What are biosimilars?

FDA definition: A biological product that is approved based on showing that it is highly similar to an FDA-approved biological product, known as the reference product, and has no clinically meaningful differences in terms of safety and effectiveness from the reference product.

Biologics have high molecular complexity and may be sensitive to minor changes in the manufacturing process. Compared to generics, which has no clinical trial requirements, biosimilars do have to go through an abbreviated process with at least one clinical study. Biosimilars might not include all indications and the cost of development is way more expensive.


Why do we need biosimilars?

  • Reduces the cost for patients
  • Saves cost for the health care system
  • Increases global access to effective biologics
  • Prevents monopolization by pharmaceutical companies


Requirements for Registration of Biosimilars Products

The Department of Health has endorsed a new set of guidelines for registration of biosimilar products which effective from 1 January 2016.

According to the Pharmacy and Poisons Regulations, all pharmaceutical products must satisfy the criteria of safety, quality, and efficacy before they can be registered with the Pharmacy and Poisons Board and be sold in Hong Kong. However, biological products often have complex molecular structures and therefore the copy of the products cannot be exactly the same as the originator product due to their different manufacturing processes. The copy products cannot be considered as identical, so they are referred as ‘biosimilar’.

Disclaimer in the guidelines:

As biosimilar product is similar but not identical to the reference product, approval for registration of a biosimilar product does not imply bioequivalence or clinical equivalence between the biosimilar and reference products. The Department of Health does not endorse the substitution of reference product with biosimilar product. Healthcare professionals should exercise their own judgment and inform their patients if necessary regarding the risk of substitution of reference product with biosimilar product.



1. Potential immunogenicity
Biologics may have a higher chance of causing immune response due to their large molecular size and complex structure. “Immunogenicity” refers to a drug that causes an immune response in the body, such as allergic symptoms, including rash, itching, and shortness of breath. In general, it is not a common situation, but it can be life-threatening in certain cases.

According to Department of Health guidelines:

Immunogenicity of the biosimilar product should always be investigated in humans before the biosimilar product can be approved for registration.


2. Interchangeability

Although the reference product and biosimilar are highly similar, however, the similarity between agents cannot translate to interchangeability. There have been numerous debates about the interchangeability of biosimilars and reference products based on concerns of immunogenicity by switching between biological products, which may cause lack of effect and toxicity.

Therefore, healthcare professional should exercise professional judgment and patient’s agreement is needed before substituting the reference product with biosimilar.


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