RT Journal Article SR Electronic T1 GPR183 mediates the capacity of the novel CD47-CD19 bispecific antibody TG-1801 to heighten ublituximab-umbralisib (U2) anti-lymphoma activity JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.03.31.486558 DO 10.1101/2022.03.31.486558 A1 Marcelo Lima Ribeiro A1 Núria Profitós-Pelejà A1 Juliana Carvalho Santos A1 Pedro Blecua A1 Diana Reyes Garau A1 Marc Armengol A1 Miranda Fernández-Serrano A1 Hari P. Miskin A1 Francesc Bosch A1 Manel Esteller A1 Emmanuel Normant A1 Gael Roué YR 2022 UL http://biorxiv.org/content/early/2022/04/01/2022.03.31.486558.abstract AB Targeted therapies have considerably improved the survival rate of B-cell non-Hodgkin lymphoma (B-NHL) patients in the last decade; however, most subtypes remain incurable. TG-1801, a bispecific antibody that targets CD47 selectively on CD19+ B-cells, is under clinical evaluation in relapsed/refractory B-NHL patients either as a single-agent or in combination with ublituximab, a CD20 antibody, which is also being combined with the PI3Kδ/CK1e inhibitor, umbralisib (“U2”-regimen). In this study, we demonstrated that TG-1801 potentiates ublituximab-mediated antibody-dependent cell death (ADCC) and antibody-dependent cell phagocytosis (ADCP), leading to an additive anti-tumour effect of the TG-1801/U2 combination in B-NHL co-cultures. Accordingly, in a B-NHL xenotransplant model, the triplet achieved a 93% tumour growth inhibition, with 40% of the animals remaining tumour-free 35 days after the last dosing. Transcriptomic analysis further uncovered the upregulation of the G protein-coupled receptor, GPR183, as a crucial event associated with TG-1801/U2 synergism, while pharmacological blockade or genetic depletion of this factor impaired ADCP initiation, as well as cytoskeleton remodelling and cell migration, in B-NHL cultures exposed to the drug combination. Thus, our results set the preclinical rationale and support a combination strategy of TG-1801 with PI3Kδ- and CD20-targeting agents in patients with B-NHL.Competing Interest StatementH. Miskin reports personal fees from TG Therapeutics, Inc. during the conduct of the study. E. Normant reports employment and ownership of stock with TG Therapeutics. G. Roué reports grants from TG Therapeutics and Instituto de Salud Carlos III during the conduct of the study. The remaining authors have no competing financial interests.