Anti-Human CD3 x CD20 (Mosunetuzumab) [Clone RG7828] — Fc Muted™,Leinco,C955

Mosunetuzumab is a CD20xCD3 Bispecific T cell Engager (BiTE) antibody developed as a cancer immunotherapeutic drug 1 using knobs-in-holes engineering 2 . Simultaneous targeting of CD20 B cell on lymphomas and CD3 on T cells, leads to T cell activation, the release of perforin and granzymes, and ultimately the depletion of malignant B cells through lysis and cell death 1 . Mosunetuzumab benefits from CH mutations that limit its effector functions 3 , having a modified, aglycosylated 2 Fc with no Fcγ receptor or complement binding and only one binding site to CD20 3 . Mosunetuzumab is subject to splicing-mediated mechanisms of epitope loss 4 . CD20 is a nonglycosylated 33-37 kDa phosphoprotein member of the MS4A family 5,6 that encodes four variants (V1-4) 4 , with V1 and V3 being the most abundant. Mosunetuzumab is only effective against V3-expressing B cells, and this likely plays a role in resistance to Mosunetuzumab in some patients 4 . Mosunetuzumab is approved to treat follicular lymphoma, the second most common subtype of non-Hodgkin’s lymphoma 1 . The biological role of CD20 remains poorly understood; however, it is thought to be involved in calcium ion influx 5,6 . CD20 has no natural ligand and is not immediately internalized upon antibody binding. Thus, mAbs directed against CD20 depend on the recruitment of a host response. CD3 is an invariant antigen of the T cell TCR (T cell receptor), which is responsible for recognizing peptides bound to major histocompatibility complex molecules.