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Both anti-PD1/PD-L1 therapy and oncolytic virotherapy have demonstrated promise, yet have exhibited efficacy in only a small fraction of cancer patients. Here we hypothesized that an oncolytic poxvirus would attract T cells into the tumour, and induce PD-L1 expression in cancer and immune cells, leading to more susceptible targets for anti-PD-L1 immunotherapy. Our results demonstrate in colon and ovarian cancer models that an oncolytic vaccinia virus attracts effector T cells and induces PD-L1 expression on both cancer and immune cells in the tumour. The dual therapy reduces PD-L1 + cells and facilitates non-redundant tumour infiltration of effector CD8 + , CD4 + T cells, with increased IFN-γ, ICOS, granzyme B and perforin expression. Furthermore, the treatment reduces the virus-induced PD-L1 + DC, MDSC, TAM and T reg , as well as co-inhibitory molecules-double-positive, severely exhausted PD-1 + CD8 + T cells, leading to reduced tumour burden and improved survival. This combinatorial therapy may be applicable to a much wider population of cancer patients. Anti-PD-L1 therapy often fails in cancers with minimal lymphocytic infiltrates and low PD-L1 expression. Here, the authors show that an oncolytic virus increases PD-L1 expression in cancer models and that the combination with an anti-PD-L1 antibody enhances therapy by increasing the infiltration of activated T cells, and reducing exhausted T cells.

Oncolytic viruses (OVs) represent a new class of multi-modal immunotherapies for cancer, with OV-elicited antitumor immunity being key to their overall therapeutic efficacy. Currently, the clinical effectiveness of OV as monotherapy remains limited, and thus investigators have been exploring various combinations with other anti-cancer agents and demonstrated improved therapeutic efficacy. As cancer cells have evolved to alter key signaling pathways for enhanced cell proliferation, cancer progression and metastasis, these cellular and molecular changes offer promising targets for rational cancer therapy design. In this regard, key molecules in relevant signaling pathways for cancer cells or/and immune cells, such as EGFR-KRAS (e.g., KRAS G12C ), PI3K-AKT-mTOR, ERK-MEK, JAK-STAT, p53, PD-1-PD-L1, and epigenetic, or immune pathways (e.g., histone deacetylases, cGAS-STING) are currently under investigation and have the potential to synergize with OV to modulate the immune milieu of the tumor microenvironment (TME), thereby improving and sustaining antitumor immunity. As many small molecule modulators of these signaling pathways have been developed and have shown strong therapeutic potential, here we review key findings related to both OV-mediated immunotherapy and the utility of small molecule modulators of signaling pathways in immuno-oncology. Then, we focus on discussion of the rationales and potential strategies for combining OV with selected modulators targeting key cellular signaling pathways in cancer or/and immune cells to modulate the TME and enhance antitumor immunity and therapeutic efficacy. Finally, we provide perspectives and viewpoints on the application of novel experimental systems and technologies that can propel this exciting branch of medicine into a bright future.

The immunotherapy of cancer has made significant strides in the past few years due to improved understanding of the underlying principles of tumor biology and immunology. These principles have been critical in the development of immunotherapy in the laboratory and in the implementation of immunotherapy in the clinic. This improved understanding of immunotherapy, enhanced by increased insights into the mechanism of tumor immune response and its evasion by tumors, now permits manipulation of this interaction and elucidates the therapeutic role of immunity in cancer. Also important, this improved understanding of immunotherapy and the mechanisms underlying immunity in cancer has fueled an expanding array of new therapeutic agents for a variety of cancers. Pegylated interferon-α2b as an adjuvant therapy and ipilimumab as therapy for advanced disease, both of which were approved by the United States Food and Drug Administration for melanoma in March 2011, are 2 prime examples of how an increased understanding of the principles of tumor biology and immunology have been translated successfully from the laboratory to the clinical setting. Principles that guide the development and application of immunotherapy include antibodies, cytokines, vaccines, and cellular therapies. The identification and further elucidation of the role of immunotherapy in different tumor types, and the development of strategies for combining immunotherapy with cytotoxic and molecularly targeted agents for future multimodal therapy for cancer will enable even greater progress and ultimately lead to improved outcomes for patients receiving cancer immunotherapy. [PUBLICATION ABSTRACT]

