Retrospective study of the safety of caspofungin in immunocompromised pediatric patients

Advances in the treatment of invasive neonatal candidiasis

INTRODUCTION

Invasive candidiasis is responsible for ∼ 10% of nosocomial sepsis in very-low-birth-weight infants and is associated with substantial morbidity and mortality. Over the last two decades, the antifungal armamentarium against Candida spp. has increased; however, efficacy and safety studies in this population are lacking.

AREAS COVERED

We reviewed the medical literature and extracted information on clinical and observational studies evaluating the use of antifungal agents in neonates with invasive candidiasis.

EXPERT OPINION

Efficacy and safety data for antifungals in neonates are lacking, and the majority of studies conducted to date have concentrated on pharmacokinetic/pharmacodynamic evaluations. Unlike other anti-infective agents, efficacy data in the setting of neonatal candidiasis cannot be extrapolated from adult studies due to differences in the pathophysiology of the disease in this population relative to older children and adults. Data for amphotericin B deoxycholate, fluconazole, and micafungin suggest that these are the current agents of choice for this disease in neonates until data for newer antifungal agents become available. For prophylaxis, data from fluconazole randomized controlled trials will be submitted to the regulatory agencies for labeling. Ultimately, the field of therapeutics for neonatal candidiasis will require multidisciplinary collaboration given the numerous challenges associated with conducting clinical trials in neonates.

Pharmacokinetics and pharmacodynamics of antifungals in children: clinical implications

Invasive fungal disease (IFD) remains life threatening in premature infants and immunocompromised children despite the recent development of new antifungal agents. Optimal dosing of antifungals is one of the few factors clinicians can control to improve outcomes of IFD. However, dosing in children cannot be extrapolated from adult data because IFD pathophysiology, immune response, and drug disposition differ from adults. We critically examined the literature on pharmacokinetics (PK) and pharmacodynamics (PD) of antifungal agents and highlight recent developments in treating pediatric IFD. To match adult exposure in pediatric patients, dosing adjustment is necessary for almost all antifungals. In young infants, the maturation of renal and metabolic functions occurs rapidly and can significantly influence drug exposure. Fluconazole clearance doubles from birth to 28 days of life and, beyond the neonatal period, agents such as fluconazole, voriconazole, and micafungin require higher dosing than in adults because of faster clearance in children. As a result, dosing recommendations are specific to bracketed ranges of age. PD principles of antifungals mostly rely on in vitro and in vivo models but very few PD studies specifically address IFD in children. The exposure-response relationship may differ in younger children compared with adults, especially in infants with invasive candidiasis who are at higher risk of disseminated disease and meningoencephalitis, and by extension severe neurodevelopmental impairment. Micafungin is the only antifungal agent for which a specific target of exposure was proposed based on a neonatal hematogenous Candida meningoencephalitis animal model. In this review, we found that pediatric data on drug disposition of newer triazoles and echinocandins are lacking, dosing of older antifungals such as fluconazole and amphotericin B products still need optimization in young infants, and that target PK/PD indices need to be clinically validated for almost all antifungals in children. A better understanding of age-specific PK and PD of new antifungals in infants and children will help improve clinical outcomes of IFD by informing dosing and identifying future research areas.

A review of clinical experience with newer antifungals in children

Fungal infections are a significant cause of morbidity and mortality in immunocompromised children. Since the beginning of the 21st century, many new antifungals including the echinocandins (i.e., caspofungin, micafungin, anidulafungin) and the newer generation triazoles (i.e., voriconazole and posaconazole) have received Food and Drug Administration approval. Unfortunately, despite making great strides in the adult arena, these agents are not currently approved in the pediatric population. However, pharmacokinetic data and clinical experiences with these agents in infants, children, and adolescents are mounting. As such, this review will discuss key concepts in pediatric pharmacology and clinical use of these newer antifungal agents.

Caspofungin as antifungal prophylaxis in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation: a retrospective analysis

Background

Pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) often receive intravenous liposomal amphotericin B (L-AmB) as antifungal prophylaxis. There are no guidelines for antifungal prophylaxis in children in this situation. Caspofungin (CAS), a broad-spectrum echinocandin, could be an effective alternative with lower nephrotoxicity than L-AmB.

