Intratumoral Immunotherapy Research Articles

Plant Virus Intratumoral Immunotherapy with CPMV and PVX Elicits Durable Antitumor Immunity in a Mouse Model of Diffuse Large B-Cell Lymphoma.

Plant viruses are naturally occurring nanoparticles and adjuvants that interact with the mammalian immune system. This property can be harnessed in vaccines and immunotherapy. We have previously demonstrated that intratumoral immunotherapy with cowpea mosaic virus (CPMV) stimulates systemic and durable antitumor immunity in mouse tumor models and canine cancer patients. Here we compared the antitumor efficacy of CPMV with potato virus X (PVX) using a mouse model B-cell lymphoma (A20 and BALB/c mice). Despite their diverse morphologies and physiochemical properties, both plant viruses elicited systemic and long-lasting antitumor immune memory, preventing the recurrence of A20 lymphoma in rechallenge experiments. Data indicate differences in the underlying mechanism: CPMV persists longer in the tumor microenvironment (TME) compared to PVX; CPMV is a potent and multivalent toll-like receptor (TLR) agonist (activating TLRs 2, 4 and 7) while PVX may only weakly engage with TLR7. While CPMV and PVX recruit myeloid cells (neutrophils)─CPMV also recruits macrophages. Data further indicate that antiviral T cells may play a role in antitumor efficacy in the case of CPMV immunotherapy, however this may not be the case for PVX. Regardless of the mechanism of action, both CPMV and PVX elicited a durable antitumor response against a B-cell lymphoma tumor model and thus are intratumoral immunotherapy candidates for clinical development.

Therapeutic Immunomodulation of Tumor-Lymphatic Crosstalk via Intratumoral Immunotherapy.

Intra- and peritumoral lymphatics and tumor-draining lymph nodes play major roles in mediating the adaptive immune response to cancer immunotherapy. Despite this, current paradigms of clinical cancer management seldom seek to therapeutically modulate tumor-lymphatic immune crosstalk. This review explores recent developments that set the stage for how this regulatory axis can be therapeutically manipulated, with a particular emphasis on tumor-localized immunomodulation. Building on this idea, the nature of tumor-lymphatic immune crosstalk and relevant immunotherapeutic targets and pathways are reviewed, with a focus on their translational potential. Engineered drug delivery systems that enhance intratumoral immunotherapy by improving drug delivery to both the tumor and lymph nodes are also highlighted.

Cellular fate of a plant virus immunotherapy candidate

Cowpea mosaic virus (CPMV) is a plant virus that is currently being developed for intratumoral immunotherapy. CPMV relieves the immune system from tumor-induced immunosuppression; reprograms the tumor microenvironment to an activated state whereby the treated and distant tumors are recognized and eradicated. Toward translational studies, we investigated the safety of CPMV, specifically addressing whether pathogenicity would be induced in mammalian cells. We show that murine macrophage immune cells recognize CPMV; however, there is no indication of de novo viral protein synthesis or RNA replication. Furthermore, we show that CPMV does not induce hemolysis, platelet aggregation and plasma coagulation amongst other assays in human blood and immune cells. Taken together, we anticipate that these results will reinforce the development of CPMV as an immunotherapeutic platform.

Neo-adjuvant radiation and intratumoral immunotherapy followed by surgery-NARIS trial for extremity soft tissue sarcoma.

Extremity soft tissue sarcoma (ESTS) is a rare malignant nonepithelial disease, calling for combined modality treatments with surgery to further improve local control rates and long-term survival, especially in patients with multiple local recurrences with or without risk of amputation. In this double-arm, open-label, Phase II clinical trial, we will enroll 30 patients with pathologically confirmed ESTS without nodal involvement or distant metastases. Patients are randomly assigned to the combination treatment group or the radiation monotherapy group. Additionally, tumor and biological samples will be obtained directly before and after neoadjuvant therapy, allowing for studies of immune response and primary drug resistance mechanisms.Clinical Trial Registration: ChiCTR2200060659 (http://www.chictr.org.cn) (ClinicalTrials.gov).

An Abscopal Effect on Lung Metastases in Canine Mammary Cancer Patients Induced by Neoadjuvant Intratumoral Immunotherapy with Cowpea Mosaic Virus Nanoparticles and Anti-Canine PD-1.

