Repurposing the Antiviral Agent Pibrentasvir: In Vitro Synergistic Effects in Combination with Different Azole Antifungal Agents

ObjectiveTo investigate the combined effects of multiple drugs and provide more therapeutic options for invasive fungal infections, this study evaluated the in vitro susceptibility of Aspergillus spp., Candida auris, Cryptococcus neoformans, and Exophiala dermatitidis to pibrentasvir (PIB) in combination with itraconazole (ITR), voriconazole (VOR), posaconazole (POS), or fluconazole (FLU). MethodsAccording to the M27-A3 and M38-A2 guidelines established by the Clinical and Laboratory Standards Institute (CLSI), the in vitro antifungal activities of PIB combined with ITR, VOR, POS, or FLU against 78 clinical isolates, including Aspergillus spp., E. dermatitidis, C. auris, and C. neoformans, were determined. The minimum inhibitory concentrations (MICs) and fractional inhibitory concentration indices (FICIs) were calculated to evaluate the synergistic effects. ResultsPIB alone exhibited no antifungal activity. Significant synergistic effects were observed when PIB was combined with azole antifungal agents. The PIB-POS combination showed synergistic effects against Aspergillus spp. (27/41, 65.90%), C. auris (9/10, 90.00%), C. neoformans (2/9, 22.20%), and E. dermatitidis (11/18, 61.11%). The PIB-ITR combination also showed synergistic effects against Aspergillus spp. (18/41, 43.9%), C. auris (9/10, 90.0%), C. neoformans (2/9, 22.2%), and E. dermatitidis (10/18, 55.5%). Synergistic effects were less frequently observed with the PIB-VOR or PIB-FLU combinations, and no antagonistic effects were observed. ConclusionThis study demonstrates that PIB acts as an azole sensitizer, with the strongest synergistic effects observed when combined with POS or ITR, providing a new research direction for combination therapy against invasive fungal infections.