect in lowering tissue fungal burden. These results support the further development of VT-1161 against mucormycosis.
Assuntos
Antifúngicos/farmacologia , Substâncias Protetoras/farmacologia , Piridinas/farmacologia , Rhizopus/efeitos dos fármacos , Tetrazóis/farmacologia , Animais , Hospedeiro Imunocomprometido , Masculino , Camundongos , Testes de Sensibilidade Microbiana/métodos , Mucormicose/tratamento farmacológico , Mucormicose/microbiologia , Triazóis/farmacologiaRESUMO
Within the past few decades, the incidence and complexity of human fungal infections have increased, and therefore, the need for safer and more efficient, broad-spectrum antifungal agents is high. In the study described here, we characterized the new tetrazole-based drug candidate VT-1598 as an inhibitor of sterol 14α-demethylase (CYP51B) from the filamentous fungus Aspergillus fumigatus VT-1598 displayed a high affinity of binding to the enzyme in solution (dissociation constant, 13 ± 1 nM) and in the reconstituted enzymatic reaction was revealed to have an inhibitory potency stronger than the potencies of all other simultaneously tested antifungal drugs, including fluconazole, voriconazole, ketoconazole, and posaconazole. The X-ray structure of the VT-1598/A. fumigatus CYP51 complex was determined and depicts the distinctive binding mode of the inhibitor in the enzyme active site, suggesting the molecular basis of the improved drug potency and broad-spectrum antifungal activity. These data show the formation of an optimized hydrogen bond between the phenoxymethyl oxygen of VT-1598 and the imidazole ring nitrogen of His374, the CYP51 residue that is highly conserved across fungal pathogens and fungus specific. Comparative structural analysis of A. fumigatus CYP51/voriconazole and Candida albicans CYP51/VT-1161 complexes supports the role of H bonding in fungal CYP51/inhibitor complexes and emphasizes the importance of an optimal distance between this interaction and the inhibitor-heme iron interaction. Cellular experiments using two A. fumigatus strains (strains 32820 and 1022) displayed a direct correlation between the effects of the drugs on CYP51B activity and fungal growth inhibition, indicating the noteworthy anti-A. fumigatus potency of VT-1598 and confirming its promise as a broad-spectrum antifungal agent.
Assuntos
Antifúngicos/farmacologia , Aspergillus fumigatus/efeitos dos fármacos , Aspergillus fumigatus/enzimologia , Drogas em Investigação/farmacologia , Esterol 14-Desmetilase/metabolismo , Aspergillus fumigatus/genética , Candida albicans/efeitos dos fármacos , Candida albicans/enzimologia , Candida albicans/genética , Fluconazol/farmacologia , Cetoconazol/farmacologia , Testes de Sensibilidade Microbiana , Piridinas/farmacologia , Esterol 14-Desmetilase/genética , Tetrazóis/farmacologia , Triazóis/farmacologia , Voriconazol/farmacologiaRESUMO
Prior to characterization of antifungal inhibitors that target CYP51, Trichophyton rubrum CYP51 was expressed in Escherichia coli, purified, and characterized. T. rubrum CYP51 bound lanosterol, obtusifoliol, and eburicol with similar affinities (dissociation constant [Kd ] values, 22.7, 20.3, and 20.9 µM, respectively) but displayed substrate specificity, insofar as only eburicol was demethylated in CYP51 reconstitution assays (turnover number, 1.55 min-1; Km value, 2 µM). The investigational agent VT-1161 bound tightly to T. rubrum CYP51 (Kd = 242 nM) with an affinity similar to that of clotrimazole, fluconazole, ketoconazole, and voriconazole (Kd values, 179, 173, 312, and 304 nM, respectively) and with an affinity lower than that of itraconazole (Kd = 53 nM). Determinations of 50% inhibitory concentrations (IC50s) using 0.5 µM CYP51 showed that VT-1161 was a tight-binding inhibitor of T. rubrum CYP51 activity, yielding an IC50 of 0.14 µM, whereas itraconazole, fluconazole, and ketoconazole had IC50s of 0.26, 0.4, and 0.6 µM, respectively. When the activity of VT-1161 was tested against 34 clinical isolates, VT-1161 was a potent inhibitor of T. rubrum growth, with MIC50, MIC90, and geometric mean MIC values of ≤0.03, 0.06, and 0.033 µg ml-1, respectively. With its selectivity versus human CYP51 and drug-metabolizing cytochrome P450s having already been established, VT-1161 should prove to be safe and effective in combating T. rubrum infections in patients.
Assuntos
Antifúngicos/farmacologia , Piridinas/farmacologia , Tetrazóis/farmacologia , Trichophyton/efeitos dos fármacos , Azóis/farmacologia , Candida albicans/efeitos dos fármacos , Clotrimazol/farmacologia , Farmacorresistência Fúngica , Fluconazol/farmacologia , Proteínas Fúngicas/metabolismo , Itraconazol/farmacologia , Cetoconazol/farmacologia , Testes de Sensibilidade Microbiana , Esterol 14-Desmetilase/metabolismo , Especificidade por Substrato , Voriconazol/farmacologiaRESUMO
Although antifungal drug resistance in the human fungal pathogen Cryptococcus neoformans is relatively uncommon, fluconazole-resistant strains are problematic for preemptive treatment of cryptococcal antigenemia or during cryptococcal meningitis consolidation therapy. We analyzed activity of the experimental antifungal VT-1129 on 51 clinical Cryptococcus neoformans isolates previously screened for fluconazole resistance; with an emphasis on fluconazole dose-dependent (MIC 16-32 µg/ml) or resistant (MIC ≥ 64 µg/ml) isolates. Overall, the VT-1129 geometric mean MIC was 0.027 µg/ml. The VT-1129 MIC50 was 0.05 µg/ml and 0.25 µg/ml for dose-dependent (n = 27) and resistant isolates (n = 6), respectively. These data suggest VT-1129 shows potential for use against fluconazole-resistant Cryptococcus.
Assuntos
Antifúngicos/farmacologia , Cryptococcus neoformans/efeitos dos fármacos , Farmacorresistência Fúngica , Fluconazol/farmacologia , Piridinas/farmacologia , Tetrazóis/farmacologia , Criptococose/microbiologia , Cryptococcus neoformans/isolamento & purificação , Humanos , Testes de Sensibilidade MicrobianaRESUMO
While the orally-active azoles such as fluconazole and posaconazole are effective antifungal agents, they potently inhibit a broad range of off-target human cytochrome P450 enzymes (CYPs) leading to various safety issues (e.g., drug-drug interactions, liver, and reproductive toxicities). Recently we described the rationally-designed, antifungal agent VT-1161 that is more selective for fungal CYP51 than related human CYP enzymes such as CYP3A4. Herein, we describe the use of a homology model of Aspergillus fumigatus to design and optimize a novel series of highly selective, broad spectrum fungal CYP51 inhibitors. This series includes the oral antifungal VT-1598 that exhibits excellent potency against yeast, dermatophyte, and mold fungal pathogens.
