ASBM recently submitted a letter opposing California Senate Bill 1094, which would permit generic-style pharmacy-level substitution of non-interchangeable biosimilars.

While biosimilars are safe and effective, they are not generics—and substitution decisions for biologics should remain grounded in evidence, physician judgment, and patient-specific considerations. 

California’s current framework appropriately allows substitution only for biosimilars that meet the FDA’s higher standard for interchangeable biosimilars. Interchangeable status is granted by the FDA only after additional data are provided by the biosimilar manufacturer to demonstrate that switching will not reduce either safety or treatment efficacy.

“Nationwide, support for permitting biosimilar substitution from state medical societies and patient advocacy organizations was conditional on it being limited to interchangeable biosimilars,” says ASBM Executive Director Michael Reilly. “SB 1094 would remove that safeguard, potentially disrupting treatment stability for California patients and reducing physician and patient confidence in biosimilars.”

A recent survey of 270 physicians found only 11% believe that all biosimilars should be treated as interchangeables; i.e., substitutable by third parties without prescriber involvement, as SB 1094 would permit.

Read ASBM’s opposition letter here.