Induction Of Antitumor Immune Responses Research Articles

A phase 2a safety run-in and preliminary efficacy study of liposomal gemcitabine (FF-10832) in combination with pembrolizumab in patients with advanced solid tumors.

2615 Background: FF-10832 (FF832) [liposomal gemcitabine (GEM)] has demonstrated superior activity preclinically compared to GEM via preferential tumor accumulation & induction of antitumor immune responses. Further enhanced activity has been shown in combination with immune checkpoint inhibitors. We evaluated the tolerability & preliminary efficacy of FF832 in combination with the PD-1 antibody pembrolizumab (PEM) in a Phase 2a safety run-in study in patients (pts) with advanced solid tumors. Methods: Pts received 200 mg PEM followed by 40 mg/m2 FF832 on Day 1 of a 21-day cycle to validate the recommended Phase 2 dose (RP2D) for combination therapy; treatment was continued until disease progression or unacceptable toxicity. Response was assessed by RECIST 1.1 every 2 cycles. Tumor PD-L1 expression, mutational burden, and modulation of circulating immune cells were assessed, & population PK modeling performed. Results: Twelve pts [NSCLC (6), urothelial cancer, UC (4), renal cell carcinoma (2); 6M/6F; median age, 69 (42-82) & median # prior therapies, 5 (1-7); prior GEM (5), prior PEM (9)] received a median of 2 (1-8) cycles FF832+PEM. Median time on study was 6.1 (1.1–23.7) weeks. FF832+PEM was well-tolerated. Common AEs related to FF832 were Gr≤2 fatigue (50%) with 1 Gr 3, anemia (33%) with 2 Gr 3, & Gr ≤2 decreased appetite, diarrhea, ↑AST, ↑AlkPhos, muscular weakness, nausea, and pyrexia (25% each). Common AEs related to FF832+PEM were Gr≤2 fatigue (33%) & nausea (25%). Three pts had Gr≤2 infusion reactions with the first FF832 infusion; all resolved & were successfully rechallenged. FF832 dose was reduced to 30 mg/m2 after Cycle 1 in 3 pts due to Gr 3 rash (1), Gr 2 fatigue (1), & one DLT of Gr 3 malaise, pain, and arthralgia. Of 9 pts evaluable for response, one achieved an unconfirmed PR after one cycle (UC, prior GEM/PEM, 42%↓ in target lesions). Five pts had a best response of SD with 2 maintained for 6-8 cycles. Median PFS was 6 weeks (95%CI: 3.1–NR); median OS was 23.3 weeks (95%CI: 4–NR). An extended plasma t1/2 (~30 hours) & exposures consistent with FF832 monotherapy at the RP2D were observed. As with FF832 monotherapy, multi-log decreases were observed in circulating Ki67+ Tregs relative to total CD4+ cells while CD8+ cells increased, suggesting FF832+PEM could enhance shifts to a more immunocompetent tumor microenvironment. Conclusions: The safety and preliminary efficacy of FF832+PEM was demonstrated in heavily pre-treated pts with solid tumors whose disease progressed on prior GEM and/or PEM. Continuous GEM exposure from FF832 along with immune checkpoint blockade may improve antitumor activity. Evaluation of FF832 at the RP2D/schedule of 40 m/gm2 Q 21 days alone and in combination with PEM is ongoing in a randomized expansion study in pts with metastatic NSCLC and UC with prior disease progression on PD-1/L1 therapy. Clinical trial information: NCT05318573 .

Synergistic antitumor immune response mediated by paclitaxel-conjugated nanohybrid oncolytic adenovirus with dendritic cell therapy.

Dendritic cell (DC)-based vaccines have emerged as a promising strategy in cancer immunotherapy due to low toxicity. However, the therapeutic efficacy of DC as a monotherapy is insufficient due to highly immunosuppressive tumor environment. To address these limitations of DC as immunotherapeutic agent, we have developed a polymeric nanocomplex incorporating (1) oncolytic adenovirus (oAd) co-expressing interleukin (IL)-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) and (2) arginine-grafted bioreducible polymer with PEGylated paclitaxel (APP) to restore antitumor immune surveillance function in tumor milieu and potentiate immunostimulatory attributes of DC vaccine. Nanohybrid complex (oAd/APP) in combination with DC (oAd/APP+DC) induced superior expression level of antitumor cytokines (IL-12, GM-CSF, and interferon gamma) than either oAd/APP or DC monotherapy in tumor tissues, thus resulting in superior intratumoral infiltration of both endogenous and exogenous DCs. Furthermore, oAd/APP+DC treatment led superior migration of DC to secondary lymphoid organs, such as draining lymph nodes and spleen, in comparison with either monotherapy. Superior migration profile of DCs in oAd/APP+DC treatment group resulted in more prolific activation of tumor-specific T cells in these lymphoid organs and greater intratumoral infiltration of T cells. Additionally, oAd/APP+DC treatment led to lower subset of tumor infiltrating lymphocytes and splenocytes being immunosuppressive regulatory T cells than any other treatment groups. Collectively, oAd/APP+DC led to superior induction of antitumor immune response and amelioration of immunosuppressive tumor microenvironment to elicit potent tumor growth inhibition than either monotherapy.

