Anti-Human CD3 x CD20 (Mosunetuzumab) – Fc Muted™ (C955-500ug)

Mosunetuzumab is a CD20xCD3 Bispecific T cell Engager (BiTE) antibody developed as a cancer immunotherapeutic drug1 using knobs-in-holes engineering2. 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 death1. Mosunetuzumab benefits from CH mutations that limit its effector functions3, having a modified, aglycosylated2 Fc with no Fcγ receptor or complement binding and only one binding site to CD203. Mosunetuzumab is subject to splicing-mediated mechanisms of epitope loss4. CD20 is a nonglycosylated 33-37 kDa phosphoprotein member of the MS4A family5,6 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 patients4. Mosunetuzumab is approved to treat follicular lymphoma, the second most common subtype of non-Hodgkin’s lymphoma1. The biological role of CD20 remains poorly understood; however, it is thought to be involved in calcium ion influx5,6. 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.