Neoadjuvant intratumoral (IT) therapy could amplify the weak responses to checkpoint blockade therapy observed in breast cancer (BC). In this study, we administered neoadjuvant IT anti-canine PD-1 therapy (IT acPD-1) alone or combined with IT cowpea mosaic virus therapy (IT CPMV/acPD-1) to companion dogs diagnosed with canine mammary cancer (CMC), a spontaneous tumor resembling human BC. CMC patients treated weekly with acPD-1 (n = 3) or CPMV/acPD-1 (n = 3) for four weeks or with CPMV/acPD-1 (n = 3 patients not candidates for surgery) for up to 11 weeks did not experience immune-related adverse events. We found that acPD-1 and CPMV/acPD-1 injections resulted in tumor control and a reduction in injected tumors in all patients and in noninjected tumors located in the ipsilateral and contralateral mammary chains of treated dogs. In two metastatic CMC patients, CPMV/acPD-1 treatments resulted in the control and reduction of established lung metastases. CPMV/acPD-1 treatments were associated with altered gene expression related to TLR1-4 signaling and complement pathways. These novel therapies could be effective for CMC patients. Owing to the extensive similarities between CMC and human BC, IT CPMV combined with approved anti-PD-1 therapies could be a novel and effective immunotherapy to treat local BC and suppress metastatic BC.

Machine Learning-Directed Conversion of Glioblastoma Cells to Dendritic Cell-Like Antigen-Presenting Cells as Cancer Immunotherapy.

Immunotherapy has limited efficacy in glioblastoma (GBM) due to the blood-brain barrier and the immunosuppressed or "cold" tumor microenvironment (TME) of GBM, which is dominated by immune-inhibitory cells and depleted of CTL and dendritic cells (DC). Here, we report the development and application of a machine learning precision method to identify cell fate determinants (CFD) that specifically reprogram GBM cells into induced antigen-presenting cells with DC-like functions (iDC-APC). In murine GBM models, iDC-APCs acquired DC-like morphology, regulatory gene expression profile, and functions comparable to natural DCs. Among these acquired functions were phagocytosis, direct presentation of endogenous antigens, and cross-presentation of exogenous antigens. The latter endowed the iDC-APCs with the ability to prime naïve CD8+ CTLs, a hallmark DC function critical for antitumor immunity. Intratumor iDC-APCs reduced tumor growth and improved survival only in immunocompetent animals, which coincided with extensive infiltration of CD4+ T cells and activated CD8+ CTLs in the TME. The reactivated TME synergized with an intratumor soluble PD1 decoy immunotherapy and a DC-based GBM vaccine, resulting in robust killing of highly resistant GBM cells by tumor-specific CD8+ CTLs and significantly extended survival. Lastly, we defined a unique CFD combination specifically for the human GBM to iDC-APC conversion of both glioma stem-like cells and non-stem-like cell GBM cells, confirming the clinical utility of a computationally directed, tumor-specific conversion immunotherapy for GBM and potentially other solid tumors.

Cowpea mosaic virus intratumoral immunotherapy maintains stability and efficacy after long-term storage.

Cowpea mosaic virus (CPMV) has demonstrated superior immune stimulation and efficacy as an intratumoral immunotherapy, providing a strong argument for its clinical translation. One important consideration for any new drug candidate is the long-term stability of the drug and its formulation. Therefore, our lab has evaluated the physical stability and biological activity, that is, anti-tumor potency, of formulations of CPMV in buffer (with and without a sucrose preservative) in multiple temperature conditions ranging from ultralow freezers to a heated incubator over a period of 9 months. We found that non-refrigerated temperatures 37°C and room temperature quickly led to CPMV destabilization, as evidenced by significant protein and RNA degradation after just 1 week. Refrigerated storage at 4°C extended physical stability, though signs of particle breakage and RNA escape appeared after 6 and 9 months. CPMV stored in frozen conditions, including -20°C, -80°C, and liquid N2, remained intact and matched the characteristics of fresh CPMV throughout the duration of the study. The biological activity was evaluated using a murine dermal melanoma model, and efficacy followed the observed trends in physical stability: CPMV stored in refrigerated and warmer conditions exhibited decreased anti-tumor efficacy compared to freshly prepared formulations. Meanwhile, frozen-stored CPMV performed similarly to freshly purified CPMV, resulting in reduced tumor growth and extended survival. Data, therefore, indicates that CPMV stored long-term in cold or frozen conditions remains stable and efficacious, providing additional support to advance this powerful plant virus to translation.

