Caspofungin versus liposomal amphotericin B for empirical antifungal therapy in patients with persistent fever and neutropenia

Echinocandins: role in antifungal therapy, 2005

Novel therapies to treat invasive fungal infections have revolutionised the care of patients with candidiasis, aspergillosis and other less common fungal infections. Physicians in the twenty first century have access to safer versions of conventional drugs (i.e., lipid amphotericin B products), extended-spectrum versions of established drugs (i.e., voriconazole), as well as a new class of antifungal agents; the echinocandins. The increased number of options in the antifungal armamentarium is well timed, as the incidence of both invasive candidiasis and invasive aspergillosis, and the financial burden associated with these infections, have increased significantly in the past several decades. The increasing incidence of fungal infections has risen in parallel with the increase in critically ill and immunocompromised patients. Candida is the fourth most common bloodstream isolate, approximately 50% of which are non-albicans species. Estimates suggest there to be 9.8 episodes of invasive candidiasis per 1000 admissions to surgical intensive care units, with attributable mortality at 30% and cost per episode of US44,000 dollars. The burden of candidiasis is even higher in the paediatric population, with Candida being the second most common bloodstream infection. The increase in non-albicans candidiasis mandates the introduction of new antifungal agents capable of treating these often azole-resistant isolates. In addition, there has been a rise in the incidence of invasive aspergillosis, the most common invasive mould infection following haematopoietic stem cell transplantation, with an estimated incidence of 10 - 20%. The mortality associated with invasive aspergillosis has increased by 357% since 1980. Unfortunately, the overall survival rate among patients treated with amphotericin B, and even voriconazole, remains suboptimal, as evidenced by the failure of treatment in 47% of patients in the landmark voriconazole versus amphotericin B trial. Given the increasing incidence and suboptimal outcomes of these serious fungal infections, novel therapies represent an opportunity for significant advancement in clinical care. The current challenge is to discover the optimal place for the echinocandins in the treatment of invasive fungal infections.

Cytokines and fungal infections

The very poor outcome of invasive fungal infections (IFI) in patients with haematological malignancies or recipients of haematopoietic stem cell transplantation is largely attributed to their compromised host defence mechanisms. The restoration or augmentation of immune responses in these patients is now considered as one of the cornerstones of effective antifungal therapy. Major advances in the field of experimental immunology have provided insight on the important regulatory role of cytokines in both innate and adaptive immunity to fungal pathogens. Preclinical studies have convincingly demonstrated that immunomodulation with cytokines can enhance the antifungal activity of neutrophils and monocytes/macrophages as well as upregulate protective T-helper type 1 adaptive immune responses. Evidence on the clinical use of cytokines in immunocompromised hosts with IFI is, however, still scant and inconclusive. The present review summarizes experimental and clinical data on the role of cytokines in the immune response to fungal pathogens and on their potential use for prevention or treatment of fungal infections. Implications for future research are also briefly discussed.

Changing face of health-care associated fungal infections

PURPOSE OF REVIEW

The purpose of this review was to evaluate recent publications on the epidemiology, diagnosis and management of invasive fungal infections.

RECENT FINDINGS

Epidemiological surveys have highlighted significant differences between Europe and the United States regarding the incidence and etiology of Candida bloodstream infections. Today, invasive aspergillosis is occurring in a much broader patient population than the classical immunocompromised hosts and includes mechanically ventilated intensive care unit patients and patients receiving corticosteroids for treatment of chronic lung diseases. Diagnosis is often delayed in these patients and prognosis is dismal. Measurement of galactomannan, mannan and antimannan antibodies, and beta-(1-3)-D-glucan may help to speed up diagnosis. The epidemiology of invasive mold infections is changing. The frequency of non-fumigatus Aspergillus species is increasing, uncommon hyalo-or phaeo-hyphomycoses are emerging and breakthrough mold infections intrinsically resistant to azoles have been reported. Clinical trials have shown that new azoles and echinocandins are as efficacious as amphotericin B or fluconazole for the treatment of eosophageal or invasive candidiasis, for prophylaxis of invasive fungal infections in transplant patients, or for empirical antifungal therapy in patients with persistent fever and neutropenia.

