IV-to-Subcutaneous Drug Reformulations Gain Momentum Through Streamlined Regulatory Pathways

Speaking during an interview at AAPS NPC 2026, Charles Theuer highlighted the growing momentum behind IV-to-subcutaneous reformulations, emphasizing their potential to significantly reduce administration burden while improving tolerability.

During his presentation, entitled “Development Pathways and Considerations for Subcutaneous Biologic Formulations,” Theuer described dramatic reductions in dosing times when therapies transition from IV infusion to subcutaneous delivery. In one example, a biologic that initially required a 10-hour infusion over two days was reformulated into a five-minute subcutaneous injection. According to Theuer, these conversions can simultaneously improve patient convenience and reduce toxicity.

“You decrease the administration time, literally from hours to minutes and sometimes as little as seconds,” Theuer said.

How Are PK-Driven Approval Strategies Accelerating IV-to-Subcutaneous Biologic Conversions?

Beyond patient convenience, Theuer emphasized the safety advantages associated with subcutaneous administration. He explained that IV infusions often create high peak drug concentrations, or Cmax levels, that can contribute to toxicities such as infusion-related reactions. By contrast, subcutaneous administration may reduce these adverse events despite dramatically shorter dosing times.

The interview’s most important takeaway centered on the evolving regulatory framework supporting these reformulations. Earlier comparative studies between IV and subcutaneous formulations typically required both PK and efficacy endpoints. However, since 2020, regulators have increasingly accepted primary endpoints based solely on PK or pharmacodynamic comparability, simplifying pivotal non-inferiority study designs.

Theuer also pointed to the growing use of label extrapolation strategies. Using Bristol Myers Squibb’s nivolumab as an example, he explained that a pivotal study in renal cell carcinoma supported a broader subcutaneous label covering multiple previously approved IV indications, despite the subcutaneous formulation not being directly studied in each disease setting.

The trend reflects broader industry movement toward patient-centric biologic delivery strategies and alternative dosage forms discussed in prior BioPharm International coverage of formulation and drug delivery trends and alternative biologic dosage forms.

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About the speaker

Charles Theuer, MD, PhD

Dr. Charles Theuer has served as Chief Medical Officer at Halozyme since October 2024, leading subcutaneous drug development initiatives involving ENHANZE® technology and auto-injectors. Previously, he was CEO, CMO, and Director of TRACON Pharmaceuticals and held senior leadership roles at TargeGen, Pfizer, and IDEC Pharmaceuticals, contributing to the development of therapies including Inrebic®, Sutent®, Rituxan®, and Zevalin®. A board-certified general surgeon for more than a decade, Theuer earned degrees from MIT, UCSF, and UC Irvine, and completed training at Harbor-UCLA Medical Center and the National Cancer Institute.