A dual mechanism of sensitivity to PLK4 inhibition by RP-1664 in neuroblastoma

A novel therapeutic strategy was recently proposed for high-risk neuroblastoma carrying copy number gain of the TRIM37 gene: centriole loss upon inhibition of polo-like kinase 4 (PLK4), while tolerated by normal cells, induces aberrant mitotic spindle formation and p53-dependent cell death in TRIM37 -overexpressing cells. Interestingly, while full PLK4 inhibition causes centriole loss, partial inhibition is known to elevate centriole numbers. Here we show using a novel selective PLK4 inhibitor RP-1664 that both centriole loss and amplification contribute to hypersensitivity of neuroblastoma cells. Whereas inactivation of TRIM37 and TP53 rescues neuroblastoma cell death at higher concentrations of RP-1664, at lower doses cell death is TRIM37/TP53 -independent. With CRISPR screens and live cell imaging we demonstrate that upon centriole amplification, neuroblastoma cells succumb to multipolar mitoses due to inability to cluster or inactivate supernumerary centrosomes. In vivo , RP-1664 shows robust efficacy in neuroblastoma xenografts at doses consistent with centriole amplification.