Over the past decade, we described a novel tumour targeted approach that sought to design “combi-molecules” to hit two distinct targets in tumour cells. Here, to generate small combi-molecules with strong DNA damaging potential while retaining EGFR inhibitory potency, we developed the first synthetic strategy to access the 6-N, N-disubstituted quinazoline scaffold and designed JS61 to possess a nitrogen mustard function directly attached to the 6-position of the quinazoline ring. We compared its biological activity with that of structures containing either a hemi mustard or a non-alkylating substituent. Surprisingly, the results showed that JS61, while capable of inducing strong DNA damage, exhibited moderate EGFR inhibitory potency. In contrast, “combi-molecules” with no bulky substituent at the N-6 position (e.g. ZR2002 and JS84) showed stronger EGFR and growth inhibitory potency than JS61 in a panel of lung cancer cells. To rationalize these results, X-ray crystallography and molecular modeling studies were undertaken, and the data obtained indicated that bulkiness of the 6-N, N-disubstituted moieties hinder its binding to the ATP site and affects binding reversibility.

在过去的十年中，我们描述了一种新颖的靶向肿瘤的方法，该方法旨在设计“复合分子”以击中肿瘤细胞中的两个不同靶标。在这里，为了产生具有强大的DNA破坏潜力并同时保持EGFR抑制潜能的小组合分子，我们开发了第一个合成策略来使用6-N，N-二取代的喹唑啉支架，并设计了JS61使其具有直接与氮芥子气相连的功能喹唑啉环的6位。我们将其生物活性与含有半芥子或非烷基化取代基的结构进行了比较。令人惊讶的是，结果表明JS61虽然能够诱导强烈的DNA损伤，但具有中等的EGFR抑制能力。相反，在一组肺癌细胞中，在N-6位没有大取代基的“复合分子”（例如ZR2002和JS84）显示出比JS61更强的EGFR和生长抑制能力。为了合理化这些结果，进行了X射线晶体学和分子建模研究，并且获得的数据表明6-N，N-二取代部分的庞大性阻碍了其与ATP位点的结合并影响了结合可逆性。