Effect of high mannose glycan pairing on IgG antibody clearance.

IgG antibodies contain N-linked glycans on the Fc portion of each heavy chain. The glycan on one heavy chain can either match the glycan on the other heavy chain (symmetrical pairing) or be different (asymmetrical pairing). These Fc glycans influence effector functions and can alter clearance rates. Previous studies showing that high mannose forms result in faster mAb clearance in humans were incapable of differentiating the impact of symmetrically vs. asymmetrically paired HM forms, and, therefore, the effect of pairing on clearance was not clear. Traditional analytical methods, which are used to measure glycans in such studies, do not determine the number of HM glycans per antibody. With a sensitive method designed to measure HM pairing, we followed the levels of symmetrically and asymmetrically paired HM on antibodies in human pharmacokinetic serum samples to determine the impact of Fc HM glycan pairing on therapeutic human IgG clearance in humans. The two HM paired forms cleared at the same rate, indicating that the effect on clearance was not proportional to the degree of modification. Since both forms can exist on therapeutic antibodies and the ratio can differ between products, measuring their relative levels is necessary to properly estimate effects on clearance.