Methods

We retrospectively analyzed the safety, feasibility, and efficacy of CAS in our center, and compared the results with L-AmB as antifungal monoprophylaxis in pediatric patients undergoing HSCT. 60 pediatric patients received L-AmB (1 or 3 mg/kg bw/day) and another 60 patients received CAS (50 mg/m²/day) as antifungal monoprophylaxis starting on day one after HSCT. The median ages of patients receiving L-AmB and CAS were 7.5 years and 9.5 years, respectively.

Results

No proven breakthrough fungal infection occurred in either group during the median treatment period of 23 days in the L-AmB group and 24 days in the CAS group. One patient receiving CAS developed probable invasive aspergillosis. During L-AmB treatment, potassium levels significantly decreased below normal values. Patients treated with L-AmB had more drug-related side effects and an increased need for oral supplementation with potassium, sodium bicarbonate and calcium upon discharge as compared with the CAS group. CAS was well-tolerated and safe in this cohort of immunocompromised pediatric patients, who underwent high-dose chemotherapy and HSCT.

Conclusion

Prophylactic CAS and L-AmB showed similar efficacy in this biggest cohort of pediatric patients after allogeneic HSCT reported, so far. A prospective randomized trial in children is warranted to allow for standardized guidelines.

Emergent Complications in the Pediatric Hematopoietic Stem Cell Transplant Patient

Hematopoietic cell transplantation is the only potentially curative option for a variety of pediatric malignant and nonmalignant disorders. Despite advances in transplantation biology and immunology as well as in posttransplant management that have contributed to improved survival and decreased transplant-related mortality, hematopoietic cell transplantation does not come without significant risk of complications. When patients who have undergone hematopoietic cell transplantation present to the emergency department, it is important to consider a variety of therapy-related complications to optimize management and outcome. In this article, we use clinical cases to highlight some of the more common emergent complications after hematopoietic cell transplantation.

Caspofungin therapy in immunocompromised children and neonates

The prevalence of invasive fungal infections is increasing and the infections are becoming a major problem in immunocompromised children and neonates. Fortunately, there has been a recent surge in the development of new antifungal agents. Caspofungin, the first licensed echinocandin, is a novel class of antifungal and is approved for use in children 3 months of age or older for the treatment of invasive candidiasis, salvage therapy for invasive aspergillosis and as empirical therapy for febrile neutropenia. This article reviews the published data on the use of caspofungin in immunocompromised children and neonates with invasive fungal infections.

Comparison of echinocandin antifungals

The incidence of invasive fungal infections, especially those due to Aspergillus spp. and Candida spp., continues to increase. Despite advances in medical practice, the associated mortality from these infections continues to be substantial. The echinocandin antifungals provide clinicians with another treatment option for serious fungal infections. These agents possess a completely novel mechanism of action, are relatively well-tolerated, and have a low potential for serious drug-drug interactions. At the present time, the echinocandins are an option for the treatment of infections due Candida spp (such as esophageal candidiasis, invasive candidiasis, and candidemia). In addition, caspofungin is a viable option for the treatment of refractory aspergillosis. Although micafungin is not Food and Drug Administration-approved for this indication, recent data suggests that it may also be effective. Finally, caspofungin- or micafungin-containing combination therapy should be a consideration for the treatment of severe infections due to Aspergillus spp. Although the echinocandins share many common properties, data regarding their differences are emerging at a rapid pace. Anidulafungin exhibits a unique pharmacokinetic profile, and limited cases have shown a potential far activity in isolates with increased minimum inhibitory concentrations to caspofungin and micafungin. Caspofungin appears to have a slightly higher incidence of side effects and potential for drug-drug interactions. This, combined with some evidence of decreasing susceptibility among some strains of Candida, may lessen its future utility. However, one must take these findings in the context of substantially more data and use with caspofungin compared with the other agents. Micafungin appears to be very similar to caspofungin, with very few obvious differences between the two agents.