Intratumoral Injection of Immunotherapeutics: State of the Art and Future Directions.

Systemic immunotherapies have led to tremendous progress across the cancer landscape. However, several challenges exist, potentially limiting their efficacy in the treatment of solid tumors. Direct intratumoral injection can increase the therapeutic index of immunotherapies while overcoming many of the barriers associated with systemic administration, including limited bioavailability to tumors and potential systemic safety concerns. However, challenges remain, including the lack of standardized approaches for administration, issues relating to effective drug delivery, logistical hurdles, and safety concerns specific to this mode of administration. This article reviews the biologic rationale for the localized injection of immunotherapeutic agents into tumors. It also addresses the existing limitations and practical considerations for safe and effective implementation and provide recommendations for optimizing logistics and treatment workflows. It also highlights the critical role that radiologists, interventional radiologists, and medical physicists play in intratumoral immunotherapy with respect to target selection, image-guided administration, and response assessment.

Phase III randomized trial evaluating tilsotolimod in combination with ipilimumab versus ipilimumab alone in patients with advanced refractory melanoma (ILLUMINATE 301).

LBA9516 Background: There are limited treatment options for advanced melanoma that has progressed during or after immune checkpoint inhibitor therapy. Intratumoral (IT) immunotherapy may improve tumor-specific immune activation by promoting local tumor antigen presentation while avoiding systemic toxicities. The Phase 3 ILLUMINATE-301 study (NCT03445533) evaluated tilsotolimod, a toll-like receptor 9 agonist, with or without ipilimumab in patients with anti-programmed death-1 (PD-1)-advanced refractory melanoma. Methods: Patients with unresectable Stage III–IV melanoma that progressed during or after anti-PD-1 therapy were randomized 1:1 to receive 24 weeks of tilsotolimod plus ipilimumab or 10 weeks of ipilimumab alone. Nine IT injections of tilsotolimod were administered to a single designated lesion over 24 weeks. Intravenous ipilimumab 3 mg/kg was administered every 3 weeks from Week 2 in the tilsotolimod arm and Week 1 in the ipilimumab arm. The primary endpoint was efficacy measured using objective response rate (ORR; independent review) and overall survival (OS). Results: A total of481 patients received tilsotolimod plus ipilimumab (n = 238) or ipilimumab alone (n = 243). ORRs were 8.8% in the tilsotolimod arm and 8.6% in the ipilimumab arm, with disease control rates of 34.5% and 27.2%, respectively. Median OS was 11.6 months in the tilsotolimod arm and 10.0 months in the ipilimumab arm (hazard ratio (HR) 0.96 [95% confidence interval (CI) 0.77–1.19]; P = 0.7). Grade ≥3 treatment-emergent adverse events occurred in 61.1% and 55.5% of patients in the tilsotolimod and ipilimumab arms, respectively. Conclusion: Adding tilsotolimod to ipilimumab did not improve response or OS in patients with PD-1 refractory advanced melanoma. However, the results represent the largest prospective dataset reported to date on using ipilimumab in this setting and are a valuable addition to the knowledge base. Clinical trial information: NCT03445533 .

Multifaceted cancer alleviation by cowpea mosaic virus in a bioprinted ovarian cancer peritoneal spheroid model

Ovarian cancer (OvCa) is a leading cause of mortality among gynecological malignancies and usually manifests as intraperitoneal spheroids that generate metastases, ascites, and an immunosuppressive tumor microenvironment. In this study, we explore the immunomodulatory properties of cowpea mosaic virus (CPMV) as an adjuvant immunotherapeutic agent using an in vitro model of OvCa peritoneal spheroids. Previous findings highlighted the potent efficacy of intratumoral CPMV against OvCa in mouse tumor models. Leveraging the precision control over material deposition and cell patterning afforded by digital-light-processing (DLP) based bioprinting, we constructed OvCa-macrophage spheroids to mimic peritoneal spheroids using gelatin methacrylate (GelMA), a collagen-derived photopolymerizable biomaterial to mimic the extracellular matrix. Following CPMV treatment, bioprinted spheroids exhibited inhibited OvCa progression mediated by macrophage activation. Our analysis indicates that CPMV regulates and activates macrophage to both induce OvCa cell killing and restore normal cell-cell junctions. This study deepened our understanding of the mechanism of CPMV intratumoral immunotherapy in the setting of OvCa. This study also highlights the potential of studying immunotherapies using high throughput tissue models via DLP bioprinting.

