Bortezomib promotes the TRAIL-mediated killing of resistant rhabdomyosarcoma by ErbB2/Her2-targeted CAR-NK-92 cells via DR5 upregulation

Treatment resistance and immune escape are hallmarks of metastatic rhabdomyosarcoma (RMS), underscoring the urgent medical need for therapeutic agents against this disease entity as a key challenge in pediatric oncology. Chimeric antigen receptor (CAR)-based immunotherapies, such as the ErbB2 (Her2)-CAR-engineered natural killer (NK) cell line NK-92/5.28.z, provide antitumor cytotoxicity primarily through CAR-mediated cytotoxic granule release and thereafter-even in cases with low surface antigen expression or tumor escape-by triggering intrinsic NK cell-mediated apoptosis induction via additional ligand/receptors. In this study, we showed that bortezomib increased susceptibility toward apoptosis in clinically relevant RMS cell lines RH30 and RH41, and patient-derived RMS tumor organoid RMS335, by upregulation of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor DR5 in these metastatic, relapsed/refractory (r/r) RMS tumors. Subsequent administration of NK-92/5.28.z cells significantly enhanced antitumor activity in vitro. Applying recombinant TRAIL instead of NK-92/5.28.z cells confirmed that the synergistic antitumor effects of the combination treatment were mediated via TRAIL. Western blot analyses indicated that the combination treatment with bortezomib and NK-92/5.28.z cells increased apoptosis by interacting with the nuclear factor κB, JNK, and caspase pathways. Overall, bortezomib pretreatment can sensitize r/r RMS tumors to CAR- and, by upregulating DR5, TRAIL-mediated cytotoxicity of NK-92/5.28.z cells.

Functional remodeling of intraperitoneal macrophages by oncolytic adenovirus restores anti-tumor immunity for peritoneal metastasis of gastric cancer

Intraperitoneal tumor-associated macrophages (TAMs) are involved in evading anti-tumor immunity and promoting the peritoneal metastasis (PM) of gastric cancer (GC). Oncolytic viruses are known to induce the activation of host anti-tumor immunity in addition to tumor lysis. This study investigated whether a wild-type p53-loading telomerase-specific oncolytic adenovirus (OBP-702) could elicit the remodeling of intraperitoneal macrophages and enhance the efficacy of immune therapy. Increased numbers of CD163 TAMs and few CD8+ lymphocytes were immunohistochemically observed in clinical samples with PM, which suggested that TAMs were associated with the suppression of anti-tumor immunity. OBP-702 induced immunogenic cell death and upregulated PD-L1 expression in human and murine GC cell lines. Intraperitoneal administration of OBP-702 increased recruitment of CD8+ lymphocytes into the PM via the functional remodeling of intraperitoneal macrophages from TAM toward a pro-inflammatory phenotype, resulting in significantly suppressed tumor growth for the in vivo model. Furthermore, the combination of intraperitoneal OBP-702 with anti-programmed cell death-1 antibody enhanced anti-tumor immunity and prolonged the survival of mice bearing PM. Intraperitoneal immunotherapy using OBP-702 restores anti-tumor immunity via the remodeling of intraperitoneal macrophages in addition to direct tumor lysis and cooperates with immune checkpoint inhibitors to suppress PM in GC.

Conditionally replicative adenovirus as a therapy for malignant peripheral nerve sheath tumors

Oncolytic adenoviruses (Ads) stand out as a promising strategy for the targeted infection and lysis of tumor cells, with well-established clinical utility across various malignancies. This study delves into the therapeutic potential of oncolytic Ads in the context of neurofibromatosis type 1 (NF1)-associated malignant peripheral nerve sheath tumors (MPNSTs). Specifically, we evaluate conditionally replicative adenoviruses (CRAds) driven by the cyclooxygenase 2 (COX2) promoter, as selective agents against MPNSTs, demonstrating their preferential targeting of MPNST cells compared with non-malignant Schwann cell control. COX2-driven CRAds, particularly those with modified fiber-knobs exhibit superior binding affinity toward MPNST cells and demonstrate efficient and preferential replication and lysis of MPNST cells, with minimal impact on non-malignant control cells. In vivo experiments involving intratumoral CRAd injections in immunocompromised mice with human MPNST xenografts significantly extend survival and reduce tumor growth rate compared with controls. Moreover, in immunocompetent mouse models with MPNST-like allografts, CRAd injections induce a robust infiltration of CD8+ T cells into the tumor microenvironment (TME), indicating the potential to promote a pro-inflammatory response. These findings underscore oncolytic Ads as promising, selective, and minimally toxic agents for MPNST therapy, warranting further exploration.

Induction of necroptosis in multinucleated giant cells induced by conditionally replicating syncytial oHSV in co-cultures of cancer cells and non-cancerous cells

Viral modifications enabling syncytium formation in infected cells can augment lysis by oncolytic herpes simplex viruses (oHSVs) which selectively kill cancer cells. In the case of receptor-retargeted oHSVs (RR-oHSVs) that exclusively enter and spread to cancer cells, anti-tumor effects can be enhanced in a magnitude of >100,000-fold by modifying the virus to a syncytial type (RRsyn-oHSV). However, when syncytia containing non-cancerous cells are induced by conditionally replicating syncytial oHSV (CRsyn-oHSV), syncytial death occurs at an early stage. This results in limited anti-tumor effects of the CRsyn-oHSV. Here, we investigated whether necroptosis is involved in death of the syncytia formed by the fusion of cancer cells and non-cancerous cells. Mixed-lineage kinase domain-like (MLKL), a molecule executing necroptosis, was expressed in all murine cancer cell lines examined, while receptor-interacting protein kinase 3 (RIPK3), which phosphorylates MLKL, was absent from most cell lines. In contrast, RIPK3 was expressed in non-cancerous murine fibroblast cell lines. When a CRsyn-oHSV-infected RIPK3-deficient cancer cell line was co-cultured with the fibroblast cell line, but not with the cancer cells themselves, MLKL was phosphorylated and syncytial death was induced. These results indicate that early necroptosis is induced in multinucleated giant cells formed by CRsyn-oHSV when they also contain non-cancerous cells.