SUMMARY

Recent data suggest that the epidemiology of invasive fungal infections may be changing with the emergence of uncommon molds and the occurrence of invasive aspergillosis in 'nonclassical' immunocompromised hosts. New diagnostic tools and improved antifungal agents are available to facilitate early diagnosis and offer new treatment options.

[Antimycotic drugs under continuous renal replacement therapy]

In critically ill patients with acute renal failure and continuous renal replacement therapy (CRRT), the elimination of antimycotic agents is influenced by many factors; these include not only the nature and dose of the renal replacement therapy but also the properties of the medicine. High protein binding, a high molecular weight and little or no renal elimination even in subjects with normal renal function suggest that a substance is not eliminated by CRRT. This is the case with amphotericin B, caspofungin, itraconazole and voriconazole, but not with fluconazole. In the case of fluconazole, an increase in dose than that used in patients with normal renal function may be required according to the nature and dose of CRRT, because the clearance of fluconazole can be substantially higher under CRRT than in subjects with normal renal function. Daily doses of 800 mg or more may be necessary. As a result of the diverse influences on elimination in patients receiving CRRT, the determination of fluconazole through concentrations cannot be dispensed with, in order to avoid underdosing and a failure of the antimycotic therapy.

Caspofungin is less nephrotoxic than amphotericin B in vitro and predominantly damages distal renal tubular cells

BACKGROUND

Caspofungin (CAS) has recently been approved for treatment of invasive aspergillosis. In clinical trials, CAS-induced nephrotoxicity was markedly less pronounced compared to amphotericin B (AmB). Nevertheless, in a recent trial, nephrotoxicity in CAS-treated patients was considerably more pronounced than in preceding studies. Therefore, the aim of this study was to assess toxic effects of CAS on human renal proximal and distal tubular epithelial cells (PTC and DTC) in vitro, and to compare them to those of AmB.

METHODS

Cells were isolated from human kidney tissue, and exposed to clinically relevant concentrations of CAS and AmB for 24 h. Total DNA content and cell viability were determined by DAPI staining and a modified MTT assay. For testing of cytotoxicity, LDH activity was measured in cell culture supernatants. To assess apoptotic effects, AnnexinV-binding assay and DAPI staining for detection of fragmented DNA were performed.

RESULTS

DTC were more vulnerable towards the antifungal agents than PTC. In contrast to AmB, cell-damaging effects of CAS were less severe. DAPI staining revealed slight and dose-dependent antiproliferative effects of CAS at concentrations reflecting relevant plasma levels. At these concentrations, cell viability, determined by MTT assay, was not decreased in PTC and DTC. LDH release was marginally increased in a dose-dependent manner; apoptosis was not detected. Nevertheless, at CAS concentrations reflecting potential tissue concentrations, cell damaging effects were considerably more pronounced.

CONCLUSION

Our results suggest that CAS is less nephrotoxic than AmB in vitro. The antiproliferative and cytotoxic effects of CAS predominantly affect DTC, which seem to be more susceptible to CAS-induced damage.

Invasive candidiasis in cancer patients: observations from a randomized clinical trial

BACKGROUND

Invasive candidiasis is a common and serious complication of cancer and its therapy.

METHODS

We retrospectively identified patients with malignancies enrolled in a double-blind randomized trial of caspofungin (50 mg/day after a 70 mg loading dose) vs. conventional amphotericin B (0.6-1.0 mg/kg/day) as treatment of documented invasive candidiasis. A favorable response required complete resolution of signs and symptoms plus eradication of the Candida pathogen(s). The primary efficacy analysis used a modified intention-to-treat (MITT) approach that included all patients with a confirmed diagnosis of invasive candidiasis who received > or =1 dose of study medication.

