Renal impairment and amphotericin B formulations in patients with invasive fungal infections

A systematic review was performed to examine renal function in patients with invasive fungal infections, comparing the nephrotoxicity caused by conventional amphotericin B deoxycholate (c-AmB) with that induced by the use of lipid-based amphotericin B formulations. The analysis considered all comparative studies published in the literature between January 1996 and May 2007. The outcome data reviewed herein focused on renal toxicity as measured by serum creatinine (S-Cr) and the doubling or the mean difference in S-Cr levels from baseline to the end of therapy or the need for dialysis. We found that AmB lipid complex (ABLC), liposomal AmB (L-AmB) and AmB colloidal dispersion (ABCD) were significantly less nephrotoxic than c-AmB in all reported studies. ABLC and L-AmB caused low and comparable nephrotoxicity in nine studies. In one randomized study, L-AmB was significantly less nephrotoxic than ABLC. No studies compared ABCD nephrotoxicity to the other lipid formulations. Based on our review we conclude that lipid formulations of amphotericin B are an important strategy to preserve renal function and improve survival in critically ill patients who require treatment for systemic fungal infections.     

Carrier effects on biological activity of amphotericin B.

Amphotericin B (AmB), the drug of choice for the treatment of most systemic fungal infections, is marketed under the trademark Fungizone, as an AmB-deoxycholate complex suitable for intravenous administration. The association between AmB and deoxycholate is relatively weak; therefore, dissociation occurs in the blood. The drug itself interacts with both mammalian and fungal cell membranes to damage cells, but the greater susceptibility of fungal cells to its effects forms the basis for its clinical usefulness. The ability of the drug to form stable complexes with lipids has allowed the development of new formulations of AmB based on this property. Several lipid-based formulations of the drug which are more selective in damaging fungal or parasitic cells than mammalian cells and some of which also have a better therapeutic index than Fungizone have been developed. In vitro investigations have led to the conclusion that the increase in selectivity observed is due to the selective transfer of AmB from lipid complexes to fungal cells or to the higher thermodynamic stability of lipid formulations. Association with lipids modulates AmB binding to lipoproteins in vivo, thus influencing tissue distribution and toxicity. For example, lipid complexes of AmB can be internalized by macrophages, and the macrophages then serve as a reservoir for the drug. Furthermore, stable AmB-lipid complexes are much less toxic to the host than Fungizone and can therefore be administered in higher doses. Experimentally, the efficacy of AmB-lipid formulations compared with Fungizone depends on the animal model used. Improved therapeutic indices for AmB-lipid formations have been demonstrated in clinical trials, but the definitive trials leading to the selection of an optimal formulation and therapeutic regimen have not been done.     

A brain-vectored angiopep-2 based polymeric micelles for the treatment of intracranial fungal infection

One of the most common life-threatening infections in immunosuppressive patients, like AIDs patients, is cryptococcal meningitis or meningoencephalitis. Current therapeutic options are mostly ineffective and mortality rates remain high. Hydrophobic antifungal drug Amphotericin B (AmB), has become a golden standard in severe systemic fungal infection therapy. However, most AmB commercial formulations, including deoxycholate AmB and lipid formulations of AmB, show poor penetration into the CNS and difficulty to reach the therapeutic levels. To improve the CNS permeability of AmB, we have successfully developed an effective brain-targeting polymeric micellar system with angiopep-2 modified, named Angiopep-PEG-PE/AmB polymeric micelles. An immunosuppressive murine model with Cryptococcus neoformans meningoencephalitis (CNME) was established to evaluate the CNS penetration efficiency and antifungal treatment efficacy of the AmB-incorporated brain-vectored polymeric micellar formulation, compared with the AmB commercial formulations. After three consecutive days of i.v. administration, the results showed that the group treated with Angiopep-PEG-PE/AmB achieved the greatest treatment efficacy, which reached the highest AmB level in brain, reduced the brain fungal burden significantly, decreased histopathological severity and prolonged the median survival time. The increased treatment efficacy could be attributed to the brain-targeting delivery system promoted AmB crossing the BBB and penetrating into the brain to reach the therapeutic concentration. The underlying mechanism was also explored in this work. Therefore, the brain-targeting delivery system could have potential and promising implications for treatment of intracerebral fungal infection.     

