Abstract 3464: Advancing antibody therapeutics: a 3D <i>in vitro</i> model for penetration assessment of immunoglobulins in human tumor spheroids

Abstract The advancements in biotechnology and the successful application of monoclonal antibody therapeutics have incited the development of innovative therapeutic antibody modalities, including bi-or tri-specific antibodies, antibody fragments (e.g. Fab), and other formats (e.g. DARPin). These have transformed cancer treatments; however, monoclonal antibodies often demonstrate limited efficacy in cancer therapy due to poor tumor penetration, leaving regions of untargeted and untreated tumor areas that can escape therapy. Addressing this limitation requires the development of advanced in vitro culture models that accurately replicate tumor-tumor microenvironment (TME) interactions. To bridge the gap between traditional 2D in vitro cultures and animal models, 3D human tumor spheroids offer a promising solution. In this context, InSphero has developed an in vitro 3D Antibody Penetration Assay. We demonstrate that 3D InSight™ Human Tumor Microtissues closely mimic the complexity and heterogeneity of the TME, while maintaining uniform composition and size across spheroids, providing reliable and reproducible models to enhance drug discovery. Using 3D InSight™ human tumor spheroids, we evaluated the efficacy, distribution, and penetration depth of a therapeutic antibody and an antibody-drug conjugate (ADC). Results showed that both modalities successfully penetrated the 3D InSight™ lung cancer tumor (A549) model. After 30 minutes of treatment, antibodies were detected at the periphery of the spheroids, while longer treatment windows resulted in progressively deeper penetration. This assay offers a robust and reliable platform for assessing the distribution and penetration of antibody therapeutics, biologics, ADCs, and other agents in solid tumor models, leveraging advanced in vitro 3D human tumor models to improve drug discovery and therapeutic development. Citation Format: Sue Fontaine Grepper, Maja Nedic, Charlotte Veser, Michal Rudnik, Matthias Zbinden, Irina Agarkova, Madhu Nag, Laure-Anne Ligeon. Advancing antibody therapeutics: a 3D in vitro model for penetration assessment of immunoglobulins in human tumor spheroids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3464.