Inhibition Of Glucan Synthesis Research Articles

Hope on the Horizon: Novel Fungal Treatments in Development.

The treatment of invasive fungal infections remains challenging due to limitations in currently available antifungal therapies including toxicity, interactions, restricted routes of administration, and drug resistance. This review focuses on novel therapies in clinical development, including drugs and a device. These drugs have novel mechanisms of action to overcome resistance, and some offer new formulations providing distinct advantages over current therapies to improve safety profiles and reduce interactions. Among agents that target the cell wall, 2 glucan synthesis inhibitors are discussed (rezafungin and ibrexafungerp), as well as fosmanogepix and nikkomycin Z. Agents that target the cell membrane include 3 fourth-generation azoles, oral encochleated amphotericin B, and aureobasidin A. Among agents with intracellular targets, we will review olorofim, VL-2397, T-2307, AR-12, and MGCD290. In addition, we will describe neurapheresis, a device used as adjunctive therapy for cryptococcosis. With a field full of novel treatments for fungal infections, the future looks promising.

Use of herbal extract from Artemisia herba-alba (Shih) in pharmaceutical preparations for dental hygiene

Antibiotic resistance in bacterial species is opening new avenues to search for alternative modes of antimicrobial treatment, medicinal plant extracts being one among them. The aim of this study was to access the possibility of medicinal plant extract from Shih in the manufacture of pharmaceutical preparations for oral hygiene specifically for the prevention and treatment of dental caries due to Streptococcus mutans. Antimicrobial effects of crude organic extract of Shih on S. mutans isolated from the saliva were examined by taking S. mutans with culture media only (−ve control); S. mutans treated with the antibiotic gentamicin (+ve control) and S. mutans treated with Shih. Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were Determination by Iodonitrotetrazolium chloride (INT) colorimetric assay Time-kill dynamic assay was performed using broth microdilution method. The metabolic reason behind the bacteriostatic and bactericidal effect were studied by measuring the glucose utilization by the microbes, pH as a measure of acid production, nucleic acids quantitation to check the DNA status and inhibition of water-insoluble glucan synthesis were undertaken. Shih MIC for S. mutans was at 2.5 mg/ml and MBC was 4 mg/ml. S. mutans bacterial population started reclining within 60 min of incubation with Shih at MBC. Utilization of added glucose was very high at MIC due to bacteria overcoming the stress, whereas at MBC its utilization was less. Accordingly pH also became acidic to 2.9 with MIC and 4.03 with MBC. There was a great degree of inhibition in the formation of nucleic acids indicating this crude extract interferes with DNA replication. Inhibition of glucan synthesis was to the tune of 45% as compared to control. Thus we conclude that Shih has potentially effective antibacterial activity hence it can be proposed as a potentially effective antiplaque and anticariogenic agent in the form of mouth wash or gum paint. However, the cytotoxicity of the extract needs to be evaluated in in-vitro and in-vivo conditions before it is considered as a safe antiplaque and anticariogenic agent.

Vaginal concentrations of SCY-078, a novel glucan synthesis inhibitor, following oral administration in mice

The objective of this study was to determine the exposure of SCY-078, a first in class orally-bioavailable glucan synthase inhibitor, in vaginal tissue and secretions, and their relationship to concentrations in plasma, following oral administration of SCY-078 to mice as a recognized model for Candida infections.

Drugs in Clinical Development for Fungal Infections.

Despite increasing rates of invasive fungal infections being reported globally, only a single antifungal drug has been approved during the last decade. Resistance, toxicity, drug interactions and restricted routes of administration remain unresolved issues. This review focuses on new antifungal compounds which are currently in various clinical phases of development. We discuss two azoles with a tetrazole moiety that allows selective activity against the fungal CYP: VT-1161 for Candida infections and VT-1129 for cryptococcal meningoencephalitis. We also discuss two glucan synthesis inhibitors: CD101, an echinocandin with an increased half-life, and SCY-078 with oral bioavailability and increased activity against echinocandin-resistant isolates. Among the polyenes, we discuss MAT023, an encochleated amphotericin B formulation that allows oral administration. Two novel classes of antifungal drugs are also described: glycosylphosphatidylinositol inhibitors, and the leading drug APX001, which disrupt the integrity of the fungal wall; and the orotomides, inhibitors of pyrimidine synthesis with the leading drug F901318. Finally, a chitin synthesis inhibitor and progress on human monoclonal antifungal antibodies are discussed.

