A Multiscale Immuno-Oncology on-Chip System (MIOCS) establishes that collective T cell behaviors govern tumor regression

T cell-based tumor immunotherapies such as CAR T cells or immune checkpoint inhibitors harness the cytotoxic potential of T cells to promote tumor regression. However, patient response to immunotherapy remains heterogeneous, highlighting the need to better understand the rules governing a successful T cell attack. Here, we develop a microfluidic-based method to track the outcome of T cell activity on many individual cancer spheroids simultaneously, with a high spatiotemporal resolution. By combining these parallel measurements of T cell behaviors and tumor fate with probabilistic modeling, we establish that the first recruited T cells initiate a positive feedback loop leading to an accelerated effector accumulation on the spheroid. We also provide evidence that cooperation between T cells on the spheroid during the killing phase facilitates tumor destruction. We propose that tumor destruction does not simply reflect the sum of individual T cell activities but relies instead on collective behaviors promoting both T cell accumulation and function. The possibility to track many replicates of immune-tumor interactions with such a level of detail should help delineate the mechanisms and efficacy of various immunotherapeutic strategies. ### Competing Interest Statement CNB is inventor on several patents relating to the microfluidic technology. CNB is co-founder and scientific advisor to Okomera.