Glycosylation profiles of therapeutic antibody pharmaceuticals.

Recombinant antibodies specific for human targets are often used as therapeutics and represent a major class of drug products. Their therapeutic efficacy depends on the formation of antibody complexes resulting in the elimination of a target molecule or the modulation of specific signalling pathways. The physiological effects of antibody therapeutics are known to depend on the structural characteristics of the antibody molecule, specifically on the glycosylation which is the result of posttranslational modifications. Hence, production of therapeutic antibodies with a defined and consistent glycoform profile is needed which still remains a considerable challenge to the biopharmaceutical industry. To provide an insight into the industries capability to control their manufacturing process and to provide antibodies of highest quality, we conducted a market surveillance study and compared major oligosaccharide profiles of a number of monoclonal antibody pharmaceuticals sampled on the Swiss market. Product lot-to-lot variability was found to be generally low, suggesting that a majority of manufacturers have implemented high quality standards in their production processes. However, proportions of G0, G1 and G2 core-fucosylated chains derived from different products varied considerably and showed a bias towards the immature agalactosidated G0 form. Interestingly, differences in glycosylation caused by the production cell type seem to be of less importance compared with process related parameters such as cell growth.

Use of substances of animal origin in pharmaceutics and compliance with the TSE-risk guideline -- a market survey.

The risk of infection with transmissible spongiform encephalopathy (TSE) from the use of animal-derived substances in drug manufacturing was assessed [Swissmedic. TSE guideline to the ordinance. 2001; http://www.swissmedic.ch/files/pdf/Anleitung_TSE.pdf; The European Directorate for the Quality of Medicines. Minimising the risk of transmitting animal spongiform encephalopathy agents via medicinal products. In: European Pharmacopoeia 2002; General chapter 5.2.8. http://www.pheur.org/medias/download/50208E.pdf]. In addition, the compliance of the Swiss Market Authorisation holders to implement the Swissmedic TSE guidelines was examined. To assess the compliance with the TSE guideline for products on the Swiss market a representative number of drugs were selected based on a statistical approach. The documents for the biological, anatomical and geographical origin of the animal substances used for drug manufacturing as well as for the manufacturing processes were requested to be provided within a short response period and were subsequently reviewed. A total of 438 drugs with 655 substances of animal origin were assessed during the survey. The documentation provided by the Market Authorisation holders showed, that in general the measures described in the TSE guidelines were implemented well. Therefore, the risk of these pharmaceutics to transmit TSE was considered minimized. However, the TSE documentation provided by drug companies was incomplete for approximately two-third of the drugs at the beginning of the survey. In particular for those containing excipients such as tallow derivatives or gelatine, numerous clarifications were needed prior assessment. The efforts of the drug companies to correspond to regulatory actions and to implement authoritative guidelines should be improved.

Unrestricted lineage differentiation of parthenogenetic ES cells.

The developmental potential of parthenogenetic embryonic stem (P-ES) cells was studied in teratomas and mouse chimaeras. Teratomas derived from P-ES cells contained a mixture of tissue types with variable proportions of specific tissues. Three of the eight P-ES cell lines analysed showed high proportions of striated muscle in teratomas, similar to teratomas from normal embryos or ES cell lines derived from fertilised embryos (F-ES cells). Our study also revealed that one P-ES cell line showed little lineage restriction in injection chimaeras. Descendants of the P-ES cells contributed to most tissues of chimaeric fetuses in patterns similar to F-ES cells. Normal colonisation of muscle, liver and pancreas was found in adult chimaeras. P-ES cells also showed similar haematopoietic differentiation and maturation as F-ES cells. However, extensive P-ES cell contribution was associated with a reduction in body size. These findings suggest that, while P-ES cells display more extensive developmental potential than the cells of parthenogenetic embryos from which they were derived, they only retained properties related to the presence of the maternal genome. To elucidate the molecular basis for the lack of lineage restriction during in vivo differentiation, the expression of four imprinted genes, H19, Igf2r, Igf2 and Snrpn was compared among five P-ES and two F-ES cell lines. Expression levels of these genes varied among the different ES cell lines, both in undifferentiated ES cells and in embryoid bodies.