Abstract 817: Spatial characterization, of T-cell receptors at subcellular resolution using in situ sequencing-by-synthesis and spatial protein detection on the same tissue section.

Abstract Abstract: Analyzing the tumor microenvironment (TME) and its immune context based on protein and RNA expression, alongside RNA sequencing, offers a powerful approach to understand tumor biology, predict treatment response, and guide the development of personalized therapies. It provides a more comprehensive understanding of tumor biology and the interplay between genetic alterations, cellular environment, and immune response. Currently, commercially available spatial transcriptomics methods require cDNA barcoding on tissue and ex situ cDNA sequencing on a separate instrument which limits the ability to directly sequence known or unknown regions in situ, such as T-cell or B-cell receptor (TCR/BCR) complementarity determining regions. This limitation can impact the detailed analysis of immune responses within tissue. Advances in technology are needed to enable direct in situ sequencing for more comprehensive insights. Here, we present a novel approach combining in situ sequencing-by-synthesis with high-plex protein detection (30+), H Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 817.