多靶点制剂可提供对肿瘤的选择性，降低药物耐药性和剂量限制性毒性。我们先前描述了一种对早期和晚期胰腺肿瘤具有有限肿瘤选择性的多靶点的6-取代吡咯并[3,2-d]嘧啶抗叶酸类似物1。通过结构基础设计，使用我们的人源丝氨酸羟甲基转移酶(SHMT) 2和甘氨酸核糖核苷酸甲酰转移酶(GARFTase)结构，以及5-氨基咪唑-4-羧酸核苷酸甲酰转移酶/肌苷酸单磷酸环水合酶(ATIC)，SHMT1和叶酸受体(FR)α和β的已发布X射线晶体结构，我们获得了11个类似物。通过在分子中引入具有广泛构象灵活性的结构，设计了多靶点抑制和选择性肿瘤转运。通过代谢物拯救，我们确定了线粒体C1代谢以及新陈代谢嘌呤生物合成作为目标途径。与1相比，我们确定了通过叶酸受体(FRs)进行肿瘤选择性转运并增加SHMT2、SHMT1和GARFTase抑制力的类似物(分别增加了28倍、21倍和11倍)。这些多靶点制剂代表了一种令人兴奋的用于靶向癌症治疗的新结构模式，具备比临床使用的抗叶酸类药物更高的选择性和效力优势。

Multitargeted agents provide tumor selectivity with reduced drug resistance and dose-limiting toxicities. We previously described the multitargeted 6-substituted pyrrolo[3,2-d]pyrimidine antifolate 1 with activity against early- and late-stage pancreatic tumors with limited tumor selectivity. Structure-based design with our human serine hydroxymethyl transferase (SHMT) 2 and glycinamide ribonucleotide formyltransferase (GARFTase) structures, and published X-ray crystal structures of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC), SHMT1, and folate receptor (FR) α and β afforded 11 analogues. Multitargeted inhibition and selective tumor transport were designed by providing promiscuous conformational flexibility in the molecules. Metabolite rescue identified mitochondrial C1 metabolism along with de novo purine biosynthesis as the targeted pathways. We identified analogues with tumor-selective transport via FRs and increased SHMT2, SHMT1, and GARFTase inhibition (28-, 21-, and 11-fold, respectively) compared to 1. These multitargeted agents represent an exciting new structural motif for targeted cancer therapy with substantial advantages of selectivity and potency over clinically used antifolates.