Invasive respiratory aspergillosis is a treatable disease with early diagnosis and aggressive therapy

This study aimed to document outcome of invasive respiratory aspergillosis (IRA) in pediatric malignancy patients. Patients with febrile neutropenia episodes followed between January 2003 and May 2007 were enrolled. Antifungal therapy was added to those who were still febrile on the 5th day of febrile neutropenia treatment. Patients were screened with computerized tomographies. IRA was identified in 22 of 98 patients. There were 13 males and the mean age was 97 months. Proven infection was established in 3, probable in 7, and possible in 12 patients. Liposomal amphotericin B was administered to all patients and was successful in 10 patients. Modifications with caspofungin or voriconazole were done in liposomal amphotericin B failures. The median duration of antifungal therapy was 5.5 months. The median follow-up time was 29 months. There was no evidence of IRA in 12 patients after completion of cancer chemotherapy. Six patients died due to underlying disease, whereas IRA was either in remission or stable disease. Four patients were lost due to IRA. The remission rate for IRA was 82%. Survival at 37 months was 55% (95% confidence interval 25-47 months). The amount of time that absolute neutrophil count after initiation of treatment for IRA remained at zero was found to be an independent prognostic factor on survival (P = .01). These results suggest that early diagnosis and aggressive treatment may increase the successful outcome of IRA.

A Clinical Review of Echinocandins in Pediatric Patients

OBJECTIVE

To identify and evaluate available data on pediatric echinocandin use.

DATA SOURCES

A PubMed search, limited to English-language articles, was conducted (1990-August 2009) using the search terms echinocandin, pediatric, child, pharmacokinetics, caspofungin, micafungin, and anidulafungin. Additional articles were retrieved from citations of selected references.

STUDY SELECTION AND DATA EXTRACTION

Relevant information on the pharmacology, pharmacokinetics, efficacy, and safety of echinocandins in children was selected. Clinical trials, retrospective reviews, and case series were identified and evaluated. Data from these sources were included in this review.

DATA SYNTHESIS

Caspofungin is the only echinocandin approved by the Food and Drug Administration for use in children. Pediatric pharmacokinetics has been evaluated with all 3 echinocandins but is limited with anidulafungin. Micafungin is the most well-studied agent in prospective clinical trials for antifungal prophylaxis in stem cell transplantation and treatment of invasive fungal infections. Caspofungin has been studied prospectively for febrile neutropenia and treatment of invasive fungal infections, but most published data are from retrospective reviews or case reports. One case report of anidulafungin for neonatal candidiasis has been published. The role of echinocandins in the management of invasive pediatric fungal infections has expanded. Micafungin and caspofungin are recommended as primary or alternative treatment of candidemia and esophageal or invasive candidiasis, and as salvage therapy for invasive aspergillosis. Micafungin is recommended for neutropenic prophylaxis in stem cell transplantation, while caspofungin may be used in febrile neutropenia as an alternative to azoles. Dosing has been well established for caspofungin only in children 3 months of age and above. Anidulafungin should be avoided in children until more pharmacokinetic and clinical data become available.

CONCLUSIONS

Further comparative trials are needed to more clearly define the role of echinocandins, either as monotherapy or in combination for difficult-to-treat infections, in the pediatric population.

Therapeutic strategies for invasive fungal infections in neonatal and pediatric patients

Invasive Candida and Aspergillus infections are the most commonly encountered fungal infections. They appear to be life threatening in the setting of profound immunosuppression, whereas cases that are resistant to antifungal therapy are occasionally encountered. Novel antifungal triazole and echinocandin agents appear to exhibit good activity as first-line or salvage therapy, whereas the use of amphotericin B formulations is particularly valuable in neonates. Significant differences in toxicity have been demonstrated among various antifungal agents with in vitro activity from available comparative data on fungal infections in children: however, no clear difference in treatment efficacy has been demonstrated. However, very little data are available about neonates. Host factors and responsible fungal species most frequently guide the choice of therapy.

