Abstract

Simple Summary Diffuse large B-cell lymphoma is the most common type of lymphoma. Despite initial treatment, up to 40% of patients do not achieve a cure and need second-line therapy. For those experiencing late relapse or lacking access to CAR-T cell therapy, platinum-based chemotherapy followed by stem cell transplantation remains the standard of care. In this study, we used genomewide CRISPR/Cas9 screens and single-gene knockout experiments to identify the genes associated with responses to platinum-based drugs. We provide a comprehensive list of genes involved in the response to cisplatin in DLBCL. Our functional experiments highlight the critical roles of the DNA damage response genes XPA and ERCC6, in addition to BTK, in the response to platinum-based drugs. Additionally, we show that inhibition of BTK at lower concentrations sensitizes DLBCL cells to platinum-based drugs. Abstract The recurrence of diffuse large B-cell lymphoma (DLBCL) has been observed in 40% of cases. The standard of care for refractory/relapsed DLBCL (RR-DLBCL) is platinum-based treatment prior to autologous stem cell transplantation; however, the prognosis for RR-DLBCL patients remains poor. Thus, to identify genes affecting the cisplatin response in DLBCL, cisplatin-based whole-genome CRISPR-Cas9 knockout screens were performed in this study. We discovered DNA damage response (DDR) pathways as enriched among identified sensitizing CRISPR-mediated gene knockouts. In line, the knockout of the nucleotide excision repair genes XPA and ERCC6 sensitized DLBCL cells to platinum drugs irrespective of proliferation rate, thus documenting DDR as essential for cisplatin sensitivity in DLBCL. Functional analysis revealed that the loss of XPA and ERCC6 increased DNA damage levels and altered cell cycle distribution. Interestingly, we also identified BTK, which is involved in B-cell receptor signaling, to affect cisplatin response. The knockout of BTK increased cisplatin sensitivity in DLBCL cells, and combinatory drug screens revealed a synergistic effect of the BTK inhibitor, ibrutinib, with platinum drugs at low concentrations. Applying local and external DLBCL cohorts, we addressed the clinical relevance of the genes identified in the CRISPR screens. BTK was among the most frequently mutated genes with a frequency of 3–5%, and XPA and ERCC6 were also mutated, albeit at lower frequencies. Furthermore, 27–54% of diagnostic DLBCL samples had mutations in pathways that can sensitize cells to cisplatin. In conclusion, this study shows that XPA and ERCC6, in addition to BTK, are essential for the response to platinum-based drugs in DLBCL.