INTASYL PH-762: PD-1 intratumoral immunotherapy for cutaneous carcinoma.

TPS9620 Background: Immune checkpoint-targeted antibodies directed at PD-1 or PD-L1 block co-inhibitory receptors expressed by anti-tumor T cells, breaking immune tolerance against tumor cells and generating cancer immunity. Intratumoral (IT) immunotherapy aims to use the tumor as a ‘self-vaccine’. Local immune stimulation may induce robust priming of an anti-tumor immune response and generate abscopal tumor responses, mediated by circulating activated anti-tumor immune cells. Local delivery of immunotherapy minimizes systemic exposure and off-target toxicities and may decrease tumor size and improve surgical morbidity. PH-762 is an INTASYL compound designed to precisely silence PD-1 mRNA. INTASYL is a patented, self-delivering RNAi technology platform designed to impart specific properties to small interfering RNAs. PH-762’s unique structural and chemical modifications ensure an optimized cell and tissue uptake profile with IT administration. In vitro investigations have demonstrated efficient uptake of PH-762 by human T cells, silencing of PD-1 mRNA and subsequent protein reduction. Preclinical studies have shown that IT injections of murine-targeted PH-762 (mPH-762) can silence PD-1 mRNA in T cells within the tumor and increase the secretion of IFN-γ. mPH-762 was well tolerated at the maximum administered dose and treatment with mPH-762 provided robust and statistically significant inhibition of tumor growth. Toxicokinetic studies conducted in marmoset monkeys demonstrated that PH-762, when administered intravenously at doses of up to 147 mg/kg, is well-tolerated. No cytokine-release associated cytokines were detected in the plasma of treated monkeys at this dose. Methods: This open-label Phase 1 clinical study (NCT 06014086) is designed to evaluate the safety and tolerability of neoadjuvant use of IT PH-762 in cutaneous squamous cell carcinoma, melanoma, or Merkel cell carcinoma, to determine the pharmacokinetic profile of PH-762 after IT injection, to observe pathologic and immunologic tumor responses, and to determine the recommended dose for development. Escalating dose concentrations of PH-762 (from 1.14 mg/mL through 22.00 mg/mL) are tested serially in cohorts of 3 patients each. Patients receive IT PH-762 once weekly, 4 times over a 3-week period prior to surgical excision, which occurs 5 weeks after the initial injection. Following excision of the tumor, patients are followed for approximately 11 weeks. Tumor changes are evaluated per iRECIST criteria and pathological response. Immunological response in tumor tissue and blood samples are assessed as secondary endpoints. This clinical study, enrolling patients since November 2023, will establish the basis for continued clinical development of PH-762. Clinical trial information: 06014086.

Intratumoral delivery of immunotherapy to treat breast cancer: current development in clinical and preclinical studies.

Breast cancer poses one of the largest threats to women's health. Treatment continues to improve for all the subtypes of breast cancer, but some subtypes, such as triple negative breast cancer, still present a significant treatment challenge. Additionally, metastasis and local recurrence are two prevalent problems in breast cancer treatment. A newer type of therapy, immunotherapy, may offer alternatives to traditional treatments for difficult-to-treat subtypes. Immunotherapy engages the host's immune system to eradicate disease, with the potential to induce long-lasting, durable responses. However, systemic immunotherapy is only approved in a limited number of indications, and it benefits only a minority of patients. Furthermore, immune related toxicities following systemic administration of potent immunomodulators limit dosing and, consequently, efficacy. To address these safety considerations and improve treatment efficacy, interest in local delivery at the site of the tumor has increased. Numerous intratumorally delivered immunotherapeutics have been and are being explored clinically and preclinically, including monoclonal antibodies, cellular therapies, viruses, nucleic acids, cytokines, innate immune agonists, and bacteria. This review summarizes the current and past intratumoral immunotherapy clinical landscape in breast cancer as well as current progress that has been made in preclinical studies, with a focus on delivery parameters and considerations.

