Survival Of Tumor-bearing Mice Research Articles

Detoxified pneumolysin derivative ΔA146Ply inhibits triple- negative breast cancer metastasis mainly via mannose receptor-mediated autophagy inhibition

ABSTRACT The detoxified pneumolysin derivative ΔA146Ply has been proven to have a direct anti-triple negative breast cancer effect by our group, but its work model remains unclear. In this study, we focused on its ability to inhibit triple-negative breast cancer metastasis. We found that ΔA146Ply suppressed the migration and invasion of triple-negative breast cancer cells by activating mannose receptor and toll-like receptor 4. Their activation triggers the activation of the mammalian target of rapamycin signaling, sequentially leading to autophagy, transforming growth factor-β1, and epithelial-mesenchymal transition inhibition. Furthermore, the combination of doxorubicin and ΔA146Ply significantly inhibited triple-negative breast cancer progression and prolonged survival in tumor-bearing mice. Taken together, our study provides an alternative microbiome-based mannose receptor-targeted therapy for triple-negative breast cancer and a novel theoretical and experimental basis for the downstream signaling pathway of the mannose receptor.

A paracrine circuit of IL-1β/IL-1R1 between myeloid and tumor cells drives genotype-dependent glioblastoma progression.

Monocytes and monocyte-derived macrophages (MDMs) from blood circulation infiltrate glioblastoma (GBM) and promote growth. Here, we show that PDGFB-driven GBM cells induce the expression of the potent proinflammatory cytokine IL-1β in MDM, which engages IL-1R1 in tumor cells, activates the NF-κB pathway, and subsequently leads to induction of monocyte chemoattractant proteins (MCPs). Thus, a feedforward paracrine circuit of IL-1β/IL-1R1 between tumors and MDM creates an interdependence driving PDGFB-driven GBM progression. Genetic loss or locally antagonizing IL-1β/IL-1R1 leads to reduced MDM infiltration, diminished tumor growth, and reduced exhausted CD8+ T cells and thereby extends the survival of tumor-bearing mice. In contrast to IL-1β, IL-1α exhibits antitumor effects. Genetic deletion of Il1a/b is associated with decreased recruitment of lymphoid cells and loss-of-interferon signaling in various immune populations and subsets of malignant cells and is associated with decreased survival time of PDGFB-driven tumor-bearing mice. In contrast to PDGFB-driven GBM, Nf1-silenced tumors have a constitutively active NF-κB pathway, which drives the expression of MCPs to recruit monocytes into tumors. These results indicate local antagonism of IL-1β could be considered as an effective therapy specifically for proneural GBM.

Preclinical Characterization of AZD9574, a Blood-Brain Barrier Penetrant Inhibitor of PARP1.

We evaluated the properties and activity of AZD9574, a blood-brain barrier (BBB) penetrant selective inhibitor of PARP1, and assessed its efficacy and safety alone and in combination with temozolomide (TMZ) in preclinical models. AZD9574 was interrogated in vitro for selectivity, PARylation inhibition, PARP-DNA trapping, the ability to cross the BBB, and the potential to inhibit cancer cell proliferation. In vivo efficacy was determined using subcutaneous as well as intracranial mouse xenograft models. Mouse, rat, and monkey were used to assess AZD9574 BBB penetration and rat models were used to evaluate potential hematotoxicity for AZD9574 monotherapy and the TMZ combination. AZD9574 demonstrated PARP1-selectivity in fluorescence anisotropy, PARylation, and PARP-DNA trapping assays and in vivo experiments demonstrated BBB penetration. AZD9574 showed potent single agent efficacy in preclinical models with homologous recombination repair deficiency in vitro and in vivo. In an O6-methylguanine-DNA methyltransferase (MGMT)-methylated orthotopic glioma model, AZD9574 in combination with TMZ was superior in extending the survival of tumor-bearing mice compared with TMZ alone. The combination of three key features-PARP1 selectivity, PARP1 trapping profile, and high central nervous system penetration in a single molecule-supports the development of AZD9574 as the best-in-class PARP inhibitor for the treatment of primary and secondary brain tumors. As documented by in vitro and in vivo studies, AZD9574 shows robust anticancer efficacy as a single agent as well as in combination with TMZ. AZD9574 is currently in a phase I trial (NCT05417594). See related commentary by Lynce and Lin, p. 1217.

