Despite substantial progress in lung cancer immunotherapy, the overall response rate in patients with
-mutant lung adenocarcinoma (LUAD) remains low. Combining standard immunotherapy with adjuvant ...approaches that enhance adaptive immune responses-such as epigenetic modulation of antitumor immunity-is therefore an attractive strategy. To identify epigenetic regulators of tumor immunity, we constructed an epigenetic-focused single guide RNA library and performed an
CRISPR screen in a
/
LUAD model. Our data showed that loss of the histone chaperone
in tumor cells sensitizes tumors to anti-PD-1 treatment. Mechanistic studies revealed that tumor cell-intrinsic
deficiency induced immunogenic macrophage differentiation in the tumor microenvironment by upregulating GM-CSF expression and potentiated T-cell activation in combination with anti-PD-1. Our results provide a rationale for a novel combination therapy consisting of ASF1A inhibition and anti-PD-1 immunotherapy. SIGNIFICANCE: Using an
epigenetic CRISPR screen, we identified
as a critical regulator of LUAD sensitivity to anti-PD-1 therapy.
deficiency synergized with anti-PD-1 immunotherapy by promoting M1-like macrophage polarization and T-cell activation. Thus, we provide a new immunotherapeutic strategy for this subtype of patients with LUAD.
.
.
Purpose: The vascular targeting antibody bavituximab is being combined with chemotherapy in clinical trials in cancer patients. Bavituximab
targets the membrane phospholipid, phosphatidylserine, ...complexed with β2-glycoprotein I. Phosphatidylserine is normally intracellular
but becomes exposed on the luminal surface of vascular endothelium in tumors. Phosphatidylserine exposure on tumor vessels
is increased by chemotherapy and irradiation. Here, we determined whether treatment with the murine equivalent of bavituximab,
2aG4, combined with irradiation can suppress tumor growth in a rat model of glioblastoma.
Experimental Design: F98 glioma cells were injected into the brains of syngeneic rats where they grow initially as a solid tumor and then infiltrate
throughout the brain. Rats with established tumors were treated with 10 Gy whole brain irradiation and 2aG4.
Results: Combination treatment doubled the median survival time of the rats, and 13% of animals were rendered disease free. Neither
treatment given individually was as effective. We identified two mechanisms. First, irradiation induced phosphatidylserine
exposure on tumor blood vessels and enhanced antibody-mediated destruction of tumor vasculature by monocytes/macrophages.
Second, the antibody treatment induced immunity to F98 tumor cells, which are normally weakly immunogenic. Surviving rats
were immune to rechallenge with F98 tumor cells. In vitro, 2aG4 enhanced the ability of dendritic cells (DCs) to generate F98-specific cytotoxic T cells. Phosphatidylserine exposure,
which is induced on tumor cells by irradiation, likely suppresses tumor antigen presentation, and 2aG4 blocks this tolerogenic
effect.
Conclusion: Bavituximab combined with radiotherapy holds promise as a vascular targeting and immune enhancement strategy for the treatment
of human glioblastoma. (Clin Cancer Res 2009;15(22):6871–80)
Purpose: New treatment strategies aimed at damaging tumor vasculature could potentially improve tumor response to radiation therapy.
We recently showed that anionic phospholipids, principally ...phosphatidylserine, are specifically exposed on the luminal surface
of tumor blood vessels. Here we tested the hypothesis that radiation therapy can increase phosphatidylserine exposure on lung
tumor vasculature, thereby enhancing the antitumor properties of the anti-phosphatidylserine antibody 2aG4.
Experimental Design: The therapeutic efficacy of radiation therapy plus 2aG4 was tested in nude mice bearing radiation-resistant A549 human lung
tumors. Radiation-induced phosphatidylserine exposure on endothelial cells and A549 tumor cells was analyzed by immunofluoresence
staining. The mechanism of the enhanced antitumor effect was examined by histology and antibody-dependent cell-mediated cytotoxicity
experiments.
Results: Focal irradiation of A549 human lung cancer xenografts increased the percentage of tumor vessels with exposed phosphatidylserine
from 4% to 26%. Treatment of mice bearing A549 tumors with 2aG4 plus focal radiation therapy inhibited tumor growth by 80%
and was superior to radiation therapy or 2aG4 alone ( P < 0.01). Combination therapy reduced blood vessel density and enhanced monocyte infiltration into the tumor mass beyond that
observed with individual treatments. In vitro , 2aG4 enhanced the ability of macrophages to kill endothelial cells with exposed phosphatidylserine in an Fc′-dependent manner.
Conclusion: These results suggest that 2aG4 enhances the antitumor effects of radiation therapy by increasing antibody-dependent cell-mediated
cytotoxicity toward tumor vessels with externalized phosphatidylserine. Bavituximab, a chimeric version of 2aG4 in clinical
trials, has the potential to enhance the therapeutic efficacy of radiation therapy in lung cancer patients.
