Long-term in vivo microscopy of CAR T cell dynamics during eradication of CNS lymphoma in mice

Abstract

T cells expressing anti-CD19 chimeric antigen receptors (CARs) demonstrate impressive efficacy in the treatment of systemic B cell malignancies, including B cell lymphoma. However, their effect on primary central nervous system lymphoma (PCNSL) is unknown. Additionally, the detailed cellular dynamics of CAR T cells during their antitumor reaction remain unclear, including their intratumoral infiltration depth, mobility, and persistence. Studying these processes in detail requires repeated intravital imaging of precisely defined tumor regions during weeks of tumor growth and regression. Here, we have combined a model of PCNSL with in vivo intracerebral 2-photon microscopy. Thereby, we were able to visualize intracranial PCNSL growth and therapeutic effects of CAR T cells longitudinally in the same animal over several weeks. Intravenous (i.v.) injection resulted in poor tumor infiltration of anti-CD19 CAR T cells and could not sufficiently control tumor growth. After intracerebral injection, however, anti-CD19 CAR T cells invaded deeply into the solid tumor, reduced tumor growth, and induced regression of PCNSL, which was associated with long-term survival. Intracerebral anti-CD19 CAR T cells entered the circulation and infiltrated distant, nondraining lymph nodes more efficiently than mock CAR T cells. After complete regression of tumors, anti-CD19 CAR T cells remained detectable intracranially and intravascularly for up to 159 d. Collectively, these results demonstrate the great potential of anti-CD19 CAR T cells for the treatment of PCNSL.

The Cerebroventricular Environment Modifies CAR T Cells for Potent Activity against Both Central Nervous System and Systemic Lymphoma

“…These data support our observation that differences in outcomes in mice treated with ICV and IV delivery reflected differences in capacity for anti-tumor activity promoted by the two routes of delivery. The long-term persistence of memory CAR T cells following ICV administration in absence of antigen, also observed by Mulazzani et al (45), could be due to homeostatic mechanisms driven by factors such as cytokines that are species cross-reactive, such as IL-7 (46,47).…”

“…Absence of GVHD suggests that there is limited engagement of the endogenous TCR in our model and, therefore, xenoreactivity likely does not affect our conclusions. In line with these observations, a recent study by Mulazzani et al (45) showed that intracerebral infusion of CAR T cells exhibits superior anti-tumor efficacy and persistence compared to IV delivery, where…”

The Role of BAFF-R Signaling in the Growth of Primary Central Nervous System Lymphoma

“…Cranial window implantation was performed as described (27)(28)(29). After anesthesia (intraperitoneal injection of medetomidine, midazolam, and fentanyl) and subcutaneous injection of cefotaxime and dexamethasone, mice were placed on a heating pad (37 • C) and fixed in a modified surgery frame (David Kopf Instruments, USA).…”

Commentary: Long-term in vivo microscopy of CAR T cell dynamics during eradication of CNS lymphoma in mice

“…The authors developed a mouse model of orthotopic, fluorescent-labeled PCNSL with intracerebral and periventricular tumor growth and created chronic cranial windows, which allowed longitudinal observation of tumor and T-cell kinetics (4). Three-dimensional quantification of intratumoral T cells by use of two-photon laser scanning microscopy (TPLSM) demonstrated that intravenously administered anti-CD19 CAR T cells accumulated in limited numbers at a late time point, at levels equal to mock CAR T cells, resulting in tumor regression in a fraction of treated mice.…”

“…IC, intracerebral; IV, intravenous. This figure includes cropped figures from the article "Long-term in vivo microscopy of CAR T cell dynamics during eradication of CNS lymphoma in mice" by Mulazzani et al (4), under Creative Commons CC-BY-NC-ND 4.0. Permission has been provided by authors of the original work to share modified material.…”