Assuntos
Inibidores de 14-alfa Desmetilase/química , Inibidores de 14-alfa Desmetilase/farmacologia , Antifúngicos/química , Antifúngicos/farmacologia , Azóis/química , Azóis/farmacologia , Fungos/enzimologia , Aspergilose/tratamento farmacológico , Aspergilose/microbiologia , Aspergillus fumigatus/efeitos dos fármacos , Aspergillus fumigatus/enzimologia , Família 51 do Citocromo P450/antagonistas & inibidores , Família 51 do Citocromo P450/metabolismo , Desenho de Fármacos , Fungos/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Micoses/tratamento farmacológico , Micoses/microbiologia , Piridinas/química , Piridinas/farmacologia , Tetrazóis/química , Tetrazóis/farmacologiaRESUMO
Cryptococcosis is a life-threatening disease often associated with HIV infection. Three Cryptococcus species CYP51 enzymes were purified and catalyzed the 14α-demethylation of lanosterol, eburicol, and obtusifoliol. The investigational agent VT-1129 bound tightly to all three CYP51 proteins (dissociation constant [Kd] range, 14 to 25 nM) with affinities similar to those of fluconazole, voriconazole, itraconazole, clotrimazole, and ketoconazole (Kd range, 4 to 52 nM), whereas VT-1129 bound weakly to human CYP51 (Kd, 4.53 µM). VT-1129 was as effective as conventional triazole antifungal drugs at inhibiting cryptococcal CYP51 activity (50% inhibitory concentration [IC50] range, 0.14 to 0.20 µM), while it only weakly inhibited human CYP51 activity (IC50, â¼600 µM). Furthermore, VT-1129 weakly inhibited human CYP2C9, CYP2C19, and CYP3A4, suggesting a low drug-drug interaction potential. Finally, the cellular mode of action for VT-1129 was confirmed to be CYP51 inhibition, resulting in the depletion of ergosterol and ergosta-7-enol and the accumulation of eburicol, obtusifolione, and lanosterol/obtusifoliol in the cell membranes.
Assuntos
Antifúngicos/farmacologia , Cryptococcus/efeitos dos fármacos , Piridinas/efeitos adversos , Piridinas/farmacologia , Esterol 14-Desmetilase/metabolismo , Tetrazóis/efeitos adversos , Tetrazóis/farmacologia , Antifúngicos/efeitos adversos , Clotrimazol/efeitos adversos , Clotrimazol/farmacologia , Cryptococcus/metabolismo , Ativação Enzimática/efeitos dos fármacos , Ergosterol/metabolismo , Fluconazol/efeitos adversos , Fluconazol/farmacologia , Humanos , Itraconazol/efeitos adversos , Itraconazol/farmacologia , Cetoconazol/efeitos adversos , Cetoconazol/farmacologia , Lanosterol/análogos & derivados , Lanosterol/metabolismo , Voriconazol/efeitos adversos , Voriconazol/farmacologiaRESUMO
Thein vitroactivities of the novel fungal Cyp51 inhibitor VT-1129 were evaluated against a large panel ofCryptococcus neoformansandCryptococcus gattiiisolates. VT-1129 demonstrated potent activities against bothCryptococcusspecies as demonstrated by low MIC50and MIC90values. ForC. gattii, thein vitropotency was maintained against all genotypes. In addition, significantly lower geometric mean MICs were observed for VT-1129 than for fluconazole againstC. neoformans, including isolates with reduced fluconazole susceptibility.
Assuntos
Inibidores de 14-alfa Desmetilase/farmacologia , Antifúngicos/farmacologia , Drogas em Investigação/farmacologia , Proteínas Fúngicas/antagonistas & inibidores , Piridinas/farmacologia , Esterol 14-Desmetilase/metabolismo , Tetrazóis/farmacologia , Inibidores de 14-alfa Desmetilase/síntese química , Antifúngicos/síntese química , Cryptococcus gattii/efeitos dos fármacos , Cryptococcus gattii/enzimologia , Cryptococcus gattii/genética , Cryptococcus neoformans/efeitos dos fármacos , Cryptococcus neoformans/enzimologia , Cryptococcus neoformans/genética , Farmacorresistência Fúngica/genética , Drogas em Investigação/síntese química , Fluconazol/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Expressão Gênica , Genótipo , Testes de Sensibilidade Microbiana , Piridinas/síntese química , Esterol 14-Desmetilase/genética , Tetrazóis/síntese químicaRESUMO
We studied the efficacy of the investigational drug VT-1161 against mucormycosis. VT-1161 had more potent in vitro activity against Rhizopus arrhizus var. arrhizus than against R. arrhizus var. delemar. VT-1161 treatment demonstrated dose-dependent plasma drug levels with prolonged survival time and lowered tissue fungal burden in immunosuppressed mice infected with R. arrhizus var. arrhizus and was as effective as high-dose liposomal amphotericin B treatment. These results support further development of VT-1161 against mucormycosis.