CAR'TCR-T cells co-expressing CD33-CAR and dNPM1-TCR as superior dual-targeting approach for AML treatment

Acute myeloid leukemia (AML), a fast-progressing hematological malignancy affecting myeloid cells, is typically treated with chemotherapy or hematopoietic stem cell transplantation. However, approximately half of the patients face relapses and 5-year survival rates are poor. With the goal to facilitate dual-specificity, boosting anti-tumor activity, and minimizing the risk for antigen escape, this study focused on combining chimeric antigen receptor (CAR) and T cell receptor (TCR) technologies. CAR'TCR-T cells, co-expressing a CD33-CAR and a transgenic dNPM1-TCR, revealed increased and prolonged anti-tumor activity in vitro, particularly in case of low target antigen expression. The distinct transcriptomic profile suggested enhanced formation of immunological synapses, activation, and signaling. Complete elimination of AML xenografts in vivo was only achieved with a cell product containing CAR'TCR-T, CAR-T, and TCR-T cells, representing the outcome of co-transduction with two lentiviral vectors encoding either CAR or TCR. A mixture of CAR-T and TCR-T cells, without CAR'TCR-T cells, did not prevent progressive tumor outgrowth and was comparable to treatment with CAR-T and TCR-T cells individually. Overall, our data underscore the efficacy of co-expressing CAR and transgenic TCR in one T cell, and might open a novel therapeutic avenue not only for AML but also other malignancies.

Oncolytic virus V937 in combination with PD-1 blockade therapy to target immunologically quiescent liver and colorectal cancer

V937 is an investigational, genetically unmodified Kuykendall strain of coxsackievirus A21, which has been evaluated in the clinic for advanced solid tumor malignancies. V937 specifically infects and lyses tumor cells that overexpress intercellular adhesion molecule-1 (ICAM-1). Intratumoral V937 as a monotherapy and in combination with anti-PD-1 antibody pembrolizumab has shown clinical response in patients with metastatic melanoma, which overexpresses ICAM-1. Here, we investigate in preclinical studies the potential bidirectional cross-talk between hepatocellular carcinomas (HCC) or colorectal carcinomas (CRC) and immune cells when treated with V937 alone or in combination with pembrolizumab. We show that while V937 treatment of tumor cell lines or organoids or peripheral blood mononuclear cells (PBMCs) alone induced a minimal immunological response, V937 treatment of non-contact co-cultures of tumor cell lines or CRC organoids with PBMCs led to robust production of proinflammatory cytokines and immune cell activation. In addition, both recombinant interferon-gamma and pembrolizumab increased ICAM-1 on tumor cell lines or organoids and, in turn, amplified V937-mediated oncolysis and immunogenicity. These findings provide critical mechanistic insights on the cross-talk between V937-mediated oncolysis and immune responses, demonstrating the therapeutic potential of V937 in combination with PD-1 blockade to treat immunologically quiescent cancers.

The crosstalk between non-coding RNAs and cell-cycle events: A new frontier in cancer therapy

The cell cycle comprises sequential events during which a cell duplicates its genome and divides it into two daughter cells. This process is tightly regulated to ensure that the daughter cell receives identical copied chromosomal DNA and that any errors in the DNA during replication are correctly repaired. Cyclins and their enzyme partners, cyclin-dependent kinases (CDKs), are critical regulators of G- to M-phase transitions during the cell cycle. Mitogenic signals induce the formation of the cyclin/CDK complexes, resulting in phosphorylation and activation of the CDKs. Once activated, cyclin/CDK complexes phosphorylate specific substrates that drive the cell cycle forward. The sequential activation and inactivation of cyclin-CDK complexes are tightly controlled by activating and inactivating phosphorylation events induced by cell-cycle proteins. The non-coding RNAs (ncRNAs), which do not code for proteins, regulate cell-cycle proteins at the transcriptional and translational levels, thereby controlling their expression at different cell-cycle phases. Deregulation of ncRNAs can cause abnormal expression patterns of cell-cycle-regulating proteins, resulting in abnormalities in cell-cycle regulation and cancer development. This review explores how ncRNA dysregulation can disrupt cell division balance and discusses potential therapeutic approaches targeting these ncRNAs to control cell-cycle events in cancer treatment.

The heterogeneous sensitivity of pediatric brain tumors to different oncolytic viruses is predicted by unique gene expression profiles

Despite decades of research, the prognosis of high-grade pediatric brain tumors (PBTs) remains dismal; however, recent cases of favorable clinical responses were documented in clinical trials using oncolytic viruses (OVs). In the current study, we employed four different species of OVs: adenovirus Delta24-RGD, herpes simplex virus rQNestin34.5v1, reovirus R124, and the non-virulent Newcastle disease virus rNDV-F0-GFP against three entities of PBTs (high-grade gliomas, atypical teratoid/rhabdoid tumors, and ependymomas) to determine their in vitro efficacy. These four OVs were screened on 14 patient-derived PBT cell cultures and the degree of oncolysis was assessed using an ATP-based assay. Subsequently, the observed viral efficacies were correlated to whole transcriptome data and Gene Ontology analysis was performed. Although no significant tumor type-specific OV efficacy was observed, the analysis revealed the intrinsic biological processes that associated with OV efficacy. The predictive power of the identified expression profiles was further validated in vitro by screening additional PBTs. In summary, our results demonstrate OV susceptibility of multiple patient-derived PBT entities and the ability to predict in vitro responses to OVs using unique expression profiles. Such profiles may hold promise for future OV preselection with effective oncolytic potency in a specific tumor, therewith potentially improving OV responses.