There is increasing evidence indicating the significant role of DDX5 (also called p68), acting as a master regulator and a potential biomarker and target, in tumorigenesis, proliferation, metastasis and treatment resistance for cancer therapy. However, DDX5 has also been reported to act as an oncosuppressor. These seemingly contradictory observations can be reconciled by DDX5’s role in DNA repair. This is because cancer cell apoptosis and malignant transformation can represent the two possible outcomes of a single process regulated by DDX5, reflecting different intensity of DNA damage. Thus, targeting DDX5 could potentially shift cancer cells from a growth-arrested state (necessary for DNA repair) to apoptosis and cell killing. In addition to the increasingly recognized role of DDX5 in global genome stability surveillance and DNA damage repair, DDX5 has been implicated in multiple oncogenic signaling pathways. DDX5 appears to utilize distinct signaling cascades via interactions with unique proteins in different types of tissues/cells to elicit opposing roles (e.g., smooth muscle cells versus cancer cells). Such unique features make DDX5 an intriguing therapeutic target for the treatment of human cancers, with limited low toxicity to normal tissues. In this review, we discuss the multifaceted functions of DDX5 in DNA repair in cancer, immune suppression, oncogenic metabolic rewiring, virus infection promotion, and negative impact on the human microbiome (microbiota). We also provide new data showing that FL118, a molecular glue DDX5 degrader, selectively works against current treatment-resistant prostate cancer organoids/cells. Altogether, current studies demonstrate that DDX5 may represent a unique oncotarget for effectively conquering cancer with minimal toxicity to normal tissues.

BackgroundProgrammed cell death protein-1 (PD-1)-blocking immune checkpoint inhibitors (ICIs) are effective against highly immunogenic “hot” tumors containing high numbers of cytotoxic T-lymphocytes (CTLs), but not against poorly immunogenic “cold” tumors. We previously reported that the combination of TLR3 agonist rintatolimod with interferon (IFN)-α selectively induces CTL-attracting chemokines (CXCL9, CXCL10, CCL5) in the tumor microenvironment (TME), but not healthy tissues, raising the possibility of their systemic application to promote local CTL attraction to TME.MethodsWe used mouse colorectal cancer (CRC) cells implanted in syngeneic mice to test the effects of chemokine modulatory regimen (CKM) in combination with PD-1 blockade applied at different schedules. Tumor-bearing mice were treated and monitored for survival. In addition, we evaluated the reliance of CKM+αPD-1 treatment on various immune cell subsets. Finally, we observed treatment-induced changes in immune markers within TME.ResultsHere, we report that both local or systemic application of CKM, a combination of rintatolimod and IFN-α, but not each of them individually, induces intratumoral CTL attractants and sensitizes PD-1-resistant MC38 and CT26 tumors to PD-1 blockade. The CKM/αPD-1 combination promotes intratumoral influx of BATF3-positive cDC1s and CTLs, inhibits tumor growth and prolongs survival, inducing cures in 20–100% of animals, depending on the tumor model and stage, and the route of delivery (local or systemic). CKM/αPD-1-treated mice develop local and systemic tumor-specific CTL responses and resistance to tumor re-challenge. The effectiveness of CKM requires its application at the time of or directly before PD-1 blockade and is strongly reduced by even a 24-hour delay in αPD-1 administration. CKM-driven intratumoral CTL accumulation and antitumor effects require host’s BATF3+cDC1s, CD8+T-lymphocytes, and CXCR3 and CCR5 (receptors for CXCL9/CXCL10 and CCL5).ConclusionsThe ability of systemic CKM to eliminate the PD-1-resistance of cold tumors indicates that intratumoral CTL accumulation, rather than tumor immunogenicity, is the key factor limiting the therapeutic effectiveness of ICI. These data suggest a broad therapeutic potential of TME-reprogramming strategies.

Immunotherapy is currently effective in less than half of patients with solid tumors, and most responders develop secondary progression. High infiltration of the tumor microenvironment (TME) with CD8 + cytotoxic T cells (CTLs) and low infiltration with regulatory T cells (Treg) predicts the patients’ responses to immunotherapy and long-term outcomes. To identify the mechanisms regulating long-term stability of CTL infiltration, we analyzed the impact of CTL-produced cytokines on the TME by co-culturing patient-isolated ascites cells with activated T cells. Unexpectedly, we observed that activated CTLs selectively induce cytotoxic T cell-attracting chemokines but not chemokines that attract T regulatory cells in ovarian cancer TME and tumor-associated myeloid cells, resulting in recruitment of additional CTLs without Tregs. This selectivity resulted from the unique dependence of CCL22 induction on both canonical and alternative NF-κB and the suppression of alternative NF-κB signaling by T cell-released IFNγ. Our data demonstrate that T cell-produced IFNγ suppresses alternative NF-κB signaling in TME-associated myeloid cells, allowing for the induction of CTL-attracting chemokines with the concomitant suppression of Treg-attracting CCL22. These novel functions of IFNγ and activated T cells in regulating the balance between canonical and alternative NF-κB signaling in myeloid cells provide new opportunities to enhance and stabilize the selective CTL influx in the TME.

