Development of Dual Aurora-A and Aurora-B Degrading PROTACs for MYCN-Amplified Neuroblastoma

In neuroblastoma, MYCN amplification is associated with survival rates of <50 %. Overexpression of the mitotic kinases Aurora-A and Aurora-B are also associated with low survival and exacerbate the oncogenic effects of N-Myc. As N-Myc is stabilized by Aurora-A, Aurora-A targeting proteolysis targeting chimeras (PROTACs) have been developed that reduce Aurora-A and N-Myc levels. However, simultaneous degradation of N-Myc, Aurora-A, and Aurora-B has not been previously achieved. Given the contributions of both Aurora kinases to MYCN-amplified neuroblastoma, we designed PROTACs capable of degrading both Aurora-A and Aurora-B. Dual-degrading PROTACs dAurAB2 and dAurAB5 potently degraded Aurora-A (DC₅₀=59 nM and 8.8 nM, respectively) and Aurora-B (DC₅₀=39 nM and 6.1 nM), eliminated 89 %–97 % of Aurora-A and Aurora-B, and reduced N-Myc levels by 38 % and 45 % in MYCN-amplified IMR32 neuroblastoma cells. Global proteomics screening revealed that while dAurAB2 demonstrated good selectivity, dAurAB5 downregulated additional targets including threonine tyrosine kinase (TTK). Interestingly, TKK is also associated with MYCN-amplified neuroblastoma, and multi-target PROTAC dAurAB5 reduced the viability of neuroblastoma IMR32 cells by 55 % at 24 hours. The development of dAurAB2 and dAurAB5 generates new modalities for inhibiting the oncogenic activities of Aurora-A, Aurora-B, N-Myc, and TTK in neuroblastoma and other cancers.