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Chapter 1: Bioseperations
I. Introduction
The biotechnology industry has evolved significantly since the introduction in 1982 of human insulin synthesized in Escherichia coli-the first Food and Drug Administration (FDA)-approved recombinant therapeutic agent in the United States. Since then, over 75 other recombinant proteins have been introduced. The list is comprised of cytokines, hormones, monoclonal antibodies, and vaccines. There are more than 1100 companies competing for this market, and the current sale of these products comprises approximately 10% of the sales of all therapeutic products sold in the United States. One such product, erythropoietin, an erythropoiesis-stimulating factor also known as Epogen, is a circulating glycoprotein that stimulates red blood cell formation in higher organisms and has worldwide sales in excess of 1 billion U.S. dollars. The financial potential of these products is indeed great. This is apparent from the fact that over 500 biotechnology-related drugs are currently in clinical trials. Bioseparations, or separations of biological interest, have played a significant role in the development and growth of the biotechnology industry. These separations have to be performed on both analytical and industrial scales-and everything in between.
Bioseparations frequently entail separations of proteins and related materials from biological matrices.' This book is planned to serve as a handbook of bioseparations, where the primary focus is separations of proteins; however, separations of other materials of interest such as nucleic acids and oligonucleotides are also covered to assist the reader in tackling their particular bioseparation problems. Included in this text is a chapter on the separation of monoclonal antibodies, as these materials have found numerous uses in the biopharmaceutical industry. As a matter of fact, in the last few decades, monoclonal antibodies and recombinant antibodies have become one of the largest classes of proteins that have received FDA approval as therapeutics and diagnostics.
A. Regulatory Considerations
The regulatory considerations applying to bioseparations are covered in various sections of this book. It is important to assure that separation and purification methods, when operating within the established limits, produce a product of appropriate and consistent quality. The method and process validations provide assurance that product quality is derived from a careful consideration of various factors such as process design, selection, and control of the process through appropriate in-process and end-process testing! Validation studies should be performed through each of the three phases of a product's life span: development, pilot scale, and end-process testing. In addition to validated testing methods and standards, the FDA requires a thorough validation program, quality assurance (QA) oversight, statistically sound sampling methods, rigorous training, and a comprehensive documentation trail.
Undeniably, biopharmaceuticals should be safe and effective. This must be demonstrated by effectively planned studies as well as documentation to the satisfaction of regulatory agencies. The young age of this industry is demonstrated by the fact that in 1985, the FDA issued a document entitled "Points to Consider in the Production and Testing of New Drugs and Biologicals Produced by Recombinant DNA Technology." In 1997 a similar document was issued for monoclonal antibodies. Also in 1997, the Center for Biologics Evaluation and Research (CBER) issued guidance on the preparation of a Biologics License Application (BLA). For the first time, manufacturers can file a BLA instead of an Establishment License Application (ELA) and a Product License Application (PLA). The BLA brings the drug and biotechnology therapeutics registration process closer together.
The CBER was established in 1987 as a spin-off of the FDA's Center for' Drugs and Biologics in response to a growing number of applications for new biotechnology products. "Guidelines," "Guidance," "Points to Consider," and other documents are available from CBER (Office of Training and Manufacturers Assistance, HFM-40, Rockville, MD, 20852. Information can be obtained by telephone at 800-835-4709 or by fax at 301-827-3844). It is important to keep current with the latest regulations. Generally, this information can be obtained from the FDA Web site.
A joint regulatory-industry initiative was taken to provide international harmonization of the drug approval process. The guidelines recommended by the International Conference on Harmonization (ICH) address quality, safety, and efficacy. The ICH issued draft guidelines on analytical validation procedures in 1996 and a document entitled "Draft Consensus Guidelines and Specifications: Test Procedures and Acceptance Criteria for Biotechnological/ Biological Products" in 1998. Further information relating to ICH can be found at the Web site ifpma.org of the International Federation of Pharmaceutical Manufacturers Association.
The contents of this book have been broadly classified into three sections:
- Analytical methodologies
- Separation and purification methods
- Other important considerations
The analytical methodology section covers a variety of methodologies that are commonly used in bioseparations. The section on separation and purification methods covers a broad range of methods, including process-scale separations. Plant and process equipment, engineering process control of bioseparation processes, economic considerations, and future developments are discussed under the heading of other important considerations-those elements that are sometimes forgotten but should never be ignored when one is dealing with bioseparations. Processing plants and equipment are discussed in this book to assist the scientist or engineer in selecting a method of bioseparation that will be suited to the particular requirements of the process and the product at a commercial scale of operation. A chapter on economics of bioseparations has been included to help evaluate cost considerations prior to the initiation of any project. Finally, the chapter on future developments attempts to provide some insight into what is coming down the pike in the field of bioseparations, a field that is continually evolving and thus defies any fixed descriptive definitions.
II. Analytical Methodologies
The purity analysis of a recombinant produced product is difficult because the accuracy of protein purity is method-dependent and is influenced by the shortcomings of the analytical procedures (Chapter 2). Proteins are highly complex molecules; therefore, it is generally very desirable to utilize more than one method to define a given protein's purity.