The clinical management of bladder cancer continues to present significant challenges. Bacillus Calmette–Guérin (BCG) immunotherapy remains the gold standard of treatment for non-muscle invasive bladder cancer (NMIBC), but many patients develop recurrence and progression to muscle-invasive disease (MIBC), which is resistant to BCG. This review focuses on the immune mechanisms mobilized by BCG in bladder cancer tumor microenvironments (TME), mechanisms of BCG resistance, the dual role of the BCG-triggered NFkB/TNFα/PGE2 axis in the regulation of anti-tumor and tumor-promoting aspects of inflammation, and emerging strategies to modulate their balance. A better understanding of BCG resistance will help develop new treatments and predictive biomarkers, paving the way for improved clinical outcomes in bladder cancer patients.

Immune checkpoint inhibition (ICI) targeting programmed cell death protein-1 (PD1) prevents the elimination of activated cytotoxic T lymphocytes (CTLs) by programmed death-ligand 1/2-expressing cancer and myeloid cells in the tumor microenvironment (TME). ICI has shown its effectiveness in many solid tumors, but it lacks activity against “cold” tumors which lack CTL infiltration, including most of the colon, prostate, lung and breast cancers. Metastatic triple-negative breast cancer (TNBC) responds to PD-1 blockade only in 5–20% cases. Chemotherapy has been shown to have a PD1-sensitizing effect in a fraction of patients with TNBC but the underlying mechanism and the reasoning behind its limitation to only a subset of patients are unknown. Recent data demonstrate the key roles played by paclitaxel-driven Toll-like receptor 4 (TLR4) signaling and the resulting activation of type-1 and type-2 interferon pathways in tumor-associated macrophages, resulting in local M2 to M1 transition and enhanced tumor antigen cross-presentation, in the paclitaxel-driven sensitization of “cold” tumors to ICI. These data and the known ability of the TLR4-activated MyD88-NFκB pathway to mobilize both antitumor and tumor-promoting events in the TME provide new tools to enhance the efficacy of chemo-immunotherapy for metastatic, and potentially early, TNBC and other taxane-sensitive cancers.

Early-stage triple negative breast cancer (TNBC) has been traditionally treated with surgery, radiation, and chemotherapy. The current standard of care systemic treatment of early-stage II and III TNBC involves the use of anthracycline-cyclophosphamide and carboplatin-paclitaxel with pembrolizumab in the neoadjuvant setting followed by adjuvant pembrolizumab per KEYNOTE-522. It is increasingly clear that not all patients with early-stage TNBC need this intensive treatment, thus paving the way for exploring opportunities for regimen de-escalation in selected subgroups. For T1a tumors (≤5 mm), chemotherapy is not used, and for tumors 6–10 mm (T1b) in size with negative lymph nodes, retrospective studies have failed to show a significant benefit with chemotherapy. In low-risk patients, anthracycline-free chemotherapy may be as effective as conventional therapy, as shown in some studies where replacing anthracyclines with carboplatin has shown non-inferior results for pathological complete response (pCR), which may form the backbone of future combination therapies. Recent advances in our understanding of TNBC heterogeneity, mutations, and surrogate markers of response such as pCR have enabled the development of multiple treatment options in the (neo)adjuvant setting in order to de-escalate treatment. These de-escalation studies based on tumor mutational status, such as using Poly ADP-ribose polymerase inhibitors (PARPi) in patients with BRCA mutations, and new immunotherapies such as PD1 blockade, have shown a promising impact on pCR. In addition, the investigational use of (bio)markers, such as high levels of tumor-infiltrating lymphocytes (TILs), low levels of tumor-associated macrophages (TAMs), and complete remission on imaging, also look promising. In this review, we cover the current standard of care systemic treatment of early TNBC and review the opportunities for treatment de-escalation based on clinical risk factors, biomarkers, mutational status, and molecular subtype.

Vascularized composite tissue allotransplantation (VCA) has transformed patients’ lives by enabling limb, face, abdominal wall, and penile transplants. Despite advancements in screening and immunosuppression, chronic rejection continues to limit the success of VCA. Lack of reliable preclinical models exacerbates this challenge. Here, we report on new mouse models of chronic rejection following heterotopic hind limb VCA. We employed different levels of MHC mismatch using CD8 knockout C57BL/6 mice as recipients along with BALB/c or B6 H2-Ab1 bm12 mice as donors. Transient CD4 T cell depletion was induced to allow graft maturation. Evaluation included gross findings, changes in immune status changes, production of donor-specific antibodies (DSA), C4d levels, and histopathological alterations. Two chronic rejection models displayed common features of clinical chronic graft rejection, such as skin stricture, hair loss, adnexal atrophy, extensive fibrosis and mast cell infiltration without widespread necrotic changes common in acute rejection. Similar to chronic rejection patients, large populations of activated B and plasma cells were detected in the recipient’s immune system as well as increased DSA and C4d production. Collectively, our models closely replicate the immunological and histopathological aspects of chronic graft rejection post-VCA, and could provide a new platform for evaluation of novel therapeutic interventions prior to clinical evaluation.