Adverse effects of antifungal therapies in invasive fungal infections: review and meta-analysis

Amphotericin B is the main therapeutic agent for the treatment of invasive fungal infections; however, it is associated with significant toxicities that limit its use. Other systemic antifungal agents have been developed to improve tolerability while maintaining the efficacy profile of conventional amphotericin B. Fifty-four studies involving 9,228 patients were assessed for the frequency of adverse effects of the main systemic antifungal agents. While the results suggest that liposomal amphotericin B (L-AmB) is the least nephrotoxic of the lipid formulations (14.6%), that conventional amphotericin B (AmB) is the most nephrotoxic (33.2%), and that itraconazole is the most hepatotoxic (31.5%), the lack of standard definitions of antifungal-related adverse effects limits the validity of these results. Furthermore, heterogeneous patient pools and differing protocols make it difficult to draw direct comparisons between studies. With the advent of newer classes of systemic antifungal agents, future trials should conform to definitions that are universally applicable and clinically relevant to allow for such comparisons and to enable evidence-based decision-making.     

Amphotericin B for treatment of visceral leishmaniasis: systematic review and meta-analysis of prospective comparative clinical studies including dose-ranging studies

ObjectivesTo evaluate the evidence for use of different formulations of amphotericin B (AmB), minimum effective dose for each formulation and its comparative efficacy against other drugs in achieving definitive cure of visceral leishmaniasis.MethodsThis systematic review and meta-analysis included following data sources: PubMed, Embase, Scopus, Web of Science and CINAHL. Controlled prospective clinical trials (randomized or nonrandomized, including dose-ranging studies) conducted between 1996 and 2017 with at least one treatment group receiving AmB were included (published data only). The primary outcome was definitive cure at 6 months. Adverse events and mortality were assessed as secondary outcomes. The PROSPERO registration number for this review is CRD42017067488.ResultsThirty-one studies (26 from India) that enrolled 6903 patients into 84 study groups met the selection criteria. In India, liposomal AmB was not inferior to AmB deoxycholate (relative risk 1.00, 95% confidence interval (CI) 0.96–1.03, two randomized controlled trials (RCTs), 514 participants, high-quality evidence), and a single dose of the earlier formulation as low as 3.75 mg/kg achieved a cure rate of over 89% (95% CI 70.6–97.2). AmB deoxycholate was as effective as miltefosine (relative risk 0.99, 95% CI 0.95–1.03, two trials, 523 participants, high-quality evidence) and may be better than paromomycin (relative risk 1.04, 95% CI 1.02–1.07, one trial, 667 participants, low-quality evidence) in achieving definitive cure.ConclusionsAmB is an efficacious drug in the Indian subcontinent. Further evidence is needed from prospective clinical trials in other endemic geographical regions.     

Differential effects of amphotericin B and liposomal amphotericin B on inflammatory cells in vitro

OBJECTIVE AND DESIGN: To understand whether the pseudo-allergic reactions to amphotericin B (AmB) administration are due to AmB or to the solubilizing vehicles, a study was designed to evaluate the effects of AmB, liposomal AmB, (L-AmB), AmB-deoxycholate micellar complex (AmB-DC) and deoxycholate (DC) on the responses of rat serosal mast cells (RSMC) and of human basophils (HB), in vitro. MATERIALS AND METHODS: Serosal mast cells were obtained by density gradient centrifugations from male Wistar albino rats. Partially purified HB were obtained from healthy donors. The cells were exposed to AmB, L-AmB, AmB-DC and DC. Histamine release was measured fluorometrically, and the release of lactic dehydrogenase (LDH) was measured spectrophotometrically. HB activation was evaluated cytofluorimetrically by CD63 expression. RESULTS: AmB and L-AmB did not evoke histamine or LDH release from either RSMC or HB. CD63 expression was not induced in HB challenged with AmB and L-AMB. On the other hand, AmB-DC and DC produced a cytotoxic histamine release from both RSMC and HB, and a sustained increase of CD63 expression on HB. CONCLUSIONS: Only AmB-DC was able to induce the release of inflammatory mediators from RSMC and HB. Conceivably, the cytotoxic effect is accounted for by the micellar complexes with DC, which has been confirmed as a powerful histamine releaser, and held responsible for the pseudo-allergic reactions after AmB-DC administration. The data lend support to a better safety profile of L-AmB.     