The novel oral glucan synthase inhibitor SCY-078 shows in vitro activity against sessile and planktonic Candida spp.

We studied the antifungal activity of SCY-078 (an orally bioavailable 1,3-β -d- glucan synthesis inhibitor), micafungin and fluconazole against the planktonic and sessile forms of 178 Candida and non- Candida isolates causing fungaemia in patients recently admitted to a large European hospital. The in vitro activity of SCY-078, micafungin and fluconazole against the planktonic form of the isolates was assessed using EUCAST EDef 7.3 and CLSI M27-A3. Antibiofilm activity was assessed using the XTT reduction assay. SCY-078 and micafungin showed potent in vitro activity against Candida and non- Candida isolates. The in vitro activity of both drugs was similar, but SYC-078 displayed significantly lower MIC values than micafungin against Candida parapsilosis and non- Candida isolates, whereas micafungin displayed significantly lower MIC values for the remaining species ( P <0.001). In contrast, SCY-078 and micafungin showed essentially the same activity against the biofilms with the exception of Candida glabrata , in which the micafungin sessile MIC values were significantly lower ( P <0.001). These observations were confirmed by assessing biofilm structure by scanning electron microscopy after antifungal treatment. Our study showed that the high in vitro activity of SCY-078 against invasive Candida isolates in both sessile and planktonic forms is comparable to that of micafungin.

The Emerging Pathogen Candida auris: Growth Phenotype, Virulence Factors, Activity of Antifungals, and Effect of SCY-078, a Novel Glucan Synthesis Inhibitor, on Growth Morphology and Biofilm Formation

ABSTRACTCandida auris, a new multidrug-resistant Candida spp. which is associated with invasive infection and high rates of mortality, has recently emerged. Here, we determined the virulence factors (germination, adherence, biofilm formation, phospholipase and proteinase production) of 16 C. auris isolates and their susceptibilities to 11 drugs belonging to different antifungal classes, including a novel orally bioavailable 1,3-β-d-glucan synthesis inhibitor (SCY-078). We also examined the effect of SCY-078 on the growth, ultrastructure, and biofilm-forming abilities of C. auris. Our data showed that while the tested strains did not germinate, they did produce phospholipase and proteinase in a strain-dependent manner and had a significantly reduced ability to adhere and form biofilms compared to that of Candida albicans (P = 0.01). C. auris isolates demonstrated reduced susceptibility to fluconazole and amphotericin B, while, in general, they were susceptible to the remaining drugs tested. SCY-078 had an MIC90 of 1 mg/liter against C. auris and caused complete inhibition of the growth of C. auris and C. albicans. Scanning electron microscopy analysis showed that SCY-078 interrupted C. auris cell division, with the organism forming abnormal fused fungal cells. Additionally, SCY-078 possessed potent antibiofilm activity, wherein treated biofilms demonstrated significantly reduced metabolic activity and a significantly reduced thickness compared to the untreated control (P < 0.05 for both comparisons). Our study shows that C. auris expresses several virulence determinants (albeit to a lesser extent than C. albicans) and is resistant to fluconazole and amphotericin B. SCY-078, the new orally bioavailable antifungal, had potent antifungal/antibiofilm activity against C. auris, indicating that further evaluation of this antifungal is warranted.

Preclinical Pharmacokinetics and Pharmacodynamic Target of SCY-078, a First-in-Class Orally Active Antifungal Glucan Synthesis Inhibitor, in Murine Models of Disseminated Candidiasis.

