Abstract 811: Multi-targeted inhibitors of mitochondrial one-carbon metabolism and cytosolic de novo purine synthesis enzymes as anti-tumor agents

Abstract

Abstract Targeting cellular one-carbon (1C) metabolism in cancer cells with pyrrolo[3,2-d]pyrimidine analogs provides in vivo antitumor efficacy. We discovered a first-in-class series of 5-substituted pyrrolo[3,2-d]pyrimidine analogs (AGF291, AGF320, AGF347) with inhibition of serine hydroxymethyltransferase 2 (SHMT2), a key enzyme in mitochondrial 1C metabolism and a reported oncodriver. In addition, AGF291, AGF320 and AGF347 inhibited de novo purine nucleotide biosynthesis at glycinamide ribonucleotide formyltransferase (GARFTase) and 5-aminoimidazole-4-carboxamide (AICA) ribonucleotide formyltransferase (AICARFTase), and serine hydroxymethyltransferase 1 (SHMT1). In vivo studies demonstrated excellent antitumor efficacy for AGF347 against MIA PaCa-2 pancreatic adenocarcinoma xenografts in SCID mice with a median tumor growth delay (T-C) of >38 days for 4 mice, and 1 of 5 mice tumor-free 122 days post-treatment. AGF359, a new analog in this series, was a potent inhibitor of KB human tumor cell proliferation in vitro. AGF359 inhibition of KB human tumor cells was reversed with glycine and adenosine, establishing mitochondrial 1C metabolism and de novo purine biosynthesis as the targeted pathways; AICA plus glycine was incompletely protective, implicating AICARFTase as a direct cellular target. AGF359, like AGF291, AGF320, and AGF347, inhibited purified human SHMT2 (Ki = 0.399 ± 0.174 µM), SHMT1 (Ki = 0.70 ± 0.088 µM) and AICARFTase (Ki = 8.86 ± 2.83 µM). There was no inhibition of 5,10-methylene tetrahydrofolate dehydrogenase 2 (MTHFD2). Further structural modifications of these multi-targeted agents afforded pyrrolo[3,2-d]pyrimidine analogs AGF307 and AGF312. Cell-based glycine/nucleotide rescue experiments in KB tumor cells established that, as with AGF359, AGF307 and AGF312 were dual inhibitors of the mitochondrial 1C metabolism (AGF307) and de novo purine biosynthesis (AGF307, AGF312). These compounds are currently in further preclinical evaluation as a prelude to possible clinical development as antitumor agents. Citation Format: Md Junayed Nayeen, Khushbu Shah, Aamod Dekhne, Changwon Ning, Carrie O'Connor, Jade M. Katinas, Jennifer Wong, Zhanjun Hou, Charles E. Dann III, Larry H. Matherly, Aleem Gangjee. Multi-targeted inhibitors of mitochondrial one-carbon metabolism and cytosolic de novo purine synthesis enzymes as anti-tumor agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 811.