The protein therapeutic market is valued at $99 billion and is the fastest growing segment of the $600 billion pharmaceutical industry. Nearly half of all approved biopharmaceuticals are post-translationally modified by glycosylation [1]. Glycosylation influences protein solubility, serum half-life, immunogenicity and/or biological activity. Animal cell lines are primarily used for the production of therapeutic glycoproteins, due to their ability to generate products with therapeutically acceptable glycoprofiles. However, animal cell lines have limitations including high production costs, reduced safety, and heterogeneity of glycoforms [2,3]. Glycoform heterogeneity can be found both in the site occupancy of the glycan and the structure of the attached glycan;and is influenced by cell culture parameters such as age, pH, nutrient levels, and temperature [4]. Thus, a major challenge for the production of therapeutic glycoproteins from animal cell lines is glycoprofile consistency, and/or the purification of a desirable glycoform from a heterogeneous mixture [2]. Furthermore, an estimated $26 billion worth of biologics will lose patent protection by 2016, creating significant market opportunities for price-competitive biosimilars [5]. In light of these challenges and predicted market pressures, significant research is ongoing to develop alternative expression platforms for therapeutic glycoproteins with acceptable glycoprofiles. Triton Algae Innovations, Inc. (Triton) is developing a recombinant protein production platform utilizing a photosynthetic singled-celled green alga, Chlamydomonas reinhardtii. There are several advantages to using green microalgae as an expression platform for protein therapeutics: cost, safety, scalability, productivity, ease of genetic manipulation, and ability to produce complex eukaryotic proteins. We have proven the value of this platform with the production of an aglycosylated mammalian protein [6] that will be commercially available next year. Despite these attributes and validation, several questions need to be addressed as the system develops into a bio-manufacturing platform, especially the glycosylation profile of recombinantly expressed human therapeutic proteins. Triton will use a well-characterized and therapeutically valuable protein, human erythropoietin (EPO), to better understand glycan structures attached to recombinant glycoproteins produced by C. reinhardtii.
Nearly half of all approved protein therapeutics are glycosylated. Due to limitations associated with the production of recombinant glycoproteins from animal cell lines, the development of an alternative bio-manufacturing platform is warranted. This application seeks to evaluate the use of microalgae as a platform for the production of glycosylated human bio-pharmaceuticals.