ABSTRACTSCY-078 (MK-3118) is a novel, semisynthetic derivative of enfumafungin and represents the first compound of the triterpene class of antifungals. SCY-078 exhibits potent inhibition of β-(1,3)-d-glucan synthesis, an essential cell wall component of many pathogenic fungi, including Candida spp. and Aspergillus spp. SCY-078 is currently in phase 2 clinical development for the treatment of invasive fungal diseases. In vitro disposition studies to assess solubility, intestinal permeability, and metabolic stability were predictive of good oral bioavailability. Preclinical pharmacokinetic studies were consistent with once-daily administration to humans. After intravenous delivery, plasma clearance in rodents and dogs was low, representing <15% and <25% of hepatic blood flow, respectively. The terminal elimination-phase half-life was 5.5 to 8.7 h in rodents, and it was ∼9.3 h in dogs. The volume of distribution at steady-state was high (4.7 to 5.3 liters/kg), a finding suggestive of extensive tissue distribution. Exposure of SCY-078 in kidney tissue, a target organ for invasive fungal disease such as candidiasis, exceeded plasma by 20- to 25-fold for the area under the concentration-time curve from 0 h to infinity (AUC0–∞) and Cmax. SCY-078 achieved efficacy endpoints following oral delivery across multiple murine models of disseminated candidiasis. The pharmacokinetic/pharmacodynamic indices Cmax/MIC and AUC/MIC correlated with outcome. Target therapeutic exposure, expressed as the plasma AUC0–24, was comparable across models, with an upper value of 11.2 μg·h/ml (15.4 μM·h); the corresponding mean value for free drug AUC/MIC was ∼0.75. Overall, these results demonstrate that SCY-078 has the oral and intravenous (i.v.) pharmacokinetic properties and potency in murine infection models of disseminated candidiasis to support further investigation as a novel i.v. and oral treatment for invasive fungal diseases.

Effect of Liposomal Phosphatidylcholine Acyl Chain Length on the Bactericidal Activity of Liposome-Encapsulated Nisin on Cariogenic Streptococcus mutans

Background: Dental caries is an infectious oral disease caused by cariogenic Streptococcus mutans. The streptococci inhabit dental-biofilms which comprise insoluble glucans. Objectives: To prevent dental caries, liposome-encapsulated nisin prepared from phosphatidylcholines with different acyl chain lengths were tested for bactericidal activity against cariogenic S. mutans. Materials and Methods: Liposomal nisins prepared from dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), and distearoyl phoshatidylcholine (DSPC) were tested for their bactericidal activity against S. mutans 10449 and as a consequence, to inhibit the synthesis of insoluble glucan by the streptococci in vitro. Results: The bactericidal activities by minimum inhibitory concentration assay, DSPC-nisin, DPPC-nisin, and DMPC-nisin were higher by factors of 10, 3.3, and 2.5 compared with unencapsulated nisin. Inhibition of glucan synthesis was sustained the longest by DSPC-nisin. On the release assay of these liposomes, nisin was released at the highest and lowest rates from DMPC-nisin and DSPC-nisin, respectively. The highest and most sustained levels of bactericidal activity correlated with the slow release of encapsulated nisin. Conclusion: The DSPC-nisin may be useful for preventing the formation of dental caries due to sustained release of nisin. Thus, prophylaxis with the liposomal nisin may serve to maintain oral health.

Macrophage Reporter Cell Assay for Screening Immunopharmacological Activity of Cell Wall-Active Antifungals

Antifungal exposure can elicit immunological effects that contribute to activity in vivo, but this activity is rarely screened in vitro in a fashion analogous to MIC testing. We used RAW 264.7 murine macrophages that express a secreted embryonic alkaline phosphatase (SEAP) gene induced by transcriptional activation of NF-κB and activator protein 1 (AP-1) to develop a screen for immunopharmacological activity of cell wall-active antifungal agents. Isolates of Candida albicans and Aspergillus fumigatus that conditionally express genes involved in cell wall synthesis were also tested with the reporter macrophages. We found that growth of fungi in subinhibitory concentrations of glucan synthesis inhibitors (caspofungin and enfumafungin A) or repression of the β-glucan catalytic subunit of glucan synthase, FKS1, increased macrophage NF-κB/AP-1 activation in a dectin-1-dependent manner. This pattern of activation was also transiently observed with repression of chitin synthesis in C. albicans or when yeast cells were incubated in low concentrations of the chitin synthesis inhibitor nikkomycin Z.

