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Biosimilars: Advancing Science to Help Improve Patient Access to Medicines

Image: A computer illustration of the production of monoclonal antibodies, a type of biosimilar drug that is used to treat cancer, autoimmune diseases and other conditions. Getty RF

Biologics are among the most powerful drugs to treat cancer and autoimmune diseases today. Made from living organisms, such as bacteria or yeast, these therapies can specifically target cells or stimulate the immune system to fight tumors or inflammation. In cancer, they’re often used in combination with other treatments, such as chemotherapy.

But these transformative medicines can be quite costly. As many patents for biologics have expired, or will do so in the near future, biosimilar medicines may help lower costs and deliver efficiencies to the healthcare system, which ultimately may help more patients receive the best possible care. As their name suggests, biosimilars are highly similar versions of a biologic drug, commonly referred to as the innovator or reference product.

Since biosimilars are based on an already-approved product, their path to authorization can be quicker. To be approved by the FDA, a biosimilar manufacturer must demonstrate that its candidate has “no clinically meaningful differences in terms of safety and efficacy” from the reference product. This is done through rigorous research and clinical testing. “There’s a lot of work that goes into designing a biosimilar program to efficiently show that it has exactly the same performance as the innovator,” says Martin Summers, Medicine Team Leader for biosimilars based at Pfizer’s La Jolla, Calif. research site.

Pfizer has more than 12 years of experience in producing biosimilars with nine biosimilars that have received regulatory approval in major markets, including six for the treatment of cancer or cancer-supportive care and three for autoimmune conditions, such as rheumatoid arthritis and ulcerative colitis.

Pfizer has several monoclonal antibody (mAb) biosimilars within its portfolio. These therapies are based on antibodies, the defense proteins produced by our immune cells, but developed in a lab and mass produced in manufacturing facilities. One type of mAb binds to cancer cells, helping the immune system recognize and destroy the diseased cell.

Using science to show similarity

Common small molecule medicines, such as aspirin or statins, are made by combining chemicals as building blocks. They’re relatively simple in structure and can be easily reproduced into lower-cost generic drugs. Biologic drugs, on the other hand, have highly complex protein structures, with each molecule containing up to tens of thousands of atoms. These medicines can only be produced by living cells, such as mammalian cells or bacteria. Because of this complexity, it’s impossible to make an exact copy. This is where the challenge of developing biosimilars comes into play.

In order to be approved as a biosimilar, the FDA requires the biosimilar manufacturer to carefully examine the structure and function of both the proposed biosimilar and the reference product, which serves as the foundation for the biosimilar development program.

Using state-of-the-art technology, the products are analyzed for key quality criteria, such as purity, chemical identity and bioactivity. And because the originator product can have some variability between molecules and different batches—with no impact on the performance of the product—manufacturers must examine multiple batches to capture this range of variability. “And then for each and every one of these quality criteria, we can ensure our own biosimilar doesn’t fall outside any of these ranges, providing confidence in ‘sameness,’” says Summers.

Once multiple batches of originator and potential biosimilar have been analyzed, and demonstrated to be similar by these laboratory tests, then and only then is the biosimilar introduced to the clinic for human trials. “Ironically the biosimilar will usually have been through more extensive laboratory testing at this stage than the originator molecule itself,” says Summers.

And with these recent advances in developing biosimilars, patients could ultimately benefit with increased access to these essential medicines.