Targeted treatment of chondrosarcoma with a bacteriophage-based particle delivering a secreted tumor necrosis factor-related apoptosis-inducing ligand

Chondrosarcoma (CS) is a malignant cartilage-forming bone tumor that is inherently resistant to chemotherapy and radiotherapy, leaving surgery as the only treatment option. We have designed a tumor-targeted bacteriophage (phage)-derived particle (PDP), for targeted systemic delivery of cytokine-encoding transgenes to solid tumors. Phage has no intrinsic tropism for mammalian cells; therefore, it was engineered to display a double cyclic RGD4C ligand on the capsid to target tumors. To induce cancer cell death, we constructed a transgene cassette expressing a secreted form of the cytokine tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL). We detected high expression of αvβ3 and αvβ5 integrin receptors of the RGD4C ligand, and of the TRAIL receptor-2 in human CS cells (SW1353), but not in primary normal chondrocytes. The RGD4C.PDP-Luc particle carrying a luciferase reporter gene, Luc, effectively and selectively mediated gene delivery to SW1353 cells, but not primary chondrocytes. Transduction of SW1353 cells with RGD4C.PDP-sTRAIL encoding a human sTRAIL, resulted in the expression of TRAIL and subsequent cell death without harming the normal chondrocytes. Intravenous administration of RGD4C.PDP-sTRAIL to mice with established human CS resulted in a decrease in tumor size and tumor viability. Altogether, RGD4C.PDP-sTRAIL can be used to target systemic treatment of CS with the sTRAIL.

MicroRNA-34a-5p: A pivotal therapeutic target in gallbladder cancer

Gallbladder cancer incidence has been increasing globally, and it remains challenging to expect long prognosis with the current systemic chemotherapy. We identified a novel nucleic acid-mediated therapeutic target against gallbladder cancer by using innovative organoid-based gallbladder cancer models generated from KrasLSL-G12D/+; Trp53f/f mice. Using comprehensive microRNA expression analyses and a bioinformatics approach, we identified significant microRNA-34a-5p downregulation in both murine gallbladder cancer organoids and resected human gallbladder cancer specimens. In three different human gallbladder cancer cell lines, forced microRNA-34a-5p expression inhibited cell proliferation and induced cell-cycle arrest at the G1 phase by suppressing direct target (CDK6) expression. Furthermore, comprehensive RNA sequencing revealed the significant enrichment of gene sets related to the cell-cycle regulators after microRNA-34a-5p expression in gallbladder cancer cells. In a murine xenograft model, locally injected microRNA-34a-5p mimics significantly inhibited gallbladder cancer progression and downregulated CDK6 expression. These results provide a rationale for promising therapeutics against gallbladder cancer by microRNA-34a-5p injection, as well as a strategy to explore therapeutic targets against cancers using organoid-based models, especially for those lacking useful genetically engineered murine models, such as gallbladder cancer.

Engineering Proteus mirabilis improves antitumor efficacy via enhancing cytotoxic T cell responses

Cancer immunotherapy based on bioengineering of bacteria can effectively increase anticancer immune responses. However, few studies have investigated the antitumor potential of engineering Proteus mirabilis. Here, we genetically engineered P. mirabilis to overexpress Vibrio vulnificus flagellin B (FlaB) protein in a murine CT26 tumor model. We found that a large number of FlaB-expressing P. mirabilis colonized tumor tissues, enhanced T cell infiltration and secretion of cytokines and cytotoxic proteins in tumors, and significantly restrained tumor growth. Our results also showed that programmed death ligand 1 (PD-L1) expression in tumor-infiltrating immune cells was elevated after treatment with FlaB-expressing P. mirabilis. In addition, combination therapy with FlaB-expressing P. mirabilis and PD-L1 blockade synergistically improved antitumor efficacy by enhancing infiltration of CD8+ cells. Furthermore, serum liver biochemical indices of mice increased in the short term in both the P. mirabilis and the FlaB-expressing P. mirabilis treatment groups but gradually recovered in the later stage of treatment so that FlaB protein expression did not increase the toxicity of P. mirabilis in vivo. Taken together, our results suggest that P. mirabilis could serve as an engineered bacterium for bacterium-based cancer immunotherapy.

Cancer testis antigens: Emerging therapeutic targets leveraging genomic instability in cancer

Cancer care has witnessed remarkable progress in recent decades, with a wide array of targeted therapies and immune-based interventions being added to the traditional treatment options such as surgery, chemotherapy, and radiotherapy. However, despite these advancements, the challenge of achieving high tumor specificity while minimizing adverse side effects continues to dictate the benefit-risk balance of cancer therapy, guiding clinical decision making. As such, the targeting of cancer testis antigens (CTAs) offers exciting new opportunities for therapeutic intervention of cancer since they display highly tumor specific expression patterns, natural immunogenicity and play pivotal roles in various biological processes that are critical for tumor cellular fitness. In this review, we delve deeper into how CTAs contribute to the regulation and maintenance of genomic integrity in cancer, and how these mechanisms can be exploited to specifically target and eradicate tumor cells. We review the current clinical trials targeting aforementioned CTAs, highlight promising pre-clinical data and discuss current challenges and future perspectives for future development of CTA-based strategies that exploit tumor genomic instability.

