Citations

Despite the remarkable outcomes of CD19-directed chimeric antigen receptor T (CART19) cell therapy in B-cell malignancies, the durable responses in diffuse large B-cell lymphoma are less than 40%, and strategies to enhance this response are desperately needed. Inhibition of AXL RTK with TP0903, a high-affinity AXL inhibitor has been found to induce robust apoptosis of malignant B cells. Here, we aimed to examine the role of AXL RTK inhibition with TP0903 on T-cell function in B-cell malignancies. First, we investigated the influence of TP0903 on CART19 cell phenotype and functions. Here, we used 41BB costimulated, lentiviral-transduced CART cells. AXL inhibition led to polarization of CART cells into a Th1 phenotype when T cells were stimulated with the CD19+ mantle cell lymphoma (MCL) cell line Jeko or with leukemic B cells isolated from patients with chronic lymphocytic leukemia (CLL), in the presence of TP0903 (Fig 1A). Exposure of activated CART cells to TP0903 also resulted in significant downregulation of inhibitory receptors on activated CART cells (Fig 1B), a reduction of conical cytokines known to be associated with the development of cytokine release syndrome (CRS) (Fig 1C). To investigate the effect of AXL RTK inhibition of CART cells with TP0903 in vivo, we established MCL xenografts through the injection of 1.0x106 of Jeko into NSG mice. A week later, mice were treated with either vehicle alone, TP0903 (20 mg/kg/day) alone, 0.5x106 of CART19 alone, or TP0903 (20mg/kg/day)+0.5x106 of CART19. Three weeks after the treatment, mice were rechallenged with 1.0x106 of Jeko. Mice treated with CART19 and TP0903 rejected the tumor challenge while mice previously treated with CART19 alone redeveloped MCL, suggesting that AXL inhibition enhanced CART cell persistence (Fig 1D). Finally, we validated our preclinical findings in correlative analyses of phase 1 clinical trial of TP0903 in patients with solid tumors (NCT02729298). Similar to our findings, there was a significant reduction in Tregs, reduction of inhibitory receptors and polarization to a Th1 phenotype. These findings will be further investigated in a planned phase 1 clinical trial of TP0903 in relapsed/refractory CLL (NCT03572634) In summary, we demonstrated for the first time that AXL inhibition polarizes T cells into a Th1 phenotype, downregulates inhibitory receptors, and synergizes with CART cells in B-cell malignancies. These findings encourage further study of TP0903 as an enhancer of T-cell immunotherapies.

Background: Unprecedented clinical outcomes were reported after CD19 chimeric antigen receptor T-cell (CART19) therapy. However, the complete response rate in chronic lymphocytic leukemia (CLL) is much lower, at approximately 20%–30%. Several immune defects have been identified in CLL that result from the complex interaction between CLL cells and the microenvironment. This leukemic microenvironment is rich with extracellular vesicles (EVs) secreted by B-CLL cells. Here, we aimed to investigate the role of EVs play in the diminished CART response seen in some CLL patients. Methods: EVs were isolated from peripheral blood of 16 patients with untreated CLL at different Rai stages and risk profile by FISH. Cytometry was used to determine size, number of particles per μl, and CD19 expression. To investigate the impact of EVs on CAR T-cell functions, CART19 cells were stimulated with either CLL B cells or the CD19-positive cell line JEKO and different effector functions were analyzed. Results: Two patterns of EVs in CLL patients were identified; a single versus 2 distinct EV populations, characterized by size (small [EVssmall] and large [EVslarge], Fig 1A). In 25% of patients, EVs were CD19 positive (EVCD19+). CD19 positivity was detected only in patients with the EVslarge (Fig 1B). The EVs concentration, CD19 expression (EVsCD19+ vs EVsCD19-), or the size (EVssmall vs EVslarge) did not correlate with disease stage (early vs advanced Rai stage) or risk profile of CLL (low vs high risk). To investigate our hypothesis that EVs could modulate CART19 function, CART19 cell effector functions were examined in the presence of EVsCD19+, EVsCD19-, EVssmall, or EVslarge. EVs alone were insufficient to stimulate CART19 cells. However when CART19 cells were stimulated with the CD19-positive cell line JEKO, their effector functions were reduced only in the presence of EVsCD19+ but not EVsCD19-. This included a significant reduction in CART-specific killing (Fig 1C) and a reduction in cytokine production. The impairment of CART cell functions was independent of the size of EVs, ie, there was no impairment of CART functions with large or small size EVCD19- in co-culture. Conclusion: We identify CD19-positive large size EVs from patients with CLL and demonstrate that these EVs play a role in the leukemic microenvironment by reducing CAR T-cell activity. Studies are ongoing to define the mechanism(s).