Enhanced Efficacy of a TLR3 Agonist Delivered by Cowpea Chlorotic Mottle Virus Nanoparticles

Intratumoral immunotherapies are those that are administered directly into a tumor to remodel the local tumor microenvironment and stimulate systemic anti‐tumor immunity. Small molecule toll‐like receptor (TLR) agonists are undergoing development as intratumoral immunotherapies, and here the TLR3 agonist poly(I:C) is considered. Because small molecule therapeutics often suffer rapid washout effects and ineffective immune cell uptake, poly(I:C) is encapsulated into nanoparticles derived from cowpea chlorotic mottle virus (CCMV). The particles (but not the separate components) stimulate the activity of macrophages in vitro and are able to reduce tumor growth and prolong survival in mouse models of colon cancer and melanoma. CCMV‐poly(I:C) is also combined with oxaliplatin and found the combination therapy to be even more potent, strongly inhibiting tumor growth and increasing survival. The analysis of immune markers reveals that CCMV‐poly(I:C) VLPs with oxaliplatin promoted the infiltration and activation of CD4+ and CD8+ cells and the production of IL‐4 and IFN‐γ, indicating a synergistic immunogenic effect. The combined treatment also enhances the rate of apoptosis and immunogenic cell death (ICD). The data support the development of combination therapies involving immunomodulatory plant virus nanoparticles and antineoplastic drugs to attack tumors directly and via the activation of innate and adaptive immune responses.

Abstract CT023: Prostate cancer in situ autovaccination with the intratumoral viral mimic poly-ICLC: Making a cold tumor hot

Abstract PURPOSE To test the safety of sequential intratumoral plus systemic intramuscular injection of poly-ICLC, and its efficacy in priming antitumor immune responses in patients with prostate cancer (PCa). EXPERIMENTAL PROCEDURES This is an open-label dose-escalating phase 1 neoadjuvant clinical trial of poly-ICLC (NCT03262103) in 12 patients diagnosed with clinically localized PCa with plans to undergo radical prostatectomy (RP). Poly-ICLC was administered intratumorally (Artemis MRI-TRUS-guided) and intramuscularly (e.g., deltoid muscle). Comprehensive transcriptional profiling of tissues, phenotypic and transcriptional analysis of longitudinally collected peripheral blood, and analysis of the prostate tumor microenvironment (TME) were performed before and after poly-ICLC treatment in order to identify innate and adaptive antitumor immune responses within the tumor and in peripheral blood. This trial is the first to use human intratumoral immunotherapy instead of systemic immunomodulation for high-risk PCa patients. RESULTS Poly-ICLC was well tolerated (safe) in all 12 patients. There were no dose-limiting toxicities or TEAE (treatment-emergent adverse events) withdrawals during treatment. Eight of 10 evaluable patients (80%) had undetectable PSA (<0.1 ng/ml) at 1 year of follow-up post-RP. Eight of 12 evaluable patients (66.7%) and 7 of 10 patients (70%) with biopsy Gleason 8-10 had a lower Gleason score in the post-treatment RP specimen. Transcriptome profiling of paired biopsy and RP specimens showed significant upregulation of gene signatures associated with immune cell infiltration and TP53-associated metabolic genes, but downregulation of gene signatures associated with metastasis and DNA replication. Genes upregulated by poly-ICLC were associated with a good prognosis. Treatment with poly-ICLC increased systemic immune responses, as demonstrated by an increase in cytolytic signatures, T- and NK-cell signatures, and NK-cell subsets in the blood. Multiplex immunohistochemistry analysis revealed a significant increase in the densities of CD4- and CD8-T cells and B cells, as well as evidence of tertiary lymphoid structures (TLS) within the TME of post-treatment RP specimens compared to baseline. CONCLUSIONS Poly-ICLC treatment can reliably transform the cold TME of PCa into a hot, immune-enhanced ecosystem. The identified baseline and response biomarkers, tertiary lymphoid structures, potential clinical benefit, and immunologic correlates require validation in larger studies. Citation Format: Sujit S. Nair, Dimple Chakravarty, Sreekumar Balan, Alexander Hakansson, Manuel Duval, Elai Davicioni, Yang Liu, Swati Bhardwaj, Tin Htwe Thin, Monica Garcia-barros, Kenneth Haines, Majd Al Shaarani, Rachel Weil, Marcia Meseck, Parita Ratnani, Monali Fatterpekar, Ivan Jambor, Elena Gonzalez-Gugel, Adam Farkas, Vinayak Wagaskar, Kacie Schlussel, Cristina Pasat-karasik, Kamala Bhatt, Zachary Dovey, Adriana Pedraza, Akriti Gupta, Dara Lundon, Ante Peros, Sneha Parekh, Lily Davenport, Xiangfu Zhang, Raghav Gupta, Macy Robison, Cynthia Knauer, Ethan Ellis, Dmitry Rykunov, Boris Reva, Babu Padanilam, Matthew D. Galsky, Rachel Brody, Mani Menon, Andres Salazar, Nina Bhardwaj, Ashutosh K. Tewari. Prostate cancer in situ autovaccination with the intratumoral viral mimic poly-ICLC: Making a cold tumor hot [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT023.

