Abstract 3857: Discovery and structure-activity relationship studies of TP-2846: a novel tetracycline antileukemia agent
Authors: Sun Cuixiang , Zhao Peng , Hunt Diana , Kerstein Kathryn , Newman Joseph , McKellip Sara , Bostwick Robert , Dumas Jacques , Xiao Xiao-Yi 
Published: August 2019

Abstract
Tetracyclines are broad-spectrum antibacterial agents. They inhibit bacterial protein synthesis by binding to the 30S subunit of the bacterial ribosome. Besides tetracyclines’ potent antibacterial activity, there is accumulating in vitro and in vivo evidence that tetracycline derivatives, including COL-3, doxycycline, minocycline, and tigecycline (Škrtić, Cancer Cell (2011) 20(5): 10.015), also possess anticancer properties against both liquid and solid tumors. Several tetracyclines have been investigated in various cancer clinical trials. However, most of these human trials, including the recent phase 1 study of tigecycline in patients with acute myeloid leukemia (AML) (Reed, Cancer Med (2016) 5(11): cam4.845), have yielded disappointing results. We believe that the failure of tigecycline in the AML trial is due to its inadequate in vitro potency (single-to-double digits µM range). To identify more potent anticancer tetracyclines, we explored the anticancer, particularly antileukemia activities of novel tetracycline analogs created by the proprietary tetracycline total synthesis platform during our antibacterial drug discovery efforts.
A collection of 2368 novel, structurally diverse tetracycline analogs was screened against the leukemia cell line THP-1 in an HTS format (386-well). From the 68 hits (2.9% hit rate) with sub-µM antiproliferation activity, five lead compounds derived from two sub-series were selected for further profiling, including TP-2846, which displayed one of the lowest GI50 values at 0.75 µM. As a comparison, tigecycline had a GI50 of 29 µM in the same assay. The five lead compounds were subsequently evaluated for antiproliferation activity in other liquid and solid tumor lines, including MV4-11 (0.020 µM), MOLT-4 (0.09 µM), K-562 (0.43 µM), HL-60 (0.37 µM), CCRF-CEM (0.067 µM), KG-1 (0.27 µM), Kasumi-1 (0.16 µM), U-87 (0.09 µM), HepG2 (1.6 µM), CCL-247 (0.26 µM), CCL-222 (0.48 µM), HTB-77 (0.26 µM), and CRL-1923 (6.2 µM) (values in parentheses are GI50 of TP-2846). TP-2846 and another lead compound were also screened against the NCI60 panels. TP-2846 demonstrated the highest overall antiproliferation potency against most cell lines tested and is 10-50 folds more potent than tigecycline.
Using MV4-11 as the primary screening cell line, we subsequently evaluated and studied the structure-activity relationships of more than 170 analogs of TP-2846 with systematic variations at the C4, C7, and C8 positions of the tetracycline core. Although a number of new analogs displayed comparable antiproliferation activity in MV4-11, TP-2846 remains the most potent analog overall in vitro and was selected to be further profiled in vitro and in vivo (see accompanying abstracts “In vitro characterization of TP-2846: a novel tetracycline antileukemia agent” and “In vivo activities of TP-2846: a novel tetracycline antileukemia agent”).
Citation Format: Cuixiang Sun, Peng Zhao, Diana Hunt, Kathryn Kerstein, Joseph Newman, Sara McKellip, Robert Bostwick, Jacques Dumas, Xiao-Yi Xiao. Discovery and structure-activity relationship studies of TP-2846: a novel tetracycline antileukemia agent [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 3857.