Despite advancements in treatment options, the overall cure and survival rates for non-small cell lung cancers (NSCLC) remain low. While small-molecule inhibitors of epigenetic regulators have ...recently emerged as promising cancer therapeutics, their application in patients with NSCLC is limited. To exploit epigenetic regulators as novel therapeutic targets in NSCLC, we performed pooled epigenome-wide CRISPR knockout screens
and
and identified the histone chaperone nucleophosmin 1 (
) as a potential therapeutic target. Genetic ablation of
significantly attenuated tumor progression
and
. Furthermore,
-mutant cancer cells were more addicted to NPM1 expression. Genetic ablation of
rewired the balance of metabolism in cancer cells from predominant aerobic glycolysis to oxidative phosphorylation and reduced the population of tumor-propagating cells. Overall, our results support
as a therapeutic vulnerability in NSCLC. SIGNIFICANCE: Epigenome-wide CRISPR knockout screens identify
as a novel metabolic vulnerability and demonstrate that targeting
is a new therapeutic opportunity for patients with NSCLC.
We developed a screening assay in which luciferized ID8 expressing OVA was cocultured with transgenic CD8
T cells specifically recognizing the model antigen in an H-2b-restricted manner. The assay ...was screened with a small-molecule library to identify compounds that inhibit or enhance T cell-mediated killing of tumor cells. Erlotinib, an EGFR inhibitor, was the top compound that enhanced T-cell killing of tumor cells. Subsequent experiments with erlotinib and additional EGFR inhibitors validated the screen results. EGFR inhibitors increased both basal and IFNγ-induced MHC class-I presentation, which enhanced recognition and lysis of tumor cell targets by CD8
cytotoxic T lymphocytes. The ID8 cell line was also transduced to constitutively express Cas9, and a pooled CRISPR screen, utilizing the same target tumor cell/T-cell assay, identified single-guide (sg)RNAs targeting
that sensitized tumor cells to T cell-mediated killing. Combination of PD-1 blockade with EGFR inhibition showed significant synergistic efficacy in a syngeneic model, further validating EGFR inhibitors as immunomodulatory agents that enhance checkpoint blockade. This assay can be screened in high-throughput with small-molecule libraries and genome-wide CRISPR/Cas9 libraries to identify both compounds and target genes, respectively, that enhance or inhibit T-cell recognition and killing of tumor cells. Retrospective analyses of squamous-cell head and neck cancer (SCCHN) patients treated with the combination of afatinib and pembrolizumab demonstrated a rate of clinical activity exceeding that of each single agent. Prospective clinical trials evaluating the combination of an EGFR inhibitor and PD-1 blockade should be conducted.
B lymphocyte stimulator (BLyS) is a member of the TNF superfamily of cytokines. The biological activity of BLyS is mediated by three cell surface receptors: BR3/BAFF-R, TACI and BCMA. The expression ...of these receptors is highly restricted to B cells, both normal and malignant. A BLyS-gelonin fusion toxin (BLyS-gel) was generated consisting of the recombinant plant-derived toxin gelonin fused to the N-terminus of BLyS and tested against a large and diverse panel of B-NHL cell lines. Interestingly, B-NHL subtypes mantle cell lymphoma (MCL), diffuse large B cell lymphoma (DLBCL) and B cell precursor-acute lymphocytic leukemia (BCP-ALL) were preferentially sensitive to BLyS-gel mediated cytotoxicity, with low picomolar EC(50) values. BLyS receptor expression did not guarantee sensitivity to BLyS-gel, even though the construct was internalized by both sensitive and resistant cells. Resistance to BLyS-gel could be overcome by treatment with the endosomotropic drug chloroquine, suggesting BLyS-gel may become trapped within endosomal/lysosomal compartments in resistant cells. BLyS-gel induced cell death was caspase-independent and shown to be at least partially mediated by the "ribotoxic stress response." This response involves activation of p38 MAPK and JNK/SAPK, and BLyS-gel mediated cytotoxicity was inhibited by the p38/JNK inhibitor SB203580. Finally, BLyS-gel treatment was shown to localize to sites of disease, rapidly reduce tumor burden, and significantly prolong survival in xenograft mouse models of disseminated BCP-ALL, DLBCL, and MCL. Together, these findings suggest BLyS has significant potential as a targeting ligand for the delivery of cytotoxic "payloads" to malignant B cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mapatumumab and lexatumumab are fully human monoclonal antibodies that bind and activate human tumor necrosis factor-related
apoptosis-inducing ligand receptors 1 and 2, respectively. These ...antibodies induce apoptosis in various tumor cell types,
although the degree of sensitivity can vary from highly sensitive to completely resistant. Importantly, tumor cells that are
partially or completely resistant to mapatumumab or lexatumumab can often be sensitized when treated in combination with chemotherapeutic
drugs. In this regard, the proteasome inhibitor bortezomib has recently shown synergistic activity against established lymphoma
cell lines and primary lymphomas when combined with mapatumumab and lexatumumab. Here, we report similar findings using a
panel of human non-small cell lung cancer (NSCLC) cell lines. Specifically, we show that bortezomib rapidly induces sensitivity
to mapatumumab and lexatumumab in NSCLC cell lines that are completely resistant to antibody alone and that bortezomib concentrations
as low as 25 nmol/L sensitize NSCLC cells to the antibodies. Furthermore, bortezomib at the tested concentration has minimal
effect on its own, indicating the combination generates synergistic cytotoxicity. Combination treatment induces activation
of the caspase cascade and the effect of the combination is caspase dependent. Bortezomib treatment increases the intracellular
levels of several important apoptosis regulators that may mediate enhanced sensitivity to mapatumumab and lexatumumab. These
results suggest future evaluation of mapatumumab or lexatumumab in combination with bortezomib is warranted in NSCLC patients.