Nanofluidic delivery implant sustains localization and maximizes efficacy of intratumoral immunotherapy

Intratumoral immunotherapy holds promise for improving cancer treatment efficacy. However, rapid clearance from the tumor upon bolus volume injections limits efficacy and impedes assessment of dose-dependent effects on the tumor immune microenvironment (TIME). To this end, we developed a drug-agnostic nanofluidic implant to deliver immunotherapy within the tumor, providing a mechanism for sustained and controlled intratumoral dosing. Diffusive drug elution from the implant reservoir is controlled by a nanofluidic membrane, which abrogates rapid drug elimination from the tumor and maximizes immunotherapy localization. Here we first achieve in vitro sustained release of agonist CD40 monoclonal antibody (mAb), anti-programmed death ligand-1 (PDL1) mAb, and immune-cell targeted polymeric prodrugs of Resiquimod (toll-like receptor 7/8,TLR 7/8) and a small molecule STING agonist. We then demonstrated in vivo sustained intratumoral drug localization of agonist CD40 Ab and anti-PDL1 Ab in the 4T1 murine model of triple-negative breast cancer (TNBC). Further, we show highly effective anti-tumor efficacy with radiation therapy and sustained intratumoral co-delivery of agonist CD40 Ab and anti-PDL1 Ab in the EMT6 TNBC murine model. Finally, we demonstrate the versatility of this implant by showing that sustained intratumoral delivery of the STING or Resiquimod polymeric prodrugs strongly inhibits 4T1 tumor growth. Collectively, these results support our nanofluidic system as a therapeutic platform technology to investigate sustained intratumoral dosing of immunotherapy.

Anchored intratumoral cytokine immunotherapy

Anchored intratumoral cytokine immunotherapy

Intra-tumoral immunomodulatory therapy for advanced abdominal cancers using lipopolysaccharide: The Regional Immuno-Oncology Trial-1 (RIOT-1) protocol (NCT05751837)

BackgroundIntra-tumoral immunotherapy has shown potential in treating advanced cancers. Delivery challenges have limited exploration of these modalities in intra-abdominal tumors. In this study, we explore the safety of injecting intra-abdominal tumors with lipopolysaccharide (LPS) from Escherichia coli 0113. This agonist of toll-like receptor 4 (TLR4) holds promise as an agent to enhance the anti-tumor immune response within the tumor microenvironment. MethodsThis Phase I study will recruit adult patients with peritoneal metastases from gastrointestinal primary malignancies who have at least two suitable intra-abdominal soft tissue tumors for injection. LPS will be administered as a single 1 μg dose during diagnostic laparoscopy in patients in whom a subsequent interval laparotomy is planned. A control injection of saline will be injected into a second lesion. Primary outcome is safety, with secondary outcomes being biomarkers of the tumor immune microenvironment in pre- and post-treatment biopsies. ResultsThe primary endpoint is to determine the safety (frequency and nature of adverse events) following intra-tumoral LPS injection. Adverse events will be classified using Common Terminology Criteria for Adverse Events. Secondary endpoints include cellular and molecular biomarkers of immune response. The study will proceed until twelve patients have completed the protocol. DiscussionPatients undergoing standard-of-care laparoscopy in preparation for interval cytoreductive surgery may be ideal candidates for intra-tumoral immunotherapy. This study seeks to establish the safety of using E. coli LPS for injection into intra-abdominal tumors and to establish precedent for interval tumor immune microenvironment assessment as a window-of-opportunity concept in the context of abdominal metastatic disease. Trial RegistrationThe trial is registered at Clinical Trials.gov; NCT05751837 (registered February 28th, 2023).

Abstract 6663: Innovative CPMV immunotherapy: A canine model for poor-prognosis breast cancer treatment

Abstract Cowpea Mosaic Virus (CPMV) is a plant comovirus non-infectious to humans or animals. In mice models, intratumor immunotherapy (ITI) with CPMV devoid of nucleic acids (empty CPMV, eCPMV) and full CPMV results in a highly potent, systemic, antitumor immune response, with full CPMV being much more effective. Dogs with spontaneous mammary (breast) cancer (MC) serve as a valuable model for studying breast cancer (BC), bridging the gap between studies in rodents and human clinical trials. Canine MC develops in the presence of an intact immune system and has a unique advantage of shorter endpoint periods compared to women BC clinical trials. New immunotherapeutic approaches are necessary for poor-prognosis BC, such as triple-negative BC, metastatic BC, and the very aggressive and lethal inflammatory BC (IBC). Previous studies by our group using eCPMV ITI in dogs with MC revealed a substantial reduction in tumor size in both injected and non-injected tumors (abscopal effect), extended survival, and improved quality of life without any adverse effects or toxicity. In this clinical trial, we employed full CPMV nanoparticles ITI in dogs with poor-prognosis (inoperable) MC, comparing them with untreated controls. Regular tumor volume assessments and clinical evaluations have been conducted. Histopathology and immunohistochemistry of immune cell populations were performed to study tumor microenvironment (TME) modifications. Thus far, 5 dogs have been treated: four cases of inflammatory mammary cancer (IMC) and one case of metastatic MC. After at least two weekly CPMV ITI sessions, a significant reduction in tumor volumes was observed. In IMC cases, marked clinical improvement of typical signs (warmth, edema, erythema, and cutaneous pain) was observed in 3 out of 4 cases, and tumor reduction was so remarkable in one dog that surgery was recommended and successfully carried out. In IMC CPMV ITI cases, the survival of 2 dogs exceeded historical IMC records; the dog with metastatic MC maintains stable disease after one year, which is also superior to controls. TME studies showed that eCPMV immunotherapy significantly increased intratumor inflammatory infiltrates, neutrophils, T lymphocytes, and macrophages. Additionally, Treg cells (FOXP3+)/T lymphocytes (CD3+) ratio was significantly reduced. Our results demonstrate that immunotherapy with eCPMV induces a potent immunostimulatory effect on dogs with poor-prognosis MC by recruiting and activating neutrophils as the main drivers of the inflammatory response. This process reduces the immunosuppressive action of regulatory T lymphocytes and produces a breakdown of tumor immune suppression. These findings underscore the therapeutic potential of CPMV nanoparticles ITI in the management of canine IMC and metastatic MC. From a translational point of view, this study lays the groundwork for advancing the treatment of human breast cancer. Citation Format: Guillermo Valdivia, Dolores Pérez-Alenza, Lucía Barreno, Ángela Alonso-Diez, Jessica Fernanda Affonso de Oliveira, María Suárez-Redondo, Steven F. Fiering, Nicole F. Steinmetz, Laura Peña. Innovative CPMV immunotherapy: A canine model for poor-prognosis breast cancer treatment [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 6663.

Abstract 3185: Glatiramer acetate enhances tumor retention and mitigates systemic toxicity of toll-like receptor 9 agonists as intratumoral immunotherapy

