IRF8 regulates efficacy of therapeutic anti-CD20 monoclonal antibodies

Grzelak, L.; Roesch, F.; Vaysse, A.; Biton, A.; Porrot, F.; Commere, P.-H.; Planchais, C.; Mouquet, H.; Vignuzzi, M.; Bruel, T.; Schwartz, O.

doi:10.1101/2022.06.09.495444

bioRxiv · 10.1101/2022.06.09.495444

IRF8 regulates efficacy of therapeutic anti-CD20 monoclonal antibodies

Grzelak, L.·Roesch, F.·Vaysse, A.·Biton, A.·Porrot, F.·Commere, P.-H.·Planchais, C.·Mouquet, H.·Vignuzzi, M.·Bruel, T.·Schwartz, O.

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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 knockout 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.

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Grzelak, L., Roesch, F., Vaysse, A., Biton, A., Porrot, F., Commere, P.-H., Planchais, C., Mouquet, H., Vignuzzi, M., Bruel, T., Schwartz, O.. 2022-06-10. IRF8 regulates efficacy of therapeutic anti-CD20 monoclonal antibodies. https://doi.org/10.1101/2022.06.09.495444

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