RESULTS

74/224 (33%) patients in the MITT population had active malignancies. 25/30 (83%) hematological malignancies were acute or chronic leukaemias. 22/44 (50%) solid tumors were related to the gastrointestinal tract. Patients with hematological malignancies tended to be younger (median [range] age: 49 [19-74] vs. 59 [19-81] years) and have higher baseline acute physiology and chronic health evaluation (APACHE) II scores (mean [range]: 17 [0-28] vs. 15 [5-35]) than patients with solid tumors. Neutropenia [< or =500/microl] was present on entry in 23 (77%) patients with hematological malignancies and in one (3%) patient with a solid tumor. Candidemia was demonstrated in 56 (88%) cancer patients. C. albicans was the single most frequent isolate in cancer patients, although the majority of cases were caused by non-albicans species. Cancer patients in the caspofungin arm had more hematological malignancies (55 vs. 29%), higher baseline APACHE II scores (>20 in 36 vs. 15%), more frequent neutropenia (42 vs. 24%), and less C. albicans infections (27 vs. 49%) than the amphotericin B-treated cancer patients. Favorable response rates were 11/18 (61%) and 6/12 (50%) for patients with hematological malignancies treated with caspofungin or amphotericin B, respectively; the corresponding outcomes in patients with solid tumors were 12/15 (80%) and 17/29 (59%) for the 2 treatment arms. 7/14 (50%) caspofungin- and 4/10 (40%) amphotericin B-treated patients who were neutropenic on entry responded favorably. All-cause mortality rates during the study for caspofungin recipients were 11/18 (61%) with hematological malignancies and 6/15 (40%) with solid tumors, and for amphotericin recipients were 4/12 (33%) with hematological malignancies and 6/29 (21%) with solid tumors.

CONCLUSIONS

Underlying cancers, most commonly leukaemias and gastrointestinal tumors, were present in one-third of patients enrolled in this study of invasive candidiasis. Overall, 70% of caspofungin-treated and 56% of amphotericin B-treated cancer patients responded favorably. Response rates were lower for neutropenic leukaemic patients than for non-neutropenic patients with solid tumors in both treatment groups.

Caspofungin versus amphotericin B for candidemia: A pharmacoeconomic analysis

BACKGROUND

In a randomized, comparative, clinical trial, caspofungin was found to be as effective as amphotericin B deoxycholate (ampho B) for treating candidemia (favorable outcomes in 71.7% and 62.8% of patients, respectively) and exhibited a generally better safety profile, particularly with respect to impaired renal function (IRF) (P = 0.02).

OBJECTIVE

The goal of this study was to examine whether cost savings generated from the reduced rates of IRF observed in the clinical trial would be enough to offset the higher acquisition cost of caspofungin relative to ampho B.

METHODS

We developed an economic model in which 100 hypothetical patients with candidemia were treated with caspofungin or ampho B. Rates of IRF and duration of drug therapy were taken from the clinical trial. Information on the cost of treating IRF was obtained through a search of MEDLINE using the terms amphotericin and cost, amphotericin and resource, amphotericin and hospital, and amphotericin and toxicity; and the medical subject headings kidney failure, acute/drug therapy; kidney failure, acute/epidemiology; kidney failure, acute/etiology; kidney/drug effects; cost of illness; costs and cost analysis; kidney failure, acute, and economics; and kidney failure, acute/economics. In addition, the Web site was searched for relevant references, and the Merck publication alert system was used. Antifungal drug costs were estimated using data from IMS Health. Costs were reported in year-2003 US dollars.

RESULTS

In the base case, the model projected that using caspofungin instead of ampho B would result in substantially lower treatment costs for IRF, which would more than offset the higher drug acquisition cost (cost-offset percentage, 122%), leading to a net mean savings of 758.60 US dollars per patient. These results were not very sensitive to the difference in daily drug cost, but were sensitive to the mean cost attributable to treating IRF. As that varied, the cost-offset percentage varied from 61% (substantial cost offset) to 183% (cost savings).

CONCLUSIONS

The results of this economic model suggest that, based only on differences in drug acquisition cost and renal toxicity, the use of caspofungin instead of ampho B in patients with candidemia may be a cost-saving strategy from the perspective of a hospital.

