P039 | 3D MODELING OF MATRIX-DRIVEN IBRUTINIB RESISTANCE AND CYTOKINE-MEDIATED CHEMOATTRACTION IN DLBCL

Bone marrow involvement in diffuse large B-cell lymphoma (DLBCL) is linked to worse prognosis, likely due to tumor-supportive cues from the bone marrow microenvironment. We recently showed that, in a bone-based 3D in vitro model, interaction between DLBCL cells and human bone matrix induces chemoresistance. Here, we investigated the cytokine and chemokine milieu generated in this 3D model, its chemoattractive effects, and whether DLBCL–bone matrix interaction modulates sensitivity to ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor with potential activity in DLBCL. Activated B-cell (ABC)-derived DLBCL cell lines (NU-DUL-1, RIVA) and germinal center B-cell (GCB)-derived lines (OCI-LY18, OCI-LY1) were tested. Migration and cytokine assays assessed the chemoattractive potential of 3D-conditioned media. Compared to standard 2D cultures, 3D cultures produced higher levels of cytokines and chemokines, especially CXCL9 and CCL22. 3D-conditioned media significantly promoted lymphocyte migration in a dose-dependent fashion, enhancing scaffold recellularization. Ibrutinib induced significant apoptosis in all DLBCL cell lines in 2D (OCI-LY18: 48.3±13.9%; OCI-LY1: 78.6±6.1%; NU-DUL-1: 45.7±10.2%; RIVA: 69.5±2.1% AnnexinV+). However, in 3D, OCI-LY18 and RIVA cells showed reduced sensitivity to ibrutinib-induced apoptosis compared to 2D (21.8±5.6% vs. 43.3±16.8%, p=0.0001; 44.1±9.9% vs. 69.5±2.1%). Conversely, NU-DUL-1 cells showed increased apoptosis in 3D (67.4±10.1% vs. 47.3±10.6%, p=0.047), while OCI-LY1 was unchanged. Notably, OCI-LY18 cells detached from 3D and re-cultured in 2D regained sensitivity to ibrutinib. These results indicate that bone matrix interaction can confer protection from ibrutinib-induced apoptosis in selected DLBCL lines (OCI-LY18, RIVA) but not others, independently of cell-of-origin subtype. This differential drug response is apparent only in the 3D microenvironment. Ingenuity Pathway Analysis performed in a model of ibrutinib-resistant cells of ABC and GCB origin displays downregulation of FAK signaling and ECM pathways, suggesting altered cell–ECM interactions. ABC-resistant cells showed changes in immune signaling (e.g., PD-1/PD-L1), while GCB-resistant cells were enriched for epigenetic and inflammatory pathways. Our 3D model provides a valuable tool to study matrix-induced drug resistance mechanisms and develop new personalized therapies for DLBCL.