Optimizing outpatient serial sputum colony counting for studies of tuberculosis treatment in resource-poor settings

Serial Sputum Colony Counting (SSCC) is an important technique in clinical trials of new treatments for tuberculosis (TB). Quantitative cultures on selective Middlebrook agar are used to calculate the rate of bacillary elimination from sputum collected from patients at different time points during the first 2 months of therapy. However, the procedure can be complicated by high sample contamination rates. This study, conducted in a resource-poor setting in Malawi, assessed the ability of different antifungal drugs in selective agar to reduce contamination. Overall, 229 samples were studied and 15% to 27% were contaminated. Fungal organisms were particularly implicated, and samples collected later in treatment were at particular risk (P < 0.001). Amphotericin B (AmB) is the standard antifungal drug used on SSCC plates at a concentration of 10 mg/ml. On selective Middlebrook 7H10 plates, AmB at 30 mg/ml reduced sample contamination by 17% compared with AmB at 10 mg/ml. The relative risk of contamination using AmB at 10 mg/ml was 1.79 (95% confidence interval [CI], 1.25 to 3.55). On Middlebrook 7H11 plates, a combination of AmB at 10 mg/ml and carbendazim at 50 mg/ml was associated with 10% less contamination than AmB at 30 mg/ml. The relative risk of contamination with AmB at 30 mg/ml was 1.79 (95% CI, 1.01 to 3.17). Improved antifungal activity was accompanied by a small reduction in bacillary counts, but this did not affect modeling of bacillary elimination. In conclusion, a combination of AmB and carbendazim optimized the antifungal activity of selective media for growth of TB. We recommend this method to reduce contamination rates and improve SSCC studies in African countries where the burden of TB is highest.     

Current experience in treating invasive zygomycosis with posaconazole

The treatment of zygomycosis has two cornerstones, namely, surgery and antifungal drugs. In many patients, both need to be applied to achieve treatment success; without treatment, the mortality rate of zygomycosis approaches 100%. Because treatment options are limited, no well-designed randomized clinical trial has been conducted and data are predominantly derived from compassionate-use programmes or case reports. Amphotericin B (AmB) lipid complex (ABLC) was clinically evaluated for efficacy against zygomycosis in a single series and resulted in cure or improvement in 52% and in the stabilizing of disease in 20% of patients. Liposomal AmB (L-AmB) is frequently used, but no large series have yet been published. Posaconazole has demonstrated in vitro and in vivo activity against Zygomycetes. Two series demonstrated salvage treatment response rates of 60% and 79%, respectively. Antifungal combinations have not been evaluated thoroughly enough to warrant recommendations outside of clinical trials. Survival is usually associated with surgical debridement and improvement in underlying diseases. Currently, surgical debridement should be performed. Antifungal treatment should consist of either ABLC ≥5 mg/kg once per day or L-AmB ≥3 mg/kg once per day. When toxicity occurs or stable fungal disease is achieved, treatment can be switched to oral posaconazole 200 mg four times per day. If impaired kidney function is overt or expected on the grounds of, for example, uncontrolled diabetes, primary treatment of zygomycosis with posaconazole is an option.     

High rate of breakthrough invasive aspergillosis among patients receiving caspofungin for persistent fever and neutropenia

A number of agents are now available for empirical antifungal treatment (EAFT) of patients with persistent fever and neutropenia. We carried out a study of efficacy of antifungal drugs to prevent breakthrough invasive aspergillosis by reviewing the medical records of all consecutive patients who received EAFT from November 2005 to February 2006. Patients’ characteristics and the type, dose and duration of antifungal therapy were recorded. Breakthrough invasive fungal infections were documented according to the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) definition. Fifty-six episodes of persistent fever with neutropenia requiring EAFT were recorded among 49 patients. All patients received high-dose chemotherapy for acute myeloid leukaemia (51%), acute lymphoid leukaemia (12%), lymphoma (14%) or other haematologic conditions (22%). Fourteen (29%) and five (10%) patients were allogeneic and autologous haematopoietic stem cell transplant recipients, respectively. Caspofungin was prescribed initially in 40 episodes (71%), amphotericin B (AmB) desoxycholate and liposomal AmB being prescribed in six (10%) and ten (18%) episodes, respectively. Six patients were switched from liposomal AmB to caspofungin because of adverse events. The median duration of antifungal therapy was 9 days. During follow-up, six patients (12%) were diagnosed with invasive aspergillosis after a median of 8 days (range 3–16 days) of EAFT. Invasive aspergillosis breakthrough occurred in 6/46 (13%) caspofungin recipients and in 0/16 (0%) AmB recipients (OR 3.1, p 0.32). The observed high rate of invasive aspergillosis among caspofungin recipients requires further evaluation.     

Update on antifungal agents for paediatric patients

Paediatric age groups display important differences in host biology, predisposing conditions, epidemiology and presentation of fungal infections relative to the adult population. During the past decade, several new antifungal agents have been developed. Although not all of these agents are yet approved for children, the paediatric development of antifungal agents has moved forwards in an exemplary manner. Invasive fungal infections will remain important causes of morbidity and mortality in immunocompromised paediatric patients. Whereas the availability of new therapeutic options is an important advance, antifungal therapy has become increasingly complex, and a thorough understanding of the available antifungal armamentarium is essential for the successful management of the individual patient. This article provides an update on the pharmacokinetics, safety and dosing of antifungal agents in paediatric patients, and their clinical indications.     

The Exciting Future of Antifungal Therapy

 Invasive fungal infections are becoming more common. Current therapy is generally limited to amphotericin B in its parent and lipid formulations, 5-fluctyosine, fluconazole, and itraconazole. Toxicity, drug-drug interactions, and increasing fungal resistance reduce the usefulness of these drugs, and the need for new therapies is pressing. This article briefly discusses the limitations of antifungal minimum inhibitory testing, and then summarizes new antifungal drugs in development that have been tested in humans. It also addresses novel treatment strategies such as drug combination therapy, pharmacological reformulations to improve the efficacy or reduce the toxicity of current antifungal drugs, immune function augmentation, and vaccine development. All of these strategies, although in their infancy, will enhance the clinician's ability to care for patients with invasive fungal infections.     

Invasive candidiasis in non neutropenic critically ill - need for region-specific management guidelines

Use of antifungal agents has increased over past few decades. A number of risk factors such as immunosuppression, broad spectrum antibiotics, dialysis, pancreatitis, surgery, etc., have been linked with the increased risk of invasive candidiasis. Though there are various guidelines available for the use of antifungal therapy, local/regional epidemiology plays an important role in determining the appropriate choice of agent in situations where the offending organism is not known (i.e. empirical, prophylactic or preemptive therapy). Developing countries like India need to generate their own epidemiological data to facilitate appropriate use of antifungal therapy. In this article, the authors have highlighted the need for region-specific policies/guidelines for treatment of invasive candidiasis. Currently available Indian literature on candidemia epidemiology has also been summarized here.     

In vitro and in vivo role of heat shock protein 90 in Amphotericin B resistance of Aspergillus terreus

Aspergillus terreus (A. terreus) is of serious concern because of a high propensity to dissemination and in vitro and in vivo resistance to Amphotericin B (AmB). The underlying molecular mechanism of AmB is not known yet and here we want to explore whether fungal heat shock protein 90 (HSP90) is involved in polyene resistance in A. terreus. AmB-susceptible (ATS) and AmB-resistant (ATR) A. terreus and AmB-susceptible Aspergillus fumigatus (AFS) were investigated in response to AmB with a special focus on HSP90. HSP90 inhibitors resulted in significant improvement of AmB activity against ATR as minimum inhibitory concentrations (MIC) decreased from 32 to 0.38 mg/L. Gene expression profiling showed a greater basal amount of HSP90 levels in ATR and ATS when compared with AFS. HSP90 blockers in combination with AmB were evaluated in a murine model of disseminated aspergillosis. HSP90 inhibitors were not beneficial for mice infected with ATR, and neither mono- nor combination treatment with AmB yielded clinical improvement. HSP90 inhibition with 17-allylamino-17-demethoxygeldanamycin (17-AAG) was harmful. HSP90 seems to play a vital role in antifungal stress response in all aspergilli tested, whereas HSP90 does not substantiate the origin of AmB resistance in ATR.     

Zygomycosis: the re-emerging fungal infection

Invasive fungal infections are major medical complications in immunocompromised patients. The recent rise in the incidence of cancer and the increased use of newer medical treatment modalities, including organ transplantations, have resulted in growing numbers of highly immunosuppressed individuals. Although aspergillosis and candidiasis are among the most common invasive mycoses in such patients, there is evidence that the incidence of infectious diseases caused by Zygomycetes has risen significantly over the past decade. Patients with diabetes, malignancies, solid organ or bone marrow transplants, or iron overload and those receiving immunosuppressive agents, deferoxamine therapy, or broad-spectrum antimicrobial drugs are at highest risk for zygomycosis. This review details the emergence and importance of zygomycosis in current clinical practice and its manifestations and management. The etiologic species, pathogenesis and risk factors for zygomycosis are reviewed and updated. The clinical spectrum of zygomycosis is now broader, and it can be difficult to distinguish between mucormycosis and enthomophthoramycosis, both of which can manifest as disease ranging from a superficial infection to an angioinvasive infection with high mortality. Finally, the three-part treatment strategy (antifungal drugs, surgery, control of underlying diseases) is reviewed. Lipid formulations of amphotericin B are the antifungal agents of choice for treatment of zygomycosis. A novel antifungal triazole, posaconazole, has been developed and may become approved for treatment of zygomycosis. The clinical experience with adjunctive treatments like colony-stimulating factors, interferon-gamma, and hyperbaric oxygen therapy is still limited.     