Differential cell wall remodeling of two chitin synthase deletants Δchs3A and Δchs3B in the pathogenic yeast Candida glabrata

It is known that cell wall remodeling and the salvaging pathway act to compensate for an impaired or a damaged cell wall. Lately, it has been indicated that this mechanism is partly required for resistance to the glucan synthesis inhibitor echinocandin. While cell wall remodeling has been described in mutants of glucan or mannan synthesis, it has not yet been reported in a chitin synthesis mutant. Here, we describe a novel cell wall remodeling and salvaging pathway in chitin synthesis mutants, Δchs3A and Δchs3B, of the pathogenic yeast Candida glabrata. Electron microscopic analysis revealed a thickened mannoprotein layer in Δchs3A cells and a thickened chitin-glucan layer of Δchs3B cells, and it indicated the hypothesis that mannan synthase and chitin-glucan synthase indemnify Δchs3A and Δchs3B cells, respectively. The double-mutant CHS3A and MNN10, encoding α-1,6-mannosyltransferase, showed synergistic stress sensitization, and the Δchs3B strain showed supersensitivity to echinocandins. Hence, these findings support the above hypothesis of remodeling. Furthermore, unlike Δchs3A cells, Δchs3B cells showed supersensitivity to calcineurin inhibitor FK506 and Tor1p kinase inhibitor rapamycin, indicating that the Δchs3B strain uses the calcineurin pathway and a Tor1p kinase for cell wall remodeling.

ChemInform Abstract: Structure Elucidation of L-687,781, a New β-1,3-D-Glucan Synthesis Inhibitor.

Abstract A new β-1,3 glucan synthesis inhibitor, L-687,781 is produced by the cultivation of Dictyochaeta simplex ATCC 20960. Through NMR, mass spectroscopy, and degradation studies the structure of L-687,781 was determined to be 1 , a novel member of the papulacandin family of antifungal agents. L-687,781 exhibits potent in vitro antifungal activity as well as anti-Pneumocystis activity in a rat model.

Differential Effects of Inhibiting Chitin and 1,3-β- d -Glucan Synthesis in Ras and Calcineurin Mutants of Aspergillus fumigatus

Aspergillus fumigatus must be able to properly form hyphae and maintain cell wall integrity in order to establish invasive disease. Ras proteins and calcineurin each have been implicated as having roles in these processes. Here, we further delineate the roles of calcineurin and Ras activity in cell wall biosynthesis and hyphal morphology using genetic and pharmacologic tools. Strains deleted for three genes encoding proteins of these pathways, rasA (the Ras protein), cnaA (calcineurin), or crzA (the zinc finger transcription factor downstream of calcineurin), all displayed decreased cell wall 1,3-beta-d-glucan content. Echinocandin treatment further decreased the levels of 1,3-beta-d-glucan for all strains tested yet also partially corrected the hyphal growth defect of the DeltarasA strain. The inhibition of glucan synthesis caused an increase in chitin content for wild-type, dominant-active rasA, and DeltarasA strains. However, this important compensatory response was diminished in the calcineurin pathway mutants (DeltacnaA and DeltacrzA). Taken together, our data suggest that the Ras and calcineurin pathways act in parallel to regulate cell wall formation and hyphal growth. Additionally, the calcineurin pathway elements cnaA and crzA play a major role in proper chitin and glucan incorporation into the A. fumigatus cell wall.

Contribution of Galactofuranose to the Virulence of the Opportunistic Pathogen Aspergillus fumigatus

The filamentous fungus Aspergillus fumigatus is responsible for a lethal disease called invasive aspergillosis that affects immunocompromised patients. This disease, like other human fungal diseases, is generally treated by compounds targeting the primary fungal cell membrane sterol. Recently, glucan synthesis inhibitors were added to the limited antifungal arsenal and encouraged the search for novel targets in cell wall biosynthesis. Although galactomannan is a major component of the A. fumigatus cell wall and extracellular matrix, the biosynthesis and role of galactomannan are currently unknown. By a targeted gene deletion approach, we demonstrate that UDP-galactopyranose mutase, a key enzyme of galactofuranose metabolism, controls the biosynthesis of galactomannan and galactofuranose containing glycoconjugates. The glfA deletion mutant generated in this study is devoid of galactofuranose and displays attenuated virulence in a low-dose mouse model of invasive aspergillosis that likely reflects the impaired growth of the mutant at mammalian body temperature. Furthermore, the absence of galactofuranose results in a thinner cell wall that correlates with an increased susceptibility to several antifungal agents. The UDP-galactopyranose mutase thus appears to be an appealing adjunct therapeutic target in combination with other drugs against A. fumigatus. Its absence from mammalian cells indeed offers a considerable advantage to achieve therapeutic selectivity.

