Abstract 4052: Direct selection of PD1+ CD39+ tumor infiltrating lymphocytes (TIL) from tumor dissociates enrich for functional tumor-reactive cells
Authors: Pedros Christophe , Pikor Larissa , Fritzsche Anna , Jilesen Zachary K. , Macleod Bethany , Khojandi Niloufar , Thompson Bryant , Thayer Matthew , Bryan Nikolas , Carron Emily , Ratliff Sowbarnika S , Fraley April , Nikota Jake , Fisher Robert , Delpeut Sebastien , Kluew Anna , Scott Madysson , Laing Christian , He Leo , Bernard Antoine , Brassard Nathalie , Turcotte Simon , Langer Timothy J , Stojdl David , Abbot Stewart , Sennino Barbara 
Published: April 2023

Abstract
Background: The autologous cell therapy field has investigated numerous novel strategies and processes to improve response rates and expand the use of adoptive cell therapies (ACT) to patient suffering from a broad range of cancers. Tumor infiltrating lymphocytes (TIL) can be harvested from tumors, expanded in vitro, and infused to patients leading to substantial clinical benefits in some patient populations. Tumor reactivity of TIL can vary greatly, representing a key limiting factor of bulk TIL therapies. The ability to generate an autologous cell product enriched in tumor reactive cells while limiting the presence of potentially detrimental and/or competitive non-reactive cells is highly desirable for next generation TIL products. Here we demonstrate that direct selection of antigen experienced TIL from tumor dissociates is feasible and allows to obtain functional cells enriched for tumor reactivity from various tumor indications.
Methods: Patient-derived tumor material from various indications, including ovarian, kidney, colorectal cancer and lung tumors were first processed into single cell suspensions, maximizing TIL recovery and viability. Antigen experienced TIL were immediately selected based on the co-expression of PD-1 and CD39, using fluorescence-activated single cell sorting (FACS). The sorted cells or the unselected counterparts were expanded in a rapid expansion protocol (REP), then analyzed for phenotypic and functional characteristics and reactivity against autologous tumor cells.
Results: The PD-1+ CD39+ selection strategy consistently allowed sorting of a population of viable TIL that was amenable to in vitro culture from tumors of various cancer indications. The selected TIL successfully expanded in a rapid expansion protocol. TCR sequencing analysis revealed that the PD-1+ CD39+ sorted populations were enriched in unique clones compared to the unselected populations. Expanded PD-1+ CD39+ selected cells demonstrated the ability to produce key effector cytokines upon restimulation in polyclonal assays. Importantly, the PD-1+ CD39+ expanded TIL were enriched for tumor reactive T cells and showed improved cytotoxic activity against autologous tumors.
Conclusions: PD-1+ CD39+ selected TIL can be successfully isolated and expanded in vitro, generating a TIL product of superior reactivity in multiple cancer indications. PD-1+ CD39+ selected TIL showed increased cytokine secretion and cytotoxic activity against autologous material, indicating that this selection strategy enriches for functional tumor-reactive lymphocytes, which is likely to be a key feature of successful ACT.
Citation Format: Christophe Pedros, Larissa Pikor, Anna Fritzsche, Zachary K. Jilesen, Bethany Macleod, Niloufar Khojandi, Bryant Thompson, Matthew Thayer, Nikolas Bryan, Emily Carron, Sowbarnika S Ratliff, April Fraley, Jake Nikota, Robert Fisher, Sebastien Delpeut, Anna Kluew, Madysson Scott, Christian Laing, Leo He, Antoine Bernard, Nathalie Brassard, Simon Turcotte, Timothy J Langer, David Stojdl, Stewart Abbot, Barbara Sennino. Direct selection of PD1+ CD39+ tumor infiltrating lymphocytes (TIL) from tumor dissociates enrich for functional tumor-reactive cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4052.