EXTH-21. FKBP38 REGULATES SELF-RENEWAL AND SURVIVAL OF GBM NEUROSPHERES

Abstract Glioblastoma (GBM) is the most common malignant primary brain tumor. The outcome is dismal, despite the multimodal therapeutic approach that includes surgical resection followed by radiation and chemotherapy. The quest for novel therapeutic targets to treat GBM is underway. FKBP38, a member of the immunophilin family of proteins, is a multidomain protein that plays an important role in the regulation of cellular functions including apoptosis and autophagy. In this study, we tested the role of FKBP38 in GBM tumor biology. Expression of FKBP38 is upregulated in the patient-derived primary GBM neurospheres (GBMNS) compared to normal human astrocytes. Attenuation of FKBP38 expression decreased the viability of GBMNS and increased the caspase 3/7 activity indicating that FKBP38 is required for the survival of GBMNS. Further, the depletion of FKBP38 significantly reduced the number of neurospheres that were formed implying that FKBP38 regulates the self-renewal of GBMNS. Also, the transient knockdown of FKBP38 increased the LC3-II/I ratio suggesting the induction of autophagy with the depletion of FKBP38. Further investigation showed that the negative regulation of autophagy by FKBP38 in GBMNS is mediated through the JNK/C-Jun-PTEN-AKT pathway. In vivo, FKBP38 depletion significantly extended the survival of tumor-bearing mice. Overall, our results suggest targeting FKBP38 imparts an anti-GBM effect by inducing apoptosis and autophagy and thus can be a potential therapeutic target for GBM therapy.

DNAR-12. ATR INHIBITION AS A NOVEL RADIOSENSITIZATION STRATEGY FOR GLIOBLASTOMA

Abstract Glioblastomas (GBM) are lethal brain tumors for which surgical resection followed by ionizing radiation (IR) with concurrent and adjuvant Temozolomide (TMZ) remains the mainstay of therapy. GBMs are extremely radioresistant, and radiosensitization approaches are desperately needed for these tumors. IR induces DNA double-strand breaks (DSBs), and these lesions can be repaired either by error-prone non-homologous end joining (NHEJ) or the error-free homologous recombination (HR) pathway. Research in our and other laboratories has shown that the ATR kinase promotes the HR pathway. We therefore hypothesized that ATR inhibition would block DSB repair in rapidly-dividing GBM cells that are HR dependent but not in non-dividing normal brain cells that are dependent upon NHEJ for repair. We treated a panel of GBM cell lines and normal human astrocytes with the ATR inhibitor VX-803 and/or IR and assessed for multiple endpoints including HR, DSB repair, and cell survival. We found that VX-803 blocks HR and DSB repair in GBM cells but does not significantly affect repair in non-dividing normal human astrocytes. Hence, treatment with VX-803 sensitizes GBM lines to IR in vitro as measured by the colony formation assay. Next, PDX mouse models of GBM were treated with VX-803 followed by XRT, and monitored for tumor growth and survival. We found that the drug can cross the blood-brain barrier and, in conjunction with IR, block DNA repair in intracranial tumors, attenuate tumor growth, and consequently extend survival of tumor-bearing mice. Importantly, the drug does not significantly affect DSB repair in normal brain cells indicating that ATR inhibition might selectively block repair in GBM cells, thereby minimizing normal tissue toxicity. Our results indicate that regulation of HR by ATR is critical for optimal DSB repair, especially in rapidly-dividing GBM cells, and that ATR inhibition could be used to improve GBM radiotherapy in the clinic.

CSIG-17. NICOTINAMIDE N-METHYLTRANSFERASE (NNMT) AS A POTENTIAL THERAPEUTIC TARGET FOR EGFRVIII-DRIVEN GLIOBLASTOMA

Abstract Nicotinamide N-methyltransferase (NNMT) is an enzymatic catalyst involved in converting methyl groups from S-adenosyl-L-methionine (SAM) to nicotinamide (NAM), generating S-adenosine hyperblastoids (SAH) and 1-methylnicotinamide (MNA). Increased NNMT expression is frequently observed in various cancers and is associated with tumor progression, metastasis, unfavorable clinical outcomes, and drug resistance. Notably, NNMT stands out as one of the most up-regulated metabolism-related genes in glioblastoma, although the underlying mechanism for its overexpression remains elusive. Glioblastoma commonly exhibits genetic lesions in the epidermal growth factor receptor (EGFR) gene, including amplification or mutation, with EGFRvIII being the predominant mutant contributing to glioblastoma cell proliferation, invasion, therapeutic resistance, metastasis, and stemness. In this study, we demonstrate that activation of wild-type EGFR by EGF or the constitutively active mutant EGFRvIII promotes NNMT expression and enzyme activity in established glioblastoma cell lines and glioblastoma stem-like cells via the p38 mitogen-activated protein kinase pathway. Additionally, we identify STAT1 as a downstream transcription factor essential for EGFR/EGFRvIII-induced NNMT upregulation. RNA interference-mediated knockdown of NNMT in glioblastoma cells significantly inhibits EGFRvIII-promoted invasion and proliferation in vitro. Targeting NNMT effectively suppresses EGFRvIII-driven glioblastoma tumorigenicity and prolongs the survival of tumor-bearing mice. Clinically, NNMT is highly expressed and positively correlated with EGFR expression in human glioblastoma tumors. Collectively, these findings establish NNMT as a previously unrecognized downstream target gene of EGFR/EGFRvIII expression and highlight its potential as a therapeutic target for inhibiting EGFRvIII-driven glioblastoma.

