Fc-mediated antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) are considered to be particularly important for successful therapeutic antibody intervention. Generally, ADCC and CDC activation is usually ideal for therapeutic antibodies, but in some cases, preference is given to antibodies that fail to activate ADCC / CDC effector functions. Inspired by our mature ADCC enhanced antibody technology, Creative Biolabs has developed ADCC / CDC decreased antibody modification technology for customer research and analysis development.
ADCC / CDC Mechanisms
ADCC interacts with Fc receptors (FcR) on effector cells (including natural killer (NK) cells, monocytes, macrophages, neutrophils, eosinophils and dendritic cells) through the Fc region of antibodies. To trigger. Activated effector cells induce lysis of target cells by releasing cytotoxic substances (lyase, perforin, granzyme, TNF). In CDC, C1q binds to antibodies that trigger the complement cascade and form a membrane attack complex (MAC) (C5b to C9) on the surface of target cells, thereby activating the classical pathway complement.
Both ADCC / CDC mechanisms are highly dependent on the glycosylation profile of the Fc portion and the polymorphism of the Fcγ receptor. Therefore, the Fc region is the main focus of our ADCC / CDC reduction technology.
ADCC / CDC Decrease Strategies
For ADCC / CDC decreased purposes, Fc engineering methods are commonly used to determine the key interaction sites of the Fc domain with the Fcγ receptor and C1q, and these positions are then engineered to reduce or eliminate Fc receptor binding. Fc engineering strategy often requires years of technical accumulation. Creative Biolabs is positioned as a technology company and establishes independent Fc engineering technology, which belongs to an innovative engineering model.
Currently, we provide three Fc engineering strategies to reduce the ADCC / CDC function:
Through proprietary algorithm scanning software, we determined the key interaction sites for the Fc domain with Fcγ receptors and C1q and then directly mutate these positions to reduce or abolish binding. Our researchers identified mutants K322A, L234A, and L235A, and their combination was sufficient to completely eliminate the binding of FcyR and C1q.
ADCC enhanced antibodies are glycosylation site mutants on asparagine 297 in the Fc region. This is because the glycosylation site of the Fc domain is required for optimal FcR interaction. We reverse-mutated the N-glycosylation site of A297 of the IgG1 ADCC+ antibody and inserted the GGSG sequence in CH2, which showed a reduced ADCC / CDC effect.
IgG4 has been widely used, but has been unpopular in recent years due to the unique ability of this subclass to undergo Fab arm exchange. However, in general, the rank order for ADCC is IgG1 (+++) = IgG3 (+++)> IgG2 (±) ≥ IgG4 (±). In this case, we developed an IgG1 antibody replacement method - Fc shuffling to reduce ADCC.
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