Abscopal Tumor Research Articles

Pivotal roles of tumor-draining lymph nodes in the abscopal effects from combined immunotherapy and radiotherapy.

BackgroundCurrently, due to synergy enhancement of anti‐tumor effects and potent stimulation of abscopal effects, combination therapy with irradiation and programmed cell death protein 1/programmed death‐ligand 1 (PD‐1/PD‐L1) immune checkpoint inhibition (immuno‐radiotherapy, iRT) has revolutionized the therapeutic guidelines. It has been demonstrated that tumor‐draining lymph nodes (TDLN) are essential for effective antitumor immunity induced by radiotherapy, immunotherapy, or iRT. Given that the function of TDLN in iRT remains unclear, this study aimed to investigate the function and mechanism of TDLN in iRT‐induced abscopal effects.MethodsThe function of TDLN was evaluated using unilateral or bilateral MC38 and B16F10 subcutaneous tumor models with or without indicated TDLN. The flow cytometry, multiple immunofluorescence analysis, and NanoString analysis were utilized to detect the composition and function of the immune cells in the primary and abscopal tumor microenvironment. Additionally, we tempted to interrogate the possible mechanisms via RNA‐sequencing of tumor‐infiltrating lymphocytes and TDLN.ResultsTDLN deficiency impaired the control of tumor growth by monotherapy. Bilateral TDLN removal rather than unilateral TDLN removal substantially curtailed iRT‐stimulated anti‐tumor and abscopal effects. Furthermore, in the absence of TDLN, the infiltration of CD45+ and CD8+ T cells was substantially reduced in both primary and abscopal tumors, and the anti‐tumor function of CD8+ T cells was attenuated as well. Additionally, the polarization of tumor‐associated macrophages in primary and abscopal tumors were found to be dependent on intact bilateral TDLN. RNA‐sequencing data indicated that impaired infiltration and anti‐tumor effects of immune cells partially attributed to the altered secretion of components from the tumor microenvironment.ConclusionsTDLN play a critical role in iRT by promoting the infiltration of CD8+ T cells and maintaining the M1/M2 macrophage ratio.

Transdermal delivery system based on heparin-modified graphene oxide for deep transportation, tumor microenvironment regulation, and immune activation

Enhancing skin penetration and facilitating tumor infiltration in melanoma treatment through transdermal administration remains an intractable challenge. In the present study, docetaxel- and 1-methyl-D-tryptophan-loaded heparin-modified graphene oxide (D-1/GH) nanosheets were developed to overcome these barriers. Through heparin (Hep)-mediated stratum corneum (SC) hydration, D-1/GH permeates the skin through the intercellular route and the appendage pathway. Based on the relatively leaky structure of the tumor and the high affinity of Hep for tumors, D-1/GH can infiltrate tumors. Subsequently, D-1/GH is transported to deeper tumors through blood and lymphatic vessels. Theoretically, D-1/GH is wrapped in lymphatic vessels through the lymphatic vessel endothelial receptor-1 (LYVE-1)-mediated lymphatic transmigratory cup structure and enters blood vessels through the enhanced permeation and retention (EPR) effect, which is reported here for the first time. D-1/GH-mediated combinational therapy augments the therapeutic effect of chemotherapy and photothermal therapy (PTT) while inducing immunogenic cell death (ICD), thereby recruiting immune cells, and eliciting an immune response. D-1/GH reverses the immunosuppressive tumor microenvironment to potentiate the immune response, thus suppressing abscopal tumors and lung metastases. Collectively, this study identified a novel permeation mode, providing a new perspective to improve antitumor efficacy, boost immune response, and avert systemic distribution.

Radiation therapy enhances systemic antitumor efficacy in PD-L1 therapy regardless of sequence of radiation in murine osteosarcoma.

Recent studies demonstrate that immune checkpoint blockade (ICB) increases the chances of the abscopal effect, an anti-tumor effect outside the radiation field in radiation therapy. However, the optimal sequence between radiation and ICB remains unclear. To investigate the impact of sequence of radiation in anti-PD-L1 antibody (P1) therapy on immune microenvironments and antitumor efficacies in local and abscopal tumors, metastatic LM8 osteosarcoma cells were inoculated into both legs of C3H mice. For irradiation, only one side leg was irradiated at 10 Gy. Then mice were divided into four groups: administrated anti-PD-L1 antibody three times (P1 monotherapy), receiving radiation 3 days prior to P1 therapy (P1+pre-Rad), and receiving concurrent radiation with P1 therapy (P1+conc-Rad). Thereafter, tumor immune microenvironment and tumor volume changes were analyzed in irradiated and unirradiated tumors. The P1+pre-Rad regimen increased the proportion of CD8+ programmed cell death 1 (PD-1)+ granzyme B (GzmB)+ reinvigorated T cells and decreased the proportion of CD8+ PD-1+ GzmB- exhausted T cells than P1+conc-Rad regimen in unirradiated tumors. Combination regimens suppressed tumor growth in irradiated tumors compared with that in P1 monotherapy. In both irradiated and unirradiated tumors, significant tumor growth suppression and prolonged overall survival were observed under both combination treatment regimens compared with P1 monotherapy. However, no distinct differences in unirradiated tumor volume and survival were observed between P1+pre-Rad and P1+conc-Rad groups. These results suggest that local irradiation is necessary to improve systemic treatment efficacy in P1 therapy regardless of sequence of local irradiation.