Single-Cell Multi-Omics Reveals Type-2 Functionality in Maintaining CAR T Cell Longevity Associated with 8-Year Leukemia Remission

Despite a high response rate in chimeric antigen receptor (CAR) T therapy for acute lymphocytic leukemia (ALL), ~50% of patients relapse within the first year, representing an urgent question to address in the next stage of cellular immunotherapy. The pioneering clinical trials conducted at Upenn/CHOP provide a unique opportunity to examine the molecular determinants of ultra-long CAR T persistence. We performed single-cell multi-omics profiling of ~700k pre-infusion CD19-targeted 4-BB CAR T cells from 82 pediatric ALL patients and 6 healthy donors. Patient demographics were collected between Sep-2012 to July-2022. To uncover the hallmarks of CAR T longevity, we correlated the single-cell atlas with the duration of B-cell aplasia (BCA), a widely used pharmacodynamic measurement of CAR T persistence, and classified all the patients into 5 groups (Table 1). Five patients in our cohort have exhibited a median BCA duration of 8.4 years (BCA-L group) and another 11 patients continue to have BCA with a median time of 5.1 years (BCA-O group). To remove potential confounding variables between trial design, 42 patients including the 5 BCA-L were analyzed as the Discovery Cohort, while the other 40 patients including the 11 BCA-O were used as Validation Cohort. Our analysis of CD19-specific stimulated CAR T cells from the Discovery Cohort revealed a prominent role of type-1 function, which was highly represented but had no discernible correlation with long-term persistence. Unexpectedly, we identified that elevated type-2 functionality was significantly associated with BCA-L patients maintaining CAR T persistence of 8.4 years, and this signature was robustly presented in the BCA-O patients in our Validation Cohort. Higher type-2 cytokine level of long-term persistent CAR T cells was independently validated using both flow cytometry and multiplexed secretomic assay. Through ligand-receptor interaction analysis, type-2 cytokines were found to regulate a cluster of Tim-3+terminal effector cells showing over activation of cytotoxicity, impaired immune function, elevated exhaustion signature and diminished proliferative potentiality, and CAR T cells from BCA-L patients showed reduced dysfunctional hallmarks. We next conducted in vitro functional studies to assess the impact of adding type-2 cytokine (IL-4) during CAR-specific activation on CAR T fitness. The addition of 10ng/mL IL-4 significantly boosted the proliferation and mitigated dysfunction of CAR T cells from 6 patients in the BCA2 group that only mediated short-term response (~3 months) and had negligible impact on their type-1 functionality. Remarkably, the functional profile of short-term BCA2 CAR T cells after IL-4 supplementation exhibited a comparable pattern to that of long-term BCA-L CAR T cells, particularly in terms of type-2 pathway, oxidative phosphorylation metabolism, PI3K/AKT signaling, mTOR signaling, and cell cycle regulation. To investigate the response of the host following CAR T infusion, we performed a comprehensive proteomic profiling of post-infusion serum proteins in a total of 41 patients. Baseline measurements (-2 to 0 days before CAR T infusion) showed a significantly higher level of type-2 cytokines in long-term patients. From the rapid expansion period (day 6-8) until 11 days post-infusion, we consistently observed significantly higher levels of circulating type-2 cytokines in 5-year or 8-year relapse-free responders. Conversely, no difference was observed in type-1 cytokines. In a leukemic NSG mouse model, both type-2 high and low CAR T cells were highly effective in reducing tumor burden in the first two weeks. However, type-2 high CAR T had significantly superior expansion, and the absolute CAR+ cell counts in peripheral blood were 10-fold higher than type-2 low CAR T at day 8 and day 12. To mimic tumor cell relapse, a second dose of tumor cells were injected into mice on day 17. Notably, type-2 high CAR T cells demonstrated a potent capability to elicit recall responses upon leukemia rechallenge, significantly prolonging the survival of tumor-bearing mice compared to type-2 low CAR T. The superior performance could be associated with their decreased exhaustion and increased memory phenotype. Our findings provide key insights into the mediators of CAR T longevity and suggest a potential therapeutic strategy to maintain long-term remission by enhancing type-2 functionality in CAR T cells.