Abstract 6660: The novel codon-modified Zika virus CDX-602 shows anti-tumor efficacy and remodels the tumor microenvironment in preclinical models

Abstract Multiple oncolytic viruses have been shown to induce multifaceted changes in the tumor microenvironment, that ultimately support induction of anti-tumor immune responses. We have previously demonstrated that CodaLytic, a codon-modified influenza virus, can kickstart the cancer immunity cycle at various steps in several mouse models with differing baseline immune contextures. Here, we are describing the activity of a new codon-modified virotherapeutic derived from the same synthetic viral engineering platform [Coleman et al., Science 2008]. Zika virus strain MR766 was synthetically codon-modified at 664 positions in the envelop gene to yield CDX-602. Virus was originally passaged in Vero cells and working stocks were expanded in BSR-T7 cells for in vivo use after titration on MA104.1 cells. Efficacy after intratumoral injection of 107 PFU/dose CDX-602 alone or in combination with 200 μg/dose αPD-1 blockade (RMP1-14, i.p.) was determined in subcutaneous B16-F10 melanoma and orthotopic EMT6 breast cancer models (n = 10). Changes in the tumor immune infiltrate were characterized using flow cytometry 6 or 8 days after treatment initiation, respectively (n = 5). In the immunotherapy-resistant B16-F10 model, CDX-602 monotherapy led to highly reproducible tumor growth inhibition (TGI, 52%, p < 0.0001 vs vehicle control), resulting in modest, but significant prolongation of median survival (25%, p < 0.01). Anti-tumor efficacy correlated with increased tumor immune infiltration with CD4+ and CD8+ T cells (R2 = 0.68 and 0.67, respectively, p < 0.01). Importantly, frequencies of cross-presenting dendritic cells (cDC) were increased 3.8-fold (p < 0.0001) after virus treatment, while no compensatory influx of CD206+ macrophages was observed, suggesting immune contexture changes conducive to anti-tumor immune induction. Efficacy was confirmed in the EMT6 model, in which monotherapy TGI was 44% and thus on par with αPD-1 blockade (50%, both p < 0.0001 vs control). Combination viroimmunotherapy in this model further improved efficacy, leading to 71% TGI and a doubling in complete regressions to 40%. Inclusion of CDX-602 in the treatment regimen led to similar changes in immune infiltration, in particular recruitment of CD8+ T cells and cDCs (9.7-fold and 6.9-fold increase after combination, respectively). Additional ex vivo analyses to confirm induction of anti-tumor immune responses are ongoing. Taken together, this preclinical data establishes CDX-602 as a novel virotherapeutic candidate that engages multiple mechanisms of action that contribute to anti-tumor activity. CDX-602 is the second virotherapeutic candidate derived from Codagenix’s codon modification platform, further supporting the utility of this synthetic viral engineering technology for viroimmunotherapy of cancer and highlighting its potential across multiple viral species. Citation Format: Nusrat Jahan, Yiwen Zhao, Katarina Blagovic, Ying Wang, J Robert Coleman, Steffen Mueller, Johanna K. Kaufmann. The novel codon-modified Zika virus CDX-602 shows anti-tumor efficacy and remodels the tumor microenvironment in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6660.

YB-1-based oncolytic virotherapy in combination with CD47 blockade enhances phagocytosis of pediatric sarcoma cells.

Oncolytic viruses (OVs) selectively replicate in tumor cells resulting in lysis, spreading of new infectious units and induction of antitumor immune responses through abrogating an immunosuppressive tumor microenvironment (TME). Due to their mode of action, OVs are ideal combination partners with targeted immunotherapies. One highly attractive combination is the inhibition of the 'don't-eat-me'-signal CD47, which is known to increase the phagocytic potential of tumor-associated macrophages. In this work, we analyzed the combination approach consisting of the YB-1-based oncolytic adenovirus XVir-N-31 (XVir) and the CD47 inhibitor (CD47i) B6.H12.2 concerning its phagocytic potential. We investigate phagocytosis of XVir-, adenovirus wildtype (AdWT)-, and non-infected established pediatric sarcoma cell lines by different monocytic cells. Phagocytes (immature dendritic cells and macrophages) were derived from THP-1 cells and healthy human donors. Phagocytosis of tumor cells was assessed via FACS analysis in the presence and absence of CD47i. Additional characterization of T cell-stimulatory surface receptors as well as chemo-/cytokine analyses were performed. Furthermore, tumor cells were infected and studied for the surface expression of the 'eat-me'-signal calreticulin (CALR) and the 'don't-eat-me'-signal CD47. We herein demonstrate that (1) XVir-infected tumor cells upregulate both CALR and CD47. XVir induces higher upregulation of CD47 than AdWT. (2) XVir-infection enhances phagocytosis in general and (3) the combination of XVir and CD47i compared to controls showed by far superior enhancement of phagocytosis, tumor cell killing and innate immune activation. In conclusion, the combination of CD47i and XVir causes a significant increase in phagocytosis exceeding the monotherapies considerably accompanied by upregulation of T cell-stimulatory receptor expression and inflammatory chemo/-cytokine secretion.