Modern management of respiratory failure due to pulmonary mycoses following allogeneic hematopoietic stem-cell transplantation

Pulmonary mycoses count among the most dangerous complications in allogeneic hematopoietic stem cell transplantation. Despite the establishment of antifungal chemoprophylaxis and empirical antifungal treatment, they frequently lead to respiratory failure and are still associated with an extraordinarily poor prognosis. However, the emergence of new antimycotics with alternative mechanisms of actions and decreased toxicity in combination with the development of new non culture-based diagnostic techniques may allow earlier, more aggressive and more effective antifungal treatment approaches. In addition, the optimized use of new technologies designed to augment spontaneous breathing efforts by patients, mechanical ventilation, as well as the advantages of early tracheostomy lead us to expect better outcomes in the treatment of respiratory failure due to pulmonary mycoses following allogeneic hematopoietic stem cell transplantation.

Antifungal agents in children

Fungal pathogens are an increasingly recognized complication of organ transplantation and the ever more potent chemotherapeutic regimens for childhood malignancies. This article provides a brief overview of the current state of systemic antifungal therapy. Currently licensed drugs, including amphotericin B and its lipid derivates; 5-fluorocytosine; the azoles, including fluconazole, itraconazole, and voriconazole; and a representative of the new class of echinocandin agents, caspofungin, are discussed. Newer second-generation azoles (posaconazole and ravuconazole) and echinocandins (micafungin and anidulafungin) that are likely to be licensed in the United States in the next few years also are addressed.

[New medications for treatment of systemic mycoses]

The past few years have seen the advent of several new antifungal agents. The echinocandin, caspofungin, has greatly expanded the antifungal armamentarium by providing a cell wall-active agent with candidacidal activity as well as demonstrated clinical efficacy in the therapy of aspergillosis refractory to available therapy. In addition, in clinical trials, caspofungin exhibited efficacy comparable to amphotericin B for invasive and/or fluconazole-resistant Candida infections. According to a randomised trial, voriconazole has added a significantly improved therapeutic option for primary therapy of invasive aspergillosis. Additionally, voriconazole may be used successfully as salvage therapy for other fungal infections, i.e. cryptococcosis. Despite the advances offered by each of these drugs, the morbidity and mortality associated with invasive fungal infections remains high. Considering the adverse effects of the available antifungal agents and the considerable costs for their application, meaningful clinical trials for a precise indication in different clinical situations are urgently needed.

Hepatic uptake of the novel antifungal agent caspofungin

Caspofungin (CANCIDAS, a registered trademark of Merck & Co., Inc.) is a novel echinocandin antifungal agent used in the treatment of esophageal and invasive candidiases, invasive aspergillosis, and neutropenia. Available data suggest that the liver is a key organ responsible for caspofungin elimination in rodents and humans. Caspofungin is primarily eliminated by metabolic transformation; however, the rate of metabolism is slow. Accordingly, it was hypothesized that drug uptake transporters expressed on the basolateral domain of hepatocytes could significantly influence the extent of caspofungin uptake and subsequent elimination. In this study, experiments ranging from perfused rat livers to heterologous expression of individual hepatic uptake transporters were utilized to identify the transporter(s) responsible for the observed liver-specific uptake of this compound. Data from perfused rat liver studies were consistent with the presence of carrier-mediated caspofungin hepatic uptake, although this process appeared to be slow. To identify a relevant hepatic uptake transporter, we developed novel Tet-on HeLa cells expressing OATP1B1 (OATP-C, SLC21A6) and OATP1B3 (OATP8, SLC21A8), whose target gene can be overexpressed by the addition of doxycycline. A modest but statistically significant uptake of caspofungin was observed in cells overexpressing OATP1B1, but not OATP1B3. Taken together, these findings suggest that OATP1B1-mediated hepatic uptake may contribute to the overall elimination of this drug from the body.

