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Health Sciences Authority

Common questions related to Biosimilars

Questions and answers relating to biosimilar registration in Singapore.

Last updated 13 March 2026
Why are some brands of trastuzumab intravenous formulation labelled as 440 mg per vial whereas some as 420 mg per vial? Are there any differences in the strength of the solution after reconstitution?

440 mg per vial refers to the nominal vial content whereas 420 mg per vial refers to the actual withdrawable amount when reconstituted in accordance with the directions in the approved package inserts. There is no difference after reconstitution, which yields a solution containing 21 mg/ml of trastuzumab.

Why might comparative clinical efficacy studies not be necessary for the approval of certain biosimilars of well-characterised biologic drugs under current scientific and regulatory considerations?

Health Sciences Authority (HSA) has updated its regulatory guidance* for biosimilar products to reflect current scientific considerations where clinical comparability data to innovator reference biologic products may not be required. Specifically, this approach may be considered for certain well-characterised biosimilars with the advancements in analytical technologies and prior knowledge gained over more than 10 years of regulatory developments. One key consideration is the extensive characterisation and analytical data available for these biosimilars. This data can demonstrate that the biosimilar is highly similar to the reference product in terms of structure, function, and purity, which can be sufficient to establish biosimilarity without the need for additional clinical comparability studies.

Secondly, comparative pharmacokinetic/pharmacodynamic (PK/PD) endpoints are validated surrogates to demonstrate clinical comparability in terms of efficacy and safety where PK/PD properties are well established and correlate with clinical outcomes.

Thus, the totality of evidence based on comprehensive analytical and non-clinical comparability data along with well-established PK/PD profiles, is carefully assessed to determine therapeutic comparability. In such cases, additional clinical trials may not provide significant additional value in assessing the efficacy and safety. This approach is expected to enhance efficiency in drug development, potentially accelerating patient access to affordable therapies while maintaining high standards of safety and efficacy.

*Guidance on therapeutic product registration in Singapore, Chapter E, Section 21.4.2