Biosimilars: what does a primary care clinician need to know?

Biosimilars are biological medicines that are developed to be comparable versions of an existing, approved, biological medicine once patent protection on the original has expired. Worldwide, biosimilar medicines are available for the treatment of cancer, diabetes and diseases with an inflammatory or immune component, such as rheumatoid arthritis and inflammatory bowel disease. In New Zealand, two biosimilar medicines are currently approved and subsidised: Zarzio (filgrastim, for neutropenia) and Omnitrope (recombinant human growth hormone); more biosimilars are likely become available as patents expire in the next few years.

Key points for primary care clinicians:

• Biosimilars are not just generic versions of a biological medicine; manufacturing and analysis complexities mean that biosimilars cannot be made, or cannot be demonstrated to be, exactly the same as an existing biological medicine. In comparison, generic medicines can be synthesised to be identical to the original patented pharmaceutical.
• The same degree of clinical benefit is expected to be achieved with a biosimilar as with the original biological medicine
• When a biosimilar medicine is subsidised in New Zealand, whether the original biological medicine will continue to be funded will vary on a case by case basis; the innovator versions of Zarzio and Omnitrope are no longer subsidised
• Decisions regarding switching a patient from a biologic to a biosimilar are likely to be managed in secondary care, but primary care clinicians may help to monitor treatment response and adverse effects
• A patient could have adverse effects, including immune reactions, with a biosimilar that they did not experience while using the original biologic, or vice versa, or from different batches of a biologic or biosimilar medicine
• If a patient develops an adverse reaction after initiating or switching to a biosimilar medicine, the clinician managing the patient’s care should be advised and an adverse drug reaction report submitted to the Centre for Adverse Reactions Monitoring (CARM)

For further information, see: “Biosimilars - what does a primary care clinician need to know?”, BPJ 71 (Oct, 2015).