FKBP38 Regulates Self-Renewal and Survival of GBM Neurospheres.

Glioblastoma is the most common malignant primary brain tumor. The outcome is dismal, despite the multimodal therapeutic approach that includes surgical resection, followed by radiation and chemotherapy. The quest for novel therapeutic targets to treat glioblastoma is underway. FKBP38, a member of the immunophilin family of proteins, is a multidomain protein that plays an important role in the regulation of cellular functions, including apoptosis and autophagy. In this study, we tested the role of FKBP38 in glioblastoma tumor biology. Expression of FKBP38 was upregulated in the patient-derived primary glioblastoma neurospheres (GBMNS), compared to normal human astrocytes. Attenuation of FKBP38 expression decreased the viability of GBMNSs and increased the caspase 3/7 activity, indicating that FKBP38 is required for the survival of GBMNSs. Further, the depletion of FKBP38 significantly reduced the number of neurospheres that were formed, implying that FKBP38 regulates the self-renewal of GBMNSs. Additionally, the transient knockdown of FKBP38 increased the LC3-II/I ratio, suggesting the induction of autophagy with the depletion of FKBP38. Further investigation showed that the negative regulation of autophagy by FKBP38 in GBMNSs is mediated through the JNK/C-Jun-PTEN-AKT pathway. In vivo, FKBP38 depletion significantly extended the survival of tumor-bearing mice. Overall, our results suggest that targeting FKBP38 imparts an anti-glioblastoma effect by inducing apoptosis and autophagy and thus can be a potential therapeutic target for glioblastoma therapy.

The Oligosaccharyltransferase Complex: A Novel Vulnerability in Multiple Myeloma

Abstract Multiple myeloma (MM) is described as a clonal expansion of malignant plasma cells in the bone marrow characterized by several clinical symptoms: bone lesions, hypercalcemia, anemia, serum monoclonal gammopathy, immune suppression, and multiple organ failure. Despite the success of advanced treatments, disease relapse is common and incurable. Thus, there is an unmet clinical need to identify novel targets for relapsed/refractory MM treatment. The oligosaccharyltransferase (OST) complex catalyzes the transfer of N-glycan to a nascent translated protein which is a critical step in N-glycosylation, the most abundant post-translational modification of secretory and membrane-bound proteins. Aberrant expression of the OST complex or N-glycosylation is a diagnostic marker for solid tumors. However, the roles of the OST complex and N-glycosylation in MM development are virtually unknown. The mammal OST complex has two isoforms: OST-A and OST-B, with distinct catalytic subunits. Both isoforms share six subunits: OST4, RPN1, RPN2, DDOST, DAD1, and TMEM258. Analyzing the publicly available genomic data, we found that the shared subunits of the OST complex are abundantly expressed in MM cell lines and MM patient-derived cells. The expression levels of the OST subunits in relapsed MM patients are significantly higher than those in newly diagnosed MM patients. Intriguingly, patients expressing elevated levels of the OST complex are highly correlated with poor prognosis. These findings lead us to hypothesize that the OST complex might play a crucial role in MM. To address this hypothesis, we used the CRISPR/Cas9 system to knockout the OST's shared subunits and found that MM cells are dependent on the OST complex. Deletion of DDOST and DAD1 (two central structural subunits of the OST complex) impaired MM cell growth, arrested the cell cycle, and induced apoptosis. Using the subcutaneous xenograft model, we found that knockout of DDOST or DAD1 suppressed MM growth in vivo and extended the survival of tumor-bearing mice. Intriguingly, suppression of the OST complex's enzymatic activity by a specific inhibitor, NGI-1, recapitulated the phenotypes of the OST complex deletion. Of note, NGI-1 sensitizes the MM cells and bortezomib-resistant MM cells (both MM cell lines and primary patient cells) to bortezomib treatment. Mechanistically, we found that disruption of the OST complex in MM cells significantly suppressed transcriptomic signatures of MM pathology (NF-κB signaling, glycolysis, MYC targets, and cell cycle) and induced apoptosis pathway as well as inflammatory pathway (interferon alpha and gamma). Intriguingly, we found that all known genes responsible for the bortezomib-resistant phenotype were significantly downregulated upon the suppression of the OST complex. In conclusion, we identified the OST complex as a novel vulnerability in MM cells. Targeting the OST complex incorporation with Bortezomib might provide a novel and effective combined treatment for relapsed/refractory MM patients. We're currently investigating the underlying mechanisms of how the OST complex regulates MM pathology and developing patient-derived xenograft models to validate the therapeutic efficacy of combined treatment (NGI-1 and Bortezomib).