Successful treatment of refractory chronic disseminated candidiasis after prolonged administration of caspofungin in a child with acute myeloid leukemia

This report documents the clinical activity of caspofungin in a 13-year-old girl with acute myeloid leukemia (AML) and chronic disseminated candidiasis (CDC), refractory to amphotericin B and fluconazole. Caspofungin was started at 50 mg/d resulting in a temporary response. With no further clinical improvement and radiological progress after 2 months of therapy, the dose of caspofungin was increased to 100 mg/d, leading to a sustained clinical response. Therapy was given for a total of 12 months and had no attributable adverse effects. This approach resulted in successful treatment of refractory CDC with caspofungin.

Invasive candidiasis in pediatric intensive care patients: epidemiology, risk factors, management, and outcome

BACKGROUND

The incidence of candidemia in pediatric patients follows the same pattern of increase as in adults, but the rate of increase is greater. Pediatric patients in critical condition, particularly young infants, are especially vulnerable to invasive Candida infections (ICI), partly because of their age and severe underlying disease and partly because of the invasive procedures used.

DISCUSSION

Central venous catheters and arterial lines, parenteral nutrition, mechanical ventilation and extended use of antimicrobials enhance the risk of ICI. C. albicans continues to be the most prevalent isolate. However, an increasing role of non-C. albicans (NAC) spp., some of which are intrinsically or potentially resistant to antifungal agents, has been observed. NAC spp., particularly C. parapsilosis and C. tropicalis, account for almost half of ICI. The increased use of antifungals in immunocompromised patients, mainly prophylactically, is considered the strongest contributory factor to the changes in species distribution, which have subsequently affected the mortality and choice of empirical treatment.

CONCLUSIONS

Prompt removal of lines and initiation of antifungal treatment are the milestones of management. Conventional amphotericin B remains a commonly used antifungal agent, but its lipid formulations and fluconazole are also used frequently. Novel antifungal agents such as second-generation triazoles and echinocandins exhibit potential as alternative agents in critically ill children with ICI. Although response rates are still far from satisfactory, improved understanding of risk factors, preventive strategies and new treatment options promise a better future outcome.

Utilisation hors recommandations des médicaments innovants et coûteux en pédiatrie

OBJECTIVE

The objective of this study was to analyze in a pediatric hospital the use of expensive drugs as part of the new activity-based system (T2A) of funding for French public hospitals. We identified and analyzed the therapeutic use of these drugs in indications not included in the expert recommendations issued to accompany this change, with the goal of proposing specific pediatric recommendations.

METHOD

Analysis of prescriptions from May through September 2005 showed that 259 patients received expensive drugs subject to special reimbursement. The computerized prescription system enabled us to monitor and validate prescriptions daily. Indications for these expensive drugs were ranked by relevance.

RESULTS

The prescriptions analyzed covered 26 expensive drugs. Among the 344 "patient-drugs", 80% were expensive drugs for an accepted therapeutic use, 5% for a pertinent therapeutic use (under evaluation), and 15% for "off-label" uses (2% "not approved" and 13% for indications not considered by the recommendations).

CONCLUSION

This study showed that some therapeutic uses not approved by the official recommendations are nevertheless justified. Gathering data from other pediatric hospitals is essential to determine the need for pediatric clinical trials.

Antifungal therapy in children with invasive fungal infections: a systematic review

Invasive fungal infections are associated with significant morbidity and mortality. Differences between children and adults are reported, yet few trials of antifungal agents have been performed in pediatric populations. We performed a systematic review of the literature to guide appropriate pediatric treatment recommendations. From available trials that compared antifungal agents in either prolonged febrile neutropenia or invasive candidal or Aspergillus infection, no clear difference in treatment efficacy was demonstrated, although few trials were adequately powered. Differing antifungal pharmacokinetics between children and adults were demonstrated, requiring dose modification. Significant differences in toxicity, particularly nephrotoxicity, were identified between classes of antifungal agents. Therapy needs to be guided by the pathogen or suspected pathogens, the degree of immunosuppression, comorbidities (particularly renal dysfunction), concurrent nephrotoxins, and the expected length of therapy.