Carbon ion irradiation exerts antitumor activity by inducing cGAS-STING activation and immune response in prostate cancer-bearing mice.

As an advanced radiotherapy technique, carbon ion radiotherapy has demonstrated good efficacy and low toxicity for prostate cancer patients, but the radiobiological mechanism of killing tumor cells has not been fully elucidated. This study aims to explore the antitumor effects of carbon ion irradiation (CIR) through investigating the immune response induced by CIR in prostate cancer-bearing mice and the underlying molecular mechanism. We established subcutaneous transplantation tumor models of prostate cancer to evaluate the tumor inhibition effect of CIR. Investigation of immunophenotype alterations were assessed by flow cytometry. Immunofluorescence, western blot, and real-time quantitative PCR was employed to analyze the activation of cGAS-STING pathway. CIR showed more powerful tumor growth control than photon irradiation in immunocompetent syngeneic C57BL/6 mice. CIR exerts antitumor effect by triggering immune response, characterized by increased CD4+ T cells and macrophages in tumor, enhanced CD8+ T cells and T effector memory cells in spleen, improved IFN-γ production of CD8+ tumor-infiltrating lymphocytes, and reduced exhausted T cells in tumor and spleen. Additionally, production of cytoplasmic double-stranded DNA, protein levels of p-TBK1 and p-IRF3 in the cGAS-STING pathway, and gene expression levels of downstream interferon-stimulated genes were significantly increased after CIR in a dose-dependent manner. Treatment of RM1 tumor-bearing mice with the STING inhibitor C-176 impaired the antitumor effect of CIR. The excellent antitumor activity of CIR in immunocompetent prostate cancer-bearing C57BL/6 mice may be attributed to stronger induction of antitumor immune response and higher activation of cGAS-STING pathway.

Experimental and Computational Studies Reveal Novel Interaction of Lymphocytes Antigen 6K to TGF-β Receptor Complex.

TGF-β signaling promotes migration, invasion, and distant colonization of cancer cells in advanced metastatic cancers. TGF-β signaling suppresses the anti-tumor immune response in a tumor microenvironment, allowing sustained tumor growth. TGF-β plays an important role in normal physiology; thus it is no surprise that the clinical development of effective and safe TGF-β inhibitors has been hampered due to their high toxicity. We discovered that increased expression of LY6K in cancer cells led to increased TGF-β signaling and that inhibition of LY6K could lead to reduced TGF-β signaling and reduced in vivo tumor growth. LY6K is a highly cancer-specific protein, and it is not expressed in normal organs except in the testes. Thus, LY6K is a valid target for developing therapeutic strategies to inhibit TGF-β signaling in cancer cells. We employed in vitro pull-down assays and molecular dynamics simulations to understand the structural determinants of the TGF-β receptor complex with LY6K. This combined approach allowed us to identify the critical residues and dynamics of the LY6K interaction with the TGF-β receptor complex. These data are critical in designing novel drugs for the inhibition of TGF-β in LY6K expressing cancer, induction of anti-tumor immune response, and inhibition of tumor growth and metastatic spread.

Reovirus combined with a STING agonist enhances anti-tumor immunity in a mouse model of colorectal cancer.

Reovirus, a naturally occurring oncolytic virus, initiates the lysis of tumor cells while simultaneously releasing tumor antigens or proapoptotic cytokines in the tumor microenvironment to augment anticancer immunity. However, reovirus has developed a strategy to evade antiviral immunity via its inhibitory effect on interferon production, which negatively affects the induction of antitumor immune responses. The mammalian adaptor protein Stimulator of Interferon Genes (STING) was identified as a key regulator that orchestrates immune responses by sensing cytosolic DNA derived from pathogens or tumors, resulting in the production of type I interferon. Recent studies reported the role of STING in innate immune responses to RNA viruses leading to the restriction of RNA virus replication. In the current study, we found that reovirus had a reciprocal reaction with a STING agonist regarding type I interferon responses in vitro; however, we found that the combination of reovirus and STING agonist enhanced anti-tumor immunity by enhancing cytotoxic T cell trafficking into tumors, leading to significant tumor regression and survival benefit in a syngeneic colorectal cancer model. Our data indicate the combination of reovirus and a STING agonist to enhance inflammation in the tumor microenvironment might be a strategy to improve oncolytic reovirus immunotherapy.

