Abstract PO010: Engineering T cells to enhance 3D migration through mechanically and structurally complex tumor microenvironments
Authors: Tabdanov Erdem , Rodriguez-Merced Nelson , Cartagena-Rivera Alexander , Puram Vikram , Callaway Mackenzie , Ensminger Ethan , Pomeroy Emily , Yamamoto Kenta , Lahr Walker , Webber Beau , Moriarity Branden , Zhovmer Alexander , Provenzano Paolo 
Published: March 2021

Abstract
While chemical signals play a strong role in drawing T cells into solid tumors, the physical features of the stroma, such as architecture and mechanics, also strongly influence T cell infiltration as well as their ability to effectively distribute throughout, and sample, the entire tumor volume. Indeed, the mechanically and chemically complex stromal reaction in solid tumors can limit access and effective distribution of T cells creating antitumor immunity-free sanctuaries. Furthermore, many solid tumors are rich with aligned extracellular matrix (ECM) networks, which provide contact guidance for carcinoma cells, but can also direct migration of infiltrated T cells within solid tumors. Yet, our understanding of how native and engineered T cells migrate through mechanically complex tumor microenvironments (TMEs) is quite incomplete. As such, defining the principles of T cell migration in structurally and mechanically complex tumor microenvironments is critical to understanding sanctuaries from antitumor immunity and for optimizing T cell-related therapeutic strategies. In order to decipher and enhance migration of T cells through complex microenvironments, we initially engineered nanotextured elastic platforms that mimic ECM architectures observed in breast and pancreatic carcinomas. These platforms allowed us to define how the balance between contractility localization-dependent T cell phenotypes (i.e. high cortical contractility distributed along the curved cell membrane versus forces imparted onto substrates) influences migration in response to tumor-mimetic mechanical and structural and cues. From this information we characterized a mechanical optimum for migration that can be perturbed by manipulating an axis between microtubule stability and contractile force generation. In three-dimensional (3D) environments and live pancreatic tumors, we demonstrate that microtubule instability, leading to increased Rho pathway-dependent cortical contractility, promotes migration while clinically used microtubule-stabilizing chemotherapies profoundly decrease effective migration. Indeed, we show that rational manipulation of the microtubule-contractility axis, either pharmacologically or through genome engineering with CRISPR results in engineered T cells that more effectively move through and interrogate 3D matrix and tumor volumes. This suggests that T cell engineering to generate “mechanically optimized” therapeutic cells that better navigate through 3D microenvironments could be part of an effective strategy to enhance efficacy of immune therapeutics.
Citation Format: Erdem Tabdanov, Nelson Rodriguez-Merced, Alexander Cartagena-Rivera, Vikram Puram, Mackenzie Callaway, Ethan Ensminger, Emily Pomeroy, Kenta Yamamoto, Walker Lahr, Beau Webber, Branden Moriarity, Alexander Zhovmer, Paolo Provenzano. Engineering T cells to enhance 3D migration through mechanically and structurally complex tumor microenvironments [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO010.