Plasmodium immunotherapy combined with gemcitabine has a synergistic inhibitory effect on tumor growth and metastasis in murine Lewis lung cancer models.

Our previous studies have demonstrated that Plasmodium immunotherapy (infection) has antitumor effects in mice. However, as a new form of immunotherapy, this therapy has a weakness: its specific killing effect on tumor cells is relatively weak. Therefore, we tested whether Plasmodium immunotherapy combined with gemcitabine (Gem), a representative chemotherapy drug, has synergistic antitumor effects. We designed subcutaneously and intravenously implanted murine Lewis lung cancer (LLC) models to test the antitumor effect of Plasmodium chabaudi ASS (Pc) infection in combination with Gem treatment and explored its underlying mechanisms. We found that both Pc infection alone and Gem treatment alone significantly inhibited tumor growth in the subcutaneous model, and combination therapy was more effective than either monotherapy. Monotherapy only tended to prolong the survival of tumor-bearing mice, while the combination therapy significantly extended the survival of mice, indicating a significant synergistic effect of the combination. In the mechanistic experiments, we found that the combination therapy significantly upregulated E-cadherin and downregulated Snail protein expression levels, thus inhibiting epithelial-mesenchymal transition (EMT) of tumor cells, which may be due to the blockade of CXCR2/TGF-β-mediated PI3K/Akt/GSK-3β signaling pathway. The combination of Pc and Gem plays a synergistic role in inhibiting tumor growth and metastasis, and prolonging mice survival in murine lung cancer models. These effects are partially attributed to the inhibition of EMT of tumor cells, which is potentially due to the blockade of CXCR2/TGF-β-mediated PI3K/Akt/GSK-3β/Snail signaling pathway. The clinical transformation of Plasmodium immunotherapy combined with Gem for lung cancer is worthy of expectation.

Intratumoral Administration of High-Concentration Nitric Oxide and Anti-mPD-1 Treatment Improves Tumor Regression Rates and Survival in CT26 Tumor-Bearing Mice.

Immune checkpoint inhibitors have transformed clinical oncology. However, their use is limited as response is observed in only ~20-50% of patients. Previously, we demonstrated that treating CT26 tumor-bearing mice with ultra-high-concentration gaseous nitric oxide (UNO) followed by tumor resection stimulated antitumor immune responses. Accordingly, UNO may improve tumor response to immune checkpoint inhibitors. Here, we investigated the ability of UNO to improve the efficacy of a programmed cell death protein-1 (PD-1) antibody in vitro and in treating CT26 tumor-bearing mice. CT26 cells were injected into the flank of Balb/c mice (n = 15-16 per group). On day 6, CT26 cells were injected into the contralateral flank, and anti-mPD-1 injections commenced. Primary tumors were treated with intratumoral UNO on day 8. Tumor volume, response rates, toxicity, and survival were monitored. (1) Short exposure to 25,000-100,000 parts per million (ppm) UNO in vitro resulted in significant upregulation of PD-L1 expression on CT26 cells. (2) UNO treatment in vivo consistently reduced cell viability in CT26 tumors. (3) Treatment reduced regulatory T-cell (Treg) levels in the tumor and increased levels of systemic M1 macrophages. UNO responders had increased CD8+ T-cell tumor infiltration. (4) Nine days after treatment, primary tumor growth was significantly lower in the combination arm vs. anti-mPD-1 alone (p = 0.0005). (5) Complete tumor regression occurred in 8/15 (53%) of mice treated with a combination of 10 min UNO and anti-mPD-1, 100 days post-treatment, compared to 4/16 (25%) of controls treated with anti-mPD-1 alone (p = 0.1489). (6) There was no toxicity associated with UNO treatment. (7) Combination treatment showed a trend toward increased survival 100 days post-treatment compared to anti-mPD-1 alone (p = 0.0653). Combining high-concentration NO and immune checkpoint inhibitors warrants further assessment especially in tumors resistant to checkpoint inhibitor therapy.

Overcoming lung cancer immunotherapy resistance by combining nontoxic variants of IL-12 and IL-2.

