A Validation Workflow for Novel Oligonucleotide Sequences to Expand the Multiplexing Capacity of the CO-Detection by indEXing (CODEX) Platform

Antibody-based multiplexed tissue imaging has the potential to provide critical advances in biological discoveries and their translation for clinical applications. With the increasing introduction of markers and modalities for spatial analysis, there is an according demand for the expansion of multiplexing capacities of such imaging platforms. CO-Detection by indEXing (CODEX) is a widely used multiplexed tissue imaging platform that utilizes DNA-conjugated antibodies for imaging. The multiplexing capacity of CODEX is limited by the availability of unique DNA-oligonucleotide sequences for antibody barcoding. In this study, we demonstrate a workflow for the validation and the introduction of novel sets of candidate DNA-oligonucleotide sequences for CODEX. Through cross-validation multicycle experiments with the already published library of DNA barcodes, we here present a set of 27 novel oligonucleotide sequences for CODEX, increasing the potential multiplexing capacity to 85+ markers. We confirmed the utility of the new barcodes using a 74-plex antibody panel on a multitumor tissue microarray of paraffin-embedded tissues. The workflow presented here provides a reproducible method for extending the plexity of the CODEX platform, facilitating a deeper understanding of tissue microenvironments.