人类乙酰转移酶同源物EP300和CREBBP是赖氨酸乙酰化的主要调控因子，其活性与多种癌症有关。自首个药物样抑制剂报告以来，已发现了三种独特的分子骨架：吲哚螺轴环二酮（A-485）、螺环咪唑烯酮（iP300w）和氨基吡啶（CPI-1612）。尽管这些分子在赖氨酸乙酰化研究中的应用日益增多，但由于相对生化和生物学效力的缺乏数据，使得它们作为化学探针的应用具有挑战性。为了解决这一问题，我们在这里提出一项关于药物样EP300/CREBBP乙酰转移酶抑制剂的比较研究。首先，我们确定了A-485、iP300w和CPI-1612的生物化学和生物学效力，并凸显了后两种化合物在生理乙酰辅酶A浓度下的效力增强。细胞评估显示，组蛋白乙酰化和细胞生长的抑制与这些分子的生物化学效力密切相关，表明它们具有靶向机制。最后，我们通过使用比较药理学来研究PANK4基因敲除引起的辅酶A合成增加是否会竞争性拮抗EP300/CREBBP抑制剂的结合，并证明了一个有效抑制剂分子的光释放的概念验证。总体而言，我们的研究展示了相对抑制剂效力的了解如何指导EP300/CREBBP依赖机制的研究，并提出了新的递送方法，从而拓宽了这些临床前表观遗传学药物候选的治疗窗口。

The human acetyltransferase paralogues EP300 and CREBBP are master regulators of lysine acetylation whose activity has been implicated in various cancers. In the half-decade since the first drug-like inhibitors of these proteins were reported, three unique molecular scaffolds have taken precedent: an indane spiro-oxazolidinedione (A-485), a spiro-hydantoin (iP300w), and an aminopyridine (CPI-1612). Despite increasing use of these molecules to study lysine acetylation, the dearth of data regarding their relative biochemical and biological potencies makes their application as chemical probes a challenge. To address this gap, here we present a comparative study of drug-like EP300/CREBBP acetyltransferase inhibitors. First, we determine the biochemical and biological potencies of A-485, iP300w, and CPI-1612, highlighting the increased potencies of the latter two compounds at physiological acetyl-CoA concentrations. Cellular evaluation shows that inhibition of histone acetylation and cell growth closely aligns with the biochemical potencies of these molecules, consistent with an on-target mechanism. Finally, we demonstrate the utility of comparative pharmacology by using it to investigate the hypothesis that increased CoA synthesis caused by knockout of PANK4 can competitively antagonize the binding of EP300/CREBBP inhibitors and demonstrate proof-of-concept photorelease of a potent inhibitor molecule. Overall, our study demonstrates how knowledge of the relative inhibitor potency can guide the study of EP300/CREBBP-dependent mechanisms and suggests new approaches to target delivery, thus broadening the therapeutic window of these preclinical epigenetic drug candidates.