Medicare spending and use of subcutaneous biologic formulations with hyaluronidase.

Several intravenously administered biologic drugs have been reformulated with hyaluronidase to enable subcutaneous delivery. This offers greater convenience and fewer infusion reactions while also increasing overall spending if biosimilar competition for the subcutaneous versions begins later than for the original intravenous versions. As of December 2024, at least 9 biologics had investigational or approved hyaluronidase versions. Medicare spending on these drugs totaled $10.3B in 2022. For 4 of these drugs, hyaluronidase versions accounted for 5%-83% of Medicare spending in 2022, with hyaluronidase versions accounting for the highest share of spending for pertuzumab-trastuzumab and daratumumab and a lower share of spending for 2 drugs that had biosimilar competition for the original versions: rituximab and trastuzumab. The benefits of subcutaneous hyaluronidase versions must be balanced against the challenges that come with higher prices if these versions are introduced before biosimilar competition begins for the original versions. Policymakers should ensure manufacturers cannot use "hyaluronidase hopping" to delay biosimilar competition or eligibility for Medicare price negotiation.