Dr. Dan Mamelak is founder and president of contract testing lab Custom Biologics, a Health Canada audited GLP/GMP-compliant, global service provider for functional testing and characterization of biomolecules. Dan has a background in microbiology, immunology and protein biochemistry and over 20 years’ experience in developing and validating reliable and reproducible cell-based bioassays to measure the functional properties of biotherapeutics.
DM: I grew up in Toronto, Canada and did my thesis work at the University of Toronto. Following this I joined a startup biotech company called Integrative Proteomics which later became Affinium Pharmaceuticals. This was an amazing experience to work at a startup biotech in my hometown! I really like the idea of an entrepreneurial environment where scientists with different backgrounds work together to develop scientific solutions for drug development. At the time, Toronto did not have a large molecule CRO and so I thought, why not start something and see how it goes! That was 18 years ago and so far, things are going great.
DM: A lot of this work has been done in collaboration with the scientific team at BioPharmaSpec. In these cases, we have worked together to provide structural and functional characterization studies of clients’ biotherapeutics. The advantage of working together for a specific client is that the results of the structural analysis, for example glycosylation of disulfide bridging patterns, can be considered when we analyze the results of the functional / bioactivity studies at Custom Biologics. It is very rewarding when a direct correlation is shown between structural features of a biotherapeutic and its biological activity.
A correlation between reduced potency and incorrect disulfide bridging in Enbrel® samples (Sandoz, 2017)
DM: Yes, there are in fact suites of functional assays for mAbs of different isotypes. For example, IgG1 mAbs, the most common, are typically evaluated for their ability to induce antibody dependent cellular cytotoxicity (ADCC), as well as complement dependent cytotoxicity (CDC). Moreover, the ability of this class of mAbs to bind Fc receptors is also routinely measured.
Unique to each mAbs and or non-mAb is its mechanism of action, which is often characterized by its ability to induce a cytotoxic or anti proliferative effect on a target cell. But this is a broad generalization since many mAbs and non-mAbs are now designed to bind certain cellular receptors and turn on or off signals that modulate the immune response. Therefore, these biotherapeutics are not necessarily killing a target cell but rather tricking it into acting a certain way. In all cases, sophisticated and sometimes very complex cell-based assays need to be developed to measure the bioactivity of a mAb or non-mAb.
These assays are often complemented with assays that measure the relative levels of cytokines and other immune modulators. In many instances now, we are seeing bioassays that consists of two parts: Part a) treat the cells with the mAb or non-mAb and Part b) measure the immune-response.
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