Mol Cancer Ther 2009;8(2):292–302
Importance of the field: Agents that activate the TNF-related apoptosis-inducing ligand death receptors, TRAIL-R1 and TRAIL-R2, have attracted substantial attention and investment as potential ...anti-cancer therapies. Preclinical studies of TRAIL-R agonists indicate that they may be efficacious in a wide range of tumor types, especially when combined with chemotherapeutic agents.
Areas covered in this review: The rationale for clinical development of TRAIL-R agonists is described, including the basis for combining these agents with other agents that modulate the 'checks and balances' of the apoptotic pathways. Accruing data that highlight differences between TRAIL-R1 and TRAIL-R2 that could affect the clinical significance of their specific agonists are described. The clinical experience to date with each of the agonists is summarized.
What the reader will gain: The reader will gain an understanding of the rationale for the clinical development of TRAIL-R agonists, as well as the current status of clinical trials of these interesting new agents.
Take home message: Ongoing clinical trials will provide important information regarding the future development of TRAIL-R agonists.
BackgroundThe success of T cell therapies for the treatment of solid tumors has been limited. Factors limiting efficacy in solid tumors are poor infiltration, exhaustion, and an immunosuppressive ...tumor microenvironment (TME).MethodsTo address these issues, we developed multiple mouse syngeneic tumor models to conduct in vivo CRISPR screening to identify Immune Enhancing Edits (IEEs) that augment CD8+ T cell function across TMEs. Several IEEs were validated in multiple mouse syngeneic solid tumor models, displaying significant in vivo tumor control. To better understand the therapeutic potential in human T cells, we engineered Wilms Tumor 1 (WT1)-specific TCR-T cells with these IEEs and tested them against WT1-expressing human solid tumor xenografts.ResultsWT1-specific TCR-T cells with either single IEE or a combination of IEEs induced tumor regression across multiple human tumor models. These IEE targets were also able to enhance CAR-based T cell therapies against solid tumors, adding to the broad applicability of this platform.ConclusionsCoupling CRISPR-engineered immune enhancements with our allogeneic platform, Intellia is creating next-generation cell therapies for the treatment of solid tumors.Ethics ApprovalThe mouse studies described here have been performed in compliance with protocols approved by Intellia Therapeutics’ IACUC (Institutional Animal Care and Use Committee). (Mainly protocol number IT008)
A promising target on tumor vasculature is phosphatidylserine (PS), an anionic phospholipid that resides exclusively on the inner leaflet of the plasma membrane of resting mammalian cells. We have ...shown previously that PS becomes exposed on the surface of endothelial cells (EC) in solid tumors. To target PS on tumor vasculature, the murine monoclonal antibody 3G4 was developed. 3G4 localizes to tumor vasculature, inhibits tumor growth, and enhances anti-tumor chemotherapies without toxicity in mice. A chimeric version of 3G4 is in clinical trials. In this study, we investigated the basis for the interaction between 3G4 and EC with surface-exposed PS. We demonstrate that antibody binding to PS is dependent on plasma protein β-2-glycoprotein 1 (β2GP1). β2GP1 is a 50-kDa glycoprotein that binds weakly to anionic phospholipids under physiological conditions. We show that 3G4 enhances binding of β2GP1 to EC induced to expose PS. We also show that divalent 3G4-β2GP1 complexes are required for enhanced binding, since 3G4 Fab′ fragments do not bind EC with exposed PS. Finally, we demonstrate that an artificial dimeric β2GP1 construct binds to EC with exposed PS in the absence of 3G4, confirming that antibody binding is mediated by dimerization of β2GP1. Together, these data indicate that 3G4 targets tumor EC by increasing the avidity of β2GP1 for anionic phospholipids through formation of multivalent 3G4-β2GP1 complexes.
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