Voriconazole compared with liposomal amphotericin B for empirical antifungal therapy in patients with neutropenia and persistent fever

Review of the safety, tolerability, and drug interactions of the new antifungal agents caspofungin and voriconazole

Managing invasive fungal infections often presents a challenge for clinicians in the treatment of immunocompromised patients. Two very different systemic antifungal agents, voriconazole and caspofungin, have recently been introduced into the market place. Voriconazole is a new triazole antifungal, while caspofungin is the first echinocandin antifungal. Voriconazole acts by inhibiting the synthesis of ergosterol in the fungal cell membrane. Caspofungin inhibits beta-1,3-D-glucan synthesis in the cell wall, a target present in fungal cells, but absent from mammalian cells. Both agents are broad-spectrum, with efficacy against invasive Aspergillus and Candida infections. The safety and tolerability profile of caspofungin presented with a low incidence of adverse events in clinical trials. Pending further data, coadministration of cyclosporine has been recommended only if the benefit outweighs the risk for patients. Voriconazole has three important side-effects that the clinician must consider: liver abnormalities, skin abnormalities and visual disturbances. Liver abnormalities in particular should be monitored very carefully. The drug interaction profile of voriconazole also warrants a careful evaluation of the concomitant medication, mainly due to cytochrome P450 metabolism. This article reviews the available data concerning the safety and tolerability profiles of each drug, as well as drug interactions and contraindications.

Fungal infections in nontransplant patients with hematologic malignancies

Fungal infections are a major cause of morbidity and mortality in patients with hematologic malignancies. Candida and Aspergillus species are the most important opportunistic fungal pathogens in this patient population. Dimorphic fungi can cause serious infection in immunocompetent persons, but infection is more likely to be disseminated in patients with compromised cell-mediated immunity. Cryptococcus neoformans and Pneumosystis carinii typically cause infections in persons with severe T-cell suppression. The frequency of rare pathogenic fungi commonly resistant to amphotericin B has significantly increased over the past 20 years among patients with hematologic malignancies. Examples of such emerging pathogens include Trichosporon, Fusarium, and Scedosporium species, and dark-walled molds. This article reviews the epidemiology, clinical manifestations, diagnostic evaluation, and treatment of the major fungal pathogens in nontransplant patients with hematologic malignancies.

Prophylaxis of invasive mycoses in solid organ transplantation

PURPOSE OF REVIEW

Solid organ transplantation is emerging as a life-saving procedure for increasing numbers of patients and invasive fungal infections are a significant cause of mortality and morbidity for patients undergoing these procedures. This paper will review the latest data pertinent to the development of effective regimens aimed at preventing invasive mycoses in the solid organ transplantation population.

RECENT FINDINGS

Risks for developing invasive fungal infections are continuing to evolve, leading to shifts in the epidemiology of invasive mycoses occurring after transplantation. For instance, risks for the development of invasive candidiasis in the immediate postoperative period following orthotopic liver transplantation have decreased dramatically while the incidence of invasive aspergillosis appears to be on the rise. New agents have recently been approved for use in the United States and may have a role in prophylactic strategies aimed at preventing these fungal infections.

SUMMARY

An understanding of these issues is crucial to the development of targeted prophylactic regimens for the successful prevention of invasive fungal infections in the solid organ transplant recipient.

Aspergillosis. Pathogenesis, clinical manifestations, and therapy

Diseases caused by Aspergillus species are increasing in importance, especially among immunocompromised hosts. Clinical manifestations are variable, ranging from allergic to invasive disease, largely depending on the status of the host's immune system. This article focuses on the pathogenesis and clinical manifestations of diseases caused by Aspergillus species, with more detailed discussion on therapy of the most morbid manifestation, invasive aspergillosis.

Systemic Candida infections in patients with leukemia: an overview of drug therapy

Systemic fungal infections are becoming increasingly common in patients with hematologic malignancies receiving antineoplastic therapy. The presence of acute myeloid or acute lymphoid leukemia, plus the use of chemotherapy to totally ablate malignant bone marrow cells, puts patients in a protracted neutropenic state. During this profound and prolonged neutropenic phase, patients receive antibiotic therapy for suspected or identified bacterial infections. However, when fever or other signs of infection continue despite antibiotic therapy, patients frequently need to be treated for suspected or identified systemic fungal infections. These infections may occur in patients receiving either standard antileukemia therapy or research protocol therapy involving new drugs, new drug combinations, higher doses, or newer schedules of established drugs. After antifungal therapy is initiated, it may be continued postdischarge in outpatient or homecare settings. Therefore, becoming knowledgeable about antifungal therapy is important for all oncology nurses regardless of practice setting.

