Explosive growth in the area of therapeutic antibodies in recent years has stimulated new demand for improved production and manufacturing techniques. Traditionally, antibodies are produced in mammalian cells, a time- and labor-intensive process. This step immediately opens into a true bottleneck—the purification process, which typically involves at least three chromatography steps. In addition, antibodies present new challenges for analysis, characterization, and storage.
At several recent bioindustry conferences, novel technologies streamlining the manufacturing process for new biologics were discussed.
One of the most important advances in antibody production is the effort to adapt microorganisms to produce them. Since the 1980s, there have been many unsuccessful efforts to produce antibodies in yeast. Alder Biopharmaceuticals (www.alderbio.com) has implemented a plug-and-play yeast expression system that uses two proprietary vectors. When the desired nucleic acid sequence is inserted into the expression vector, the system will produce antibody at a rate of 300–1,000 mg per liter, according to the company. Per-unit time, the yeast system represents a three- to fivefold advantage over mammalian systems, which take from 12 to 20 days per cycle.
Alder has produced up to 2,000 L from a single batch, and in the hands of others the system has reportedly been ramped up to 50,000–100,000 L.
Nonmammalian antibody production comes with drawbacks. Yeast produces different carbohydrates than a mammalian cell. Some mammalian-produced antibodies are designed to take advantage of the glycosylation for the antibody dependent cell-mediated cytotoxicity or complement dependent cytotoxicity mechanism. The Alder system is incompatible with antibodies designed to use this mechanism. Instead, the engineered process results in antibodies that do not need to be glycosylated to attack their targets. Newer-generation antibody therapeutics are getting away from carbohydrate-dependent mechanisms due to side effects.
“We have a list of good targets to work on for our methodology,” said John Latham, Ph.D., CSO of Alder, who spoke in a session on microbial hosts for antibody production at BIO’s annual conference in May. “Alder provides antibody production services for corporate partners, and also has its own therapeutic pipeline, with its first product entering clinical trials in the fall of 2007 and an anti-TNF program in development for 2008.”
TNO Quality of Life (www.tno.nl) is another organization developing microbial antibody production. Peter Punt, Ph.D., project leader in the microbiology department, described filamentous fungi as “champions” in protein production, producing up to tens of grams per liter of protein. The fungi have been developed as an antibody production platform by TNO.
TNO, which is neither a public nor a private entity, was established by an act of law in the Netherlands to support the industrial needs of Dutch companies primarily, worldwide companies with Dutch interests secondarily, and all other companies on a discretionary basis. Its development of protein-production systems began with chymosin, integral for cheesemaking. Based on the company’s results with chymosin, it expanded into more specialized proteins such as interleukins and plasminogen activator. According to Dr. Punt, the output of the fungi is far superior to typical mammalian (CHO cell) systems.
Filamentous fungi also have some unique obstacles. They produce a lot of protease, so much of the TNO development effort has been directed toward preventing proteolytic degradation. Current applications of the filamentous fungi system include not only pharma and biotech, but hydrolytic enzymes for bioenergy.
“This is not only in Europe and the U.S. Developing countries are now entering into that area because of the enormous interest in bioenergy,” said Dr. Punt. Future directions for TNO include systems biology and metabolomics. “We recently merged with another department where process design and engineering design is the stronghold. We also think we can combine systems biology with process design.”