Emerging therapeutic approaches for peritoneal metastases from gastrointestinal cancers

Peritoneal metastases from gastrointestinal malignancies present difficult management decisions, with options consisting primarily of systemic chemotherapy or major surgery with or without hyperthermic intraperitoneal chemotherapy. Current research is investigating expanding therapeutic modalities, and the aim of this review is to provide an overview of the existing and emerging therapies for the peritoneal metastases from gastrointestinal cancers, primarily through the recent literature (2015 and newer). These include the current data with systemic therapy and cytoreduction with hyperthermic intraperitoneal or pressurized intraperitoneal aerosol chemotherapy, as well as novel promising modalities under investigation, including dominating oncolytic viral therapy and adoptive cellular, biologic, and bacteria therapy, or nanotechnology. The novel diverse strategies, although preliminary and preclinical in murine models, individually and collectively contribute to the treatment of peritoneal metastases, offering hope for improved outcomes and quality of life. We foresee that these evolving treatment approaches will facilitate the transfer of knowledge and data among studies and advance discovery of new drugs and optimized treatments for patients with peritoneal metastases.

Targeting MELK improves PD-1 blockade efficiency in cervical cancer via enhancing antitumor immunity

The balance between T helper 1 (Th1) and T helper 2 (Th2) has a critical function in determining intratumoral immune response and anti-PD-1 immunotherapy. The level of maternal embryonic leucine zipper kinase (MELK) is reported to correlate with infiltration of immune cells in cancers, but the underlying molecular mechanism is not clarified. In the present study, we aimed to elucidate the potential function of MELK in cervical cancer. We found that MELK was upregulated and played an oncogenic role in cervical cancer. MELK overexpression shifted Th1/Th2 balance toward Th2 predisposition in mouse cervical tumors in vivo and naive T cells from human PBMCs in vitro, whereas MELK knockdown exhibited opposite effects. MELK overexpression activated NF-κB signaling and promoted IL-6 secretion by cervical cancer cells. Depletion of IL-6 by neutralization antibodies abrogated the influence of MELK on Th1/Th2 balance. In addition, MELK modulated the antitumor activity of cytotoxic CD8+ T cells in cervical tumors, but depletion of Th2 cells by IL-4 neutralization abrogated this effect. Finally, MELK overexpression conferred tolerance to PD-1 blockade in cervical tumors, whereas targeting MELK by OTSSP167 significantly enhanced PD-1 blockade efficiency. Our data elucidated a novel role of MELK in regulating Th1/Th2 balance and anti-PD-1 immunotherapy in cervical cancer.

Mediation of antitumor activity by AZD4820 oncolytic vaccinia virus encoding IL-12

Oncolytic viruses are engineered to selectively kill tumor cells and have demonstrated promising results in early-phase clinical trials. To further modulate the innate and adaptive immune system, we generated AZD4820, a vaccinia virus engineered to express interleukin-12 (IL-12), a potent cytokine involved in the activation of natural killer (NK) and T cells and the reprogramming of the tumor immune microenvironment. Testing in cultured human tumor cell lines demonstrated broad in vitro oncolytic activity and IL-12 transgene expression. A surrogate virus expressing murine IL-12 demonstrated antitumor activity in both MC38 and CT26 mouse syngeneic tumor models that responded poorly to immune checkpoint inhibition. In both models, AZD4820 significantly upregulated interferon-gamma (IFN-γ) relative to control mice treated with oncolytic vaccinia virus (VACV)-luciferase. In the CT26 study, 6 of 10 mice had a complete response after treatment with AZD4820 murine surrogate, whereas control VACV-luciferase-treated mice had 0 of 10 complete responders. AZD4820 treatment combined with anti-PD-L1 blocking antibody augmented tumor-specific T cell immunity relative to monotherapies. These findings suggest that vaccinia virus delivery of IL-12, combined with immune checkpoint blockade, elicits antitumor immunity in tumors that respond poorly to immune checkpoint inhibitors.

Oncolytic herpes simplex viruses designed for targeted treatment of EGFR-bearing tumors

Oncolytic herpes simplex viruses (oHSVs) have emerged as leading cancer therapeutic agents. Effective oHSV virotherapy may ultimately require both intratumoral and systemic vector administration to target the primary tumor and distant metastases. An attractive approach to enhancing oHSV tumor specificity is engineering the virus envelope glycoproteins for selective recognition of and infection via tumor-specific cell surface proteins. We previously demonstrated that oHSVs could be retargeted to EGFR-expressing cells by the incorporation of a single-chain antibody (scFv) at the N terminus of glycoprotein D (gD). Here, we compared retargeted oHSVs generated by the insertion of scFv, affibody molecule, or VHH antibody ligands at different positions within the N terminus of gD. When compared to the scFv-directed oHSVs, VHH and affibody molecules mediated enhanced EGFR-specific tumor cell entry, spread and cell killing in vitro, and enabled long-term tumor-specific virus replication following intravenous delivery in vivo. Moreover, oHSVs retargeted via a VHH ligand reduced tumor growth upon intravenous injection and achieved complete tumor destruction after intratumoral injection. Systemic oHSV delivery is important for the treatment of metastatic disease, and our enhancements in targeted oHSV design are a critical step in creating an effective tumor-specific oHSVs for safe administration via the bloodstream.

Prime and pull of T cell responses against cancer-exogenous antigens is effective against CPI-resistant tumors

Neoantigen (neoAg)-based cancer vaccines expand preexisting antitumor immunity and elicit novel cancer-specific T cells. However, at odds with prophylactic vaccines, therapeutic antitumor immunity must be induced when the tumor is present and has already established an immunosuppressive environment capable of rapidly impairing the function of anticancer neoAg T cells, thereby leading to lack of efficacy. To overcome tumor-induced immunosuppression, we first vaccinated mice bearing immune checkpoint inhibitor (CPI)-resistant tumors with an adenovirus vector encoding a set of potent cancer-exogenous CD8 and CD4 T cell epitopes (Ad-CAP1), and then "taught" cancer cells to express the same epitopes by using a tumor-retargeted herpesvirus vector (THV-CAP1). Potent CD8 effector T lymphocytes were elicited by Ad-CAP1, and subsequent THV-CAP1 delivery led to a significant delay in tumor growth and even cure.