Empirical Antifungal Therapy for Patients with Neutropenia and Persitent Fever - Systematic Review and Meta-Analysis.

Background: Opportunistic invasive fungal infections (IFIs) are a major concern in the management of immunocompromised patients with hematological malignancies. The practice of administering antifungal therapy to neutropenic patients with persistent fever has become a standard care. Conflicting data exists concerning the efficacy of empirical antifungal therapy.Objectives: This study aims to evaluate if empirical antifungal therapy reduces mortality and prevents invasive fungal infections (IFI).Methods: Systematic review and meta-analysis including randomized controlled trials (RCTs) comparing empirical antifungal treatment with placebo or no intervention (control), or another regimen, in neutropenic patients with persistent fever. The Cochrane Library, MEDLINE, conference proceedings and references were searched until 2007. Outcomes assessed were: All-cause mortality, documented IFI, and adverse events. Relative risks (RR) with 95% confidence intervals (CIs) were estimated and pooled.Results: Our search yielded 26 trials, 6 of which compared polyenes or azoles to control, and 20 compared between different regimens of polyenes, azoles or glucan synthesis inhibitors. Compared to control, there was no difference in all-cause mortality (RR 0.98; 95% CI 0.58–1.66, 5 trials, Fig.1). The risk for developing documented IFI was lower (RR 0.23; 95% CI 0.08–0.65, 4 trials, 4 events in the treatment group versus 18 in the control). When azoles (fluconazole, ketoconazole, itraconazole, voriconazole) were compared to polyenes (amphotericin B in 8 trials, liposomal ampho B in 1 trial) there was a trend in favor of azoles for decreased all-cause mortality (RR 0.89; 95% CI 0.73–1.09, 9 trials) and for decreased documented IFI (RR 0.70; 95% CI 0.47–1.04, 8 trials). Adverse events of any kind were less frequent in the azole group (RR 0.40; 95% CI 0.34–0.66, 5 trials), as were those which required discontinuation (RR 0.48; 95% CI 0.38–0.62, 7 trials).Conclusions: Our review demonstrates that empirical antifungal therapy does not reduce mortality. Although it reduces IFIs, data are based on a small number of trials and events. The use of amphotericin B as empirical antifungal therapy seems unwarranted since it appears to be less effective than azoles, with no mortality benefit and an increased rate of side effects. Future trials should pursue a pre-emptive approach using improved diagnostic tools (such as galactomannan testing, high resolution CT), to identify the patients for whom antifungal treatment is warranted. [Display omitted]

Safety Profile of Concomitant Use of Caspofungin and Cyclosporine or Tacrolimus in Liver Transplant Patients

Caspofungin is the first substance of a new class of antifungal agents, the echinocandins that interfere with fungal cell wall synthesis by inhibition of glucan synthesis. Alanine aminotransferase (ALT) elevations were seen in phase I studies of patients receiving caspofungin and cyclosporine A (CyA). Actually, there is no information regarding hepatotoxicity in liver transplant patients treated concomitantly with caspofungin and immunosuppressant agents like CyA or tacrolimus (TAC). We conducted a retrospective study in 12 liver transplant patients (9 patients Child C, 3 patients acute liver failure) to assess the hepatic safety of simultaneous administration of caspofungin with CyA or TAC. Caspofungin was administered as first-line agent to patients for a 2-week period with either proofed invasive fungal infection (IFI) (n = 4), IFI-probable (n = 4), and IFI-possible (n = 4). All patients received concomitantly CyA or TAC as immunosuppressant agent. Two patients died within the first 10 days after start of treatment, caused by gram-negative rods. All other ten patients completed the 14-day treatment period. No liver enzyme elevation was recorded in these patients and administration of caspofungin with CyA or TAC was well tolerated without hepatotoxicity. The concomitant use of caspofungin with CyA or TAC in liver transplant patients is safe and seemed to be without hepatotoxic effect.

