Immutep's playing field...., page-7

this is the important bit.......

Eftilagimod alpha (efti, IMP321) is a recombinantLAG-3Ig fusion protein that binds to MHC class IIand mediates antigen-presenting cell (APC)activation followed by CD8 T cell activation.Pembrolizumab binds to the PD-1 receptor,blocking both immune-suppressing ligands, PD-L1and PD-L2, from interacting with PD-1 to helprestore effector T cell responses. The rationale tocombine efti and pembrolizumab comes from theircomplementary mechanisms of action. Eftiactivates APCs and leads to an increase inactivated T cells which effect potentially reducesthe number of non-responders to pembrolizumab.Combining an APC activator like efti topembrolizumab is therefore fundamentallydifferent from many other trials combining twocheckpoint inhibitors like an anti-LAG-3 mAb withan anti-PD-1 mAb.