Caspofungin for the treatment of azole resistant candidemia in a premature infant

Candidemia is common in extremely low birth weight infants and is associated with substantial mortality and morbidity. Treatment options have traditionally been limited to amphotericin B deoxycholate or fluconazole. We present a case of a premature infant with persistent candidemia despite antifungal treatment that responded to therapy with caspofungin, an echinocandin antifungal. The infant's Candida isolate developed resistance to azoles during fluconazole administration and also suffered from severe hypercalcemia during the initiation of caspofungin therapy.

Efficacy and safety of caspofungin therapy in children with invasive fungal infections

Twenty children with proven (n = 12) or probable (n = 8) invasive fungal infections received caspofungin treatment either as first-line (n = 7) or as salvage (n = 13) therapy and as monotherapy (n = 5) or in combination (n = 15). Eleven had aspergillosis, 7 had candidiasis, and 2 had Rhodotorula infections. Caspofungin was well tolerated. Nine patients experienced 11 drug-related adverse events, none were severe, and none led to drug discontinuation. Caspofungin as a first-line treatment was successful in 5 of the 7 children (these 5 patients survived the infectious episode, with a follow-up of 147 days), and salvage therapy rescued 8 of 13 children, but only 5 of them survived.

Caspofungin treatment in two infants with persistent fungaemia due to Candida lipolytica

Candida lipolytica has infrequently been identified as a cause of infection and is associated mostly with vascular catheter-related fungaemia. Patients reported in the literature have been successfully treated with catheter removal or amphotericin B treatment. We report 2 infants with C. lipolytica fungaemia unresponsive to catheter removal and amphotericin B therapy and treated successfully with the addition of caspofungin to amphotericin B.

Successful caspofungin treatment of multidrug resistant Candida parapsilosis septicaemia in an extremely low birth weight neonate

Candida septicaemia with multidrug resistance is an uncommon event in preterm neonates. We present an extremely low birth weight infant (gestational age of 27 weeks, birth weight of 980 g) who developed congenital Candida parapsilosis septicaemia. Because the fungus was resistant both to amphotericin B and fluconazole, caspofungin was chosen for therapy. The fungus was successfully eradicated without any clinical or laboratory adverse effects.

Neonatal candidiasis

In neonates born weighing less than 750 g, invasive candidates is common and often fatal. This situation provides an opportunity to study antifungal prophylaxis and treatment in this patient population, in which the pharmacokinetics, safety, and efficacy of antifungal products are unknown. The disease is less prevalent in larger, more mature, infants. Although some pharmacokinetic data for some products are available for term and near-term infants, optimal product choice, closing, and other treatment strategies also are unknown in this older age group.

Treatment with caspofungin in immunocompromised paediatric patients: a multicentre survey

OBJECTIVES

Although a paediatric dosage has not been established, caspofungin is occasionally used in paediatric patients. We conducted a multicentre retrospective survey to obtain data on immunocompromised paediatric patients considered to require caspofungin therapy.

METHODS

The survey identified 64 patients (median age: 11.5 years; 25 females, 39 males) with haematological malignancies (48), marrow failure (9), solid tumours (3), haematological disorders (2) and congenital immunodeficiency (2) who received caspofungin for proven (17), probable (14) and possible (17) invasive fungal infections or empirically (16). Caspofungin was administered until intolerance or maximum efficacy at dosages individually determined by the responsible physician for refractory infection (38), intolerance of other agents (10) or as best therapeutic option (16).

RESULTS

The 64 patients received caspofungin for a median of 37 days (range 3-218) as single agent (20) or in combination (44). The median daily maintenance dosage was 1.07 mg/kg (95% CI 1.09-1.35; range 0.40-2.92) or 34.3 mg/m2 (95% CI 32.3-37.3; range 16.3-57.5). In none of the patients was therapy discontinued due to adverse events (AEs). Clinical AEs were mild to moderate and observed in 34 patients (53.1%). While mean glutamate pyruvate transaminase and glutamate oxalate transaminase values were slightly (P < 0.005) higher at the end of treatment (EOT), serum bilirubin, alkaline phosphatase and creatinine values were not different from baseline. Complete responses, partial responses or stabilization were observed in 5/7/3 of 17 patients with proven, in 3/4/3 of 14 patients with probable and in 7/6/1 of 15 evaluable patients with possible invasive infections. Thirteen of 16 patients on empirical therapy completed without breakthrough infection. Overall survival was 75% at the EOT and 70% at 3 months post-EOT, respectively.

CONCLUSIONS

Caspofungin displayed favourable safety and tolerance and may have useful antifungal efficacy in severely immunocompromised paediatric patients.

Pharmacokinetics, safety, and tolerability of caspofungin in children and adolescents

Caspofungin is a parenteral antifungal that inhibits beta-1,3-D-glucan synthesis. Although licensed for adult use, the appropriate caspofungin dosing regimen in pediatric patients is not yet known. We therefore investigated the pharmacokinetics and safety of caspofungin in pediatric patients. Thirty-nine children (ages 2 to 11 years) and adolescents (ages 12 to 17 years) with neutropenia were administered caspofungin using either a weight-based regimen (1 mg/kg of body weight/day) or a body surface area regimen (50 mg/m2/day or 70 mg/m2/day). Plasma samples for caspofungin profiles were collected on days 1 and 4. These results were compared to those from adults treated with either 50 or 70 mg/day for mucosal candidiasis. In children receiving 1 mg/kg/day (maximum, 50 mg/day), the area under the concentration-time curve over 24 h (AUC(0-24)) was significantly smaller (46% after multiple doses) than that observed in adults receiving 50 mg/day (P < 0.001). In children and adolescents receiving 50 mg/m2/day (maximum, 70 mg/day), the AUC(0-24) following multiple doses was similar to that for the exposure in adults receiving 50 mg/day. The AUC(0-24) and concentration trough (at 24 h) in pediatric patients receiving the 50-mg/m2 daily regimen were consistent across the range of ages. Caspofungin was generally well tolerated in this study. None of the patients developed a serious drug-related adverse event or were discontinued for toxicity. These results demonstrate that caspofungin at 1 mg/kg/day in pediatric patients is suboptimal. Caspofungin administration at 50 mg/m2/day provides a comparable exposure to that of adult patients treated with 50 mg/day.

Experience with caspofungin in the treatment of persistent fungemia in neonates

OBJECTIVE

To review our experience of caspofungin in the treatment of persistent candidemia in the neonatal intensive care unit.

STUDY DESIGN

This was a retrospective chart review on 13 infants in whom caspofungin was added to conventional antifungals (amphotericin B and/or fluconazole or flucytosine) for the treatment of refractory candidemia.

RESULTS

A total of 12 infants were preterm (gestational age, 24 to 28 weeks) and one was term; the median birth weight was 800 g (range, 530 to 5600 g). Candidemia (Candida albicans in five, C. parapsilosis in six, C. albicans and C. parapsilosis in one and C. tropicalis in one) persisted despite 6 to 30 days of conventional antifungal therapy. After the addition of caspofungin, sterilization of blood cultures was achieved in 11 infants at the median time of 3 days (range, 1 to 21 days). Adverse events included thrombophlebitis (one patient), hypokalemia (two patients) and elevation of liver enzymes (four patients). Three infants had a second episode of candidemia and seven patients died.

CONCLUSION

Caspofungin may be an efficacious addition for treatment of candidemia refractory to conventional antifungal therapy. This drug should be further investigated in neonates.

New antifungal agents under development in children and neonates

PURPOSE OF REVIEW

This review focuses on only the newest antifungal agents recently approved or still under development and the available data in pediatric and neonatal patients. The larger body of data in adult patients is used for comparative purposes only in an attempt to understand pediatric implications.

RECENT FINDINGS

Pharmacokinetic data suggest differences in dosing for many newer agents in children versus adult patients, but each agent has not been fully evaluated. Voriconazole displays non-linear pharmacokinetics in adults but has linear pharmacokinetics in children, necessitating a higher dose in smaller patients and potential treatment failures using the approved adult dosing schedule. Caspofungin likewise requires higher doses relative to adult patients, and dosing in children is best accomplished on a body surface area scheme and not a body weight dosing platform. Preliminary data suggest posaconazole, an investigational triazole, in children may lead to similar levels as in adults, but very limited efficacy data are available at any dose. Micafungin dosing has been explored in neonatal patients and there is a clear trend toward lower levels obtained in the very smallest infants, highlighting the importance of the neonatal period as a separate entity to even the pediatric age group.

SUMMARY

Initial data suggest dosing differences in children with some antifungals, and other newer agents have not been fully tested for the correct dosing. The underlying concern of efficacy in children compared with adult patients has never been answered as there are no randomized, phase III antifungal clinical trials from which pediatric-specific data were obtained.

Neonatal candidiasis: prophylaxis and treatment

The incidence of candidiasis has risen in neonatal intensive care units as advances in medical therapy have allowed for increased survival of extremely preterm neonates. The mortality of candidiasis has been reported to be 20% by several multi-centre studies. Definitive guidance for prophylaxis and treatment is hindered by lack of large, multi-centre, randomised controlled trials. Systemic prophylaxis is currently not recommended for any neonatal population, and amphotericin B deoxycholate continues to be used as first-line therapy for the treatment of invasive disease.

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.

Caspofungin for invasive fungal infections: combination treatment with liposomal amphotericin B in children undergoing hemopoietic stem cell transplantation

Invasive fungal infections often prove difficult to eradicate especially in the stem cell transplant setting. Amphotericin has been the mainstay of treatment for years but has significant toxicity. Newer antifungal agents, such as caspofungin, have shown promising results in adults, particularly when used in combination with amphotericin as both drugs differ in their mode of action. However, there are few data from children and no previous published information about the use of Caspofungin after paediatric stem cell transplantation. We report our experience in children with proven invasive fungal infections after stem cell transplantation. This combination was non-toxic, and two of three patients survived their infections.

Efficacy and safety of amphotericin B lipid complex in 548 children and adolescents with invasive fungal infections

BACKGROUND

The safety and efficacy of amphotericin B lipid complex injection (ABELCET; Enzon Pharmaceuticals, Piscataway, NJ) was assessed in 548 children and adolescents 0-20 years of age who were enrolled in the Collaborative Exchange of Antifungal Research (CLEAR) registry. To our knowledge, this is the largest series of pediatric patients treated for invasive mycoses with a single agent. All patients had cancer or had received a bone marrow, cord blood or solid organ transplant and were treated with amphotericin B lipid complex for documented or suspected fungal infection.

METHODS

The CLEAR database was queried for all patients 0-20 years of age from 1996 to 2000. Data gathered included demographic variables, underlying disease type, reasons for the use of amphotericin B lipid complex injection, dosing information, clinical response and renal effects.

RESULTS

Most patients were either intolerant of or refractory to conventional antifungal therapy, and almost one-half were neutropenic at treatment onset. Of the 548 patients, 300 (54.7%) were transplant recipients and 393 (71.7%) had received one or more concomitant nephrotoxins. Candida and Aspergillus were the most commonly isolated species in patients with proven or probable infections. Response data were evaluable for 255 of the 285 patients with documented single or multiple pathogens. A complete (cured) or partial (improved) response was achieved in 54.9% of patients, with an additional 16.9% of patients having a stable outcome. Among patients with proven Aspergillus infection, the response rates (cured + improved) were 40.5 and 37.5% in transplant and nontransplant patients, respectively. When stable responses were added, the response rates were 48.6 and 71.9%, respectively. There were few clinically significant deleterious effects on renal function. There was no significant difference between the rates of new hemodialysis versus baseline hemodialysis. Elevations in serum creatinine of >1.5 x baseline and >2.5 x baseline values were seen in 24.8 and 8.8% of all patients, respectively.

CONCLUSIONS

The safety and efficacy data from this large pediatric population support the use of amphotericin B lipid complex injection for treatment of invasive fungal infections in immunocompromised children and adolescents, including the high risk subgroup of transplant recipients. The overall response rate and safety profile in pediatric patients who were largely intolerant of or refractory to conventional antifungal therapy were consistent with earlier reported findings of smaller trials.

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.