Ben-Shoshan M, Cem A, Cook VE, Khalaf R, Freigeh G
The journal of allergy and clinical immunology. In practice •
Idiopathic anaphylaxis (IA) refers to recurrent, life-threatening hypersensitivity reactions without identifiable triggers, representing a diagnostic and therapeutic challenge. We describe a 17-year-old girl presenting with recurrent episodes of flushing, pruritus, and respiratory symptoms, without consistent allergen exposure or cofactor involvement. Evaluation revealed elevated acute tryptase levels with a normal baseline, negative skin testing results, and negative galactose-α-1,3-galactose (α-gal) and KIT mutation analysis. The patient improved on daily cetirizine with no further reactions. IA remains a diagnosis of exclusion, requiring careful consideration of IgE-mediated allergies, cofactor-dependent anaphylaxis, clonal mast cell disorders, and systemic mimics such as neuroendocrine tumors or vasovagal syncope. We summarize current evidence on IA pathogenesis, epidemiology, differential diagnosis, and management. Although antihistamines and corticosteroids are commonly used prophylactically, emerging data suggest that anti-IgE therapy with omalizumab may offer benefit in refractory cases. Diagnostic workup should include serum tryptase measurement, trigger identification, and consideration of underlying mast cell disorders. Future research is needed to clarify the natural history, standardize diagnostic pathways, and evaluate long-term treatment strategies for this heterogeneous condition.
Gupta S, Shah B, Fung CS, Chan PK, Wakefield DL, et al.
Frontiers in bioengineering and biotechnology •
Since 2015 more than 34 biosimilars have been approved by the FDA. This new era of biosimilar competition has stimulated renewed technology development focused on therapeutic protein or biologic manufacturing. One challenge in biosimilar development is the genetic differences in the host cell lines used to manufacture the biologics. For example, many biologics approved between 1994 and 2011 were expressed in murine NS0 and SP2/0 cell lines. Chinese Hamster ovary (CHO) cells, however, have since become the preferred hosts for production due to their increased productivity, ease of use, and stability. Differences between murine and hamster glycosylation have been identified in biologics produced using murine and CHO cells. In the case of monoclonal antibodies (mAbs), glycan structure can significantly affect critical antibody effector function, binding activity, stability, efficacy, and half-life. In an attempt to leverage the intrinsic advantages of the CHO expression system and match the reference biologic murine glycosylation, we engineered a CHO cell expressing an antibody that was originally produced in a murine cell line to produce murine-like glycans. Specifically, we overexpressed cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) and N-acetyllactosaminide alpha-1,3-galactosyltransferase (GGTA) to obtain glycans with N-glycolylneuraminic acid (Neu5Gc) and galactose-α-1,3-galactose (alpha gal). The resulting CHO cells were shown to produce mAbs with murine glycans, and they were then analyzed by the spectrum of analytical methods typically used to demonstrate analytical similarity as a part of demonstrating biosimilarity. This included high-resolution mass spectrometry, biochemical, as well as cell-based assays. Through selection and optimization in fed-batch cultures, two CHO cell clones were identified with similar growth and productivity criteria to the original cell line. They maintained stable production for 65 population doubling times while matching the glycosylation profile and function of the reference product expressed in murine cells. This study demonstrates the feasibility of engineering CHO cells to express mAbs with murine glycans to facilitate the development of biosimilars that are highly similar to marketed reference products expressed in murine cells. Furthermore, this technology can potentially reduce the residual uncertainty regarding biosimilarity, resulting in a higher probability of regulatory approval and potentially reduced costs and time in development.
