There are 4 IgG subclasses, that have small differences in the amino acid sequences of the constant regions (CH1, CH2 & CH3) of the heavy chains : IgG1, IgG2, IgG3, IgG4.
Binding to Fc Receptor
Anti EGF receptor antibodies can be of the IgG1 type ( cetuximab), or of the IgG2 type (panitumumab). There is no reason to link their clinical efficacies to the above general biological features of the subclasses, as many other factors are involved, such as activity on downstream phosphorylations in the EGFR controlled pathways.
ADCC antibody dependent cellular cytotoxicity
IgG1 (Cetuximab, Nimotuzumab, Matuzumab, Zalutumumab, Ipilimumab, IMC A12) & IgG2 (Panitumumab, **Tremelimumab, CP-751,871) : Biological activities on complement and ADCC*
Anti EGFR monoclonals can destroy cancer cells through many pathways, among which complement activation, and triggering of ADCC (antibody dependent cellular cytotoxicity) of immune effector cells, thanks to the activation of the Fc receptors on their membranes by the Fc regions of the monoclonals