IRF8 regulates efficacy of therapeutic anti‐CD20 monoclonal antibodies

Abstract

Anti-CD20 monoclonal antibodies such as Rituximab, Ofatumumab, and Obinutuzumab are widely used to treat lymphomas and autoimmune diseases. They act by depleting B cells, mainly through Fc-dependent effectors functions. Some patients develop resistance to treatment but the underlying mechanisms are poorly understood. Here, we performed a genome-wide CRISPR/Cas9 screen to identify genes regulating the efficacy of anti-CD20 antibodies. We used as a model the killing of RAJI B cells by Rituximab through complement-dependent-cytotoxicity (CDC). As expected, the screen identified MS4A1, encoding CD20, the target of Rituximab. Among other identified genes, the role of Interferon Regulatory Factor 8 (IRF8) was validated in two B-cell lines. IRF8 KO also decreased the efficacy of antibody-dependent cellular cytotoxicity and phagocytosis (ADCC and ADCP) induced by anti-CD20 antibodies. We further show that IRF8 is necessary for efficient CD20 transcription. Levels of IRF8 and CD20 RNA or proteins correlated in normal B cells and in hundreds of malignant B cells. Therefore, IRF8 regulates CD20 expression and controls the depleting capacity of anti-CD20 antibodies. Our results bring novel insights into the pathways underlying resistance to CD20-targeting immunotherapies.

The roles of IRF8 in nonspecific orbital inflammation: an integrated analysis by bioinformatics and machine learning

“…In instances where the expression of SIRT1 was manipulated in RAW264.7 cells via lentivirus, a discernible alteration in IRF8 expression subsequent to LPS treatment was conspicuously absent [ 42 ]. Such findings intimate a plausible regulatory relationship between IRF8 expression and SIRT1, adding a nuanced layer to our understanding of the intricate interplay within the immune regulatory network [ 43 ]. Therefore, a nuanced understanding of the role IRF plays in NSOI could not only shed light on its molecular etiology but also offer innovative therapeutic avenues for this poorly understood condition.…”

Advancements in cancer immunotherapies targeting CD20: from pioneering monoclonal antibodies to chimeric antigen receptor-modified T cells

“…The described positive regulators include transcription factors essential for B cell development and maturation, such as PU.1, PiP (IRF4), NFκB ( 14 – 16 ), as well as other factors, such as USF, TFE3.1 ( 16 ), OCT1, OCT2 ( 17 ), ELK1, ETS1 ( 18 ), SP1, CHD4 and MBD2 ( 19 ). Recently, another member of interferon regulatory factors (IRF) engaged in B cell development, IRF8, was shown to promote CD20 expression in DLBCL as well as in healthy B cells ( 20 ). Negative regulators of CD20 include FOXO1 ( 21 ), CREM ( 19 ), SMAD2/3 ( 22 ), and MYC ( 23 , 24 ).…”

“…engaged in B cell development, IRF8, was shown to promote CD20 expression in DLBCL as well as in healthy B cells (20). Negative regulators of CD20 include FOXO1 (21), CREM (19), SMAD2/3 (22), and MYC (23,24).…”