Single-cell imaging of CAR T cell activity in vivo reveals extensive functional and anatomical heterogeneity

Marine Cazaux (1, 2) , Capucine Grandjean (1) , Fabrice Lemaître (1) , Zacarias Garcia (1) , Richard Beck (3) , Idan Milo (1) , Jérémy Postat (1, 2) , Joost Beltman (3) , Eleanor Cheadle (4) , Philippe Bousso (1)

1 Dynamiques des Réponses immunes - Dynamics of Immune Responses
2 Cellule Pasteur
3 Universiteit Leiden = Leiden University
4 University of Manchester [Manchester]

CAR T cells represent a potentially curative strategy for B cell malignancies. However, the outcome and dynamics of CAR T cell interactions in distinct anatomical sites are poorly understood. Using intravital imaging, we tracked interactions established by anti-CD19 CAR T cells in B cell lymphoma-bearing mice. Circulating targets trapped CAR T cells in the lungs, reducing their access to lymphoid organs. In the bone marrow, tumor apoptosis was largely due to CAR T cells that engaged, killed, and detached from their targets within 25 min. Notably, not all CAR T cell contacts elicited calcium signaling or killing while interacting with tumors, uncovering extensive functional heterogeneity. Mathematical modeling revealed that direct killing was sufficient for tumor regression. Finally, antigen-loss variants emerged in the bone marrow, but not in lymph nodes, where CAR T cell cytotoxic activity was reduced. Our results identify a previously unappreciated level of diversity in the outcomes of CAR T cell interactions in vivo, with important clinical implications.

Domaines: Sciences du Vivant [q-bio]; Immunologie; Immunothérapie; Cancer

Marine Cazaux, Capucine Grandjean, Fabrice Lemaître, Zacarias Garcia, Richard Beck, et al.. Single-cell imaging of CAR T cell activity in vivo reveals extensive functional and anatomical heterogeneity. Journal of Experimental Medicine, 2019, 216 (5), pp.1038-1049. ⟨10.1084/jem.20182375⟩. ⟨hal-02302284⟩