Clinical Pharmacology Insights for Small Molecule and Antibody‐Based Drug Products Approved for Multiple Immune‐Mediated Indications

Developing therapeutics for multiple immune-mediated indications has become a prominent strategy, driven by advances in disease biology, pharmacology, clinical and regulatory science. We analyzed 34 FDA-approved small molecular and antibody-based drug products with more than one adult immune-mediated inflamamatory indication by December 2024. A clear trend toward pathway-driven development was seen, with shared targets (e.g., TNFα, IL-17, IL-23, and JAKs) enabling indication expansion. Approved indications per product ranged from 2 to 8 (median: 3). Over time, the median gap between subsequent indication approvals decreased from 3.2 years (range 1.1-12.8) for products first approved in 1998-2008 to 1.7 years (range 0.67-2.75) for those approved after 2018, reflecting improved efficiency likely due to broader adoption of pathway-based strategies. Route of administration also evolved for antibody-based therapies, with median delays of 5.8-6.0 years for intravenous-to-subcutaneous (IV-to-SC) and 4.4-8.5 years for subcutaneous-to-intravenous (SC-to-IV) transitions. Fewer than 25% of therapies kept the same dosing regimen across indications, with small molecules more likely to retain dosing (62.5%, 5/8) than antibodies (11.5%, 3/26), indicating the need for tailored approaches based on disease context, tissue involvement, and patient characteristics. Key clinical pharmacology considerations include rational dose selection, surrogate and extrapolation strategies, and model-informed bridging, leveraging existing data to inform subsequent indications. Early regulatory engagement, strategic target selection, robust trial design, harmonized safety database, and cross-functional coordination are critical. Our analysis provides insights to guide multi-indication development to improve patient access to therapies for diverse immune-mediated disorders.