Engineered cytokine-based approaches for immunotherapy of cancer are poised to enter the clinic, with IL-12 being at the forefront. However, little is known about potential mechanisms of resistance to cytokine therapies. We found that orthotopic murine lung tumors were resistant to systemically delivered IL-12 fused to murine serum albumin (MSA, IL12-MSA) because of low IL-12 receptor (IL-12R) expression on tumor-reactive CD8+ T cells. IL2-MSA increased binding of IL12-MSA by tumor-reactive CD8+ T cells, and combined administration of IL12-MSA and IL2-MSA led to enhanced tumor-reactive CD8+ T cell effector differentiation, decreased numbers of tumor-infiltrating CD4+ regulatory T cells, and increased survival of lung tumor-bearing mice. Predictably, the combination of IL-2 and IL-12 at therapeutic doses led to significant dose-limiting toxicity. Administering IL-12 and IL-2 analogs with preferential binding to cells expressing Il12rb1 and CD25, respectively, led to a significant extension of survival in mice with lung tumors while abrogating dose-limiting toxicity. These findings suggest that IL-12 and IL-2 represent a rational approach to combination cytokine therapy whose dose-limiting toxicity can be overcome with engineered cytokine variants.

A functional carbon dots induce ferroptosis by suppressing PLPP4 activity to inhibit glioblastoma growth

Glioblastoma is a fatal primary brain cancer lacking effective therapeutic drugs. The presence of the blood–brain barrier (BBB) severely hinders the delivery of drugs to the brain. In recent years, nanoparticles, especially carbon dots (CDs), are promising drug delivery strategy for CNS diseases. Here, we synthesized a novel carbon dots（MGA-CDs）for glioblastoma treatment by hydrothermal method using metformin and gallic acid as precursor. MGA-CDs shows dominant BBB permeability and sensitive anti-tumor activity. In addition, MGA-CDs exhibits significant capability of targeting tumor cells mitochondria without the aid of anyextra targeting molecules, resulting in the shrunken of mitochondria and reduced numbers of mitochondrial cristae. Transcriptome profiling suggested that MGA-CDs disturbs the glycerophospholipid metabolism pathway by inhibiting the expression of PLPP4, thereby inducing ferroptosis. The efficient therapeutic potency of MGA-CDs is further confirmed in human-derived orthotopic glioblastoma mice model. MGA-CDs significantly inhibited the growth of intracranial tumors and prolonged the survival of tumor-bearing mice. This work presents a viable strategy that development of CDs-based novel therapeutic agent for glioblastoma.

A Novel Allogeneic Rituximab-Conjugated Gamma Delta T Cell Therapy for the Treatment of Relapsed/Refractory B-Cell Lymphoma.

Chimeric antigen receptor T cell (CAR-T) therapy has been applied in the treatment of B-cell lymphoma; however, CAR-T manufacturing requires virus- or non-virus-based genetic modification, which causes high manufacturing costs and potential safety concerns. Antibody-cell conjugation (ACC) technology, which originated from bio-orthogonal click chemistry, provides an efficient approach for arming immune cells with cancer-targeting antibodies without genetic modification. Here, we applied ACC technology in Vγ9Vδ2 T (γδ2 T) cells to generate a novel off-the-shelf CD20-targeting cell therapy ACE1831 (rituximab-conjugated γδ2 T cells) against relapsed/refractory B-cell lymphoma. ACE1831 exhibited superior cytotoxicity against B-cell lymphoma cells and rituximab-resistant cells compared to γδ2 T cells without rituximab conjugation. The in vivo xenograft study demonstrated that ACE1831 treatment strongly suppressed the aggressive proliferation of B-cell lymphoma and prolonged the survival of tumor-bearing mice with no observed toxicity. Mass spectrometry analysis indicated that cell activation receptors including the TCR complex, integrins and cytokine receptors were conjugated with rituximab. Intriguingly, the antigen recognition of the ACC-linked antibody/receptor complex stimulated NFAT activation and contributed to ACE1831-mediated cytotoxicity against CD20-expressing cancer cells. This study elucidates the role of the ACC-linked antibody/receptor complex in cytotoxicity and supports the potential of ACE1831 as an off-the-shelf γδ2 cell therapy against relapsed/refractory B-cell lymphoma.

Discovery of Anti-CD47 Peptides as Innate Immune Checkpoint Inhibitors.

