Adverse reactions to biologics: real-world evidence from a tertiary care pediatric hospital setting

Biological therapies, particularly monoclonal antibodies (mAbs), are increasingly used in pediatric populations, although safety data remain more limited than in adults. This retrospective study evaluates adverse reactions (ARs) to biologics in children treated at Meyer Children’s Hospital IRCCS, Florence, Italy, between 2006 and 2020. Of 438 children treated with biologics, 52 (11.9%) had ARs. Clinical manifestations were heterogeneous, with predominant cutaneous symptoms being the most common (51.9%), followed by respiratory involvement (11.5%). Anaphylaxis occurred in 1.1% of patients, corresponding to 9.6% of those with ARs. Most reactions resolved spontaneously without pharmacological intervention, whereas 38.5% required pharmacological treatment, most commonly with antihistamines and corticosteroids. In univariate analysis, atopic dermatitis, biologic class and off-label use were associated with the occurrence of ARs. In multivariable analysis adjusted for age, sex, route of administration, atopic comorbidities, off-label use and biologic class, those last remained the strongest independent factors correlated with ARs: compared with anti-CD20 agents, patients receiving anti-IgE (odds ratio 0.20, p = 0.024) or anti-tumour necrosis factor agents (odds ratio 0.18, p < 0.001) had significantly lower odds of experiencing an AR. The composite atopic comorbidity variable showed only a non-significant trend toward increased risk (odds ratio 2.08, p = 0.068). However, in exploratory models in which the individual components were analysed separately, both allergic asthma (odds ratio 3.75, p = 0.028) and atopic dermatitis (odds ratio 2.64, p = 0.023) were independently associated with ARs. Off-label use showed no independent association with ARs after adjustment. Age, sex, and the route of administration were not independently associated with ARs. Switching therapy was required in a minority of patients (21.2%).