Plasmid Name
pHC-IgG1-GASDALIE
Mutation Set
G236A / S239D / A330L / I332E
Selection Marker
Ampicillin
Promoter
CMV
Fc Engineering Overview
The human IgG1 (GASDALIE) Fc variant is a premier quadruple-mutation Fc module designed to achieve maximum binding affinity for FcγRIIIa and FcγRIIa. This module yields ultra-high NK cell-mediated ADCC and macrophage-mediated ADCP potency, enabling target cell lysis even against low-density target antigens.
Functional Profile
| Property | Effect |
|---|---|
| FcγRIIIa binding (V158 & F158) | Maximum Hyper-Enhancement ↑↑↑↑ (>100× affinity boost) |
| FcγRIIa binding (H131 & R131) | Strongly Increased ↑↑↑ (A/I activation ratio optimized) |
| FcγRIIb binding (Inhibitory) | Lower relative engagement vs. FcγRIIa |
| ADCC | Ultra-High / Maximal ↑↑↑↑ (Industry Benchmark) |
| ADCP (Macrophage Phagocytosis) | Potently Enhanced ↑↑↑ |
| CDC | Mildly Reduced / Secondary (due to local CH2 loop restructuring) |
| FcRn binding & half-life | Normal / WT Baseline |
| Effector Potency | Maximal Engineered ADCC/ADCP Potency |
Mechanism of Action
The GASDALIE variant integrates four synergistic substitutions focused entirely within the lower hinge and CH2 domain:
- G236A (Lower Hinge): Restricts local backbone flexibility at the lower hinge junction, enhancing binding selectivity for activating FcγRIIa over inhibitory FcγRIIb.
- S239D (CH2 Domain): Introduces a negative charge that forms favorable electrostatic complementary interactions with FcγRIIIa surface residues.
- A330L (CH2 Domain): Optimizes hydrophobic packing interactions and structural positioning at the receptor interface.
- I332E (CH2 Domain): Inserts a second negatively charged residue to lock the receptor interface into a high-affinity conformation.
Phenotypic Effects
- Peak NK cell recruitment and maximal ADCC cytotoxicity (EC50 shifted up to 3 logs lower than wild-type).
- Overcomes low-affinity FcγRIIIa-F158 and FcγRIIa-R131 patient polymorphism limitations.
- Potent activation of macrophage-mediated tumor cell phagocytosis (ADCP).
- Preserves standard FcRn endosomal recycling and systemic serum half-life.
- Selective effector activation ideal for targets where CDC contribution is unnecessary or undesirable.
Applications
- Therapeutic oncology antibodies targeting antigens expressed at low surface copy numbers.
- Refractory cell depletion where standard IgG1 or DLE variants fail to elicit sufficient effector response.
- Industry benchmark control for hyper-enhanced ADCC and structural FcγR engagement assays.
- Preclinical antibody discovery against hard-to-deplete tumor targets.
Plasmid Map & Feature Annotation
Insert Structure: VH – CH1 – hinge – lower hinge(G236A) – CH2(S239D/A330L/I332E) – CH3(wild-type)
- VH: Variable heavy domain
- CH1: Constant heavy 1
- Hinge: Native IgG1 core hinge
- Lower Hinge (G236A): FcγRIIa-selective activation mutation
- CH2 (S239D/A330L/I332E): ADCC/ADCP hyper-enhancing electrostatic & hydrophobic structural cluster
- CH3 (WT): Native IgG1 CH3 domain
Product Note: GASDALIE (G236A/S239D/A330L/I332E) represents the apex variant in the Fusion BioLabs ADCC/ADCP-Enhanced Family. It is particularly recommended for research applications targeting ultra-low surface density receptors or when evaluating the maximum theoretical ceiling of NK- and macrophage-mediated cytotoxicity.
Fusion BioLabs ADCC/ADCP-Enhanced Family Comparison Matrix
| Variant | Mechanism | Enhancement Strength | Primary Application & Notes |
|---|---|---|---|
| human IgG1 (WT) Wild-Type |
Native baseline FcγR binding | ★★☆☆☆ | Baseline Control. Standard physiological FcγR binding and ADCC/ADCP baseline for comparative assays. |
| human IgG1 (G236A) G236A |
Lower hinge FcγRIIa selective optimization | ★★★☆☆+ | Selective ADCP Enhancer. Specifically boosts macrophage phagocytosis by maximizing the FcγRIIa/FcγRIIb activation ratio. |
| human IgG1 (DE) S239D / I332E |
CH2 domain electrostatic interface enhancement | ★★★☆☆ | Moderate ADCC/ADCP Enhancer. Core double mutation boosting FcγRIIIa and FcγRIIa engagement. |
| human IgG1 (DLE) S239D / A330L / I332E |
CH2 domain structural interface enhancement | ★★★★☆ | Strong ADCC Enhancer. Classic triple mutation optimizing NK cell-mediated lysis. |
| human IgG1 (ADE) G236A / S239D / I332E |
CH2 domain multi-residue FcγRIIIa optimization | ★★★★☆+ | High-Potency ADCC/ADCP Enhancer. Increases FcγRIIIa binding while improving the FcγRIIa/FcγRIIb binding ratio to favor activation over inhibition. |
| human IgG1 (GASDALIE) G236A / S239D / A330L / I332E |
CH2 domain hyper-enhancement (FcγRIIIa & FcγRIIa) | ★★★★★ | This Product. Ultra-Potent ADCC/ADCP Enhancer. Maximum engineered affinity variant for low antigen density targets. |
Storage & Handling
- Store plasmid at −20°C.
- Avoid repeated freeze–thaw cycles.
- Use sterile technique.
- Suitable for transient or stable mammalian expression (CHO, HEK293, NS0).
References
- Ahmed AA, Keremane SR, Vielmetter J, Bjorkman PJ. Structural characterization of GASDALIE Fc bound to the activating Fc receptor FcγRIIIa. J Struct Biol. 2016;194(1):78-89.
- Lazar GA, Dang W, Karki S, Vafa O, Peng JS, Hyun L, Chan C, Chung HS, Eivazi A, Yoder SC, Vielmetter J, Carmichael DF, Hayes RJ, Dahiyat BI. Engineered antibody Fc variants with enhanced effector function. Proc Natl Acad Sci U S A. 2006;103(11):4005-4010.
