Differential effects of zanubrutinib and ibrutinib on neutrophil antifungal functions: insights from live-cell imaging.

INTRODUCTION: Bruton Tyrosine kinase inhibitors (BTKi) impair anti-aspergillus immune responses and increase the risk of invasive fungal infections (IFI). More selective second generation BTKi have fewer off-target effects thus a better tolerance than ibrutinib. Though clinical data suggest the incidence of IFI is lower with second generation BTKi, whether they have less impact on anti-fungal immunity remain unclear. METHODS: We studied the activation phenotype and behavior of human neutrophils in vitro with fungal extracts or living Aspergillus fumigatus in the presence of either ibrutinib or zanubrutinib, a more selective second generation BTKi, using various approaches, including live microscopy. RESULTS: Both molecules inhibited the activation-induced phenotypic changes in neutrophils following exposure to hyphae. Similarly, ibrutinib and zanubrutinib impaired neutrophil-mediated inhibition of conidia germination. By contrast, live neutrophil imaging showed that neutrophils exposed to ibrutinib but not zanubrutinib kept a round morphology, suggesting a defective activation, were less mobile and showed impaired conidia phagocytosis. CONCLUSION: We confirm here that ibrutinib and zanubrutinib inhibit neutrophil antifungal activity, strongly suggesting that BTK plays a central role. However, subtle differences between ibrutinib and zanubrutinib were evidenced using live microscopy, which might indicate additional off-target effects, and potentially partially explain the lower incidence of IFI with zanubrutinib; the clinical relevance remains to be determined.