GSE201871
Total RNA from cell lines (JurkatLAG+PD1+ and Raji-PDL1)  treated with anti-PD1 antibody (MK3475) and/ or anti-LAG3  antibody (MK4280) was sequenced.
A previously established bioassay using Jurkat cells overexpressing PD1 and Lag3 allowed for assessment of simultaneous blockade of PD1 and LAG3 pathways in an in-vitro setting and demonstrated that an antibody cocktail increased IL-2 levels 5-fold better than single agent treatment. To gain understanding of signal transduction events RNA-Seq analysis of cell pellets individually treated with LAG3 or PD1 antibodies was used to reveal modest immune activation however, 5-fold more genes were upregulated upon combination treatment. There were increases in costimulatory genes like CD28, CD5, CD6 as well as other intracellular signaling molecules like LCP2 and ITK. Given the role of ERK in immune activation of T cells, pERK levels of Jurkat cells in the assay were evaluated, indicating that ERK phosphorylation was impacted on PD1 and LAG3 engagement with their ligands and this could be reversed by antibody blockade. A small molecule phosphatase inhibitor NSC87877, when combined with the PD1 antibody, could phenocopy the effect of combining PD1 and LAG3 blocking antibodies. CD28 has a recognized role in PD1 signaling but the impact on LAG3 signaling remains unknown. CD28 knockout cells demonstrated an overall muted IL-2 response but retained combination benefit in terms of IL-2 production in the context of LAG3 and PD1 co-blockade versus individual antibody treatments. Taken together, these observations provide new insights on the impact of LAG3 and PD1 co-blockade and provides additional support for ongoing immunotherapy clinical trials that combine PD1 and LAG3 antibodies. Overall design: Total RNA from  the co-culture assay (JurkatLAG+PD1+ and Raji-PDL1)  treated with anti-PD1 antibody (MK3475) and/ or anti-LAG3  antibody (MK4280) was sequenced.