Analytical Method Validation for Biotechnology Proteins, Peptides, and Antibodies -

Analytical Method Validation for Biotechnology Proteins, Peptides, and Antibodies

Jul 1, 2009
By: Michael Swartz, Ira Krull
LCGC North America

In the vast majority of previous "Validation Viewpoint" columns, we have emphasized low molecular weight (MW), conventional, synthetic, single molecule (or enantiomers) pharmaceuticals. At times, we also have devoted columns more toward biotechnology-derived products or impurities, also known as biopharmaceuticals (1–4). In one particular column installment, we discussed validation in biotechnology and well-characterized biopharmaceutical products (2), and that column should really be consulted for additional information, perhaps before the current one. Given that more and more pharmaceuticals are being derived from recombinant biotechnology proteins, especially glycoproteins, an especially difficult class of molecules to characterize fully, it would seem that guidelines and directives for true (complete) method validation of biopharmaceuticals must be forthcoming (13–14). At the moment, that which is available through ICH or FDA do not appear equivalent to the existing guidelines for synthetic, low MW pharmaceuticals (15–17). The question will then become: Why do proteins deserve a different treatment than what is now available?

Michael Swartz

We must, at the outset, indicate that characterization methods are used to characterize the drug substance product. And, that data generated by such methods are then used in regulatory filings. Typically, such assays are performed on state-of-the-art, expensive instrumentation and equipment, usually by highly trained and experienced scientists, often at the Ph.D level, within the research and development laboratories of a biotechnology firm. Such characterization studies usually are done once, perhaps twice, in the lifecycle of the final product.

Ira S. Krull

As contrasted with drug substance characterization methods, other studies are required, such as impurity profiles, stability, dissolution, storage conditions, and numerous others, to make disposition decisions regarding final release of the drug product. Typically, much simpler (usually analytical) methods are performed on "commercially available" instrumentation in quality control (QC) laboratories, and usually by B.S. level personnel. Some of the following discussion addresses release–stability methods and should not be applied to characterization methods. There do not appear to be any final regulatory guidelines that address total characterization methods. Complete analytical characterization of (often) a complex mixture of species in the final, drug substance is often impossible, even given today's state-of-the-art instrumentation and methodologies (13,14). However, recently, regulators have started to discuss qualification and validation of such methods, but nothing concrete has yet appeared in the relevant literature (International Conference on Harmonization [ICH] or U.S. Food and Drug Administration [FDA]). The biopharmaceutical industry, FDA (and other regulatory agencies around the world), and ICH have long recognized the often extremely complex nature of glycoprotein biopharmaceuticals and the difficulties inherent in their complete structural characterization. This may not change in the near future (18).

Guidelines are not requirements, but just suggestions, often made by regulatory agencies, and are always open to interpretation by the filing company. Such guidelines also are independent of the type of analytical technique or the drug substance and related drug product substances. In the biologics area of FDA (Center for Biological Evaluations and Research, CBER), which is usually where biotechnology products fall, it has become accepted practice that the process of manufacture defines the product. If the drug substance is made the same way each and every time, then it is considered by the FDA to be the very same material.

And, revalidation or recharacterization of subsequent batches is not required or desired. However, if the process is altered, it also is assumed that the product is no longer the same as before. It is likely and desirable that, in the future, more advanced characterization techniques, may lead to complete (rather than "well") characterization of complex protein products. That would help move the industry away from the current process definition of what characterizes the drug substance (namely, the process remaining the same over time).

One final subject before we actually start to discuss existing guidelines for analytical method validation of biotech products, and that has to do with something FDA calls biologics licensing application (BLA), which is not the same as an investigational new drug (IND) application to FDA. INDs are used for small molecule, low molecular weight (MW) drug substances, but BLAs are used for biotechnology products, in most cases, though some biotech products (for example, insulin) are so simple that they used INDs. As it now seems that most biotech products of the future will be considerably more complex than insulin, we would expect that the use of BLAs will remain for quite some time, within CBER/FDA. Usually, after extensive clinical testing is completed successfully, a New Drug Application (NDA) must be filed before marketability with the FDA. For biogenerics or follow-on biologics, being introduced by a generics firm, an Abbreviated New Drug Application (ANDA) must be filed, often without extensive clinical or biological testing, if true and complete chemical equivalency can be demonstrated fully and satisfactorily. This is often a tricky matter.

12 3 4 5 6