Lipid-Encapsulated mRNAs Encoding Complex Fusion Proteins Potentiate Antitumor Immune Responses

Lipid nanoparticle (LNP)-encapsulated mRNA has been used for in vivo production of several secreted protein classes, such as IgG, and has enabled the development of personalized vaccines in oncology. Establishing the feasibility of delivering complex multispecific modalities that require higher-order structures important for their function could help expand the use of mRNA/LNP biologic formulations. Here, we evaluated whether in vivo administration of mRNA/LNP formulations of SIRPα-Fc-CD40L and TIGIT-Fc-LIGHT could achieve oligomerization and extend exposure, on-target activity, and antitumor responses comparable with that of the corresponding recombinant fusion proteins. Intravenous infusion of the formulated LNP-encapsulated mRNAs led to rapid and sustained production of functional hexameric proteins in vivo, which increased the overall exposure relative to the recombinant protein controls by ∼28 to 140 fold over 96 hours. High concentrations of the mRNA-encoded proteins were also observed in secondary lymphoid organs and within implanted tumors, with protein concentrations in tumors up to 134-fold greater than with the recombinant protein controls 24 hours after treatment. In addition, SIRPα-Fc-CD40L and TIGIT-Fc-LIGHT mRNAs induced a greater increase in antigen-specific CD8+ T cells in the tumors. These mRNA/LNP formulations were well tolerated and led to a rapid increase in serum and intratumoral IL2, delayed tumor growth, extended survival, and outperformed the activities of benchmark mAb controls. Furthermore, the mRNA/LNPs demonstrated improved efficacy in combination with anti-PD-L1 relative to the recombinant fusion proteins. These data support the delivery of complex oligomeric biologics as mRNA/LNP formulations, where high therapeutic expression and exposure could translate into improved patient outcomes.

SIGNIFICANCE

Lipid nanoparticle-encapsulated mRNA can efficiently encode complex fusion proteins encompassing immune checkpoint blockers and costimulators that functionally oligomerize in vivo with extended pharmacokinetics and durable exposure to induce potent antitumor immunity.

Reshaping the tumor microenvironment with oncolytic viruses, positive regulation of the immune synapse, and blockade of the immunosuppressive oncometabolic circuitry

BACKGROUND

Oncolytic viruses are considered part of immunotherapy and have shown promise in preclinical experiments and clinical trials. Results from these studies have suggested that tumor microenvironment remodeling is required to achieve an effective response in solid tumors. Here, we assess the extent to which targeting specific mechanisms underlying the immunosuppressive tumor microenvironment optimizes viroimmunotherapy.

METHODS

We used RNA-seq analyses to analyze the transcriptome, and validated the results using Q-PCR, flow cytometry, and immunofluorescence. Viral activity was analyzed by replication assays and viral titration. Kyn and Trp metabolite levels were quantified using liquid chromatography-mass spectrometry. Aryl hydrocarbon receptor (AhR) activation was analyzed by examination of promoter activity. Therapeutic efficacy was assessed by tumor histopathology and survival in syngeneic murine models of gliomas, including Indoleamine 2,3-dioxygenase (IDO)-/- mice. Flow cytometry was used for immunophenotyping and quantification of cell populations. Immune activation was examined in co-cultures of immune and cancer cells. T-cell depletion was used to identify the role played by specific cell populations. Rechallenge experiments were performed to identify the development of anti-tumor memory.

RESULTS

Bulk RNA-seq analyses showed the activation of the immunosuppressive IDO-kynurenine-AhR circuitry in response to Delta-24-RGDOX infection of tumors. To overcome the effect of this pivotal pathway, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors. The combination therapy increased the frequency of CD8+ T cells and decreased the rate of myeloid-derived suppressor cell and immunosupressive Treg tumor populations in animal models of solid tumors. Functional studies demonstrated that IDO-blockade-dependent activation of immune cells against tumor antigens could be reversed by the oncometabolite kynurenine. The concurrent targeting of the effectors and suppressors of the tumor immune landscape significantly prolonged the survival in animal models of orthotopic gliomas.

CONCLUSIONS

Our data identified for the first time the in vivo role of IDO-dependent immunosuppressive pathways in the resistance of solid tumors to oncolytic adenoviruses. Specifically, the IDO-Kyn-AhR activity was responsible for the resurface of local immunosuppression and resistance to therapy, which was ablated through IDO inhibition. Our data indicate that combined molecular and immune therapy may improve outcomes in human gliomas and other cancers treated with virotherapy.