Prise en charge diagnostique et thérapeutique des infections à Aspergillus sp. chez le patient immunodéprimé. Recommandations du CHRU de Lille — version 4 — novembre 2004

Invasive aspergillosis is a severe complication in immunocompromised patients. The arrival of new antifungal agents motivated the redaction of guidelines, regularly updated, by a Lille University hospital multidisciplinary task force. These guidelines assess diagnostic and therapeutic issues. The main recommended diagnosis tool is the chest CT scan, ordered at the smallest suspicion and, also, measure of the blood and broncho alveolar lavage fluid galactomannan. Treatment guidelines assess prophylaxis, empirical and documented therapy. Primary prophylaxis is warranted in only two cases, pulmonary graft or stem cell transplant in patients with chronic GVH and receiving corticosteroids. Empirical therapy should use one of the available amphotericin B formulations, chosen according to the patient history. Caspofungin is another choice. Documented therapy, depending on presentation, can be a single drug or a combination. First line therapy for single drug is i.v. voriconazole. Lipid formulations of amphotericin B are another choice. A combination therapy can be used as a first line treatment, for multiple lesions, or as salvage therapy. It must include caspofungin, associated with liposomal amphotericin B or voriconazole. A tight cooperation with thoracic surgeons is recommended.

New agents for invasive mycoses in children

PURPOSE OF REVIEW

Invasive fungal infections are an important cause of morbidity and mortality in immunocompromised children of all ages. This review summarizes information on new antifungal agents, including current data on their clinical use in children, as well as alternative strategies such as antifungal combination and immunomodulation therapy.

RECENT FINDINGS

Novel antifungal agents, such as the echinocandins and the second-generation triazoles, were recently introduced that exhibit promising efficacy against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. These compounds are generally well tolerated and show substantial efficacy as salvage treatment and equal or even superior efficacy compared with older azoles or amphotericin B as first-line or empiric therapy for fungal infections. Clinical studies of pharmacokinetics and efficacy of the new agents in the pediatric population are, however, limited.

SUMMARY

The response rates observed with the recently introduced drugs, although superior in some cases compared with older antifungal agents, are still far from satisfactory. The development of new antifungal compounds as well as the use of alternative approaches of combination therapy and immunomodulation should be pursued through well-designed laboratory and clinical studies in pediatric patients.

Bad bugs need drugs: an update on the development pipeline from the Antimicrobial Availability Task Force of the Infectious Diseases Society of America

The Antimicrobial Availability Task Force (AATF) of the Infectious Diseases Society of America (IDSA) has viewed with concern the decreasing investment by major pharmaceutical companies in antimicrobial research and development. Although smaller companies are stepping forward to address this gap, their success is uncertain. The IDSA proposed legislative and other federal solutions to this emerging public health problem in its July 2004 policy report "Bad Bugs, No Drugs: As Antibiotic R&D Stagnates, a Public Health Crisis Brews." At this time, the legislative response cannot be predicted. To emphasize further the urgency of the problem for the benefit of legislators and policy makers and to capture the ongoing frustration our clinician colleagues experience in their frequent return to an inadequate medicine cabinet, the AATF has prepared this review to highlight pathogens that are frequently resistant to licensed antimicrobials and for which few, if any, potentially effective drugs are identifiable in the late-stage development pipeline.

Itraconazole added to a lipid formulation of amphotericin B does not improve outcome of primary treatment of invasive aspergillosis

BACKGROUND

Invasive aspergillosis (IA) is associated with poor outcome in patients with hematologic malignancy treated with amphotericin B (AMB)-based therapy. Itraconazole (ITC), a triazole with activity against Aspergillus, has been used in combination with AMB or lipid formulations of AMB (LipoAMB) in the treatment of IA, although the efficacy of this strategy is uncertain.

METHODS

To determine whether the addition of ITC to LipoAMB improves outcome of IA, the authors retrospectively studied 179 consecutive patients with hematologic malignancies and definite or probable IA who received primary antifungal therapy with either LipoAMB (n = 146), or lipoAMB plus ITC (n = 33) between June 1993 and June 2003. In view of the erratic absorption of ITC tablets, only patients who received either intravenous or liquid ITC were analyzed. Patients who received < 1 week of treatment were excluded.

