Successful treatment of oesophageal candidiasis by micafungin: a novel systemic antifungal agent

International, open-label, noncomparative, clinical trial of micafungin alone and in combination for treatment of newly diagnosed and refractory candidemia

Candida spp. are the fourth leading cause of bloodstream infections, and non-albicans species are increasing in importance. Micafungin is a new echinocandin antifungal agent with excellent in vitro activity against Candida spp. Pediatric, neonatal, and adult patients with new or refractory candidemia were enrolled into this open-label, noncomparative, international study. The initial dose of micafungin was 50 mg/d (1 mg/kg for patients <40 kg) for infections due to C. albicans and 100 mg/d (2 mg/kg for patients <40 kg) for infections due to other species. Dose escalation was allowed. Maximum length of therapy was 42 days. A total of 126 patients were evaluable (received at least five doses of micafungin). Success (complete or partial response) was seen in 83.3% patients overall. Success rates for treatment of infections caused by the most common Candida spp. were as follows: C. albicans 85.1%, C. glabrata 93.8%, C. parapsilosis 86.4%, and C. tropicalis 83.3%. Serious adverse events related to micafungin were uncommon. Micafungin shows promise as a safe and effective agent for the treatment of newly diagnosed and refractory cases of candidemia. Large-scale, randomized, controlled trials are warranted.

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.

Micafungin Sodium

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Safety, tolerability, and pharmacokinetics of Micafungin (FK463) in febrile neutropenic pediatric patients

Micafungin (FK463) is a new parenteral echinocandin. A multicenter, phase I, open-label, sequential-group dose escalation study was conducted to assess the safety, tolerability, and pharmacokinetics of micafungin in neutropenic pediatric patients. A total of 77 patients stratified by age (2 to 12 and 13 to 17 years) received micafungin. Therapy was initiated at 0.5 mg/kg per day and escalated to higher dose levels of 1.0, 1.5, 2.0, 3.0, and 4.0 mg/kg per day. Micafungin was administered within 24 h of initiating broad-spectrum antibacterial antibiotics for the new onset of fever and neutropenia. The most common overall adverse events in the study population were diarrhea (19.5%), epistaxis (18.2%), abdominal pain (16.9%), and headache (16.9%). Nine patients (12%) experienced adverse events considered by the investigator to be possibly related to the study drug. The most common related events were diarrhea, vomiting, and headache, all occurring in two patients each. There was no evidence of a dose-limiting toxicity as defined within the prespecified criteria of this clinical protocol. There was one death during the study due to septic shock. The pharmacokinetic profiles for micafungin over the 0.5- to 4.0-mg/kg dose range demonstrated dose linearity. Clearance, volume of distribution, and half-life remained relatively constant over the dose range and did not change with repeated administration. The overall plasma pharmacokinetic profile was similar to that observed in adults. However, there was an inverse relation between age and clearance. For patients 2 to 8 years old, clearance was approximately 1.35 times that of patients >/=9 years of age. In summary, micafungin over a dosage range between 0.5 and 4.0 mg/kg/day in 77 febrile neutropenic pediatric patients displayed linear pharmacokinetics and increased clearance as a function of decreasing age.

Pharmacokinetic and maximum tolerated dose study of micafungin in combination with fluconazole versus fluconazole alone for prophylaxis of fungal infections in adult patients undergoing a bone marrow or peripheral stem cell transplant

In this dose escalation study, 74 adult cancer patients undergoing bone marrow or peripheral blood stem cell transplantation received fluconazole (400 mg/day) and either normal saline (control) (12 subjects) or micafungin (12.5 to 200 mg/day) (62 subjects) for up to 4 weeks. The maximum tolerated dose (MTD) of micafungin was not reached, based on the development of Southwest Oncology Group criteria for grade 3 toxicity; drug-related toxicities were rare. Commonly occurring adverse events considered related to micafungin were headache (6.8%), arthralgia (6.8%), hypophosphatemia (4.1%), insomnia (4.1%), maculopapular rash (4.1%), and rash (4.1%). Pharmacokinetic profiles for micafungin on days 1 and 7 were similar. The mean half-life was approximately 13 h, with little variance after repeated or increasing doses. Mean maximum concentrations of the drug in serum and areas under the concentration-time curve from 0 to 24 h were approximately proportional to dose. There was no clinical or kinetic evidence of interaction between micafungin and fluconazole. Five of 12 patients (42%) in the control group and 14 of 62 (23%) in the micafungin-plus-fluconazole groups had a suspected fungal infection during treatment which resulted in empirical treatment with amphotericin B. The combination of micafungin and fluconazole was found to be safe in this high-risk patient population. The MTD of micafungin was not reached even at doses up to 200 mg/day for 4 weeks. The pharmacokinetic profile of micafungin in adult cancer patients with blood or marrow transplants is consistent with the profile in healthy volunteers, and the area under the curve is proportional to dose.