Vitamin C supramolecular hydrogel for enhanced cancer immunotherapy

Vitamin C (VitC) has shown great promise to promote cancer immunotherapy, however, its high hydrophilicity makes it quickly excreted, leading to limited therapeutic efficiency even with frequent high-dose administration. Herein, we provide a pioneering report about the employment of VitC amphiphile self-assembled nanofiber hydrogels for enhanced cancer immunotherapy. Specifically, driven by hydrogen bonding and hydrophobic interactions, the synthesized VitC amphiphile, consisting of a hydrophilic VitC headgroup and a hydrophobic alkyl chain, could self-assemble into an injectable nanofiber hydrogel with self-healing properties. The formed VitC hydrogel not only serves as a reservoir for VitC but also acts as an effective delivery platform for stimulator of interferon genes (STING) agonist-4 (SA). Interestingly, the VitC hydrogel itself exhibits antitumor effects by upregulating genes related to interferon (IFN) signaling, apoptotic signaling and viral recognition and defense. Moreover, the SA-encapsulated VitC hydrogel (SA@VitC hydrogel) synergistically activated the immune system to inhibit the progression of both local and abscopal tumors.

ATR-mediated CD47 and PD-L1 up-regulation restricts radiotherapy-induced immune priming and abscopal responses in colorectal cancer.

Radiotherapy (RT) of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)-expressing CRC cells systemically. However, abscopal tumor remissions are extremely rare, and the postirradiation immune escape mechanisms in CRC remain elusive. Here, we found that irradiated CRC cells used ATR-mediated DNA repair signaling pathway to up-regulate both CD47 and PD-L1, which through engagement of SIRPα and PD-1, respectively, prevented phagocytosis by antigen-presenting cells and thereby limited TAA cross-presentation and innate immune activation. This postirradiation CD47 and PD-L1 up-regulation was observed across various human solid tumor cells. Concordantly, rectal cancer patients with poor responses to neoadjuvant RT exhibited significantly elevated postirradiation CD47 levels. The combination of RT, anti-SIRPα, and anti-PD-1 reversed adaptive immune resistance and drove efficient TAA cross-presentation, resulting in robust TAA-specific CD8 T cell priming, functional activation of T effectors, and increased T cell clonality and clonal diversity. We observed significantly higher complete response rates to RT/anti-SIRPα/anti-PD-1 in both irradiated and abscopal tumors and prolonged survival in three distinct murine CRC models, including a cecal orthotopic model. The efficacy of triple combination therapy was STING dependent as knockout animals lost most benefit of adding anti-SIRPα and anti-PD-1 to RT. Despite activation across the myeloid stroma, the enhanced dendritic cell function accounts for most improvements in CD8 T cell priming. These data suggest ATR-mediated CD47 and PD-L1 up-regulation as a key mechanism restraining radiation-induced immune priming. RT combined with SIRPα and PD-1 blockade promotes robust antitumor immune priming, leading to systemic tumor regressions.

Abstract 6218: Oncolytic Seneca Valley virus (SVV-001) overcomes checkpoint inhibitor resistance and demonstrates a systemic anti-tumor immune response in a syngeneic pancreatic cancer murine model

