Tumor Targeting with Novel 6-Substituted Pyrrolo [2,3-d] Pyrimidine Antifolates with Heteroatom Bridge Substitutions via Cellular Uptake by Folate Receptor α and the Proton-Coupled Folate Transporter and Inhibition of de Novo Purine Nucleotide Biosynthes

Publication Type:

Journal Article


J Med Chem, Volume 59, Issue 17, p.7856-76 (2016)


Animals, Antineoplastic Agents, Cell Line, Tumor, Crystallography, X-Ray, Drug Screening Assays, Antitumor, Female, Folate Receptor 1, Folic Acid Antagonists, Heterografts, Humans, Mice, SCID, Molecular Docking Simulation, Neoplasm Transplantation, Phosphoribosylglycinamide Formyltransferase, Proton-Coupled Folate Transporter, Purine Nucleotides, Pyrimidines, Pyrroles, Structure-Activity Relationship


<p>Targeted antifolates with heteroatom replacements of the carbon vicinal to the phenyl ring in 1 by N (4), O (8), or S (9), or with N-substituted formyl (5), acetyl (6), or trifluoroacetyl (7) moieties, were synthesized and tested for selective cellular uptake by folate receptor (FR) α and β or the proton-coupled folate transporter. Results show increased in vitro antiproliferative activity toward engineered Chinese hamster ovary cells expressing FRs by 4-9 over the CH2 analogue 1. Compounds 4-9 inhibited de novo purine biosynthesis and glycinamide ribonucleotide formyltransferase (GARFTase). X-ray crystal structures for 4 with FRα and GARFTase showed that the bound conformations of 4 required flexibility for attachment to both FRα and GARFTase. In mice bearing IGROV1 ovarian tumor xenografts, 4 was highly efficacious. Our results establish that heteroatom substitutions in the 3-atom bridge region of 6-substituted pyrrolo[2,3-d]pyrimidines related to 1 provide targeted antifolates that warrant further evaluation as anticancer agents.</p>