RESULTS

Evaluable patients in both groups (LipoAMB: n =101; ITC and LipoAMB: n = 11) had comparable distribution of risk factors of poor outcome such as neutropenia at onset of IA, persistent neutropenia, systemic steroids, previous antifungal prophylaxis, admission to the intensive care unit, disseminated IA, previous bone marrow transplant, and IA due to infection by a non-fumigatus Aspergillus species. Response to primary antifungal therapy was equally poor in both groups (LipoAMB group: 10%; ITC and LipoAMB group: 0%; P = not significant).

CONCLUSIONS

In the authors' 10-year study of patients with hematologic malignancy and IA, the response rate to LipoAMB given as primary therapy was very poor. In a comparable group of patients, the addition of ITC did not result in a therapeutic benefit.

Safety and Potential of Drug Interactions of Caspofungin and Voriconazole in Multimorbid Patients

Due to their broad antimycotic spectrum and the relatively low rate of side effects, the two antifungals caspofungin and voriconazole are considered as attractive therapeutic alternatives to amphotericin B. However, treatment of severe mycotic infections in patients taking co-medication is associated with the risk of severe adverse drug interactions. The risk of such interactions is increased if voriconazole and, much less pronounced caspofungin, are co-administered with drugs which have an inducing or inhibiting effect on the CYP 450 system, primarily on the isoenzymes CYP2C19, CYP2C9 and CYP3A4. This review provides a comprehensive overview on the potential drug interactions of caspofungin and voriconazole in multimorbid patients.

Aspergillosis in the CLEAR outcomes trial: working toward a real-world clinical perspective

Aspergillosis is a potentially lethal infection of immunocompromised patients. Until 10 years ago, antifungal therapy was largely limited to amphotericin B deoxycholate. Perceived poor response rates and inherent toxicities with amphotericin B deoxycholate were a major stimulus for the development of newer antifungals, including lipid-formulated amphotericin B, broad spectrum azoles, and echinocandins. Response rates to antifungals are highly dependent on the underlying diagnosis and degree of immune suppression of the patient. Patients at highest risk of death from aspergillosis also have very high mortality rates from other causes as well. Outcomes reported in historical literature reviews fail to distinguish between overall mortality and death attributable to aspergillosis. While this distinction can often be difficult to assess clinically, the net effect is to underestimate the therapeutic success rates of antifungals. The CLEAR (Collaborative Exchange of Antifungal Research) project started as a post approval survey to monitor clinical use of amphotericin B lipid complex (ABLC). The scope of the CLEAR project included collection of clinical data to assess outcomes in patients with invasive fungal infections treated with ABLC. Clinical data from more than 3500 patients were entered into the CLEAR database. Outcomes were assessed for 509 patients with documented aspergillosis and complete data records. Overall response rate was 63% (cured/improved/stable) with site-specific response rates of 61%, 59%, and 32% for lung, sinus, and central nervous system infections, respectively. Solid organ transplant recipients had higher response rates than patients with hematological malignancies. Bone marrow transplant recipients had the lowest response rates. Clinical response rates with ABLC reported in the CLEAR trial are higher than response rates reported for amphotericin B deoxycholate in other trials. Since it is unlikely we will see any new comparative Phase III trials for aspergillosis, CLEAR-type outcome studies will prove useful for the foreseeable future to guide clinical management of aspergillosis.

Recent developments in the management of invasive fungal infections in patients with hematological malignancies

Despite recent advances in the last decade, invasive fungal infections are still associated with a high morbidity and mortality. Invasive fungal infections constitute severe infectious complications in patients with hematological malignancies receiving myelosuppressive chemotherapy or sustained immunosuppression after allogeneic transplant regimens. Following a long period of stagnation, considerable progress has been made during the last 5 years in non-culture-based diagnostics and in the treatment of invasive fungal infections. This review highlights recent developments in the epidemiology, diagnosis, and treatment in the context of state-of-the-art management of invasive fungal infections in cancer patients.