Cancer immunotherapy targeting adaptive immune cells has been attracting considerable interest due to its great success in treating multiple cancers. Recently, there is also increasing interest in agents that can stimulate innate immune cell activities. Immune checkpoint inhibitors targeting innate immune cells can block inhibitory interactions ('don't eat me' signals) between tumor cells and phagocytes. CD47 is a transmembrane protein overexpressed in various cancers and acts as a potent 'do not eat me' signal that contributes to the immune evasion of cancer cells. Anti-CD47 peptides that can bind to CD47 and block CD47/SIRPα interaction were discovered using a novel phage display biopanning strategy. Anti-CD47 peptides enhanced the macrophage-mediated phagocytosis of NCI-H82 tumor cells in vitro. Unlike anti-CD47 antibodies, these peptides do not induce the agglutination of RBCs. Moreover, anti-CD47 peptides exhibit high specificity for MC-38 cancer cells expressing CD47. CMP-22 peptide showed the ability to increase the antitumor activity of doxorubicin and extends the survival of CT26 tumor-bearing mice. The discovered anti-CD47 peptides can be considered potential candidates for cancer immunotherapy by blocking the CD47/SIRPα interaction, especially in combination with chemotherapy, to elicit synergistic effects.

Blockade of de novo pyrimidine biosynthesis triggers autophagic degradation of oncoprotein FLT3-ITD in acute myeloid leukemia.

The internal tandem duplication of the FMS-like tyrosine kinase 3 (FLT3-ITD) is one of the most frequent genetic alterations in acute myeloid leukemia (AML). Limited and transient clinical benefit of FLT3 kinase inhibitors (FLT3i) emphasizes the need for alternative therapeutic options for this subset of myeloid malignancies. Herein, we showed that FLT3-ITD mutant (FLT3-ITD+) AML cells were susceptible toward inhibitors of DHODH, a rate-limiting enzyme of de novo pyrimidine biosynthesis. Genetic and pharmacological blockade of DHODH triggered downregulation of FLT3-ITD protein, subsequently suppressed activation of downstream ERK and STAT5, and promoted cell death of FLT3-ITD+ AML cells. Mechanistically, DHODH blockade triggered autophagy-mediated FLT3-ITD degradation via inactivating mTOR, a potent autophagy repressor. Notably, blockade of DHODH synergized with an FDA-approved FLT3i quizartinib in significantly impairing the growth of FLT3-ITD+ AML cells and improving tumor-bearing mice survival. We further demonstrated that DHODH blockade exhibited profound anti-proliferation effect on quizartinib-resistant cells in vitro and in vivo. In summary, this study demonstrates that the induction of degradation of FLT3-ITD protein by DHODH blockade may offer a promising therapeutic strategy for AML patients harboring FLT3-ITD mutation.

Oct4 and Hypoxia Dual-Regulated Oncolytic Adenovirus Armed with shRNA-Targeting Dendritic Cell Immunoreceptor Exerts Potent Antitumor Activity against Bladder Cancer.

Immunotherapy has emerged as a promising modality for cancer treatment. Dendritic cell immunoreceptor (DCIR), a C-type lectin receptor, is expressed mainly by dendritic cells (DCs) and mediates inhibitory intracellular signaling. Inhibition of DCIR activation may enhance antitumor activity. DCIR is encoded by CLEC4A in humans and by Clec4a2 in mice. Gene gun-mediated delivery of short hairpin RNA (shRNA) targeting Clec4a2 into mice bearing bladder tumors reduces DCIR expression in DCs, inhibiting tumor growth and inducing CD8+ T cell immune responses. Various oncolytic adenoviruses have been developed in clinical trials. Previously, we have developed Ad.LCY, an oncolytic adenovirus regulated by Oct4 and hypoxia, and demonstrated its antitumor efficacy. Here, we generated a Clec4a2 shRNA-expressing oncolytic adenovirus derived from Ad.LCY, designated Ad.shDCIR, aimed at inducing more robust antitumor immune responses. Our results show that treatment with Ad.shDCIR reduced Clec4a expression in DCs in cell culture. Furthermore, Ad.shDCIR exerted cytolytic effects solely on MBT-2 bladder cancer cells but not on normal NIH 3T3 mouse fibroblasts, confirming the tumor selectivity of Ad.shDCIR. Compared to Ad.LCY, Ad.shDCIR induced higher cytotoxic T lymphocyte (CTL) activity in MBT-2 tumor-bearing immunocompetent mice. In addition, Ad.shDCIR and Ad.LCY exhibited similar antitumor effects on inhibiting tumor growth. Notably, Ad.shDCIR was superior to Ad.LCY in prolonging the survival of tumor-bearing mice. In conclusion, Ad.shDCIR may be further explored as a combination therapy of virotherapy and immunotherapy for bladder cancer and likely other types of cancer.