Abstract Pathogen-associated molecular patterns (PAMP) are conserved molecular structures produced by microorganisms that are recognized as foreign by receptors of the innate immune system. Unmethylated cytosine-guanine oligodeoxynucleotides (CpG ODNs) are a storied drug class from the PAMP family that ligates Toll-like receptor 9 (TLR9). CpG ODNs have shown promising antitumor effects in preclinical studies by inducing potent pro-inflammatory immune responses. However, there are still practical challenges that have hindered clinical success, including inefficient in vivo delivery and severe immune-related toxicities caused by systemic exposure to CpG. We previously identified that glatiramer acetate (GA), an FDA-approved, lysine-rich polypeptide, could be applied as a cationic drug delivery vector for CpG delivery proximal to the injection site while mitigating systemic release of pro-inflammatory cytokines. To dive into the mechanism and evaluate pharmacological efficacy in more pathological models that simulate colorectal carcinoma, we validated the biodistribution of GA-CpG complexes (or R4B) and explored their safety and antitumor immunity in multiple mouse colorectal carcinoma models. In the CT26 single tumor model, intratumoral R4B treatment displayed comparable antitumoral efficacy as CpG treatment. Genome-wide transcriptome analysis showed that R4B treatment elicited much more prominent immune system response pathways in both lesions and spleens. The biodistribution study proved that R4B localized and gradually released CpG around the injection site while ‘naked’ CpG diffused away from the injection site quickly. In the CT26 dual tumor-bearing model, intratumoral administration of R4B generated systemic immune efficacy that led to an abscopal effect on distant untreated cancers, comparable to treatment with CpG alone. Notably, R4B treatment accomplished these effects with greatly mitigated systemic pro-inflammatory cytokines compared to CpG alone. These data help further elucidate the noncanonical role of glatiramer acetate to serve as a nucleic acid delivery scaffold that potentiates the safety of CpG adjuvant for cancer immunotherapy. Citation Format: Huan Gong, Daniel J. Griffin, Chad E. Groer, Xiaoqing Wu, Moustafa M. Abdelaziz, Sa Wu, Liang Xu, Laird M. Forrest, Cory J. Berkland. Glatiramer acetate enhances tumor retention and mitigates systemic toxicity of toll-like receptor 9 agonists as intratumoral immunotherapy [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 3185.

Abstract 2458: Targeting the CXCR3 axis in HER2+ breast cancer to enhance anti-tumor immunity

Abstract Breast cancer (BC) is the most frequently diagnosed cancer in women worldwide with more than 2 million new cases in 2020. The efficacy of immunotherapies for BC is limited, with response rates of <10% for anti-PD-1/PDL1 monotherapy in pre-treated triple-negative breast cancer (TNBC) patients and even lower in subtypes that express human epidermal growth factor receptor 2 (HER2+) and/or hormone receptors. Hence, there is an urgent need to improve immune based strategies for BC. One possible approach to enhance response is the application of intratumoral (IT) immunotherapy utilizing IL-12; a potent pro-inflammatory cytokine that is critical in producing an anti-tumor response. However, systemic delivery of IL-12 has substantial toxicity and localized delivery of protein has insufficient residence time. To circumvent these issues, we have previously reported the efficacy of intratumorally injected plasmid IL-12 (pIL-12-EP) followed by electroporation in a TNBC mouse model and in clinical trials. Following pIL-12-EP, treated tumor expressed genes that were associated with increased CD8+ T cell infiltration, activation, trafficking, antigen presentation, and exhaustion. Single-cell RNA sequencing (scRNAseq) of tumor infiltrating immune cells from treated tumors revealed a striking enrichment of the CXCL9/10/11/CXCR3 family. This CXCR3 axis is upregulated in response to IFNγ production and has been studied extensively in melanoma and NSCLC patients as a potential predictive biomarker for responses to immune checkpoint inhibitors but has not been well characterized in BC. We hypothesized that this axis may be the critical component downstream of pIL-12-EP treatment that is responsible for anti-tumor responses and that targeting it will be effective in other molecular subtypes of BC beyond TNBC. We first evaluated the expression of CXCR3 by tumor infiltrating lymphocytes (TILs) in biopsies of human HER2+ BC. Using a single cell resolution spatial transcriptomic Xenium instrument we find not only expression of CXCR3 by TILs, but can also track the distance and gradients of the chemokine ligands CXCL9 and CXCL10 in this tumor microenvironment. Having confirmed the activity of this axis in human HER2+ BC, we used our well-established spontaneous HER2-driven mouse model to compare treatment of HER2+ tumors with pIL-12-EP or pCXCL9-EP intratumorally. We observed tumor growth inhibition in both treatment groups as compared to control treated tumors. Interestingly, the abscopal effect previously seen with pIL-12-EP was not evident for distant tumors in mice treated with pCXCL9-EP. These data suggest that IT CXCL9 therapies may benefit from combination with a systemic immune activator like a vaccine or immunogenic chemotherapy. Ongoing studies will continue to evaluate ways to better target this axis therapeutically and define clinically active combination therapies. Citation Format: Anchit Bhagat, Jesuchristopher Joseph, Joshua D. Ginzel, Christopher Rabiola, Amy C. Hobeika, Joshua C. Snyder, Herbert K. Lyerly, Erika J. Crosby. Targeting the CXCR3 axis in HER2+ breast cancer to enhance anti-tumor immunity [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 2458.