Abstract 4184: RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism

Viroimmunotherapy aims to infect cancer cells to elicit anti-tumor immune responses. In clinical trials, glioma treatment with oncolytic viruses induced durable clinical responses in a small fraction of patients. To improve the percentage of responders, it is necessary to reshape the tumor microenvironment that shields the tumor from the immune system of the patient. Thus, we engineered Delta-24-RGDOX (DNX-2440), an oncolytic adenovirus that carries the cDNA of the T-cell activator, OX40L. In this work, we observed that Delta-24-RGDOX triggered a dramatic reshaping of the tumor microenvironment dominated by strong changes in immune processes as indicated by RNA-sequencing via ingenuity pathway analyses in a murine glioblastoma model. Paradoxically, network analyses revealed that Delta-24-RGDOX also induced robust activation of the cytokine-driven immunosuppressive IDO-Kynurenine-AhR circuitry, indicating a potential mechanism of resistance of the cancer cells to oncolytic virotherapy. To reverse this immunosuppression, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors to treat glioma bearing mice. Importantly, addition of the IDO inhibitor to Delta-24-RGDOX decreased the activation of the IDO network. IDO inhibition did not affect virus infection or replication in human or murine glioma cells. Flow cytometry assays revealed that the combination therapy increased the frequency of activated CD8+ T cells and decreased the presence of the immunosuppressive cell populations, MDSCs and Tregs. Gene set enrichment analyses confirmed the decrease of MDSCs and Tregs in the combination treated glioma-bearing mice compared to the virus alone. Functional co-culture studies showed that the combined therapy activated splenocytes against tumor antigens, and that this activation was reversed by kynurenine. Importantly, the combination treatment eradicated the tumors in a CD4-dependent manner and significantly prolonged the survival of glioma-bearing mice. Altogether, these studies indicate that the combination treatment promotes an adaptive immune response while decreasing immunosuppression caused by virus-induced IDO activation. Furthermore, our data identified the striking role of immunosuppressive pathways in the resistance of gliomas to oncolytic virotherapy. Specifically, the activity of the tumor microenvironment IDO circuitry was responsible, at least partially, for the remodeling of local immunosuppression after tumor infection. Combining molecular and immune-related therapies may improve outcomes in human gliomas treated with virotherapy.

Citation Format: Teresa T. Nguyen, Dong Ho Shin, Sagar Sohoni, Sanjay K. Singh, Yisel Rivera-Molina, Hong Jiang, Xuejun Fan, Joy Gumin, Frederick F. Lang, Christopher Alvarez-Breckenridge, Marta M. Alonso, Filipa Godoy-Vitorino, Lijie Zhai, Erik Ladomersky, Kristen L. Lauing, Derek A. Wainwright, Juan Fueyo, Candelaria Gomez-Manzano. RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4184.

Abstract 3565: Viroimmunotherapy for solid tumors results in local and abscopal anti-cancer effects and the remodeling of tumor microenvironment

Oncolytic viruses are a promising experimental treatment for solid tumors. Recently, several phase 1 clinical trials have reported encouraging therapeutic effects of oncolytic viruses in adult and pediatric patients with malignant gliomas. To further improve the therapeutic outcome of viroimmunotherapy, we have developed Delta-24-RGDOX (DNX-2440), a replication competent adenovirus encompassing the T-cell activator OX40L in the genetic backbone of Delta-24-RGD. We have previously reported the effect of Delta-24-RGDOX in murine brain tumors supporting the translation of this new agent to treat patients with recurrent malignant gliomas (NCT03714334). In the work presented here, we have tested the therapeutic effect of Delta-24-RGDOX in murine syngeneic models of breast (4T1), gastric (M12) and lung cancer (LLC and CMT 167). We found that Delta-24-RGDOX infected all cancer cell lines efficiently. In addition, infection of cells was followed by the expression of the ectopic ligand in vitro and in vivo. Because the elicitation of an anti-tumor immunity is part of the mechanisms underlying the therapeutic effect of oncolytic viruses, we examined whether infection of tumors led to the reshaping of the tumor microenvironment. We observed that Delta-24-RGDOX infection was followed by increased frequencies of tumor infiltrating lymphocytes, particularly CD8+ T cells and NK cells. In addition, the CD8+/CD4+ ratio was increased in Delta-24-RGDOX-treated tumor versus PBS-treated tumors. Interestingly, abscopal modifications were observed in breast cancer brain metastases with increased frequency of CD8+ T cells at the distal, untreated site. Delta-24-RGDOX treatment induced an anti-cancer effect in orthotopically implanted breast cancer and subcutaneously implanted lung and gastric tumors, as well as in metastatic niches. In summary, our data showed that treatment of solid tumors with Delta-24-RGDOX induces robust remodeling of the tumor microenvironment and produces anti-tumor effects leading to decrease in tumor volume, along with a delay in the development and in the reduction of the number of metastases. These data suggest that Delta-24-RGDOX should be tested in the clinical setting in patients with metastatic breast, gastric and lung cancers.