Salmonella inhibits tumor metastasis by downregulating epithelial cell adhesion molecules through the protein kinase-B/mammalian target of rapamycin signaling pathway

Epithelial cell adhesion molecules (EpCAM) are highly expressed in many carcinomas and regulate the epithelial–mesenchymal transition, which is required for tumor metastasis. Furthermore, EpCAM overexpression induces tumor cells to develop a stem cell–like phenotype and promotes tumor progression. Targeting EpCAM may be a promising approach for inhibiting tumor metastasis and progression. Salmonella treatment suppresses tumor growth and reduces metastatic nodules in tumor-bearing mice. Based on these results, we hypothesized that Salmonella-based treatments could inhibit the expression of metastasis-associated proteins. The dose-dependent Salmonella treatment significantly downregulated the levels of EpCAM and decreased the phosphorylation of protein kinase-B (AKT)/mTOR (mammalian target of rapamycin) pathway, as shown by immunoblotting. In addition, Salmonella treatment increased the levels of epithelial markers and decreased the levels of mesenchymal markers in a dose-dependent manner. Wound-healing and Transwell assays showed that Salmonella treatment significantly reduced tumor cell migration. The mice were intravenously injected with B16F10 and CT26 cells pre-incubated with or without Salmonella, and the survival of tumor-bearing mice in the Salmonella group increased, indicating an antimetastatic effect. Our findings demonstrate that Salmonella plays a role in inhibiting tumor metastasis by downregulating EpCAM via the AKT/mTOR signaling pathway and has great potential for cancer therapy.

Targeted glycan degradation potentiates cellular immunotherapy for solid tumors

Immune cell-based cancer therapies, such as chimeric antigen receptor T (CAR-T)-cell immunotherapy, have demonstrated impressive potency against hematological tumors. However, the efficacy of CAR-T cells against solid tumors remains limited. Herein, we designed tumor-targeting molecule-sialidase conjugates that potently and selectively stripped different sialoglycans from a variety of cancer cells. Desialylation enhanced induced pluripotent stem cell-derived chimeric antigen receptor-macrophage (CAR-iMac) infiltration and activation. Furthermore, the combination of cancer cell desialylation and CAR-iMac adoptive cellular therapy exerted a dramatic therapeutic effect on solid tumors and significantly prolonged the survival of tumor-bearing mice; these effects were mainly dependent on blockade of the checkpoint composed of sialic acid-binding immunoglobulin-like lectin (Siglec)-5 and Siglec-10 on the macrophages, and knockout of the glycoimmune checkpoint receptors could construct a CAR-iMac cell with stronger anticancer activity. This strategy that reverts the immune escape state ("cold tumor") to a sensitive recognition state ("hot tumor") has great significance for enhancing the effect of cellular immunotherapy on solid tumors. Therefore, desialylation combined with CAR-iMac cellular immunotherapy is a promising approach to enhance treatment with cellular immunotherapy and expand the valid indications among solid tumors, which provides inspiration for the development of cellular immunotherapies with glycoimmune checkpoint inhibition for the treatment of human cancer.

Breaking Tumor Immunosuppressive Network by Regulating Multiple Nodes with Triadic Drug Delivery Nanoparticles.

Inside the tumor microenvironment, a complicated immunosuppressive network is constituted by tumor cells and suppressive immune cells as its nodes, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and regulatory T cells, which have mutual promotion on each other and superimposed inhibition on natural killer (NK) cells and cytotoxic T cells. Breaking the whole balance of this web is critical to tumor immunotherapy since modulation on a single node may be diluted by other factors in the network. To achieve multifaceted regulation on antitumor immunity against triple-negative breast cancer, in this work, a micelle, termed BEM, co-delivering the MDSC inhibitor, entinostat (ENT), and the immune checkpoint inhibitor, BMS-1, was constructed with pH-sensitive amphiphilic poly(β-amino ester) derivatives. Then, BEM and the scavenger receptor A (SR-A) ligand dextran sulfate (DXS) formed a negatively charged nanoparticle (BEN). DXS detached from BEN in the weakly acidic tumor microenvironment and blocked SR-A on TAMs, reprogramming TAMs toward the M1 type. The positively charged BEM with facilitated intratumoral penetration and cellular uptake dissociated in the lysosomes, accompanied by the release of ENT and BMS-1 to suppress MDSCs and block the programmed cell death protein (PD)-1/PD-ligand 1 pathway, respectively. As a result, NK cells and CD8+ T cells in tumors were increased, as were their effector cytokines. The activated innate and adaptive antitumor immune responses suppressed the growth and metastasis of tumors and prolonged survival of 4T1 tumor-bearing mice. BEN provides a reliable approach for improving cancer immunotherapy by destroying the immunosuppression web in tumors via multinode regulation.