Assessing Analytical and Functional Similarity of Proposed Amgen Biosimilar ABP 980 to Trastuzumab.

BACKGROUND: ABP 980 has been developed as a biosimilar to Herceptin® (trastuzumab). Comprehensive analytical characterization incorporating orthogonal analytical techniques was used to compare ABP 980 to trastuzumab reference products sourced from the United States (US) and the European Union (EU). METHODS: Physicochemical property comparisons included the following: primary structure related to amino acid sequence and post-translational modifications, including glycans; higher-order structure; product-related substances and impurities, including size and charge variants; subvisible and submicron particles, and protein content. In addition, functional similarity was assessed for Fab-mediated, Fc-mediated, and combined Fab- and Fc-mediated activities. RESULTS: ABP 980 has the same amino acid sequence as and similar post-translational modification profiles to trastuzumab (US) and trastuzumab (EU). Importantly, ABP 980 was found to be highly similar to trastuzumab for all functional activities related to the mechanism(s) of action. Higher-order structure, product-related substances and impurities, particles and aggregates were also highly similar between ABP 980 and trastuzumab. Where minor differences were noted, they were evaluated and found unlikely to impact clinical performance. The totality of evidence, including the pharmacokinetic clinical similarity of ABP 980, further supports that ABP 980 is highly similar to trastuzumab. CONCLUSION: Based on the comprehensive analytical similarity assessment, ABP 980 is analytically highly similar to the reference product, trastuzumab.

Interaction of mucin with cholesterol enriched vesicles: role of mucin structural domains.

We utilized fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS) to examine the role of gallbladder mucin (GBM) in promoting the aggregation and/or fusion of cholesterol enriched vesicles. By fluorescent labeling either the vesicle or the mucin, we could examine the change in vesicle size as well as changes in mucin's diffusion constant. Both FRAP and FCS show that GBM has a profound effect in inducing vesicles to aggregate/fuse, particularly after overnight incubation. GBM mucin domains (either protease digested or reduced GBM) are not as effective as native GBM. Intact GBM alone was able to shorten crystal appearance time and increase the number of crystals nucleated by polarized optical microscopy. In summary, our findings would suggest that both glycosylated and nonglycosylated domains of GBM are involved in early aggregation of cholesterol enriched vesicles but that this effect is reversible in the absence of nonglycosylated domains.