Purpose: The forkhead box transcription factor FoxP3 is specifically expressed in T cells with regulatory properties (Treg). Recently, high numbers of Treg were described to be associated with poor survival in different malignancies. The aim of the presented study was determine the prognostic effect of FoxP3 mRNA expression (reflecting the tissue content of Treg) in ovarian carcinoma and its relation with cytokines, such as IFN-γ. Experimental Design: Total RNA was isolated from 99 ovarian carcinoma and from 14 healthy ovarian biopsies. Real-time PCR for FoxP3 was done and correlated with IFN-γ-, CD3-, IRF-1-, SOCS-1-, HER-2-, and iNOS expression as well as patients' outcome. The mRNA data was corroborated by FoxP3 immunohistochemistry. Results: Quantitation of FoxP3 expression identified a patient subgroup (>81th percentile), which is characterized by a significantly worse prognosis in terms of overall survival (27.8 versus 77.3 months, P = 0.0034) and progression-free survival (18 versus 57.5 months; P = 0.0041). FoxP3 expression correlated with IFN-γ, IRF-1, and CD3 expression. High FoxP3 expression represents an independent prognostic factor for overall survival (P = 0.004) and progression-free survival (P = 0.004). Conclusions: High expression levels of FoxP3 might represent a surrogate marker for an immunosuppressive milieu contributing to tumor immune escape. Strategies selectively depleting Treg might improve the antitumor activity of endogenously arising tumor-reactive T cells and immunotherapies using vaccines or antibodies.

Background: Patients with hematological malignancies (HM) are at high risk of mortality from SARS-CoV-2 disease 2019 (COVID-19). A better understanding of risk factors for adverse outcomes may improve clinical management in these patients. We therefore studied baseline characteristics of HM patients developing COVID-19 and analyzed predictors of mortality. Methods: The survey was supported by the Scientific Working Group Infection in Hematology of the European Hematology Association (EHA). Eligible for the analysis were adult patients with HM and laboratory-confirmed COVID-19 observed between March and December 2020. Results: The study sample includes 3801 cases, represented by lymphoproliferative (mainly non-Hodgkin lymphoma n = 1084, myeloma n = 684 and chronic lymphoid leukemia n = 474) and myeloproliferative malignancies (mainly acute myeloid leukemia n = 497 and myelodysplastic syndromes n = 279). Severe/critical COVID-19 was observed in 63.8% of patients (n = 2425). Overall, 2778 (73.1%) of the patients were hospitalized, 689 (18.1%) of whom were admitted to intensive care units (ICUs). Overall, 1185 patients (31.2%) died. The primary cause of death was COVID-19 in 688 patients (58.1%), HM in 173 patients (14.6%), and a combination of both COVID-19 and progressing HM in 155 patients (13.1%). Highest mortality was observed in acute myeloid leukemia (199/497, 40%) and myelodysplastic syndromes (118/279, 42.3%). The mortality rate significantly decreased between the first COVID-19 wave (March–May 2020) and the second wave (October–December 2020) (581/1427, 40.7% vs. 439/1773, 24.8%, p value < 0.0001). In the multivariable analysis, age, active malignancy, chronic cardiac disease, liver disease, renal impairment, smoking history, and ICU stay correlated with mortality. Acute myeloid leukemia was a higher mortality risk than lymphoproliferative diseases. Conclusions: This survey confirms that COVID-19 patients with HM are at high risk of lethal complications. However, improved COVID-19 prevention has reduced mortality despite an increase in the number of reported cases.

