Purpose: Zinc metallochaperones (ZMCs) are a new class of anti-cancer drugs that reactivate zinc deficient mutant p53 by raising and buffering intracellular zinc levels sufficiently to restore zinc binding. In vitro pharmacodynamics of ZMCs indicate that p53 mutant activity is ON by 4-6 hours and is OFF by 24. We sought to understand the mechanism of this regulation and to translate these findings pre-clinically. We further sought to innovate the formulation of ZMCs to improve efficacy. Experimental Design: We performed in vitro mechanistic studies to determine the role of cellular zinc homeostatic mechanisms in the transient pharmacodynamics of ZMCs. We conducted pre-clinical pharmacokinetic (PK), pharmacodymanic (PD) and efficacy studies using a genetically engineered murine pancreatic cancer model (KPC) to translate these mechanistic findings and investigate a novel ZMC formulation. Results: In vitro, cellular zinc homeostatic mechanisms that restore zinc to its physiologic levels function as the OFF switch in ZMC pharmacodynamics. In vivo PK studies indicate that ZMCs have a short half life (<30 minutes), which is sufficient to significantly improve survival in mice expressing a zinc deficient allele (p53R172H) while having no effect in mice expressing a non-zinc deficient allele (p53R270H). We synthesized a novel formulation of the drug in complex with zinc and demonstrate this significantly improves survival over ZMC1. Conclusions: Cellular zinc homeostatic mechanisms function as an OFF switch in ZMC pharmacodynamics indicating that a brief period of p53 mutant reactivation is sufficient for on-target efficacy. ZMCs synthesized in complex with zinc are an improved formulation.
https://ift.tt/2K1Knnm
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου