Gri3D® is a ready-to-use platform for high-throughput and reproducible organoid culture. In collaboration with scientists at the École Polytechnique Fédérale de Lausanne, we set up a robust and scalable assay to study tumorinfiltrating lymphocytes (TIL) functionality on 3-dimensional (3D) tumoroids grown in Gri3D®. Up to 73 tumoroids are formed in a single well and subsequently co-cultured with TILs. Evaluation of T cell killing potential is performed in situ via semi-automated image analysis.