Abstract 689: The codon-modified influenza virus CodaLytic™rescues immunostimulatory activity and anti-tumor efficacy in PD-1-refractory tumor models

Abstract Multiple oncolytic viruses have been shown to induce various beneficial changes in the tumor microenvironment (TME), which ultimately support induction of anti-tumor immune responses. We have previously demonstrated that CodaLytic, a codon-modified influenza virus, can kickstart the cancer immunity cycle at various steps in several mouse models with differing baseline immune contextures. Here, we are confirming the mechanisms of action of the virus in combination with immune checkpoint inhibition in murine and human preclinical models. Efficacy after intratumoral injection of 108 PFU CodaLytic in combination with αPD-1 and/or αCTLA-4 checkpoint blockade was determined in αPD-1-resistant B16-F10 melanoma and 4T1 triple-negative breast cancer mouse models. Changes in the tumor immune infiltrate after treatment were characterized using flow cytometry. Primary human tumoroids were incubated with CodaLytic +/- 10 μg/ml pembrolizumab using the 3D-Explore platform by Nilogen Oncosystems. Tumor cell killing (TCK) was detected by high-content imaging at 72h and effects on the TME were characterized by cytokine release and RNA sequencing at 24h and/or 48h. In B16-F10, addition of CodaLytic to αPD-1 blockade rescued non-significant tumor growth inhibition (TGI) with αPD-1 alone, achieving 86% TGI (p < 0.01), 40% complete regressions and 60% survival beyond 45 days (69% TGI, 20% regressions and 30% long-term survival after CodaLytic monotherapy). Mechanistically, CodaLytic-containing regimens increased tumor immune infiltration, in particular with CD8+ T cells and cross-presenting dendritic cells (DCs). 4T1 tumors did not significantly respond to αPD-1, αCTLA-4 or CodaLytic monotherapies, but achieved 86% TGI in combination with 50% long-term survival past 55 days. CTLA-4 blockade emerged as the initial driver of slowed tumor growth and αPD-1 drove long-term survival, which was further augmented by CodaLytic addition. Infiltration with CD45+ leukocytes and cross-presenting DCs correlated with tumor volumes. The benefit of CodaLytic combination treatment was also demonstrated ex vivo in human tumoroid cultures. Meaningful TCK was observed in 50% of specimens vs 17% with pembrolizumab and 33% with CodaLytic alone. In this system without immune cell recruitment from a systemic reservoir, sustained release of CXCL9 and CXCL10 and temporal decreases of MIP-1β and CCL2 associated with response. Additional transcriptional analyses are ongoing. Taken together, this and additional preclinical data confirms the emergence of CodaLytic as a potent immunostimulatory agent capable of restoring immune cell infiltration and anti-tumor efficacy when used in combination with checkpoint inhibition in PD-1 resistant models. This data supports future development of CodaLytic for immuno-virotherapy of tumor types in which checkpoint therapy is less established. Citation Format: Yiwen Zhao, Nusrat Jahan, Marcin Stawowczyk, Katie Pfeffer, Juliana Tafrova, James Rodriguez, Chen Yang, Sybil A. Tasker, Steffen Mueller, J. Robert Coleman, Johanna K. Kaufmann. The codon-modified influenza virus CodaLytic™rescues immunostimulatory activity and anti-tumor efficacy in PD-1-refractory tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 689.

Reovirus Type 3 Dearing Variants Do Not Induce Necroptosis in RIPK3-Expressing Human Tumor Cell Lines.

Reoviruses are used as oncolytic viruses to destroy tumor cells. The concomitant induction of anti-tumor immune responses enhances the efficacy of therapy in tumors with low amounts of immune infiltrates before treatment. The reoviruses should provoke immunogenic cell death (ICD) to stimulate a tumor cell-directed immune response. Necroptosis is considered a major form of ICD, and involves receptor-interacting protein kinase 1 (RIPK1), RIPK3 and phosphorylation of mixed-lineage kinase domain-like protein (MLKL). This leads to cell membrane disintegration and the release of damage-associated molecular patterns that can activate immune responses. Reovirus Type 3 Dearing (T3D) can induce necroptosis in mouse L929 fibroblast cells and mouse embryonic fibroblasts. Most human tumor cell lines have a defect in RIPK3 expression and consequently fail to induce necroptosis as measured by MLKL phosphorylation. We used the human colorectal adenocarcinoma HT29 cell line as a model to study necroptosis in human cells since this cell line has frequently been described in necroptosis-related studies. To stimulate MLKL phosphorylation and induce necroptosis, HT29 cells were treated with a cocktail consisting of TNFα, the SMAC mimetic BV6, and the caspase inhibitor Z-VAD-FMK. While this treatment induced necroptosis, three different reovirus T3D variants, i.e., the plasmid-based reverse genetics generated virus (T3DK), the wild-type reovirus T3D isolate R124, and the junction adhesion molecule-A-independent reovirus mutant (jin-1) failed to induce necroptosis in HT29 cells. In contrast, these viruses induced MLKL phosphorylation in murine L929 cells, albeit with varying efficiencies. Our study shows that while reoviruses efficiently induce necroptosis in L929 cells, this is not a common phenotype in human cell lines. This study emphasizes the difficulties of translating the results of ICD studies from murine cells to human cells.

Nonenveloped Virus-Like Particles: A Promising Antigen-Delivery Strategy for the Induction of Antitumor Immune Responses

The use of antigen delivery systems is essential for inducing antitumor immune responses. Among these, virus-like particles (VLPs) increase the immunogenicity of coupled antigens to stimulate cellular and humoral immune responses. In particular, non-enveloped or capsid VLPs (cVLPs) are a promising antigen delivery system option due to their additional advantages of high production yields and low cost. This review summarizes the latest works on cVLPs in cancer vaccines, supporting cVLPs as a tumor antigen delivery system for immunotherapy and addressing some critical aspects of cVLP use such as production, assembly, decoration and immunization strategies, which can improve the effectiveness of cancer vaccines based on cVLPs.

Gold Nanoparticle (AuNP) as a Therapeutic Enhancer for Radio – And Immunotherapy Therapy Combination in Triple Negative Breast Cancer

<h3>Purpose/Objective(s)</h3> Triple negative breast cancer (TNBC) is the most aggressive breast cancer (BC) form, with a high metastases rate and a very low survival. The aggressiveness of TNBC coupled with a significant toxicity and suboptimal chemotherapy outcomes underscores the urgency for new TNBC treatments. In recent years, immunotherapy has emerged as a promising option. In particular, immune checkpoint blockers (ICB) targeting PD-L1/PD1 inhibitory T cell check point pathway showed clinical responses and have been explored for TNBC. Unfortunately, the response rates to standalone ICB therapy are low (15-20%), indicating the presence of inhibitory immune mechanisms. Radiation therapy (RT) has been widely used in BC therapies. In addition to antitumor (antiproliferative) effects, RT has been evidenced to stimulate immune tumor rejection through immunomodulation of the tumor microenvironment (TME) that has been shown to enhance the response to immunotherapy in mouse BC models. Antitumor RT effects, including TME immunomodulation, can be improved by using radiosensitizers, such as gold nanoparticles (AuNPs). We hypothesize that AuNP potentiates RT-induced immunomodulatory effects, leading to a more efficient response to ICB in TNBC. To test this hypothesis, we used AuNP as an enhancer of RT-induced immunological TME changes, to improve ICB therapy response in murine orthotopic syngeneic 4T1Luc TNBC model. <h3>Materials/Methods</h3> Female Balb/c mice bearing 4T1Luc tumors received intratumoral injections of 14 nm AuNPs. After 24h mice were irradiated with fractionated regimen of 3 × 6 Gy dose using 225 kV photons. After the 3rd RT dose, mice received 3 doses of anti-PD-L1 antibody that were 4 days apart. Therapeutic efficiency was determined by assessing the tumor growth and animal survival. Tumor tissue immunohistochemistry determined the expression of TME immunological markers and immune cell tumor infiltration. <h3>Results</h3> AuNPs improved response to anti PD-L1 treatment in mice receiving RT, shown by significant delay in tumor growth and increase in survival compared to the animals receiving RT+ AuNP (p<0.01) and to the animals receiving RT+ anti PD-L1 or RT alone (p<0.05). These results were accompanied with changes in the expression of TME immunological markers and T cell and macrophage infiltration. <h3>Conclusion</h3> In TNBC patients, induction of antitumor immune response may play a critical role in improving clinical outcomes. Here we show that AuNP enhanced the effect of a fractionated RT regimen that has significantly improved the response to anti PD-L1 treatment in 4T1Luc TNBC mouse model. This effect was measured by a delay in tumor growth and an increase in animal survival. These findings support the role of immunological mechanisms in TNBC and provide a platform for designing multimodal TNBC RT formulations with novel radiosensitizers or immunotherapy.

Immune checkpoint inhibition improves antimyeloma activity of bortezomib and STING agonist combination in Vk*MYC preclinical model

Multiple myeloma (MM), a hematological malignancy of plasma cells, has remained incurable despite the development of novel therapies that improve patients’ outcome. Recent evidence indicates that the stimulator of interferon genes (STING) pathway may represent a novel target for induction of antitumor immune response in multiple myeloma. Here, we investigated antitumor effects of STING agonist with bortezomib with or without checkpoint inhibitor in the treatment of MM. Methods: STING expression in bone marrow plasma cells of 58 MM patients was examined by immunohistochemical staining. The effectiveness of the proposed therapy was evaluated in vivo in a syngeneic transplantable mouse model of MM (Vĸ*MYC) in immunocompetent mice. Flow cytometry was used to assess tumor burden and investigate activation of immune response against MM. ELISA was performed to measure serum inflammatory cytokines concentrations upon treatment. Results: Combining a STING agonist [2′3′-cGAM(PS)2] with bortezomib significantly decreased tumor burden and improved the survival of treated mice compared to either of the compounds used alone. The combination treatment led to secretion of pro-inflammatory cytokines and increased the percentage of neutrophils, activated dendritic cells and T cells in the tumor microenvironment. However, it resulted also in increased expression of PD-L1 on the surface of the immune cells. Addition of anti-PD1 antibody further potentiated the therapeutic effects. Conclusions: Our findings indicate high antimyeloma efficacy of the three-drug regimen comprising bortezomib, STING agonist, and a checkpoint inhibitor.

Cell-line screening and process development for a fusogenic oncolytic virus in small-scale suspension cultures

Oncolytic viruses (OVs) represent a novel class of immunotherapeutics under development for the treatment of cancers. OVs that express a cognate or transgenic fusion protein is particularly promising as their enhanced intratumoral spread via syncytia formation can be a potent mechanism for tumor lysis and induction of antitumor immune responses. Rapid and efficient fusion of infected cells results in cell death before high titers are reached. Although this is an attractive safety feature, it also presents unique challenges for large-scale clinical-grade manufacture of OVs. Here we evaluate the use of four different suspension cell lines for the production of a novel fusogenic hybrid of vesicular stomatitis virus and Newcastle disease virus (rVSV-NDV). The candidate cell lines were screened for growth, metabolism, and virus productivity. Permissivity was evaluated based on extracellular infectious virus titers and cell-specific virus yields (CSVYs). For additional process optimizations, virus adaptation and multiplicity of infection (MOI) screenings were performed and confirmed in a 1 L bioreactor. BHK-21 and HEK293SF cells infected at concentrations of 2 × 106 cells/mL were identified as promising candidates for rVSV-NDV production, leading to infectious titers of 3.0 × 108 TCID50/mL and 7.5 × 107 TCID50/mL, and CSVYs of 153 and 9, respectively. Compared to the AGE1.CR.pIX reference produced in adherent cultures, oncolytic potency was not affected by production in suspension cultures and possibly even increased in cultures of HEK293SF and AGE1.CR.pIX. Our study describes promising suspension cell-based processes for efficient large-scale manufacturing of rVSV-NDV.Key points• Cell contact-dependent oncolytic virus (OV) replicates in suspension cells.• Oncolytic potency is not encompassed during suspension cultivation.• Media composition, cell line, and MOI are critical process parameters for OV production.• The designed process is scalable and shows great promise for manufacturing clinical-grade material.

In Situ Tumor Vaccine Expressing Anti-CD47 Antibody Enhances Antitumor Immunity.

In situ tumor vaccine is a potential cancer therapy due to their advantages in induction of antitumor immune responses. Oncolytic virotherapy utilizes natural or engineered oncolytic viruses to kill tumors selectively, representing a promising in situ tumor vaccine for cancer immunotherapy. In addition to direct oncolysis, oncolytic viruses elicit potent and durable antitumor immune responses by induction of immunogenic cell death of tumors. Membrane protein CD47 overexpressed on tumor cells engages in “don’t eat me” signal that prevents macrophages from engulfing tumor cells. CD47-targeting agents have been tested via preclinical and clinical trials. As potential tumor vaccine vectors, oncolytic viruses can be engineered to express anti-CD47 antibodies to induce potentiated tumor killing. Therefore, we developed an adenovirus-based tumor vaccine loaded with a CD47-targeting nanobody fused with the IgG2a Fc protein. B16-F10 melanoma, A20 lymphoma, and 4T1 breast cancer models in immunocompetent mice were established to evaluated in vivo antitumor efficacy of in situ tumor vaccination. The tumor vaccine armed with a nanobody against CD47 induced durable suppression of the tumor and long-term survival of tumor-bearing mice, and also elevated the number of tumor-infiltrating immune cells with an activated immunophenotype, suggesting that it could remodel the tumor immune microenvironment. Systemic antitumor effects and immune memory were also observed in immunocompetent mice following in situ vaccination with the anti-CD47 tumor vaccines; tumorigenesis was completely inhibited in these mice after tumor re-challenge. The recombinant anti-CD47 tumor vaccine has an effectual antitumor activity and may be a promising antitumor agent.

Inhibition of SUMOylation modulates the immunosuppressive microenvironment of pancreatic cancer