Low-dose decitabine enhances the efficacy of viral cancer vaccines for immunotherapy

Cancer immunotherapy requires a specific antitumor CD8+ T cell-driven immune response; however, upon genetic and epigenetic alterations of the antigen processing and presenting components, cancer cells escape the CD8+ T cell recognition. As a result, poorly immunogenic tumors are refractory to conventional immunotherapy. In this context, the use of viral cancer vaccines in combination with hypomethylating agents represents a promising strategy to prevent cancer from escaping immune system recognition. In this study, we evaluated the sensitivity of melanoma (B16-expressing ovalbumin) and metastatic triple-negative breast cancer (4T1) cell lines to FDA-approved low-dose decitabine in combination with PeptiCRAd, an adenoviral anticancer vaccine. The two models showed different sensitivity to decitabine in vitro and in vivo when combined with PeptiCRAd. In particular, mice bearing syngeneic 4T1 cancer showed higher tumor growth control when receiving the combinatorial treatment compared to single controls in association with a higher expression of MHC class I on cancer cells and reduction in Tregs within the tumor microenvironment. Furthermore, remodeling of the CD8+ T cell infiltration and cytotoxic activity toward cancer cells confirmed the effect of decitabine in enhancing anticancer vaccines in immunotherapy regimens.

A dual-luciferase bioluminescence system for the assessment of cellular therapies

Bioluminescence imaging is a well-established platform for evaluating engineered cell therapies in preclinical studies. However, despite the discovery of new luciferases and substrates, optimal combinations to simultaneously monitor two cell populations remain limited. This makes the functional assessment of cellular therapies cumbersome and expensive, especially in preclinical in vivo models. In this study, we explored the potential of using a green bioluminescence-emitting click beetle luciferase, CBG99, and a red bioluminescence-emitting firefly luciferase mutant, Akaluc, together to simultaneously monitor two cell populations. Using various chimeric antigen receptor T cells and tumor pairings, we demonstrate that these luciferases are suitable for real-time tracking of two cell types using 2D and 3D cultures in vitro and experimental models in vivo. Our data show the broad compatibility of this dual-luciferase (duo-luc) system with multiple bioluminescence detection equipment ranging from benchtop spectrophotometers to live animal imaging systems. Although this study focused on investigating complex CAR T cells and tumor cell interactions, this duo-luc system has potential utility for the simultaneous monitoring of any two cellular components-for example, to unravel the impact of a specific genetic variant on clonal dominance in a mixed population of tumor cells.

TROP2 is highly expressed in triple-negative breast cancer CTCs and is a potential marker for epithelial mesenchymal CTCs

Circulating tumor cells (CTCs) are the seeds of distant metastases of malignant tumors and are associated with malignancy and risk of metastasis. However, tumor cells undergo epithelial-mesenchymal transition (EMT) during metastasis, leading to the emergence of different types of CTCs. Real-time dynamic molecular and functional typing of CTCs is necessary to precisely guide personalized treatment. Most CTC detection systems are based on epithelial markers that may fail to detect EMT CTCs. Therefore, it is clinically important to identify new markers of different CTC types. In this study, bioinformatics analysis and experimental assays showed that trophoblast cell surface antigen 2 (TROP2), a target molecule for advanced palliative treatment of triple-negative breast cancer (TNBC), was highly expressed in TNBC tissues and tumor cells. Furthermore, TROP2 can promote the migration and invasion of TNBC cells by upregulating EMT markers. The specificity and potential of TROP2 as an EMT-associated marker of TNBC CTCs were evaluated by flow cytometry, immunofluorescence, spiking experiments, and a well-established CTC assay. The results indicated that TROP2 is a potential novel CTC marker associated with EMT, providing a basis for more efficacious markers that encompass CTC heterogeneity in patients with TNBC.

Development of a novel, high-efficacy oncolytic herpes simplex virus type 1 platform equipped with two distinct retargeting modalities

To retarget oncolytic herpes simplex virus (oHSV) to cancer-specific antigens, we designed a novel, double-retargeted oHSV platform that uses single-chain antibodies (scFvs) incorporated into both glycoprotein H and a bispecific adapter expressed from the viral genome to mediate infection predominantly via tumor-associated antigens. Successful retargeting was achieved using a nectin-1-detargeted HSV that remains capable of interacting with herpesvirus entry mediator (HVEM), the second canonical HSV entry receptor, and is, therefore, recognized by the adapter consisting of the virus-binding N-terminal 82 residues of HVEM fused to the target-specific scFv. We tested both an epithelial cell adhesion molecule (EpCAM)- and a human epidermal growth factor receptor 2-specific scFv separately and together to target cells expressing one, the other, or both receptors. Our results show not only dose-dependent, target receptor-specific infection in vitro, but also enhanced virus spread compared with single-retargeted virus. In addition, we observed effective infection and spreading of the EpCAM double-retargeted virus in vivo. Remarkably, a single intravenous dose of the EpCAM-specific virus eliminated all detectable tumors in a subcutaneous xenograft model, and the same intravenous dose seemed to be harmless in immunocompetent FVB/N mice. Our findings suggest that our double-retargeted oHSV platform can provide a potent, versatile, and systemically deliverable class of anti-cancer therapeutics that specifically target cancer cells while ensuring safety.

