Safety and Effectiveness of Isavuconazole Treatment for Fungal Infections in Solid Organ Transplant Recipients (ISASOT Study)

ABSTRACT Isavuconazole (ISA) is an alternative treatment for Aspergillus spp. and other fungal infections, but evidence regarding its use in solid organ transplant recipients (SOTR) is scarce. All SOTR who received ISA for treatment of a fungal infection (FI) at our center from December 2017 to January 2021 were included. The duration of the treatment depended on the type of infection. All patients were followed up to 3 months after treatment. Fifty-three SOTR were included, and the majority (44, 83%) were lung transplant recipients. The most frequently treated FI was tracheobronchitis (25, 46.3%). Aspergillus spp. (43, 81.1%); specially A. flavus (16, 37.2%) and A. fumigatus (12, 27.9%), was the most frequent etiology. Other filamentous fungi including one mucormycosis, and four yeast infections were treated. The median duration of treatment was 81 days (IQR 15-197). Mild gamma-glutamyltransferase elevation was the most frequent adverse event (34%). ISA was prematurely discontinued in six patients (11.3%) due to mild hepatotoxicity (2), fatigue (2), gastrointestinal intolerance (1) and myopathy (1). The mean tacrolimus dose decrease was 30% after starting ISA. Seven patients received ISA with mTOR inhibitors with good tolerability. Two patients developed breakthrough FI (3.8%). Among patients who completed the treatment, 27 (50.9%) showed clinical cure and 15 (34.1%) presented fungal persistence. Three patients (6%) died while on ISA due to FI. ISA was well tolerated and appeared to be an effective treatment for FI in SOTR. IMPORTANCE We describe 53 solid organ transplant recipients treated with isavuconazole for fungal infections. Because its use in clinical practice, there is scarce data of its use in solid organ transplant recipients, where interactions with calcineurin inhibitors and mTOR and adverse drug events have limited the use of other triazoles. To the best of our knowledge, this is the first article describing the safety regarding adverse events and drug interactions of isavuconazole for the treatment of fungal infections in a cohort of solid organ transplant recipients. Also, although this is a noncomparative study, we report some real world effectivity data of these patients, including treatment of non-Aspergillus fungal infections.