Abstract Objective Pancreatic cancer (PC) is a highly aggressive disease that is poorly responsive to available immunotherapy approaches, such as checkpoint inhibitors. Post-translational protein modification (PTM) by small ubiquitin-like modifier (SUMO) is upregulated in cancer, and high expression of SUMOylation-related factors correlates with poor survival in PC. TAK-981 is a novel inhibitor of SUMOylation that has demonstrated induction of anti-tumor immune responses in preclinical models. Our hypothesis is that TAK-981 will decrease SUMOylated proteins and subsequently modulate the tumor microenvironment to increase anti-tumor immunity. Methods In order to recapitulate the microenvironment of human PC, a 3-dimensional organoid cell line derived from a genetically-engineered “KPC” mouse was used. Organoids were injected orthotopically into the head of the pancreas via laparotomy. Once tumors reached 5–7 mm in diameter on ultrasound imaging, mice were randomized to one of two treatment groups: Control/Vehicle versus TAK-981 (15 mg/kg) delivered daily via intraperitoneal injection. Tumors were harvested on day 14 for gene expression analysis by quantitative real time PCR (RT-qPCR). Results Tumor growth (Fig. 1) in the TAK-981 15 mg/KG daily group (mean + SD volume = 207 + 109 mm3) was significantly inhibited compared to the vehicle group (595 + 141 mm3, p &amp;lt; 0.01). Immunohistochemical staining for CD 31 (Fig. 2) and Caspase 3 indicated a reduction of angiogenesis and increased apoptosis of tumor cells, consistent with the well-established roles of SUMOylation in angiogenesis and tumorigenesis. Gene expression analysis of tumor lysates showed a 26-fold increase in expression of Interferon beta (p&amp;lt;0.05), and an almost 2-fold increase in expression of genes related to dendritic cell activation, including CD80 (p&amp;lt;0.05) and CD86 (p=0.14) in the TAK-981 group, suggesting a modulation of the immune microenvironment. Conclusion Our results suggest that the inhibition of SUMOylation with TAK-981 is associated with improved local tumor control and changes in the immunosuppressive tumor microenvironment. We expect that TAK-981 will improve PC responsiveness to immunotherapy, such as with checkpoint inhibitors.

Engineering of Surface Energy of Cell-Culture Platform to Enhance the Growth and Differentiation of Dendritic Cells via Vapor-Phase Synthesized Functional Polymer Films.

Although the dendritic cell (DC)-based modulation of immune responses has emerged as a promising therapeutic strategy for tumors, infections, and autoimmune diseases, basic research and therapeutic applications of DCs are hampered by expensive growth factors and sophisticated culture procedures. Furthermore, the platform to drive the differentiation of a certain DC subset without any additional biochemical manipulations has not yet been developed. Here, five types of polymer films with different hydrophobicity via an initiated chemical vapor deposition (iCVD) process to modulate the interactions related to cell-substrate adhesion are introduced. Especially, poly(cyclohexyl methacrylate) (pCHMA) substantially enhances the expansion and differentiation of conventional type 1 DCs (cDC1s), the prime DC subset for antigen cross-presentation, and CD8+ T cell activation, by 4.8-fold compared to the conventional protocol. The cDC1s generated from the pCHMA-coated plates retain the bona fide DC functions including the expression of co-stimulatory molecules, cytokine secretion, antigen uptake and processing, T cell activation, and induction of antitumor immune responses. To the authors' knowledge, this is the first report highlighting that the modulation of surface hydrophobicity of the culture plate can be an incisive approach to construct an advanced DC culture platform with high efficiency, which potentially facilitates basic research and the development of immunotherapy employing DCs.

Bioreducible polymer-mediated delivery of oncolytic adenovirus can attenuate antiviral immune response and concurrently enhance the induction of antitumor immune response to effectively prevent metastasis.

Oncolytic virotherapy is a highly promising and novel treatment modality for cancer. Several clinical trials with oncolytic viruses have illustrated that the potent antitumor efficacy of these viruses may rely on the efficient induction of antitumor immune response. In contrast, antiviral immune response is attributed to adverse side defects and diminishing therapeutic efficacy. In the present report, we generated a nanohybrid complex incorporating immune stimulatory oncolytic adenovirus (oAd) co-expressing decorin (DCN) and interleukin (IL)-12 with a bioreducible nanomaterial composed of PEI-Arg-mPEG-S-S-mPEG-Arg-PEI blocks (PAPS), ultimately aiming to modulate both antitumor and antiviral immune responses to be favorable toward oncolytic virotherapy. The transduction efficacy of the PAPS-incorporated nanohybrid vector (Ad/PAPS) was significantly higher than that of a complex using our previously reported polymer PPSA (Ad/PPSA) regardless of the cellular coxsackievirus and adenovirus receptor expression level of cancer cells. oAd complexed with PAPS (oAd/PAPS) also elicited a more potent cancer cell killing effect, antitumor efficacy, and metastasis inhibition than naked oAd or oAd complexed with PPSA (oAd/PPSA) through a higher level of therapeutic transgenes (DCN and IL-12), viral replication, and more efficient infiltration of T cells into tumor tissues. Notably, oAd/PAPS induced the highest level of antitumor immune response while the antiviral immune response was mediated at a significantly lower level than those of naked oAd. Adaptive immune response against the virus was also significantly attenuated in the oAd/PAPS group. oAd/PAPS treatment also led to the highest level of antitumor central memory T cells and the lowest level of immunosuppressive regulatory T cells in the spleen. Collectively, our findings illustrate that oAd/PAPS can simultaneously regulate both antitumor and antiviral immune responses to be more favorable to oncolytic virotherapy, leading to improved gene expression, viral replication, and growth inhibition of both primary and metastatic tumors.

