The FDA has not yet declared any biosimilar interchangeable with its brand-name biologic originator. But if a biologic is deemed interchangeable, pharmacists will be allowed to substitute it for the brand-name biologic without consulting a prescribing physician.

That could hasten market uptake of biosimilars, increasing cost savings, Dr Alexander said.

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But Dr Schilsky voiced concern.

“ASCO’s strongly held position is that physicians and patients should have the ability to select evidence-based treatment options — including the specific biologic product — most appropriate for treatment of a particular patient,” he said.

“As such, physicians should have the authority to designate use of a biologic product with ‘Dispense as Written’ instructions. Physicians should be notified prior to substitution of a deemed interchangeable biologic for a reference product.”

Prescribing physicians believe post-marketing surveillance will be vital for the adoption of biosimilars. 

“Given the limited clinical evidence of efficacy and safety required for a product to be approved as a biosimilar, ASCO applauds the FDA for the inclusion of the post-marketing safety monitoring considerations in their draft guidance on interchangeability,” Dr Schilsky told Cancer Therapy Advisor.

“Meaningful post-marketing surveillance is essential as more biosimilars enter the market. The adoption of biosimilars by patients and physicians will depend upon the monitoring of these products for safety, efficacy, and for a demonstration that there are no meaningful clinical differences.”


  1. Considerations in demonstrating interchangeability with a reference product; draft guidance for industry; availability. Federal Registry website. Published February 18, 2017. Accessed June 2017.