Abstract Here we evaluated the efficacy of Seneca Valley Virus (SVV), an oncolytic virus in the Picornaviridae family, in combination with checkpoint inhibitors (CPI) using the CPI-resistant murine syngeneic pancreatic tumor model Pan02. SVV, serendipitously identified in 2001, is an extremely tumor selective and potent oncolytic virus for a variety of solid human cancers, primarily due to the expression of the receptor of SVV, TEM8, being selectively expressed on the surface of malignant cancer cells and cancer stem cells within a variety of solid tumors. SVV has been tested in three clinical trials of patients having neuroendocrine neoplasms as a single intravenous dose monotherapy. Despite this, the results were encouraging with patients having evidence of clinical benefit and only one DLT was reported in the 76 patients treated. Recent data have demonstrated that some oncolytic viruses can enhance efficacy in preclinical models and in clinical trials when the oncolytic virus was injected intratumorally in combination with systemic administration of a CPI(s). The mechanism is primarily believed to be due to the oncolytic virus enhancing T cell infiltration and fostering an anti-tumor immune response. SVV was injected intra-tumorally in Pan02 tumors along with aPD1and/or aCTLA4. SVV reversed any resistance to CPIs and enhanced efficacy over CPI(s) alone resulting in complete cures in >83% of mice with primary and abscopal tumors. SVV plus aPD1+aCTLA4 resulted in 5 of 6 mice cured of their primary tumor. The animals were challenged on their contralateral flank with Pan02 to evaluate systemic and abscopal immune effects. All mice (5/5) that cleared the primary Pan02 tumor also eradicated the abscopal secondary tumors. Control treated Pan02 tumor-bearing mice were all sacrificed due to tumor burden by day 70 (median survival <50 days). Control animals treated with aPD1+aCTLA4 showed transient tumor regressions but these animals all grew large tumors, requiring sacrifice. In contrast, the SVV+aPD1+aCTLA4 primary tumors were eliminated within 44 days and these animals remain tumor-free out to >110+ days. Contralateral tumors were eradicated in all 5 animals that rejected the primary tumor, demonstrating potent systemic immunity. In the control aPD1+aCTLA4 group, only one animal with contralateral tumor showed prolonged tumor regression. SVV treatment caused increases in T-cell infiltration; the combination of SVV+aPD1+aCTLA4 showing the highest infiltration. Phenotypic and gene expression analyses of infiltrating cells will be presented. These studies serve as a foundation for translating SVV oncolytic virotherapy combined with anti-PD-1 and anti-CTLA4 antibodies in patients with neuroendocrine neoplasms with a clinical trial anticipated to begin in H1, 2021. Citation Format: Paul L. Hallenbeck, Sunil Chada. Oncolytic Seneca Valley virus (SVV-001) overcomes checkpoint inhibitor resistance and demonstrates a systemic anti-tumor immune response in a syngeneic pancreatic cancer murine model [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 6218.

Abstract 3444: Administration of anti-CD40 enhances local and systemic antitumor efficacy of radiotherapy in allograft tumor model of a check-point blockade resistant melanoma

Abstract Resistance to immune checkpoint therapy develops in a subset of patients after initial response. Therefore, we hypothesized that defective antigen presentation contributes to immune resistance, and a sequential therapy comprising of ablative radiation therapy (RT) and agonist αCD40 antibody can reprogram the tumor-infiltrating myeloid and dendritic cells for effective in-situ tumor antigen presentation and activation of T cells. Palpable B16-F10-Res499 tumors in C57BL/6 mice, resistant to the systemic effects of RT and αCTLA-4 blockade, were treated with 3 fractions of 20Gy (RT) followed by agonist αCD40 antibody (3x100μg). Tumor growth, survival, and anti-tumoral immune memory after rechallenge was monitored. Mice were sacrificed on Day 16 post-RT, and immune cells from irradiated tumors and draining lymph nodes (DLN) were analyzed using flow cytometry. There was complete tumor regression and enhanced anti-tumoral immune memory in RT+αCD40-treated animals. In a dual tumor model, combination therapy significantly delayed abscopal tumor growth by 64% on D30 (p<0.0001). When compared to unirradiated or tumors treated with RT alone, there was a significant increase in cell surface expression of co-stimulatory molecules (CD80, CD86, CD40 and 4-1BBL) and TNF-α, and iNOS in the CD103+ DCs and myeloid cells (p<0.05) indicating a reprogramming of antigen presentation and co-stimulatory function in MDSCs. There was an increase in CD8+ T cells with reduced CD4/CD8 ratio (p<0.01) in abscopal tumors and DLN in the RT+αCD40 group. Combination treatment enhanced the frequency of proliferating Ki67+ (p<0.001) and IFNγ+ (p<0.01) CD8 T cells and an increase in the Ki67+ high GRZ+ (granzyme secreting) population in the pool of early exhausted cells (PD1intEOMESlow). Interestingly CD8 depletion by anti-CD8 only partially reversed the effect of the combination group. Furthermore, αCD40 showed an increase in the CD11b+Ly6C population in the tumors. Also, Ly6C depletion completely reversed the effect of the IR+anti-CD40 treatment. Conclusion: Combination of ablative RT, followed by αCD40 therapy, overcame immune resistance in murine melanoma by enhancing systemic anti-tumoral immunity, abscopal effects, survival, and anti-tumoral immune memory. The immunomodulatory effects of αCD40 are dependent upon Ly6C+ cells and partially on CD8+ T cells. Citation Format: Sanjay Pandey, Claudia G. Chavez, Indranil Basu, Andy Minn, Chandan Guha. Administration of anti-CD40 enhances local and systemic antitumor efficacy of radiotherapy in allograft tumor model of a check-point blockade resistant melanoma [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 3444.

Abstract 218: Novel SOD mimetics GC4419 & GC4711 induce synergistic tumoricidal effects combined with radiotherapy in lung cancer models

Abstract Introduction: Superoxide dismutase mimetics (SODm) synergize with radiation (IR) by converting radiolytically produced superoxide to hydrogen peroxide. Cancer cells lacking catalase function fail to clear H2O2 resulting in increased tumoricidal load. In addition, complex interactions through redox signaling and immune interplay are suggested mechanisms of action. