TABLE 4.

Classification scheme for mAb1 aggregates based on biophysical characterization

^a Class descriptions refer to metal content or aggregate properties (size, degree of native-like conformation, and reversibility) if present.

^b Values for the total stressed sample are displayed except for the FTIR data where both the supernatant and pellet are shown.

^c Oligomer (oligo.) concentration as determined by SE-HPLC (see Table 1), where the + symbol indicates the relative % HMW. Nanoparticle (nano.) concentration as determined by NTA (Table 2 and Fig. 2), where the + symbol indicates the relative fold increase. Total micron (micro.)-sized particle counts as determined by HIAC (Fig. 1), where approximate particles/ml = 10ⁿ × 10² (n equals the number of + symbols). Relative visible (vis.) particles as determined by MFI.

^d Size threshold of the bin with the largest 20 particles as measured by MFI (Fig. 3).

^e Correlation coefficient (%) between the FTIR spectra of the untreated and the supernatant (sup) or pellet fractions (Fig. 4).

^f Red shift of the wavelength (nm) of maximum fluorescence from untreated sample (Fig. 5).

^g Fluorescence intensity upon binding ANS as a percentage of the total 90 °C sample (Fig. 6).

^h Reversibility (Fig. 7) was listed as reversible (R) 90–100% reduction in 2–5 μm, partially reversible (PR) 70–89% reduction in 2–5 μm, or irreversible (I) ≤50% reduction in 20 + μm.

ⁱ For determination of chemical modifications (Chem. Mod.) see Ref. 41. + represents the relative extent of chemical modification. For class 1, only untreated was tested.

^j Percent insoluble aggregation (% Insol. Agg.) after stress treatment (Table 1).

^k Values are for members of class 1, except for pH 3.5 and store which varied slightly in some cases.

^l Explanation of symbols: −, not tested; ND, not detected.