Citation Format: Arie C. Van Wieren, Sagar Sahoni, Teresa Nguyen, Ashley Ossimetha, Yisel Rivera-Molina, Hong Jiang, Dong Ho Shin, Debora Kim, Xuejun Fan, Yanhua Yi, Natalie M. Melendez-Vazquez, Filipa Godoy-Vitorino, Joy Gumin, Frederick F. Lang, Marta M. Alonso, Juan Fueyo, Candelaria Gomez-Manzano. Viroimmunotherapy for solid tumors results in local and abscopal anti-cancer effects and the remodeling of tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3565.

Abstract B29: Systemic antimelanoma immunity induced by oncolytic adenovirus Delta-24-RGDOX

OX40 ligand (OX40L)-expressing oncolytic adenovirus Delta-24-RGDOX induces efficacious antiglioma immunity in syngeneic intracranial glioma models of immunocompetent mice. It is unknown if the virus is effective to treat metastatic melanomas. To study the abscopal immunity against metastatic melanomas induced by intratumoral injection of the virus in primary melanomas, we established subcutaneous/subcutaneous (s.c./s.c.) and subcutaneous/intracranial (s.c./i.c.) melanoma models with B16-Red-FLuc cells in C57BL/6 mice. In the s.c./s.c. model, compared to treatment with PBS, through monitoring the tumor growth with bioluminescence imaging, we found three doses of intratumoral injection of the virus significantly inhibited the growth of both the injected and the untreated distant tumors, resulting in prolonged survival of the mice with 50% long-term survival (P = 0.001). The surviving mice are resistant to rechallenging with the same tumor cells but are susceptible to lung cancer cells, suggesting the development of immune memory specific to the virus-injected tumor type. In the s.c./i.c. model, viral injection into the s.c. tumor induced antimelanoma activity in the brain, resulting in growth inhibition of both the s.c. and i.c. tumors and an improved survival of the animals (p = 0.005). Through flow cytometry analysis of the tumor-infiltrating lymphocytes, we found the virus injection increased the presence of CD3+ T lymphocytes, CD3+CD4+ helper T cells, CD3+CD8+ cytotoxic T cells, and the frequency of PD-1+ and effector (CD44+ CD62L-) T cells and decreased the amount of exhausted (PD-1+ TIM3+) and regulatory T cells in the injected tumors. Consistently, analysis of T cells in the blood, spleen, and brain hemispheres with untreated tumor revealed the same virus-mediated changes. Interestingly, through monitoring the T cells specific for tumor-associated antigen (TAA) in the mice through bioluminescence imaging, we found injecting Delta-24-RGDOX into the first s.c. B16-OVA melanoma increased the proliferation of OT-I/Luc CD8+ T cells infused in the same tumor and their migration to the distant untreated tumor originated from B16-OVA cells but not to the tumor from B16F10 cells, providing direct evidence that intratumoral viral injection promotes the in situ expansion of TAA-specific T cells. In summary, localized intratumoral injection of Delta-24-RGDOX induced an in situ autovaccination of the treated melanoma, of which the effect changes the immune landscape of the treated mice, resulting in the immunity against the disseminated s.c. or i.c. tumors.

Citation Format: Hong Jiang, Dong Ho Shin, Caroline Carrillo, Verlene Henry, Xuejun Fan, Teresa T. Nguyen, Yisel Rivera-Molina, Frederick F. Lang, Candelaria Gomez-Manzano, Juan Fueyo. Systemic antimelanoma immunity induced by oncolytic adenovirus Delta-24-RGDOX [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr B29.