Empowering pancreatic tumor homing with augmented anti-tumor potency of CXCR2-tethered CAR-NK cells

Chimeric antigen receptor (CAR)-engineered natural killer (NK) cells are a promising immunotherapy for solid cancers; however, their effectiveness against pancreatic cancer is limited by the immunosuppressive tumor microenvironment. In particular, low NK cell infiltration poses a major obstacle that reduces cytotoxicity. The current study aimed to enhance the tumor-homing capacity of CAR-NK cells by targeting the chemokine-chemokine receptor axis between NK and pancreatic cancer cells. To this end, data from a chemokine array and The Cancer Genome Atlas pan-cancer cohort were analyzed. Pancreatic cancer cells were found to secrete high levels of ligands for C-X-C motif receptor 1 (CXCR1) and CXCR2. Subsequently, we generated anti-mesothelin CAR-NK cells incorporating CXCR1 or CXCR2 and evaluated their tumor-killing abilities in 2D cancer cell co-culture and 3D tumor-mimetic organoid models. CAR-NK cells engineered with CXCR2 demonstrated enhanced tumor killing and strong infiltration of tumor sites. Collectively, these findings highlight the potential of CXCR2-augmented CAR-NK cells as a clinically relevant modality for effective pancreatic cancer treatment. By improving their infiltration and tumor-killing capabilities, these CXCR2-augmented CAR-NK cells have the potential to overcome the challenges posed by the immunosuppressive tumor microenvironment, providing improved therapeutic outcomes.

Targeting the ribosome to treat multiple myeloma

The high rates of protein synthesis and processing render multiple myeloma (MM) cells vulnerable to perturbations in protein homeostasis. The induction of proteotoxic stress by targeting protein degradation with proteasome inhibitors (PIs) has revolutionized the treatment of MM. However, resistance to PIs is inevitable and represents an ongoing clinical challenge. Our first-in-human study of the selective inhibitor of RNA polymerase I transcription of ribosomal RNA genes, CX-5461, has demonstrated a potential signal for anti-tumor activity in three of six heavily pre-treated MM patients. Here, we show that CX-5461 has potent anti-myeloma activity in PI-resistant MM preclinical models in vitro and in vivo. In addition to inhibiting ribosome biogenesis, CX-5461 causes topoisomerase II trapping and replication-dependent DNA damage, leading to G2/M cell-cycle arrest and apoptotic cell death. Combining CX-5461 with PI does not further enhance the anti-myeloma activity of CX-5461 in vivo. In contrast, CX-5461 shows synergistic interaction with the histone deacetylase inhibitor panobinostat in both the Vk∗MYC and the 5T33-KaLwRij mouse models of MM by targeting ribosome biogenesis and protein synthesis through distinct mechanisms. Our findings thus provide strong evidence to facilitate the clinical development of targeting the ribosome to treat relapsed and refractory MM.

Gut microbiota composition is associated with the efficacy of Delta-24-RGDOX in malignant gliomas

Glioblastoma, the most common primary brain tumor, has a 6.8% survival rate 5 years post diagnosis. Our team developed an oncolytic adenovirus with an OX-40L expression cassette named Delta-24-RGDOX. While studies have revealed the interaction between the gut microbiota and immunotherapy agents, there are no studies linking the gut microbiota with viroimmunotherapy efficacy. We hypothesize that gut bacterial signatures will be associated with oncolytic viral therapy efficacy. To test this hypothesis, we evaluated the changes in gut microbiota in two mouse cohorts: (1) GSC-005 glioblastoma-bearing mice treated orally with indoximod, an immunotherapeutic agent, or with Delta-24-RGDOX by intratumoral injection and (2) a mouse cohort harboring GL261-5 tumors used to mechanistically evaluate the importance of CD4+ T cells in relation to viroimmunotherapy efficacy. Microbiota assessment indicated significant differences in the structure of the gut bacterial communities in viroimmunotherapy-treated animals with higher survival compared with control or indoximod-treated animals. Moreover, viroimmunotherapy-treated mice with prolonged survival had a higher abundance of Bifidobacterium. The CD4+ T cell depletion was associated with gut dysbiosis, lower mouse survival, and lower antitumor efficacy of the therapy. These findings suggest that microbiota modulation along the gut-glioma axis contributes to the clinical efficacy and patient survival of viroimmunotherapy treated animals.

Differential landscape of immune evasion in oncogenic RAS-driven primary and metastatic colorectal cancers

Oncogenic drivers such as KRAS extensively modulate the tumor inflammatory microenvironment (TIME) of colorectal cancer (CRC). The influence of KRAS on modulating immune cell composition remains unclear. The objective of this study was to identify signatures of infiltrative immune cells and distinctive patterns that differ between RAS wild-type (WT) and oncogenic mutant (MT) CRC that explain immune evasion in MT tumors. A total of 7,801 CRC specimens were analyzed using next-generation DNA sequencing, whole-exome sequencing, and/or whole transcriptome sequencing. Deficiency of mismatch repair (dMMR)/microsatellite instability (MSI) and tumor mutation burden (TMB) were also assessed. KRAS mutations were present in 48% of CRC, similarly distributed in patients younger than vs. 50 years and older. In microsatellite stable (MSS) KRAS MT tumors, composition of the TIME included higher neutrophil infiltration and lower infiltration of B cells. MSI-H/dMMR was significantly more prevalent in RAS WT (9.1%) than in KRAS MT (2.9%) CRC. In MSS CRC, TMB-high cases were significantly higher in RAS MT (3.1%) than in RAS WT (2.1%) tumors. KRAS and NRAS mutations are associated with increased neutrophil infiltration, with codon-specific differences. These results demonstrate significant differences in the TIME of RAS mutant CRC that match previous reports of immunoevasive characteristics of such tumors.