Looking beyond highly active antiretroviral therapy: drug-related hepatotoxicity in patients with human immunodeficiency virus infection

Management of human immunodeficiency virus (HIV) has become increasingly complex since the introduction of highly active antiretroviral therapy (HAART). Patients with HIV have become exposed to an increasing array of drugs to treat HIV, prevent opportunistic infections and immune dysfunction, and manage comorbid illnesses and therapeutic complications. Hepatic complications have become common and may lead to discontinuation of treatment and significant morbidity. Up to 90% of patients with acquired immunodeficiency syndrome (AIDS) receive at least one drug that can cause hepatotoxicity. Clinicians treating patients with HIV frequently face difficulty distinguishing abnormal liver transaminase levels and toxicities in patients receiving several drugs. Some potential causes of hepatic dysfunction are viral infections, alcohol and substance abuse, and hepatotoxic drugs such as HAART. Recent reports have focused on the hepatotoxicity of HAART and the role of hepatitis viruses to the exclusion of many other agents prescribed for patients with HIV. Many of the common antibiotics, antifungals, antivirals, and ancillary agents prescribed for patients with HIV are independently associated with hepatotoxicity. Clinicians should be aware of the potential non-antiretroviral hepatotoxic agents that are frequently administered in HIV management.

The Pathophysiology and Treatment of Candida Sepsis

Sepsis can occur during disseminated candidiasis, but its pathogenesis differs from that caused by typical prokaryotic pathogens. Complex interactions between defects in host defense and "relative" virulence factors expressed by Candida lead to dissemination of the saprophyte to parenchymal organs, and subsequently to onset of multiorgan failure. This review focuses first on the pathophysiology of Candida sepsis, detailing current understanding of host-pathogen interactions. We then consider the choice of antifungal and supportive treatments.

Comparison of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing proposed standard and the E-test with the NCCLS broth microdilution method for voriconazole and caspofungin susceptibility testing of yeast species

The proposed standard of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing (AFST-EUCAST) and the E-test procedures were compared with the NCCLS reference broth microdilution method for voriconazole and caspofungin susceptibility testing of 102 clinical Candida species and Saccharomyces cerevisiae isolates. The voriconazole MIC at which 50% of strains were inhibited (MIC(50)) was < or =0.125 mg/liter for all yeast species except for Candida glabrata and Candida krusei, which yielded MIC(50) values of 0.25 to 1 mg/liter depending on the method. Caspofungin exhibited in vitro activity (MIC(50) of < or =0.125 to 2 mg/liter) against all yeast species except for Candida guilliermondii. The agreements between MICs within +/-2 dilutions obtained by the NCCLS method and the EUCAST standard were 97% for voriconazole and 96% for caspofungin. Intraclass correlation coefficients were statistically significant (P < 0.05). The agreements between voriconazole MICs provided by the E-test and the NCCLS and between the E-test and the AFST-EUCAST method were 100 and 90%, respectively. Because of lower caspofungin MICs provided by the E-test, the agreement was slightly poorer with the NCCLS method (89%) than with the AFST-EUCAST procedure (94%). Both the EUCAST and the E-test procedures can be reliable techniques for susceptibility testing of yeasts to voriconazole and caspofungin.

Antifungal drug resistance to azoles and polyenes

There is an increased awareness of the morbidity and mortality associated with fungal infections caused by resistant fungi in various groups of patients. Epidemiological studies have identified risk factors associated with antifungal drug resistance. Selection pressure due to the continuous exposure to azoles seems to have an essential role in developing resistance to fluconazole in Candida species. Haematological malignancies, especially acute leukaemia with severe and prolonged neutropenia, seem to be the main risk factors for acquiring deep-seated mycosis caused by resistant filamentous fungi, such us Fusarium species, Scedosporium prolificans, and Aspergillus terreus. The still unacceptably high mortality rate associated with some resistant mycosis indicates that alternatives to existing therapeutic options are needed. Potential measures to overcome antifungal resistance ranges from the development of new drugs with better antifungal activity to improving current therapeutic strategies with the present antifungal agents. Among the new antifungal drugs, inhibitors of beta glucan synthesis and second-generation azole and triazole derivatives have characteristics that render them potentially suitable agents against some resistant fungi. Other strategies including the use of high doses of lipid formulations of amphotericin B, combination therapy, and adjunctive immune therapy with cytokines are under investigation. In addition, antifungal control programmes to prevent extensive and inappropriate use of antifungals may be needed.

Voriconazole versus amphotericin B for primary therapy of invasive aspergillosis

BACKGROUND

Voriconazole is a broad-spectrum triazole that is active against aspergillus species. We conducted a randomized trial to compare voriconazole with amphotericin B for primary therapy of invasive aspergillosis.

