Dornase alfa is well tolerated: Data from the Epidemiologic Registry of Cystic Fibrosis

After closure of the Epiderniologic Registry of Cystic Fibrosis (ERCF), a comprehensive safety analysis of dornase alfa was performed. A planned subanalysis focused on children under 5 years old. Reported serious adverse events (SAEs) were assigned a preferred term and ascribed to a specific organ system. Possible serious adverse reactions to dornase alfa (SADRs) were identified by reporting clinics. Twenty-eight of 15,865 SAEs (0.18%), occurring in 26 of 6,829 patients ever treated with dornase alfa (0.38%), and no deaths were reported as possible SADRs: most were typical complications of cystic fibrosis (CF). There was no evidence of any unrecognized risk of treatment. During 24,586 patient-years of follow-up (FU) of ever-treated patients, SAEs (mostly typical respiratory complications of CF) were more frequent on-treatment (0.4999/patient-year; 95% Cl 0.4921-0.5076) than off-treatment (0.3889; 0.3787-0.3992). This was likely caused by within-patient prescription bias. During 655 patient-years of FU in 328 ever-treated patients under 5 years old, SAEs (mostly pulmonary exacerbations of CF) were slightly less frequent during treatment: 0.2911 (0.2367-0.3455) versus 0.3563 (0.3086-0.4040; ns). Results confirm the safety of dornase alfa in CF patients of all ages. Children under 5 years old tolerate dornase alfa at least as well as older patients.