Making Beterseron

09/23/94

Research is only the first step in the development of new therapeutic agents. To convert scientific research into widely available products, companies must move from the research setting to commercial scale production. For production of the most complicated molecules, this step can often limit or delay the widespread availability of new products.

Nowhere in pharmaceutical manufacturing has this proven more challenging than for the production of complex and sophisticated compounds created through the recombinant DNA techniques of Genetic engineering.

More akin to cultivation than traditional pharmaceutical production, the recombinant drug manufacturing process turns bacteria into tiny biological factories. These bacteria, known as altered Escherichia coli (E. coli), are organisms that require special care.

To make commercial quantities of a recombinant DNA product recombinant E. coli are modified by inserting the Gene needed for production of the desired protein. The bacteria continue to survive and reproduce themselves and in doing so, produce the desired protein.

For commercial quantities, large volumes of these Genetically identical (modified) bacteria must be produced in very carefully controlled conditions.

Chiron Corporation uses this process to produce Betaseron(R) (Interferon beta-1b) for SC Injection, a drug recently licensed for use in ambulatory patients with Relapsing/Remitting Multiple Sclerosis (MS) to reduce the frequency of exacerbations.

In developing Betaseron(R), scientists isolated the specific Human Gene that naturally produces the Protein, Interferon beta. Then in a sophisticated laboratory process, scientists manipulated the Gene in such a way that it would produce a more stable Protein.

This process substituted a Serine residue at the 17th position in the Protein's Amino Acid chain. The result was a Protein that retained the biological structure similar to natural Human Interferon beta, but had improved stability.

The Manufacturing Process

The first major step in producing commercial quantities of Betaseron(R) is known as Fermentation. During fermentation, a small volume of Genetically manipulated cells are placed into a large volume of growth media.

It is during this time that the bacteria grows and produces the necessary proteins. This occurs in a large scale fermentation vessel.

The bacteria are allowed to reproduce until they have multiplied about 20 times their original population. The bacteria are then "turned on" by chemical induction, a process that can be likened to a chemical light switch.

This "turn on" allows the bacteria to start producing the Interferon beta and the cell population is doubled again; fermentation concludes with a population about 40 times its original size.

Separation of the Interferon protein from other cellular materials is the next step in the manufacturing process. To do this, the entire fermentation batch is homogenized in a process similar to blending a milkshake.

The majority of the cell debris is then removed from the Interferon by centrifugation, which leaves a liquid portion containing the Interferon.

Further centrifugation allows the solution to be separated by weight into different layers of proteins; as a result, Interferon can be separated from many of the non-Interferon proteins produced by the E. coli.

The relatively pure Interferon is then concentrated in preparation for a second separation.

Further Purification

A second separation removes any remaining Proteins from the Interferon. This process, called size exclusion chromatography, produces an ultra-pure, highly potent Protein. To prepare Interferon beta for use in the clinic, the protein is then formulated and stabilized.

Stability is established by stopping the Protein's chemical changes through addition of specific ingredients. If this preventive step were not taken the Protein could fall apart, or change its form, leaving a Protein that would not act like Interferon when it was administered to a patient.

Human Serum Albumin, a naturally occurring Protein used commonly in medicine and Dextrose, a highly purified sugar, are added during the formulation of Betaseron(R) (Interferon beta-lb) for SC Injection.

The stabilized Betaseron(R) is then put into vials under strictly sterile conditions. Once in the vials, the liquid is freeze-dried to remove the water; this step further stabilizes the Protein, allowing for extended and convenient storage.

Before Betaseron(R) can be used by a patient, it must be reconstituted with a special Saline Solution designed to mimic the body's natural Salt balance. This reconstitution allows the Protein formulation to return to its liquid state and facilitates absorption of the Interferon by the Human body.

Manufacturing Improvements

While supplies of Betaseron(R) (Interferon beta-1b) for SC Injection were limited when the product first became available, Berlex Laboratories, the developer and marketer of the product, has been able to offer Betaseron(R) to all patients currently registered on its access list to receive therapy.

As a result of intensive efforts on the part of Chiron Corporation, Berlex's manufacturing partner for Betaseron(R), new equipment and expanded facilities for the production of this product are now in place.

Most significantly, Chiron will be producing Betaseron(R) in a new, smaller vial. While the product formulation and dosage remains unchanged, this smaller-sized vial allows more vials to be processed simultaneously, thus accelerating the manufacturing process.

Quality Assurance

At each and every stage of the production process, the product must meet stringent specifications. If, for any reason, these specifications are not met that particular batch must be discarded. This is a time-consuming, but essential safeguard to ensure the products safety and efficacy.

CONTACT:

CO: Berlex Laboratories;
Chiron Corporation
ST: New Jersey
IN: MTC SU:
9/23/94