Development of gemcitabine-modified miRNA mimics as cancer therapeutics for pancreatic ductal adenocarcinoma

Despite the recent advancement in diagnosis and therapy, pancreatic ductal adenocarcinoma (PDAC), the most common type of pancreatic cancer, is still the most lethal cancer with a low five-year survival rate. There is an urgent need to develop new therapies to address this issue. In this study, we developed a treatment strategy by modifying tumor suppressor miRNAs, miR-15a and miR-194, with the chemotherapeutic gemcitabine (Gem) to create Gem-modified mimics, Gem-miR-15a and Gem-miR-194, respectively. In a panel of PDAC cell lines, we found that Gem-miR-15a and Gem-miR-194 induce cell-cycle arrest and apoptosis, and these mimics are potent inhibitors with IC50 values up to several hundred fold less than their native counterparts or Gem alone. Furthermore, we found that Gem-miR-15a and Gem-miR-194 retained miRNA function by downregulating the expression of several key targets including WEE1, CHK1, BMI1, and YAP1 for Gem-miR-15a, and FOXA1 for Gem-miR-194. We also found that our Gem-modified miRNA mimics exhibit an enhanced efficacy compared to Gem in patient-derived PDAC organoids. Furthermore, we observed that Gem-miR-15a significantly inhibits PDAC tumor growth in vivo without observing any noticeable signs of toxicity. Overall, our results demonstrate the therapeutic potential of Gem-modified miRNAs as a treatment strategy for PDAC.

Discovery and preclinical development of a therapeutically active nanobody-based chimeric antigen receptor targeting human CD22

Chimeric antigen receptor (CAR) T cell therapies targeting B cell-restricted antigens CD19, CD20, or CD22 can produce potent clinical responses for some B cell malignancies, but relapse remains common. Camelid single-domain antibodies (sdAbs or nanobodies) are smaller, simpler, and easier to recombine than single-chain variable fragments (scFvs) used in most CARs, but fewer sdAb-CARs have been reported. Thus, we sought to identify a therapeutically active sdAb-CAR targeting human CD22. Immunization of an adult Llama glama with CD22 protein, sdAb-cDNA library construction, and phage panning yielded >20 sdAbs with diverse epitope and binding properties. Expressing CD22-sdAb-CAR in Jurkat cells drove varying CD22-specific reactivity not correlated with antibody affinity. Changing CD28- to CD8-transmembrane design increased CAR persistence and expression in vitro. CD22-sdAb-CAR candidates showed similar CD22-dependent CAR-T expansion in vitro, although only membrane-proximal epitope targeting CD22-sdAb-CARs activated direct cytolytic killing and extended survival in a lymphoma xenograft model. Based on enhanced survival in blinded xenograft studies, a lead CD22sdCAR-T was selected, achieving comparable complete responses to a benchmark short linker m971-scFv CAR-T in high-dose experiments. Finally, immunohistochemistry and flow cytometry confirm tissue and cellular-level specificity of the lead CD22-sdAb. This presents a complete report on preclinical development of a novel CD22sdCAR therapeutic.

CRISPR editing to mimic porphyria combined with light: A new preclinical approach for prostate cancer

Thanks to its very high genome-editing efficiency, CRISPR-Cas9 technology could be a promising anticancer weapon. Clinical trials using CRISPR-Cas9 nuclease to ex vivo edit and alter immune cells are ongoing. However, to date, this strategy still has not been applied in clinical practice to directly target cancer cells. Targeting a canonical metabolic pathway essential to good functioning of cells without potential escape would represent an attractive strategy. We propose to mimic a genetic metabolic disorder in cancer cells to weaken cancer cells, independent of their genomic abnormalities. Mutations affecting the heme biosynthesis pathway are responsible for porphyria, and most of them are characterized by an accumulation of toxic photoreactive porphyrins. This study aimed to mimic porphyria by using CRISPR-Cas9 to inactivate UROS, leading to porphyrin accumulation in a prostate cancer model. Prostate cancer is the leading cancer in men and has a high mortality rate despite therapeutic progress, with a primary tumor accessible to light. By combining light with gene therapy, we obtained high efficiency in vitro and in vivo, with considerable improvement in the survival of mice. Finally, we achieved the preclinical proof-of-principle of performing cancer CRISPR gene therapy.

Noncoding RNA landscape and their emerging roles as biomarkers and therapeutic targets in meningioma

Meningiomas are among the most prevalent primary CNS tumors in adults, accounting for nearly 38% of all brain neoplasms. The World Health Organization (WHO) grade assigned to meningiomas guides medical care in patients and is primarily based on tumor histology and malignancy potential. Although often considered benign, meningiomas with complicated histology, limited accessibility for surgical resection, and/or higher malignancy potential (WHO grade 2 and WHO grade 3) are harder to combat, resulting in significant morbidity. With limited treatment options and no systemic therapies, it is imperative to understand meningioma tumorigenesis at the molecular level and identify novel therapeutic targets. The last decade witnessed considerable progress in understanding the noncoding RNA landscape of meningioma, with microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) emerging as molecular entities of interest. This review aims to highlight the commonly dysregulated miRNAs and lncRNAs in meningioma and their correlation with meningioma progression, malignancy, recurrence, and radioresistance. The role of "key" miRNAs as biomarkers and their therapeutic potential has also been reviewed in detail. Furthermore, current and emerging therapeutic modalities for meningioma have been discussed, with emphasis on the need to identify and subsequently employ clinically relevant miRNAs and lncRNAs as novel therapeutic targets and biomarkers.