Introduction The reasons why women are at higher risk than men for developing dementia are unclear. Although studies implicate sex differences in the effect of stress on cognitive functioning, whether stressful life events are associated with subsequent cognitive decline has received scant research attention. Methods In Wave 3 (1993–1996) of the Baltimore Epidemiologic Catchment Area study, 337 men and 572 women (mean age = 47 years) reported recent (within the last year) and remote (from 1981 until 1 year ago) traumatic events (eg, combat) and stressful life events (eg, divorce/separation). At Waves 3 and 4 (2004–2005), they completed the Mini Mental State Examination (MMSE) and a word‐list memory test. Multivariable models were used to examine the association between traumatic and stressful life events at Wave 3 and cognitive change by Wave 4. Results A greater number of recent stressful life events at Wave 3, but not of more remote stressful events, was associated with greater verbal memory decline by Wave 4 in women but not in men. Stressful events were not associated with change in MMSE, and there were no associations between traumatic events occurring at any time and subsequent memory or MMSE decline in either sex. Conclusions Unlike men, middle‐aged women with a greater number of recent stressful life events demonstrate memory decline over a decade later. Sex differences in cognitive vulnerability to stressful life events may underlie women's increased risk of memory impairment in late life, suggesting that stress reduction interventions may help prevent cognitive decline in women.

PurposeThis work aims to develop a new framework of image quality assessment using deep learning‐based model observer (DL‐MO) and to validate it in a low‐contrast lesion detection task that involves CT images with patient anatomical background.MethodsThe DL‐MO was developed using the transfer learning strategy to incorporate a pretrained deep convolutional neural network (CNN), a partial least square regression discriminant analysis (PLS‐DA) model and an internal noise component. The CNN was previously trained to achieve the state‐of‐the‐art classification accuracy over a natural image database. The earlier layers of the CNN were used as a deep feature extractor, with the assumption that similarity exists between the CNN and the human visual system. The PLSR model was used to further engineer the deep feature for the lesion detection task in CT images. The internal noise component was incorporated to model the inefficiency and variability of human observer (HO) performance, and to generate the ultimate DL‐MO test statistics. Seven abdominal CT exams were retrospectively collected from the same type of CT scanners. To compare DL‐MO with HO, 12 experimental conditions with varying lesion size, lesion contrast, radiation dose, and reconstruction types were generated, each condition with 154 trials. CT images of a real liver metastatic lesion were numerically modified to generate lesion models with four lesion sizes (5, 7, 9, and 11 mm) and three contrast levels (15, 20, and 25 HU). The lesions were inserted into patient liver images using a projection‐based method. A validated noise insertion tool was used to synthesize CT exams with 50% and 25% of routine radiation dose level. CT images were reconstructed using the weighted filtered back projection algorithm and an iterative reconstruction algorithm. Four medical physicists performed a two‐alternative forced choice (2AFC) detection task (with multislice scrolling viewing mode) on patient images across the 12 experimental conditions. DL‐MO was operated on the same datasets. Statistical analyses were performed to evaluate the correlation and agreement between DL‐MO and HO.ResultsA statistically significant positive correlation was observed between DL‐MO and HO for the 2AFC low‐contrast detection task that involves patient liver background. The corresponding Pearson product moment correlation coefficient was 0.986 [95% confidence interval (0.950, 0.996)]. Bland–Altman agreement analysis did not indicate statistically significant differences.ConclusionsThe proposed DL‐MO is highly correlated with HO in a low‐contrast detection task that involves realistic patient liver background. This study demonstrated the potential of the proposed DL‐MO to assess image quality directly based on patient images in realistic, clinically relevant CT tasks.