METHODS

In this randomized, unblinded trial, patients received either intravenous voriconazole (two doses of 6 mg per kilogram of body weight on day 1, then 4 mg per kilogram twice daily for at least seven days) followed by 200 mg orally twice daily or intravenous amphotericin B deoxycholate (1 to 1.5 mg per kilogram per day). Other licensed antifungal treatments were allowed if the initial therapy failed or if the patient had an intolerance to the first drug used. A complete or partial response was considered to be a successful outcome.

RESULTS

A total of 144 patients in the voriconazole group and 133 patients in the amphotericin B group with definite or probable aspergillosis received at least one dose of treatment. In most of the patients, the underlying condition was allogeneic hematopoietic-cell transplantation, acute leukemia, or other hematologic diseases. At week 12, there were successful outcomes in 52.8 percent of the patients in the voriconazole group (complete responses in 20.8 percent and partial responses in 31.9 percent) and 31.6 percent of those in the amphotericin B group (complete responses in 16.5 percent and partial responses in 15.0 percent; absolute difference, 21.2 percentage points; 95 percent confidence interval, 10.4 to 32.9). The survival rate at 12 weeks was 70.8 percent in the voriconazole group and 57.9 percent in the amphotericin B group (hazard ratio, 0.59; 95 percent confidence interval, 0.40 to 0.88). Voriconazole-treated patients had significantly fewer severe drug-related adverse events, but transient visual disturbances were common with voriconazole (occurring in 44.8 percent of patients).

CONCLUSIONS

In patients with invasive aspergillosis, initial therapy with voriconazole led to better responses and improved survival and resulted in fewer severe side effects than the standard approach of initial therapy with amphotericin B.

Pharmacotherapy of Candida bloodstream infections: new treatment options, new era

Evolving medical practices and the widespread use of fluconazole have clearly affected the spectrum of invasive mycoses now encountered by clinicians. The proportion of infections due to azole-resistant Candida species and invasive moulds has increased steadily over the last decade, creating a need for broad-spectrum antifungal agents with safety profiles similar to fluconazole. Efforts to address this need have lead to the reformulation of older, broad-spectrum antifungals and the development of new agents with enhanced activity against non-C. albicans and Aspergillus species. This review highlights pharmacodynamic, pharmacokinetic, safety and cost considerations for current and emerging antifungal therapies to be used in the treatment of bloodstream candidiasis.

Prophylaxis, empirical therapy, or pre-emptive therapy of fungal infections in immunocompromised patients: which is better for whom?

Immunocompromised patients are at risk of developing fungal infections. Over time, the incidence of fungal infections and the spectrum of causative organisms have changed. In addition, treatment strategies in this high-risk population have also changed. Traditional approaches (using polyene-based therapy and older azoles), including empirical treatment strategies, have evolved to include prophylaxis in populations at the greatest risk. These strategies, although effective against Candida species, have not really impacted infections caused by Aspergillus spp. With the recent approval of antifungal agents with demonstrated activity against Aspergillus and other mould infections, there is hope for better outcomes in the treatment of established infections. Several agents, with activity against Aspergillus, have been shown to be effective in the empirical setting. The role of these new antifungal agents in the prophylactic setting remains unknown at present, but the potential for reducing Aspergillus infections is promising and requires ongoing study. The other area of significant research in fungal infections has been the search for accurate, non-invasive, rapid diagnostic tests. Over the past year, several publications have indicated that early diagnosis is possible in immunocompromised patients. These new diagnostics have paved the way for a new strategy, called pre-emptive therapy, enabling infected patients to be identified at an earlier stage of infection. This strategy will permit targeted antifungal therapy in those at greatest risk, and will avoid unnecessary, potentially toxic therapy in those not infected. Validations of the various techniques show promise and are reviewed in this paper.

Current treatment options for chronic granulomatous disease

Chronic granulomatous disease is a rare inherited disorder of phagocytic cells which results in a susceptibility to infections of catalase-positive bacteria and fungi (especially Aspergillus species), as well as granuloma formation. The mainstay of therapy is antibacterial and antifungal prophylaxis. Trimethoprim sulfamethoxazole is the drug of choice for the prevention of bacterial infection, while itraconazole is most widely used for the prevention of fungal infection. Immunomodulatory agents, such as IFN-phi, have a role in the prevention and treatment of intractable infection. New antifungal agents provide the promise of improved cure rates for invasive Aspergillus, while bone marrow transplants and gene therapy may offer the promise of complete cure.

Antifungal prophylaxis for severely neutropenic chemotherapy recipients: a meta analysis of randomized-controlled clinical trials

BACKGROUND

The overall clinical efficacy of the azoles antifungal agents and low-dose intravenous amphotericin B for antifungal chemoprophylaxis in patients with malignant disease who have severe neutropenia remains unclear.

METHODS

Randomized-controlled trials of azoles (fluconazole, itraconazole, ketoconazole, and miconazole) or intravenous amphotericin B formulations compared with placebo/no treatment or polyene-based controls in severely neutropenic chemotherapy recipients were evaluated using meta-analytical techniques.

RESULTS

Thirty-eight trials that included 7014 patients (study agents, 3515 patients; control patients, 3499 patients) were analyzed. Overall, there were reductions in the use of parenteral antifungal therapy (prophylaxis success: odds ratio [OR], 0.57; 95% confidence interval [95% CI], 0.48-0.68; relative risk reduction [RRR], 19%; number requiring treatment for this outcome [NNT], 10 patients), superficial fungal infection (OR, 0.29; 95% CI, 0.20-0.43; RRR, 61%; NNT, 12 patients), invasive fungal infection (OR, 0.44; 95% CI, 0.35-0.55; RRR, 56%; NNT, 22 patients), and fungal infection-related mortality (OR, 0.58; 95% CI, 0.41-0.82; RRR, 47%; NNT, 52 patients). Invasive aspergillosis was unaffected (OR, 1.03; 95% CI, 0.62-1.44). Although overall mortality was not reduced (OR, 0.87; 95% CI, 0.74-1.03), subgroup analyses showed reduced mortality in studies of patients who had prolonged neutropenia (OR, 0.72; 95% CI, 0.55-0.95) or who underwent hematopoietic stem cell transplantation (HSCT) (OR, 0.77; 95% CI, 0.59-0.99). The multivariate metaregression analyses identified HSCT, prolonged neutropenia, acute leukemia with prolonged neutropenia, and higher azole dose as predictors of treatment effect.

CONCLUSIONS

Antifungal prophylaxis reduced morbidity, as evidenced by reductions in the use of parenteral antifungal therapy, superficial fungal infection, and invasive fungal infection, as well as reducing fungal infection-related mortality. These effects were most pronounced in patients with malignant disease who had prolonged neutropenia and HSCT recipients.

Antifungal chemoprophylaxis after blood and marrow transplantation

Invasive fungal infections are common and deadly in recipients of blood and marrow transplants. Current diagnostic techniques do not allow accurate early diagnosis, especially of infection with mould pathogens, and delays in diagnosis are associated with treatment failure. This lack of early diagnosis has provided the impetus for the development of antifungal prophylaxis. Fluconazole prophylaxis is highly effective for the control of invasive yeast infections and associated with few breakthrough infections. The development of antimould prophylaxis in this patient population is a high priority.

Voriconazole in the treatment of aspergillosis, scedosporiosis and other invasive fungal infections in children

OBJECTIVE

To describe the safety and efficacy of voriconazole in children treated within the compassionate release program.

METHODS

Children received voriconazole on a compassionate basis for treatment of an invasive fungal infection if they were refractory to or intolerant of conventional antifungal therapy. Voriconazole was administered as a loading dose of 6 mg/kg every 12 h i.v. on Day 1 followed by 4 mg/kg every 12 h i.v. thereafter. When feasible the route of administration of voriconazole was changed from i.v. to oral (100 or 200 mg twice a day for patients weighing < 40 or > or = 40 kg, respectively). Outcome was assessed by investigators at the end of therapy or at the last visit as success (complete or partial response), stable infection, or failure, based on protocol-defined criteria.

RESULTS

Sixty-nine children (ages 9 months to 15 years; median, 7 years) received voriconazole; 58 had a proven or probable fungal infection. Among these 58 patients 27 had hematologic malignancies and 13 had chronic granulomatous disease as the most frequent underlying conditions. Forty-two patients had aspergillosis, 8 had scedosporiosis, 4 had invasive candidiasis and 4 had other invasive fungal infections. The median duration of voriconazole therapy was 93 days. At the end of therapy 26 patients (45%) had a complete or partial response. Four patients (7%) had a stable response, 25 (43%) failed therapy and 4 (7%) were discontinued from voriconazole because of intolerance. Success rates were highest in patients with chronic granulomatous disease (62%) and lowest in patients with hematologic malignancies (33%). Two patients experienced treatment-related serious adverse events (ulcerated lips with rash, elevated hepatic transaminases or bilirubin). A total of 23 patients had voriconazole-related adverse events, 3 (13%) of which caused discontinuation of voriconazole therapy. The most commonly reported adverse events included elevation in hepatic transaminases or bilirubin (n = 8), skin rash (n = 8), abnormal vision (n = 3) and a photosensitivity reaction (n = 3).

CONCLUSION

These data support the use of voriconazole for treatment of invasive fungal infections in pediatric patients who are intolerant of or refractory to conventional antifungal therapy.