The tumor microenvironment (TME) plays a central role in cancer development and progression. It represents a complex network of cancer cell (sub-)clones and a variety of stromal cell types. Recently, new technology platforms shed light on the cellular composition of the TME at very high resolution and identified a complex landscape of multi-lineage immune cells (e.g., T and B lymphocytes, myeloid cells, and dendritic cells), cancer associated fibroblasts (CAF) and tumor endothelial cells (TECs). A growing body of evidence suggests that metabolically, genetically and on their transcriptomic profile TECs exhibit unique phenotypic and functional characteristics when compared to normal endothelial cells (NECs). Furthermore, the functional role of TECs is multifaceted as they are not only relevant for promoting tumor angiogenesis but have also evolved as key mediators of immune regulation in the TME. Regulatory mechanisms are complex and profoundly impact peripheral immune cell trafficking into the tumor compartment by acting as major gatekeepers of cellular transmigration. Moreover, TECs are associated with T cell priming, activation and proliferation by acting as antigen-presenting cells themselves. TECs are also essential for the formation of tertiary lymphoid structures (TLS) within the tumor, which have recently been associated with treatment response to checkpoint antibody therapy. Further essential characteristics of TECs compared to NECs are their high proliferative potential as well as greatly altered gene expression profile (e.g., upregulation of pro-angiogenic, extracellular matrix remodeling, and stemness genes), which results in enhanced secretion of immunomodulatory cytokines and altered cell-surface receptors [e.g., major histocompatibility complex (MHC) and immune checkpoints]. The TEC phenotype may be rooted in an aggressive tumor micro-milieu based on cellular stress via hypoxia and reactive oxygen species (ROS). Vice versa TECs might modulate TME immunogenicity thereby fostering cancer-associated immune suppression. This review aims to elucidate the currently emergent pathophysiological aspects of TECs with a particular focus on their potential role as regulators of immune cell function in the TME. It is a main future challenge to deeply characterize the phenotypic and functional profile of TECs to illuminate their complex role within the TME. The ultimate goal is the identification of TEC-specific drug targets to improve cancer (immuno-)therapy.

Ruxolitinib is a small-molecule inhibitor of the JAK kinases, which has been approved for the treatment of myelofibrosis, a rare myeloproliferative neoplasm (MPN), but clinical trials are also being conducted in inflammatory-driven solid tumors. Increased infection rates have been reported in ruxolitinib-treated patients, and natural killer (NK) cells are immune effector cells known to eliminate both virus-infected and malignant cells. On this basis, we sought to compare the effects of JAK inhibition on human NK cells in a cohort of 28 MPN patients with or without ruxolitinib treatment and 24 healthy individuals. NK cell analyses included cell frequency, receptor expression, proliferation, immune synapse formation, and cytokine signaling. We found a reduction in NK cell numbers in ruxolitinib-treated patients that was linked to the appearance of clinically relevant infections. This reduction was likely due to impaired maturation of NK cells, as reflected by an increased ratio in immature to mature NK cells. Notably, the endogenous functional defect of NK cells in MPN was further aggravated by ruxolitinib treatment. In vitro data paralleled these in vivo results, showing a reduction in cytokine-induced NK cell activation. Further, reduced killing activity was associated with an impaired capacity to form lytic synapses with NK target cells. Taken together, our findings offer compelling evidence that ruxolitinib impairs NK cell function in MPN patients, offering an explanation for increased infection rates and possible long-term side effects associated with ruxolitinib treatment. Cancer Res; 75(11); 2187–99. ©2015 AACR.

Summary: Ruxolitinib (INCB018424) is the first JAK1/JAK2 inhibitor approved for treatment of myelofibrosis. JAK/STAT‐signalling is known to be involved in the regulation of CD4⁺ T cells, which critically orchestrate inflammatory responses. To better understand how ruxolitinib modulates CD4⁺ T cell responses, we undertook an in‐depth analysis of CD4⁺ T cell function upon ruxolitinib exposure. We observed a decrease in total CD3⁺ cells after 3 weeks of ruxolitinib treatment in patients with myeloproliferative neoplasms. Moreover, we found that the number of regulatory T cells (Tregs), pro‐inflammatory T‐helper cell types 1 (Th1) and Th17 were reduced, which were validated by in vitro studies. In line with our in vitro data, we found that inflammatory cytokines [tumour necrosis factor‐α (TNF), interleukin (IL)5, IL6, IL1B] were also downregulated in T cells from patients (all P < 0·05). Finally, we showed that ruxolitinib does not interfere with the T cell receptor signalling pathway, but impacts IL2‐dependent STAT5 activation. These data provide a rationale for testing JAK inhibitors in diseases triggered by hyperactive CD4⁺ T cells, such as autoimmune diseases. In addition, they also provide a potential explanation for the increased infection rates (i.e. viral reactivation and urinary tract infection) seen in ruxolitinib‐treated patients.