In another step that blurs the distinction between biosimilars and interchangeables, the U.S. Centers for Medicare & Medicaid Services (CMS) is proposing a rule to give Medicare Part D plans more flexibility to substitute biosimilars for the reference biologics so Medicare beneficiaries can have timelier access to the lower-cost drugs. The rule would permit the plans to treat the biosimilar substitutions as “maintenance changes” that don’t require prior Medicare approval. Such changes would enable the substitutions to apply to all enrollees – and not just those who begin the therapy after the effective date of the change.