Glioblastoma (GBM) is the most lethal primary brain tumor in adults. No treatment provides durable relief for the vast majority of GBM patients. In this study, we9ve tested a bispecific antibody comprised of single-chain variable fragments (scFvs) against T cell CD3ε and GBM cell interleukin 13 receptor alpha 2 (IL13Rα2). We demonstrate that this bispecific T cell engager (BiTE) (BiTE^LLON) engages peripheral and tumor-infiltrating lymphocytes harvested from patients9 tumors and, in so doing, exerts anti-GBM activity ex vivo. The interaction of BiTE^LLON with T cells and IL13Rα2-expressing GBM cells stimulates T cell proliferation and the production of proinflammatory cytokines interferon γ (IFNγ) and tumor necrosis factor α (TNFα). We have modified neural stem cells (NSCs) to produce and secrete the BiTE^LLON (NSC^LLON). When injected intracranially in mice with a brain tumor, NSC^LLON show tropism for tumor, secrete BiTE^LLON, and remain viable for over 7 d. When injected directly into the tumor, NSC^LLON provide a significant survival benefit to mice bearing various IL13Rα2⁺ GBMs. Our results support further investigation and development of this therapeutic for clinical translation. Significance Glioblastoma (GBM) is the most aggressive and lethal brain tumor in adults. The GBM microenvironment is highly immunosuppressive, rendering T cells incapable of recognizing and eliminating malignant cells. We developed bispecific T cell engagers (BiTEs) that successfully engage patients9 T cells to attack and kill GBM expressing interleukin 13 receptor alpha 2 (IL13Rα2). Neural stem cells (NSCs) engineered to secrete BiTE migrate readily within the brain tissue to established tumors and produce BiTE protein within the malignant tissue. Treatment of animals bearing IL13Rα2-expressing patient-derived GBM xenografts with therapeutic NSCs resulted in significant survival benefits in mice. These results show an exciting potential of NSCs as a delivery platform for BiTE therapy to improve outcomes for GBM patients.

Idiopathic pulmonary fibrosis (IPF) is characterized by exuberant deposition of extracellular matrix components, leading to the deterioration of lung architecture and respiratory functions. Profibrotic mechanisms are controlled by multiple regulatory molecules, including MAPKs, in turn regulated by multiple phosphorylation cascades. MAP3K8 is an MAPK kinase kinase suggested to pleiotropically regulate multiple pathogenic pathways in the context of inflammation and cancer; however, a possible role in the pathogenesis of IPF has not been investigated. In this report, MAP3K8 mRNA levels were found decreased in the lungs of IPF patients and of mice upon bleomycin-induced pulmonary fibrosis. Ubiquitous genetic deletion of Map3k8 in mice exacerbated the modeled disease, whereas bone marrow transfer experiments indicated that although MAP3K8 regulatory functions are active in both hematopoietic and nonhematopoietic cells, Map3k8 in hematopoietic cells has a more dominant role. Macrophage-specific deletion of Map3k8 was further found to be sufficient for disease exacerbation thus confirming a major role for macrophages in pulmonary fibrotic responses and suggesting a main role for Map3k8 in the homeostasis of their effector functions in the lung. Map3k8 deficiency was further shown to be associated with decreased Cox-2 expression, followed by a decrease in PGE₂ production in the lung; accordingly, exogenous administration of PGE₂ reduced inflammation and reversed the exacerbated fibrotic profile of Map3k8^−/− mice. Therefore, MAP3K8 has a central role in the regulation of inflammatory responses and Cox-2–mediated PGE₂ production in the lung, and the attenuation of its expression is integral to pulmonary fibrosis development. Key Points Pulmonary fibrosis entails a transcriptional downregulation of Map3k8 expression. Map3k8 suppress pulmonary fibrosis via Cox-2–mediated PGE₂ production.

Immune checkpoint inhibitors (ICI) have transformed the treatment of melanoma. However, the majority of patients have primary or acquired resistance to ICIs, limiting durable responses and patient survival. IFNγ signaling and the expression of IFNγ-stimulated genes correlate with either response or resistance to ICIs, in a context-dependent manner. While IFNγ-inducible immunostimulatory genes are required for response to ICIs, chronic IFNγ signaling induces the expression of immunosuppressive genes, promoting resistance to these therapies. Here, we show that high levels of Unc-51 like kinase 1 (ULK1) correlate with poor survival in patients with melanoma and overexpression of ULK1 in melanoma cells enhances IFNγ-induced expression of immunosuppressive genes, with minimal effects on the expression of immunostimulatory genes. In contrast, genetic or pharmacologic inhibition of ULK1 reduces expression of IFNγ-induced immunosuppressive genes. ULK1 binds IRF1 in the nuclear compartment of melanoma cells, controlling its binding to the programmed death-ligand 1 promoter region. In addition, pharmacologic inhibition of ULK1 in combination with anti-programmed cell death protein 1 therapy further reduces melanoma tumor growth in vivo. Our data suggest that targeting ULK1 represses IFNγ-dependent immunosuppression. These findings support the combination of ULK1 drug-targeted inhibition with ICIs for the treatment of patients with melanoma to improve response rates and patient outcomes. Implications: This study identifies ULK1, activated downstream of IFNγ signaling, as a druggable target to overcome resistance mechanisms to ICI therapy in metastatic melanoma.

It remains elusive why some triple-negative breast cancer (TNBC) patients respond poorly to existing therapies while others respond well. Our retrospective analysis of historical gene expression datasets reveals that increased expression of immunosuppressive cytokine S100A8/A9 in early-stage tumors is robustly associated with subsequent disease progression in TNBC. Although it has recently gained recognition as a potential anticancer target, S100A8/A9 has not been integrated into clinical study designs evaluating molecularly targeted therapies. Our small molecule screen has identified PIM kinase inhibitors as capable of decreasing S100A8/A9 expression in multiple cell types, including TNBC and immunosuppressive myeloid cells. Furthermore, combining PIM inhibition and immune checkpoint blockade induces significant antitumor responses, especially in otherwise resistant S100A8/A9-high PD-1/PD-L1-positive tumors. Importantly, serum S100A8/A9 levels mirror those of tumor S100A8/A9 in a syngeneic mouse model of TNBC. Thus, our data suggest that S100A8/A9 could be a predictive and pharmacodynamic biomarker in clinical trials evaluating combination therapy targeting PIM and immune checkpoints in TNBC and encourage the development of S100A8/A9-based liquid biopsy tests.

List of the putative ULK1 interactor proteins identified by mass spectrometry analysis in A375 cells

We examined the role of SLFN12, a member of the Schlafen (SLFN) family of interferon-regulated genes and proteins in leukemogenesis, and its potential as a therapeutic target in acute myeloid leukemia (AML). We explored the effects of velcrins, a class of small molecules able to modulate SLFN12 biological activity, on AML cells. Velcrin treatment of AML cells stabilized SLFN12 and promoted SLFN12 complex formation with phosphodiesterase 3A or phosphodiesterase 3B. Such effects were associated with growth-inhibitory and proapoptotic responses, as well as potent suppressive effects on leukemic cell growth. In addition, velcrin treatment suppressed clonogenic capacity of primitive leukemic progenitors and significantly extended survival in a mouse AML xenograft model. Taken together, these findings establish an important role of SLFN12 in leukemogenesis and raise the potential for the use of velcrins as a therapeutic strategy for AML.Significance:Our studies identify SLFN12 as a potential target in AML with important clinical–translational implications.