EXTH-27. ACTIVATING THE IMMUNITY WITHIN THE TUMOR USING VIROIMMUNOTHERAPY: DELTA-24-RGD ONCOLYTIC ADENOVIRUS ARMED WITH THE IMMUNOPOSITIVE REGULATOR GITRL

Based on promising results of recent clinical trials using oncolytic viruses, virotherapy is evolving as an alternative to treat patients with malignant glioma. Our group developed the oncolytic adenovirus Delta-24-RGD (DNX-2401) that is being tested, alone or in combination with anti-PD1, in clinical trials for recurrent glioblastoma (NCT00805376; NCT01956734; NCT02798406). The results suggest that, besides the expected oncolytic effect, the injection of the pathogen initiated, in a subset of patients, an anti-tumoral immunity that led to 20% of long-term survivors (3.5–5 years). To further enhance this effect, we have armed Delta-24-RGD to express the co-stimulatory ligand GITRL, and generated Delta-24-GREAT. The intracranial injection of Delta-24-GREAT prolonged the survival of GL261 glioma-bearing immunocompetent mice when compared to Delta-24-RGD treatment (P=0.002, log-rank test). Delta-24-GREAT treatment resulted in enhanced frequency of tumor-infiltrating lymphocytes: T lymphocytes (CD45+/CD3+) and cytotoxic T lymphocytes (CD45+CD3+CD8+). Functional studies performed by culturing splenocytes from Delta-24-GREAT-treated mice with glioma cells and analyzing secretion of Th1 cytokines, such as IL2 and IFN-γ, showed that lymphocytes recognized not only viral antigens but also tumoral antigens, suggesting the triggering of anti-tumoral immunity. Of interest, Delta-24-GREAT treatment resulted in an antigen-restricted anti-tumor memory effect and in the generation of central immune memory. Thus, rechallenging the survivor mice from the first experiment with a second implantation of glioma cells did not lead to tumor growth, and we detected an increased frequency of central memory CD8+ T cells (CD45+CD62L+). However, survivor mice developed lethal tumors when implanted intracranially with B16/F10 melanoma cells, strongly indicating that the developed immune response was specific for GL261 glioma antigens. This is a novel approach using an oncolytic adenovirus expressing GITRL to target cancer and to stimulate the immunity within the tumor. Our data strongly indicate that this type of strategy may be further developed to treat patients with malignant glioblastoma.

GITRL-armed Delta-24-RGD oncolytic adenovirus prolongs survival and induces anti-glioma immune memory

Background

Viroimmunotherapy is evolving as a strong alternative for the standard treatment of malignant gliomas. Promising results from a recent clinical trial testing the anticancer effect of Delta-24-RGD in patients with glioblastoma suggested the induction of antitumoral immunity after viral administration. To further enhance the anti-glioma immune effect, we have armed Delta-24-RGD with the costimulatory ligand GITRL (Delta-24-GREAT [Glucocorticoid Receptor Enhanced Activity of T cells]).

Methods

We tested the infectivity and replication of Delta-24-GREAT, and the expression of ectopic GITRL in human and murine glioma cell lines. In vivo experiments involved the intracranial implantation of glioma cells into an immunocompetent model to study the anticancer effect, and rechallenging experiments to study long-term protection. Phenotypic and functional characterization of lymphocyte populations were performed by FACS and ELISA for Th1 cytokines expression, respectively.

Results

Our results showed that Delta-24-GREAT infects and induces the expression of GITRL. Delta-24-GREAT prolonged the survival of glioma-bearing immunocompetent mice and resulted in both anti-viral and anti-glioma immune responses, including increased frequency of central memory CD8⁺ T cells. Rechallenging the surviving mice with a second implantation of glioma cells did not lead to tumor growth; however, the surviving mice developed lethal tumors when B16/F10 melanoma cells were implanted intracranially, strongly indicating that the immune response was specific for glioma antigens.

Conclusions

GITRL-armed Delta-24-RGD treatment results in an antigen-restricted antitumor memory, an enhanced anti-glioma effect, and the generation of central immune memory. Our results strongly indicate that this strategy represents a vertical advance in virotherapy designed to treat patients with malignant brain tumors.

