Abstract LB_A21: NCI60 HTS384: The next phase of the NCI60 screen

Abstract

Abstract The NCI60 human tumor cell line screen, which has operated as a free service to the cancer research community for over 20 years, has proven to be an important drug discovery tool. The screen has operated using cutting-edge technology of the 1990s including a 96-well microplate format, a 2-day drug exposure period and following cell fixation, and a visible absorbance endpoint by the protein-staining dye sulforhodamine B (SRB). The SRB endpoint determines cell density based on protein content with a lower resolution limit of 1,000 – 2,000 cells. This report describes the next phase of this important cancer research tool, the NCI60 HTS384 screen format. While the cell lines remain the same, the screen is performed using 384-well microplates with a 3-day compound exposure period and a CellTiter-Glo luminescence endpoint. The CellTiter-Glo endpoint determines cell number based upon ATP content with a lower resolution limit of <10 cells. To develop a baseline comparison, data were generated from a library of 1,000 FDA-approved and investigational small molecule anticancer agents by the two assay formats. Although the mean-graph patterns and COMPARE analyses are very similar for many compounds, there is a divergence between the two screens for some molecular targets. Within subsets of approved and investigational agents directed toward the same target (e.g., EGFR, BRAF/MEK/ERK, and PI3K inhibitors), the clustering of compound data from the NCI60 HTS384 screen is qualitatively similar to the clustering of compound data from the classic NCI60 SRB screen and there is a strong COMPARE correlation between the two screens. However, for some drug targets there is very little or no clustering between data from the two screens, although the clustering within each screen is moderate-to-good. Examples include mTOR rapalogs, BET bromodomain and NAMPRTase inhibitors. Differences in data between the two screens might be partially attributed to increases in the assay endpoint sensitivity and compound exposure time of the NCI60 HTS384 assay. Compounds submitted for NCI60 screening after September 30, 2023, will be tested in the modernized NCI60 HTS384 format. This project was funded in part with federal funds from the NCI, NIH, under contract no. HHSN261201500003I and by the Intramural Research Program of the NIH, National Cancer Institute. Citation Format: Beverly A Teicher, Mark W Kunkel, Joel Morris, Ronald C Taylor, Thomas S Dexheimer, Nathan P Coussens, James H Doroshow. NCI60 HTS384: The next phase of the NCI60 screen [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_A21.