Slow uptake of biosimilars in some regions is often attributed to a lack of knowledge combined with concerns about safety and efficacy. To alleviate physician and patient apprehensions, regulatory reviews from four major regulatory authorities (RAs) (European Medicines Agency, US Food and Drug Administration, Health Canada, and Japan Pharmaceuticals and Medical Devices Authority) across a portfolio of eight biosimilars were analyzed to provide insight into RA review focus and approach. RA queries were evaluated in an unbiased and systematic manner by major classification (Chemistry, Manufacturing and Controls [CMC], nonclinical, clinical or regulatory) and then via detailed sub-classification. There was a consistent, predominant focus on CMC from all RAs. The review focus based on sub-classification of clinical and regulatory queries was influenced by molecular complexity, with significant differences between categories (monoclonal antibody or protein) in the distribution of query topics; specifically, bioanalytical (p = 0.023), comparative safety and efficacy (p = 0.023), and statutory (including the justification of extrapolation) (p = 0.00033). Each biosimilar had a distinct distribution of clinical query topics, tailored to product-specific data. This analysis elucidated areas of heightened RA interest, and validated their application of regulatory science in the evaluation of biosimilar safety and efficacy.

Modern mass spectrometry‐based proteomic studies require reliable, and robust data analysis for a comprehensive and quantitative profile of histone post‐translational modifications (PTM). Studies involving primary tissue samples face additional challenges in comparative sample analysis, due to various protein concentrations, multiple modification sites and modification states. A novel data analysis pipeline was developed in order to streamline the analysis process and normalize samples of varying concentration. This is relevant in the proteomic analysis of addiction, where various modification isoforms can correlate with different addiction phenotypes. A self‐administration model addiction study of methamphetamine (METH) addiction was used to develop this pipeline. Following nuclear protein isolation, proteins underwent tryptic digestion and histone H3 samples were derivatized with propionic anhydride. Identification, validation, and label‐free quantification of histone modifications was performed. Protein loading of different samples was normalized, using high abundance, proteotypic unmodified peptides. To localize changes in specific site and state, peptide isoforms for each site‐ and state‐specific modification were binned. Using this approach, we were able to identify histone modifications that underwent statistically significant changes in METH self‐administrated rat brain samples. In addition, we were able to identify histone modifications that are indicative of METH controllability in tested individual subjects. This data analysis pipeline has led to robust analysis of histone PTMs. Information on changes in site‐ and state‐specific histone modifications can be integrated with RNA‐seq data to elucidate driving chromatin pathways in the formation and maintenance of pathophysiological epigenetic states. Support or Funding Information This project was supported in part by the University of New Hampshire Hamel Center for Undergraduate Research.

Methamphetamine (METH) is a highly addictive psychostimulant that has been associated with deleterious physical and social consequences. A variety of factors ranging from life experiences to genetics are believed to play a role in the addiction process. Post‐translational modifications (PTMs) on histone proteins can lead to alterations in the organization of nucleosomal arrays and the accessibility of transcriptional factors to DNA as a form of epigenetic regulation. This study investigated the effects of chronic METH self‐administration in rats on PTMs of histones H3 and H4 in the striatum using liquid chromatography‐mass spectrometry. Chronic METH use induced group downregulation of the following PTMs on histone H3: K9 dimethylation with unmodified S10 and T11 and K14 acetylation; K18 methylation with K23 acetylation; and K79 dimethylation with T80 phosphorylation. Individual economic demand for METH was positively correlated with H3K79 methylation, H3K14 acetylation, H4K5 acetylation, H4K8 acetylation, H4K12 acetylation, and H4K16 acetylation. The significant decrease of H3T80 phosphorylation supports a downregulation of neural progenitor cell proliferation and neurogenesis, which is consistent with previously discovered inhibition of astrocyte and neural progenitor propagation as a result of METH use. Our novel findings, showing correlation between individual demand and the abundance of post‐translational modifications, offer a novel insight into the epigenetic regulation associated with METH use and further the current understanding of the impact of substance use on epigenome remodeling, while also elucidating potential therapeutic targets for future studies. Support or Funding Information This project was funded by the Hamel Center for Undergraduate Research whose financial support made this research possible.