Safety of Caspofungin for Treating Invasive Nasal Sinus Aspergillosis in a Kidney Transplant Recipient

Introduction Invasive fungal sinusitis is a rare but often fatal infection in immunocompromised patients. Aggressive antifungal treatment is mandatory, but is not without risk. Caspofungin, an antifungal agent that is a member of the echinocandin family, an inhibitor of glucan synthesis in the fungal wall, is active against Aspergillus and Candidae infections. Although it works on the fungal wall, it does not affect mammalian cells; hence, its toxicity is minimal. Case Summary This report describes a case of invasive Aspergillus sinusitis in a kidney transplant recipient with diabetes mellitus. The infection involved the apex of the right orbit causing optic nerve compression. The patient was treated with transnasal endoscopic decompression of the optic nerve and intravenous AmBisome (liposomal amphotericin B) for 2 weeks without clinical improvement. The combination of caspofungin and AmBisome administered for another 2 weeks yielded partial improvement. The AmBisome had to be discontinued due to deterioration of renal and hepatic function, but the patient completed a further 7-week course of caspofungin alone. Retro-orbital biopsy confirmed a complete response to treatment; the patient’s renal and hepatic function returned to normal. Conclusion This case indicates that caspofungin is effective to treat invasive Aspergillus sinusitis in kidney transplant recipients. This agent is well tolerated and safe with respect to renal and hepatic function.

Caspofungin as second-line therapy for fever of unknown origin or invasive fungal infection following allogeneic stem cell transplantation

Caspofungin (CAS) is the first of a new class of antifungal agents, the echinocandins, that interfere with fungal cell wall synthesis by inhibition of glucan synthesis. Here, we report the results of 31 patients treated with CAS following allogeneic SCT. CAS was administered as a second-line agent to patients with invasive fungal infection (IFI) (n=15) or fever of unknown origin (n=16) who were recalcitrant to or intolerant of prior antifungal therapy. Unsuccessful first-line regimes included amphotericin B (n=17), liposomal amphotericin B (n=5), fluconazole (n=3), itraconazole (n=1), and voriconazole (n=2). All patients received concomitant immunosuppressive therapy for graft-versus-host disease. In 23 patients, cyclosporin A (CSA) and CAS were administered concurrently without any major side effects detected. Observed increases in GPT were not clinically significant. Normalization of serum creatinine and significant reductions in C-reactive protein were observed in response to CAS. Favorable outcome to CAS were documented in eight of 15 patients with IFI and in 15 of 16 patients with fever of unknown origin. CAS is a promising alternative in patients with IFI and fever of unknown origin in the setting of allogeneic SCT.

Safety and Efficacy of Caspofungin as Preventive and Empirical Antifungal Treatment of Neutropenic Allografted Patients.

Antifungal therapy is appropriate in neutropenic patients who have unexplained persistent fever, despite receipt of few days of antibacterial therapy. Conventional or liposomal amphotericin B are the preferred agents in this situation for allografted patients but toxicity or interaction with other drugs could limit their prescription. Caspofungin, the first inhibitor of fungal cell wall glucan synthesis, is the only echinocandin approved by the FDA for treatment of candidiasis. In case of suspected or documented aspergillosis infection, caspofungin is generally reserved to patients who failed to respond to amphotericin B or voriconazole. Recently, Walsh et al (ICAAC 2003) demonstrated in a randomised trial that caspofungin was comparable to liposomal amphotericine B in overall success as empirical antifungal therapy of persistently febrile neutropenic patients and was better tolerated. Here, we report our experience of caspofungin as preventive and empirical anti-fungal treatment, between November 2002 and May 2003, in 19 allografted patients with neutropenia (< 500/mm3 neutrophils) ± persistent fever despite at least 4 days of appropriate antibacterial therapy (n=12). There were 15 adult and 4 children, 11 male and 8 female. Median age was 33 years (range: 3–57). There were 6 ALL, 5 AML, 1 Myelodysplasia, 1 CML, 1 Hodgkin disease, 1 NHL, 1 myeloma, 1 aplastic anemia, 1 carcinoma and 1 Ewing sarcoma. A myeloablative conditioning regimen was used in 14 patients consisting of total body irradiation (TBI) plus high-dose chemotherapy in 9 patients and busulfan plus cyclophosphamide in 5 patients. A non myeloablative conditioning regimen was used in 5 patients. For graft-versus-host disease prophylaxis, the regimen was cyclosporin plus methotrexate in 13 patients or ATG in 6 patients. Nine patients received a bone marrow graft, 9 received granulocyte-colony-stimulating factor (G-CSF) mobilized peripheral blood stem-cells and 1 received an unrelated cord blood transplant. Twelve/19 patients have received prophylaxis with fluconazole from day 0 of the graft. Patients received caspofungin at an initial dose of 70 mg then 50 mg per day. Caspofungin was initiated within a median of 10 days after allograft (range: 0–174) including 7 patients receiving preventive caspofungin treatment at the date of aplasia. The mean duration of caspofungin therapy was 16 days (range: 3–72).Caspofungin was well tolerated and not stopped because of toxicity: WHO grade 1 and 2 hepatotoxicity occurred in 5 patients including 3 with previous hepatic abnormalities, WHO grade 1 and 2 nephrotoxicity occurred in 6 patients. No infusion reaction was observed.Only one patient developed a probable invasive bronchopulmonary aspergillosis on day 30 while receiving caspofungin. Seventeen/19 (89%) patients remain alive at least 7 days after the end of caspofungin administration without documented or suspected fungal, bacterial, or viral infection. Resolution of fever occurred in 11/12 febrile neutropenic patients in a median of 2 days (range:2–13) after starting caspofungin.We conclude that caspofungin is safe and effective as preventive and empirical antifungal treatment of neutropenic allografted patients.

