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

Abstract

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.