Oncolytic Adenovirus and Tumor-Targeting Immune Modulatory Therapy Improve Autologous Cancer Vaccination

Oncolytic viruses selectively lyse tumor cells, disrupt immunosuppression within the tumor, and reactivate antitumor immunity, but they have yet to live up to their therapeutic potential. Immune checkpoint modulation has been efficacious in a variety of cancer with an immunogenic microenvironment, but is associated with toxicity due to nonspecific T-cell activation. Therefore, combining these two strategies would likely result in both effective and specific cancer therapy. To test the hypothesis, we first constructed oncolytic adenovirus Delta-24-RGDOX expressing the immune costimulator OX40 ligand (OX40L). Like its predecessor Delta-24-RGD, Delta-24-RGDOX induced immunogenic cell death and recruit lymphocytes to the tumor site. Compared with Delta-24-RGD, Delta-24-RGDOX exhibited superior tumor-specific activation of lymphocytes and proliferation of CD8+ T cells specific to tumor-associated antigens, resulting in cancer-specific immunity. Delta-24-RGDOX mediated more potent antiglioma activity in immunocompetent C57BL/6 but not immunodeficient athymic mice, leading to specific immune memory against the tumor. To further overcome the immune suppression mediated by programmed death-ligand 1 (PD-L1) expression on cancer cells accompanied with virotherapy, intratumoral injection of Delta-24-RGDOX and an anti-PD-L1 antibody showed synergistic inhibition of gliomas and significantly increased survival in mice. Our data demonstrate that combining an oncolytic virus with tumor-targeting immune checkpoint modulators elicits potent in situ autologous cancer vaccination, resulting in an efficacious, tumor-specific, and long-lasting therapeutic effect. Cancer Res; 77(14); 3894-907. ©2017 AACR.

Abstract 3680: Cancer-killing viruses combined with tumor-targeting immune checkpoint modulation elicits an in situ vaccination effect and expansion of tumor-specific T cells responsible for efficacious systemic anti-cancer activity

Oncolytic viruses are cancer-selective and disrupt immunosuppression within the tumor, but they show suboptimal efficacy in patients. Immune checkpoint modulation is efficacious in a variety of cancers but is associated with nonspecific T-cell activation and a limited effect in tumors with a nonimmunogenic microenvironment. We hypothesized that combining these two strategies likely resulted in both efficacious and specific cancer therapy. Therefore, we constructed oncolytic adenovirus Delta-24-RGDOX expressing the immune co-stimulator OX40L and tested its activity in orthotopic GL261-C57BL/6 glioma and B16-C57BL/6 melanoma mouse models. Compared to its predecessor Delta-24-RGD, Delta-24-RGDOX was more effective to induce inflammatory activation within the tumors, enhanced the capability of the tumor cells to directly activate cancer-specific T cells and the proliferation of the cell population through OX40L expression on the cell surface, resulting in specific anti-tumor immunity. To track the expansion and migration of tumor-specific T cells during virotherapy, we first injected OVA-specific CD8+ T cells from OT-I/Luc transgenic mice in the first tumor derived from B16-OVA cells, followed by Delta-24-RGDOX injection in the same tumor. Monitoring the T cells with bioluminescent imaging revealed that the viral injection greatly augmented the T cell population than the PBS treatment within the tumor, and promoted the T cell migration to distant B16-OVA tumor but not to B16 tumor, suggesting local viral treatment enhanced the expansion of tumor-specific T cells and the migration of these cells to a distant tumor with the same tumor antigen. Consistently, flow cytometry analysis with OVA-tetramer staining showed that virus treatment greatly increased the frequency of OVA-specific CD8+ T cells in the local and distant tumors, peripheral blood and spleen (from high to low frequency). 70-80% cells of this cell population were CD44+ CD62L+ that are markers for central memory T cells. Hence, this new virus was efficacious to inhibit the virus-injected tumor and distant tumor, prolong the survival of the treated mice and induce immune memory specific to the virus-injected tumor type. Importantly, intratumoral injection of Delta-24-RGDOX and an anti-PD-L1 antibody synergized to reject gliomas and significantly increased survival in mice. Our data demonstrate that combining an oncolytic virus with tumor-targeting immune checkpoint modulation elicits potent in situ cancer vaccination and skews the injected tumor microenvironment from tumorigenic to immunogenic, resulting in a local expansion of the tumor-specific T cells. Moreover, this local effect is capable to extend to distant tumors, achieving specific and long-lasting systemic therapeutic efficacy.

Citation Format: Hong Jiang, Andrew Dong, Yisel Rivera-Molina, Karen Clise-Dwyer, Xuejun Fan, Francisco W. Martinez, Teresa Nguyen, Verlene Henry, Caroline Carrillo, Candelaria Gomez-Manzano, Juan Fueyo. Cancer-killing viruses combined with tumor-targeting immune checkpoint modulation elicits an in situ vaccination effect and expansion of tumor-specific T cells responsible for efficacious systemic anti-cancer activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3680. doi:10.1158/1538-7445.AM2017-3680