An advanced double column‐switching technique (LC‐LC) for liquid chromatography/electrospray ionisation tandem mass spectrometry for fully automated analysis of caspofungin

Caspofungin (MK-0991; L-743,872) is the first representative of a new important class of antifungal agents, the glucan synthesis inhibitors. To the authors' best knowledge, to date only one high-performance liquid chromatography (HPLC) method has been published for the determination of caspofungin in serum. Severe difficulties with sorption were described. We developed a new method which addresses these difficulties using an advanced column-switching technique for fully automated analysis of caspofungin in serum without any pre-treatment. Extraction was performed automatically inline, using a diol column, followed by chromatography on a CN column. Detection was performed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS) with isolation and fragmentation in the positive ion mode. Total analysis time was 30 min. Detection of caspofungin was achieved by retention time, isolation and fragmentation of the double positively charged caspofungin ion. This LC/MS assay was validated for between-run accuracy (max. 110%) and precision (max. CV 16.1%). The lower limit of quantification was 0.2 microg/mL. The analytical method with fully automated inline extraction of caspofungin described here removes the need for difficult and time-consuming sample pre-treatment. Sorption of caspofungin is not of importance. Additional advantages of the new method are that only a small quantity of serum (5 microL) is needed and that the method is very specific.

Paradoxical effect of caspofungin: reduced activity against Candida albicans at high drug concentrations.

Resistance problems with caspofungin, an echinocandin inhibitor of fungal cell wall glucan synthesis, have been rare. We noted paradoxical turbid growth of Candida albicans isolates in broth in some high (supra-MIC) concentrations. Among isolates submitted for susceptibility testing and screened at drug concentrations up to 12.5 microg/ml, the frequency was 16%. Analysis of the turbid growth indicated slowing of growth in the presence of drug but with numbers of CFU up to 72% those of drug-free controls. Clearing of growth again by the highest drug concentrations produced a quadriphasic pattern in a tube dilution series. Cells growing at high drug concentrations were not resistant on retesting but showed the paradoxical effect of the parent. Among a selected series of isolates tested at concentrations up to 50 microg/ml, an additional 53% showed a "mini-paradoxical effect": no turbid growth but incomplete killing at high concentrations (supra-minimum fungicidal concentration). These effects were reproducible; medium dependent in extent; noted in macro- and microdilution, in the presence or absence of serum, and on agar containing drug (but not when drug concentrations were not constant, as in agar diffusion); not seen with other echinocandins and less commonly in other Candida species; and not due to destruction of drug in tubes showing the effect. Cooperative enhancement of inhibition by a second drug could eradicate the effect. We postulate that high drug concentrations derepress or activate resistance mechanisms. The abilities of subpopulations to survive at high drug concentrations could have in vivo consequences.