COMPOSITION COMPRISING ANTIBODY THAT BINDS TO DOMAIN II OF HER2 AND ACIDIC VARIANTS THEREOF

1 . A method of making a pharmaceutical composition comprising: (1) preparing a composition comprising a main species HER2 antibody that binds to domain II of HER2, and acidic variants thereof including glycated variant, disulfide reduced variant, or non-reducible variant, and (2) evaluating the acidic variants in the composition, and confirming that the amount thereof is less than about 25%.

2 . The method of claim 1 wherein step (2) comprises evaluating the acidic variants by a method selected from the group consisting of ion exchange chromatography wherein the composition is treated with sialidase, reduced capillary electrophoresis with sodium dodecyl sulfate (CE-SDS), non-reduced CE-SDS, boronate chromatography, and peptide mapping.

3 . The method of claim 1 wherein step (2) comprises evaluating the acidic variants by ion exchange chromatography.

4 . The method of claim 3 which comprises cation exchange chromatography using a cation exchanger with a carboxylate functional group.

5 . The method of claim 4 wherein the conditions for the chromatography involve:

Buffer A of 20 mM BisTris, pH 6.0; Buffer B of 20 mM BisTris, 200 mM NaCl, pH 6.0; and a gradient of 0.5% Buffer B at 1.0 mL/min.

6 . The method of claim 1 comprising combining the composition after step (2) with a pharmaceutically acceptable carrier.

7 . The method of claim 1 wherein the composition evaluated in step (2) is in a pharmaceutically acceptable carrier.