First interchangeable insulin biosimilar gains preferred status on one of the largest national formularies in the US.

Oncology drugs are no longer immune to pharmacy benefit management formulary exclusions in the commercial market and even drugs administered in a physician’s office are increasingly being subjected to rebate-driven coverage decisions.

The number of drugs included on formulary exclusion lists in the US has surpassed more than 400 at the top three PBMs, representing dramatic growth from just five years ago. Express Scripts recently revealed its 2022 exclusions.

US FDA’s first decision on biosimilars interchangeability might have less meaning for two insulin products, but payer and prescriber responses to interchangeable biosimilars for adalimumab, which are further out on the horizon, may be more instructive regarding the importance of interchangeability status.