No abstract

The efficacy of chimeric antigen receptor (CAR) T-cell therapy in solid tumors is limited by inefficient T-cell infiltration, localization and hypofunctionality within the tumor microenvironment. Prior studies demonstrated that stromal cell targeted CAR T cells, in particular CAR T cells that target fibroblast activation protein (FAP), can effectively infiltrate, and inhibit tumor growth in mouse models of pancreatic ductal adenocarcinomas (PDAC) due to their capacity to deplete stromal cells and extracellular matrix (ECM) that otherwise present a barrier to adoptive cell therapies. However, the kinetics of tumor infiltration by FAP-CAR T cells, and the cell-cell and cell-matrix interactions that contribute to their anti-tumor activity are poorly understood. A better understanding FAP-CAR T-cell kinetics and intratumoral interactions should provide insights into the requirements for successful adoptive cell therapies in solid tumors. By combining immunostaining and real-time two-photon microscopy in tumor fragments of PDAC, we found that stromal cell targeted FAP-CAR T cells can efficiently traffic into tumors. Initially (days 1-3) FAP-CAR T cells were enriched in the stroma surrounding tumor nests but excluded from the tumor nests per se. While associated with the stroma rich region, the CAR T cells appeared activated and T cell motility was observed in loose collagen regions, but T cells migrated poorly in dense matrix areas. Aligned collagen fibers in the tumor boarder dictated the migratory trajectory of T cells and restricted them from entering tumor nests. By day 5 we observed depletion of immunosuppressive stromal cells, dissolution of the fibrillar collagen network surrounding tumor nests and infiltration of FAP-CAR T cells into tumor nests. Treatment with hyaluronidase increased the ability of T cells to infiltrate the tumor nest. Thus, FAP-CAR T cell-mediated ablation of immunosuppressive FAP+ stromal cells and disruption of the desmoplastic stroma they generate, can enhance accumulation and functionality of CAR-T cell therapy in the context of highly desmoplastic solid tumors. Citation Format: Zebin Xiao, Leslie A. Hopper, Meghan C. Kopp, Emily McMillan, Yue Li, Richard L. Barrett, Ellen Puré. Visualization of cell to cell and cell to matrix interactions in the disruption of tumor-promoting desmoplasia by adoptive transfer of fibroblast activation protein targeted chimeric antigen receptor (CAR) T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2475.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease due to the poor response to current therapeutic treatments. A major barrier to effective treatment of PDAC is the extensive remodeling of tumor stroma characterized by accumulation of cancer associated fibroblasts (CAFs) and extracellular matrix which forms a physical barrier that limits access of the drugs to the cancer cells, suppresses the immune system, and attenuates efficacy of immunotherapies. Fibroblast activation protein (FAP) is highly expressed in a pro-tumorigenic subset of CAFs in PDAC. We hypothesized that depletion of FAP+-CAFs would deplete extracellular matrix (ECM) and reduce the immune suppressive function of the stroma and thereby enhance the efficacy of tumor antigen targeted CAR T cell therapy in PDAC. Using real-time tumor fragment-based 2-photon microscopy, multiparametric flow cytometry and multiplexed immunofluorescence staining, we showed that FAP targeted CAR T cells (FAP-CAR T) efficiently traffic into tumors compared with tumor-antigen (mesothelin) targeted CAR (Meso-CAR) T cells which were trapped in the stroma-rich or matrix-dense areas and led to depletion of immunosuppressive FAP+ cells and reprogrammed the fibrillar collagen network surrounding tumor nests, advancing the infiltration of FAP-CAR T cells into tumor nests. Strikingly, FAP-CAR T cell-mediated depletion for FAP+ cells also rendered the tumor microenvironment permissive to the infiltration and anti-tumor activity of tumor antigen meso-CAR T cells. Moreover, ablation of FAP+ cells markedly enhanced endogenous T cell infiltration which further enhanced anti-tumor immunity and immunotherapy in PDAC models. Thus, our findings established that FAP-CAR T cell-mediated ablation of immunosuppressive FAP+-CAFs and disruption of the desmoplastic stroma they generate, can enhance accumulation and functionality of endogenous anti-tumor immunity and CAR-T cell therapy in the context of highly desmoplastic solid tumors. Citation Format: Zebin Xiao, Leslie A. Hopper, Meghan C. Kopp, Emily McMillan, Yue Li, Richard L Barrett, Ellen Puré. Disruption of tumor-promoting desmoplasia by adoptive transfer of fibroblast activation protein targeted chimeric antigen receptor (CAR) T cells enhances anti-tumor immunity and immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C009.

Objective: To compare conventional magnetic resonance imaging (MRI), susceptibility-weighted imaging (SWI), and perfusion-weighted imaging (PWI) characteristics in different grades of trigone meningiomas.Methods: Thirty patients with trigone meningiomas were enrolled in this retrospective study. Conventional MRI was performed in all patients; SWI (17 cases), dynamic contrast-enhanced PWI (10 cases), and dynamic susceptibility contrast PWI (6 cases) were performed. Demographics, conventional MRI features, SWI-and PWI-derived parameters were compared between different grades of trigone meningiomas.Results: On conventional MRI, the irregularity of tumor shape (ρ = 0.497, P = 0.005) and the extent of peritumoral edema (ρ = 0.187, P = 0.022) might help distinguish low-grade and high-grade trigone meningiomas. On multiparametric functional MRI, rTTP max (1.17 ± 0.06 vs 1.30 ± 0.05, P = 0.048), K ep , V e , and iAUC demonstrated their potentiality to predict World Health Organization grades I, II, and III trigone meningiomas.Conclusions: Conventional MRI combined with dynamic susceptibility contrast and dynamic contrast-enhanced can help predict the World Health Organization grade of trigone meningiomas.

BACKGROUND AND PURPOSE Diffusion and perfusion MRI can invasively define physical properties and angiogenic features of tumors, and guide the individual treatment. The purpose of this study was to investigate whether the diffusion and perfusion MRI parameters of primary central nervous system lymphomas (PCNSLs) are related to the tumor locations.MATERIALS AND METHODS We retrospectively reviewed the diffusion, perfusion, and conventional MRI of 68 patients with PCNSLs at different locations (group 1: cortical gray matter, group 2: white matter, group 3: deep gray matter). Relative maximum cerebral blood volume (rCBV max ) from perfusion MRI, minimum apparent diffusion coefficients (ADC min ) from DWI of each group were calculated and compared by one-way ANOVA test.RESULTS The rCBV max of PCNSLs yielded the lowest value in the white matter group, and the highest value in the cortical gray matter group ( P <0.001). However, the ADC min of each subgroup was not statistically different.CONCLUSIONS Our study confirms that rCBV max of PCNSLs are related to the tumor location, and provide simple but effective information for guiding clinical practice of PCNSLs.