Development of Dual Aurora‐A and Aurora‐B Degrading PROTACs for <i>MYCN</i>‐Amplified Neuroblastoma

In neuroblastoma, <i>MCYN</i> 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 <i>MYCN</i>-amplified neuroblastoma, we designed PROTACs capable of degrading both Aurora-A and Aurora-B. Dual-degrading PROTACs <b>dAurAB2</b> and <b>dAurAB5</b> 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 <i>MCYN</i>-amplified IMR32 neuroblastoma cells. Global proteomics screening revealed that while <b>dAurAB2</b> demonstrated good selectivity, <b>dAurAB5</b> downregulated additional targets including threonine tyrosine kinase (TTK). Interestingly, TKK is also associated with <i>MCYN</i>-amplified neuroblastoma, and multi-target PROTAC <b>dAurAB5</b> reduced the viability of neuroblastoma IMR32 cells by 55% at 24 hours. The development of <b>dAurAB2</b> and <b>dAurAB5</b> generates new modalities for inhibiting the oncogenic activities of Aurora-A, Aurora-B, N-Myc, and TTK in neuroblastoma and other cancers.