TheraVision: Engineering platform technology for the development of oncolytic viruses based on herpes simplex virus type 1

Viruses are able to efficiently penetrate cells, multiply, and eventually kill infected cells, release tumor antigens, and activate the immune system. Therefore, viruses are highly attractive novel agents for cancer therapy. Clinical trials with first generations of oncolytic viruses (OVs) are very promising but show significant need for optimization. The aim of TheraVision was to establish a broadly applicable engineering platform technology for combinatorial oncolytic virus and immunotherapy. Through genetic engineering, an attenuated herpes simplex virus type 1 (HSV1) was generated that showed increased safety compared to the wild-type strain. To demonstrate the modularity and the facilitated generation of new OVs, two transgenes encoding retargeting as well as immunomodulating single-chain variable fragments (scFvs) were integrated into the platform vector. The resulting virus selectively infected epidermal growth factor receptor (EGFR)-expressing cells and produced a functional immune checkpoint inhibitor against programmed cell death protein 1 (PD-1). Thus, both viral-mediated oncolysis and immune-cell-mediated therapy were combined into a single viral vector. Safety and functionality of the armed OVs have been shown in novel preclinical models ranging from patient-derived organoids and tissue-engineered human in vitro 3D tumor models to complex humanized mouse models. Consequently, a novel and proprietary engineering platform vector based on HSV1 is available for the facilitated preclinical development of oncolytic virotherapy.

Minute virus of mice shows oncolytic activity against pancreatic cancer cells exhibiting a mesenchymal phenotype

Pancreatic cancer will soon become the second cause of death by cancer in Western countries. The main barrier to increase the survival of patients with this disease requires the development of novel and efficient therapeutic strategies that better consider tumor biology. In this context, oncolytic viruses emerge as promising therapeutics. Among them, the fibrotropic minute virus of mice prototype (MVMp) preferentially infects migrating and undifferentiated cells that highly resemble poorly differentiated, basal-like pancreatic tumors showing the worst clinical outcome. We report here that MVMp specifically infects, replicates in, and kills pancreatic cancer cells from murine and human origin with a mesenchymal, basal-like profile, while sparing cancer cells with an epithelial phenotype. Remarkably, MVMp infection, at a dose that does not provoke tumor growth inhibition in athymic mice, shows significant antitumoral effect in immune-competent models; extended mouse survival; and promoted the massive infiltration of tumors by innate, myeloid, and cytotoxic T cells that exhibit a less terminally exhausted phenotype. Collectively, we demonstrate herein for the first time that MVMp is specific and oncolytic for pancreatic tumors with mesenchymal, basal-like profile, paving the way for precision-medicine opportunities for the management of the most aggressive and lethal form of this disease.

An epitope encoded by uORF of RNF10 elicits a therapeutic anti-tumor immune response

Tumor-specific antigens (TSAs) are crucial for tumor-specific immune response that reduces tumor burden and thus serve as important targets for immunotherapy. Identification of novel TSAs can provide new strategies for immunotherapies. In this study, we demonstrated that the upstream open reading frame (uORF) of RNF10 encodes an antigenic peptide (RNF10 uPeptide), capable of eliciting a T cell-mediated anti-tumor immune response. We initially demonstrated the immunogenicity of the RNF10 uPeptide in a CT26 tumor mouse model, by showing that its epitope was specifically recognized by CD8+ T cells. Vaccination of mice with the long form of the RNF10 uPeptide conferred strong anti-tumor activity. Next, we proved that the human RNF10 uORF could be translated. In addition, we predicted the binding of an RNF10 uPeptide epitope to HLA-A∗02:01 (HLA-A2). This HLA-A2-restricted epitope of the RNF10 uPeptide induced a potent specific human T cell response. Finally, we showed that an HLA-A2-restricted cytotoxic T cell (CTL) clone, derived from a pancreatic cancer patient, recognized the RNF10 uPeptide epitope (RLFGQQQRA) and lysed HLA-A2+ pancreatic carcinoma cells expressing the RNF10 uPeptide. These results indicate that the RNF10 uPeptide could be a promising target for pancreatic carcinoma immunotherapy.

Transgenic viral expression of PH-20, IL-12, and sPD1-Fc enhances immune cell infiltration and anti-tumor efficacy of an oncolytic virus

Oncolytic viruses are of significant clinical interest due to their ability to directly infect and kill tumors and enhance the anti-tumor immune response. Previously, we developed KLS-3010, a novel oncolytic virus derived from the International Health Department-White (IHD-W) strain vaccinia virus, which has robust tumoricidal effects. In the present study, we generated a recombinant oncolytic virus, KLS-3020, by inserting three transgenes (hyaluronidase [PH-20], interleukin-12 [IL-12], and soluble programmed cell death 1 fused to the Fc domain [sPD1-Fc]) into KLS-3010 and investigated its anti-tumor efficacy and ability to induce anti-tumor immune responses in CT26.WT and B16F10 mouse tumor models. A single injection of KLS-3020 significantly decreased tumor growth. The roles of the transgenes were investigated using viruses expressing each single transgene alone and KLS-3020. PH-20 promoted virus spread and tumor immune cell infiltration, IL-12 activated and reprogrammed T cells to inflammatory phenotypes, and sPD1-Fc increased intra-tumoral populations of activated T cells. The tumor-specific systemic immune response and the abscopal tumor control elicited by KLS-3020 were demonstrated in the CT26.WT tumor model. The insertion of transgenes into KLS-3020 increased its anti-tumor efficacy, supporting further clinical investigation of KLS-3020 as a novel oncolytic immunotherapy.

Oncolytic myxoma virus is effective in murine models of triple negative breast cancer despite poor rates of infection

Oncolytic viruses are being heavily investigated as novel methods to treat cancers; however, predicting their therapeutic efficacy remains challenging. The most commonly used predictive tests involve determining the in vitro susceptibility of a tumor's malignant cells to infection with an oncolytic agent. Whether these tests are truly predictive of in vivo efficacy, however, remains unclear. Here we demonstrate that a recombinant, oncolytic myxoma virus shows efficacy in two murine models of triple negative breast cancer despite extremely low permissivity of these models to viral infection. These data demonstrate that in vitro infectivity studies are not an accurate surrogate for therapeutic efficacy and suggest that other tests need to be developed.