Liposomal amphotericin B twice weekly as antifungal prophylaxis in paediatric haematological malignancy patients

Data on antifungal prophylaxis in paediatric cancer patients at high risk for invasive fungal disease (IFD) are scant. Intermittent administration of liposomal amphotericin B (LAMB) has been shown to be safe and effective in adult patients with haematological malignancies. We prospectively evaluated the safety and efficacy of prophylactic LAMB at a dosage of 2.5 mg/kg twice weekly in children at high risk for IFD. Efficacy was compared with that in a historical control group of patients with similar demographic characteristics not receiving LAMB prophylaxis. A total of 46 high-risk patients (24 boys; mean age, 7.7 years) with 187 episodes of antifungal prophylaxis were analysed. The median duration of neutropenia (<500/μL) was 10 days. LAMB was discontinued in four patients because of acute allergic reactions. Median values for creatinine and liver enzymes at end of treatment did not differ significantly from those at baseline. Hypokalaemia (<3.0 mmol/L) occurred with 13.5% of the prophylactic episodes, but was usually mild and always reversible. No proven/probable IFD occurred in patients receiving LAMB prophylaxis. In comparison, five proven and two probable IFDs were observed in 45 historical controls not receiving LAMB prophylaxis (p 0.01). LAMB prophylaxis had no impact on the use of empirical antifungal therapy. Systemic antifungal prophylaxis with LAMB 2.5 mg/kg twice weekly is feasible and safe, and seems to be an effective approach for antifungal prophylaxis in high-risk paediatric cancer patients.     

Hyperbaric oxygen therapy and other adjunctive treatments for zygomycosis

Zygomycetes are increasingly reported as a cause of life-threatening invasive fungal infections in profoundly immunocompromised patients and in those with diabetic ketoacidosis. Zygomycosis, typically presents as soft tissue, rhino-orbitocerebral, pulmonary or disseminated disease and is characterized by rapid clinical progression and high mortality rates. Treatment with amphotericin B lipid formulations in combination with surgery and, perhaps, the addition of caspofungin offers the best chance for survival; posaconazole, a new antifungal triazole, is increasingly used for consolidation or maintenance therapy. Because of the poor prognosis of zygomycosis, particularly in immunocompromised cancer patients, adjunctive treatments such as hyperbaric oxygen therapy, use of immunomodulatory cytokines, and in vivo iron starvation continue to be explored. However, although each of these modalities is based on a plausible scientific rationale and has been helpful in the management of individual patients, there is no clinical evidence for their general effectiveness as adjunctive treatments in patients with zygomycosis. Further experimental and clinical investigations are necessary to determine whether and how these treatments can impact on outcome and to determine which patients and which types of infection may benefit from them.     

Liposomal amphotericin B in secondary prophylaxis of visceral leishmaniasis in HIV-infected patients: report of five clinical cases

Treatment of visceral leishmaniasis in HIV patients encounters inefficacy and relapse due to drug resistance, toxicity and immunodepression. Our goal was to evaluate treatment of these patients by liposomal amphotericin B (L-AmB). Since 1998, five clinical files were exploitable out of 13 patients. Protocols used bolus doses ranging between 2.9 and 4.1 mg/kg dispatched on 5-24 days, followed by maintenance dose ranging from 2.7 to 3.8 mg/kg every 15 days. Attack treatment involved high bolus dose (cumulated doses ranging from 60 to 86 mg/kg at day 30) and allowed favorable clinical and biological results with healing in four patients. Secondary prophylaxis with L-AmB has been efficacious and well tolerated in three patients. Although literature and study results cannot indicate a standard therapeutic care in these patients, an initial treatment by L-AmB at doses higher than marketing-approved doses with a secondary prophylaxis by L-AmB associated with an antiretroviral treatment seem to be major asset in order to obtain healing. Expanding this study to a multicenter trial should allow to better define the frequency and duration of the secondary prophylaxis and to evaluate the risk of therapeutic escape as well as the life-span increase.