Efficacy and Safety of Micafungin as An Empirical Antifungal Therapy for Suspected Fungal Infection in Patients with Hematological Disorders

Background: Invasive fungal infections (IFIs) are of serious concern in the management of immunocompromised patients (pts) with hematological disorders. Empiric antifungal therapy is recommended for neutropenic pts with persistent fever, because treatment after confirmation of fungal infection often produces poor outcomes. Micafungin (MCFG), one of the echinocandin families, was launched first in Japan in 2002, and has now been approved in more than 11 countries and areas including the USA and the EU. Although the efficacy and safety of MCFG against both Candida and Aspergillus infections has been shown in many clinical trials, there are few clinical study reports on the empiric therapy of a suspected fungal infection. Here, we report the multi-center study results of MCFG for the empiric antifungal therapy, which were conducted from April 2005 to September 2006 in Japan. Objective: This prospective study was performed to clarify the efficacy and safety of MCFG for the empirical antifungal therapy on suspected fungal infection in pts with hematological disorders and neutropenia. Methods: Study design: A multiple-center, open, uncontrolled study. The investigator registered pts with neutropenia (< 1,000/μl) who met the following criteria to the Subject Registration Center. Suspected fungal infections were divided into two categories: possible fungal infection defined by positive clinical symptoms/findings and serological testing (beta-D-glucan or galactomannan) or diagnostic imaging (chest X-ray or CT scan), refractory fever defined by unexplained persistent fever (an axillary temperature higher than 37.5 °C) after the antibacterial treatment over 2 days and by positive clinical symptoms/findings. IFIs categorized as proven or probable were not included in this study. Efficacy evaluation was performed using an algorithm based on each of the evaluation of clinical symptoms/findings, imaging study findings, and serological tests. Results: 388 pts (M:234, F:154, mean age:57.8 years old) were registered. The mean dosage and duration of treatment with MCFG were 154.6±55.3 mg/day and 14.0±6.9 days, respectively. The main underlying hematological disorders were acute leukemia (61.3%), non-Hodgkin’s lymphoma (18.3%) and myelodysplastic syndrome (10.8%). The number of pts with hematopoietic stem cell transplantation (HSCT) was 76 (19.6%). The clinical response rate (CRR), excluding 4 non-evaluable pts was 63.3% (243/384): 60.1% (89/148) for pts with possible fungal infection and 65.3% (154/236) for pts with refractory fever, respectively. Even in persistent neutropenic pts whose neutrophil counts were < 500/μL throughout the treatment with MCFG, the CRR was high enough: 46.9% (61/130). No difference was observed in the CRR among the main underlying hematological disorders. The CRR in pts with HSCT and other conditions were 63.2% (48/76) and 63.3% (195/308), respectively. Drug-related adverse events (DAEs) were observed in 16.8% (65/388). Serious DAEs such as elevation of serum bilirubin and renal dysfunction was observed in 0.52% (2/388). Conclusion: MCFG was confirmed to have high clinical efficacy and be safe for the treatment of suspected fungal infection in pts with hematological disorders and neutropenia.