OP21 Spatial Transcriptomics of Pre-treatment Biopsies Revealing Molecular Maturation State and Chronic Crypt Damage, Reflecting Histological Severity, as Predictors of Primary Responsiveness to TNF-α Inhibitors in Bio-naive Ulcerative Colitis Patients

Abstract

Abstract Background Biologic therapies, particularly tumor necrosis factor-alpha inhibitors (TNFi), have greatly advanced the treatment of ulcerative colitis (UC), yet significant number of patients still do not respond to these treatments. For UC management, achieving both histologic and molecular healing is crucial, highlighting the need for more comprehensive therapeutic strategies. Despite extensive research, there is a significant gap in studies that simultaneously assess histologic and molecular changes at both the crypt and lamina propria (LP) levels. Our study addresses this gap by investigating TNFi-resistant UC patients, utilizing spatial transcriptomics to discern specific cell types within histologic sections and integrating these insights to enhance understanding of UC treatment responses. Methods We evaluated 56 patients categorized into test (n=23), validation (n=31), and healthy control groups (n=2). Each underwent biopsies at the same sites before (preTx) and after treatment (postTx), as shown in Figure 1A. This study focused on a 3-month follow-up of patients who were administered TNFi as a primary biologic therapy following resistance to conventional treatments. We used digital spatial profiling to analyze gene expression in the crypt and LP, as seen in Figures 1B and 1C. We then correlated molecular data with morphological characteristics and quantitatively evaluated histologic factors, especially crypt distortion and atrophy, reported as percentages (%). Results Among the study participants, 29 were classified as responders (R) to TNFi, while 25 were non-responders (non-R). A comparative analysis of gene expression between R and non-R groups revealed a differential expression pattern: 72 genes in the crypt and 105 genes in the LP across varying histologies, as shown in Figure 1D and 1E. Notably, in the preTx samples of non-R, crypts displayed significantly lower expression of genes associated with the maturation of colonocytes, including BEST4, C10orf99, CA2, CA4, CA7, PHGR1, SLC26A2, SLC26A3, LYPD8, CLCA1, and SCNN1, compared to the R group (Figure 1F). Furthermore, when correlating spatial transcriptomic data with histomorphological features, we observed that crypt distortion and atrophy were significantly more pronounced in the non-R group than in the R group in the preTx biopsy samples (Figures 1G and 1H). Conclusion Our study's spatial profiling unveils distinct molecular and histologic features between R and non-R to TNFi among bio-naive UC patients. The evaluation of chronic histological features such as crypt distortion, and molecular maturation status, in predicting TNFi response highlights the potential of early histologic assessment in guiding biologic therapy in the UC treatment pathway.