A randomized, double blind, comparative trial of micafungin (FK463) vs. fluconazole for the treatment of oesophageal candidiasis

AIM

To determine efficacy and safety of intravenous micafungin vs. intravenous fluconazole in the treatment of oesophageal candidiasis.

METHODS

A total of 523 patients > or =16 years with documented oesophageal candidiasis were randomized (1:1) in this controlled, non-inferiority study to receive either micafungin (150 mg/day) or fluconazole (200 mg/day). Response was evaluated clinically and endoscopically. Post-treatment assessments were performed at 2 and 4 weeks after discontinuation of therapy.

RESULTS

Median duration of therapy was 14 days. For the primary end-point of endoscopic cure, treatment difference was -0.3% (micafungin 87.7%, fluconazole 88.0%). Documented persistent invasive disease at the end of therapy was reported in 2.7% and 3.9% of patients, respectively. Both 84.8% of micafungin and 88.7% of fluconazole patients remained recurrence free at 4-weeks post-treatment. The overall therapeutic response rate was 87.3% for micafungin and 87.2% for fluconazole. The incidence of drug-related adverse events was 27.7% for micafungin and 21.3% for fluconazole. Six (2.3%) micafungin- and two (0.8%) fluconazole-treated patients discontinued therapy; rash was the most common event leading to discontinuation.

CONCLUSION

Intravenous micafungin (150 mg daily) is well tolerated and as efficacious as intravenous fluconazole (200 mg daily) in the primary treatment of oesophageal candidiasis, achieving high rates of clinical and endoscopic cure.

Micafungin

OBJECTIVE

To review the pharmacology, mycology, chemistry, in vitro susceptibility, pharmacokinetics, clinical efficacy, safety, tolerability, dosage, and administration of micafungin, an echinocandin antifungal agent.

DATA SOURCES

A MEDLINE search, restricted to English language, was conducted from 1978 to November 2003. Supplementary sources included program abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy and the Infectious Diseases Society of America from 1996 to 2003 and information available through the manufacturer's Web site.

STUDY SELECTION AND DATA EXTRACTION

In vitro and preclinical studies, as well as Phase II and III clinical trials, were evaluated to summarize the clinical efficacy and safety of micafungin. All published and unpublished trials and abstracts citing micafungin were selected.

DATA SYNTHESIS

Micafungin has shown in vitro activity against many yeasts and a variety of molds. Micafungin can be administered only parenterally. Efficacy has been illustrated in open noncomparative studies of esophageal candidiasis in HIV-infected patients and in comparative trials as antifungal prophylaxis in patients undergoing hematopoietic stem-cell transplantation. Adverse events appear mild and limited; the most commonly reported adverse events include hyperbilirubinemia, nausea, and diarrhea.

CONCLUSIONS

Micafungin has activity against Aspergillus spp. and a variety of Candida spp., including azole-resistant strains. Micafungin demonstrates efficacy in the treatment of esophageal candidiasis in HIV-infected patients and appears superior to fluconazole as antifungal prophylaxis in patients undergoing hematopoietic stem-cell transplantation. Based on case reports and in vitro efficacy, micafungin may prove to be a clinically useful agent in the treatment of other fungal diseases; however, these indications await the results of clinical trials.

A Randomized, Double-Blind, Parallel-Group, Dose-Response Study of Micafungin Compared with Fluconazole for the Treatment of Esophageal Candidiasis in HIV-Positive Patients

BACKGROUND

Severely immunocompromised individuals are highly susceptible to Candida infection of the esophagus. This randomized, double-blind study assessed the dose-response relationship of the new echinocandin antifungal, micafungin, compared with that of standard fluconazole treatment.

METHODS

A total of 245 patients (age, > or =18 years) with a prior diagnosis of acquired immunodeficiency syndrome/human immunodeficiency virus (HIV) infection and esophageal candidiasis, confirmed by endoscopy and culture, were randomized to receive micafungin (50, 100, or 150 mg per day) or fluconazole (200 mg per day). Both agents were administered once per day by a 1-h intravenous infusion for 14-21 days. The primary efficacy end point was endoscopic cure rate, defined as endoscopy grade of 0 at the end of therapy.

RESULTS

The endoscopic cure rate (grade 0) was dose-dependent with 50, 100, and 150 mg of micafungin per day at 68.8%, 77.4%, and 89.8%, respectively. Symptoms improved or resolved rapidly (3-7 days of treatment in the majority of patients). The endoscopic cure rate for 100 and 150 mg of micafungin per day (83.5%) was comparable to that for 200 mg of fluconazole per day (86.7%; 95% confidence interval for the difference in endoscopic cure rate, -14.0% to 7.7%). The overall safety and tolerability was acceptable, with no important differences between micafungin (all doses) and fluconazole.

CONCLUSIONS

The dose-response findings demonstrate a greater efficacy with micafungin at 100 and 150 mg per day than at 50 mg per day. This study also indicates that the efficacy of micafungin (at dosages of 100 and 150 mg per day) was comparable to that of fluconazole, suggesting that micafungin represents a valuable new treatment option for esophageal candidiasis in HIV-positive patients.