A Promising Treatment Strategy for Lung Cancer: A Combination of Radiotherapy and Immunotherapy.

Simple SummaryLung cancer is a leading cause of cancer-related deaths worldwide. In the past few decades, radiotherapy has achieved outstanding technical advances and is widely used in the management of lung cancer. The anti-tumor effect of radiotherapy is mainly caused by DNA damage in cancer cells within the irradiated field. In addition, radiotherapy induces anti-tumor immune responses that are essential in cancer control. Recently, immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4, programmed cell death-1/programmed death-ligand 1, and their inhibitors, have attracted significant attention for overcoming the immunosuppressive conditions in patients with cancer. Furthermore, some studies showed that the combination of immune checkpoint inhibitors and radiotherapy appears promising. In this review, we outlined evidence about the combination of radiotherapy, including particle therapy using protons and carbon ions, with immunotherapy in lung cancer treatment.Lung cancer is a leading cause of cancer-related deaths worldwide despite advances in treatment. In the past few decades, radiotherapy has achieved outstanding technical advances and is being widely used as a definitive, prophylactic, or palliative treatment of patients with lung cancer. The anti-tumor effects of radiotherapy are considered to result in DNA damage in cancer cells. Moreover, recent evidence has demonstrated another advantage of radiotherapy: the induction of anti-tumor immune responses, which play an essential role in cancer control. In contrast, radiotherapy induces an immunosuppressive response. These conflicting reactions after radiotherapy suggest that maximizing immune response to radiotherapy by combining immunotherapy has potential to achieve more effective anti-tumor response than using each alone. Immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4, programmed cell death-1/programmed death-ligand 1, and their inhibitors, have attracted significant attention for overcoming the immunosuppressive conditions in patients with cancer. Therefore, the combination of immune checkpoint inhibitors and radiotherapy is promising. Emerging preclinical and clinical studies have demonstrated the rationale for these combination strategies. In this review, we outlined evidence suggesting that combination of radiotherapy, including particle therapy using protons and carbon ions, with immunotherapy in lung cancer treatment could be a promising treatment strategy.

Does CCL19 act as a double-edged sword in cancer development?

Cancer is considered a life-threatening disease, and several factors are involved in its development. Chemokines are small proteins that physiologically exert pivotal roles in lymphoid and non-lymphoid tissues. The imbalance or dysregulation of chemokines has contributed to the development of several diseases, especially cancer. CCL19 is one of the homeostatic chemokines that is abundantly expressed in the thymus and lymph nodes. This chemokine, which primarily regulates immune cell trafficking, is involved in cancer development. Through the induction of anti-tumor immune responses and inhibition of angiogenesis, CCL19 exerts tumor-suppressive functions. In contrast, CCL19 also acts as a tumor-supportive factor by inducing inflammation, cell growth, and metastasis. Moreover, CCL19 dysregulation in several cancers, including colorectal, breast, pancreatic, and lung cancers, has been considered a tumor biomarker for diagnosis and prognosis. Using CCL19-based therapeutic approaches has also been proposed to overcome cancer development. This review will shed more light on the multifarious function of CCL19 in cancer and elucidate its application in diagnosis, prognosis, and even therapy. It is expected that the study of CCL19 in cancer might be promising to broaden our knowledge of cancer development and might introduce novel approaches in cancer management.

Virotherapy in Germany-Recent Activities in Virus Engineering, Preclinical Development, and Clinical Studies.

Virotherapy research involves the development, exploration, and application of oncolytic viruses that combine direct killing of cancer cells by viral infection, replication, and spread (oncolysis) with indirect killing by induction of anti-tumor immune responses. Oncolytic viruses can also be engineered to genetically deliver therapeutic proteins for direct or indirect cancer cell killing. In this review—as part of the special edition on “State-of-the-Art Viral Vector Gene Therapy in Germany”—the German community of virotherapists provides an overview of their recent research activities that cover endeavors from screening and engineering viruses as oncolytic cancer therapeutics to their clinical translation in investigator-initiated and sponsored multi-center trials. Preclinical research explores multiple viral platforms, including new isolates, serotypes, or fitness mutants, and pursues unique approaches to engineer them towards increased safety, shielded or targeted delivery, selective or enhanced replication, improved immune activation, delivery of therapeutic proteins or RNA, and redirecting antiviral immunity for cancer cell killing. Moreover, several oncolytic virus-based combination therapies are under investigation. Clinical trials in Germany explore the safety and potency of virotherapeutics based on parvo-, vaccinia, herpes, measles, reo-, adeno-, vesicular stomatitis, and coxsackie viruses, including viruses encoding therapeutic proteins or combinations with immune checkpoint inhibitors. These research advances represent exciting vantage points for future endeavors of the German virotherapy community collectively aimed at the implementation of effective virotherapeutics in clinical oncology.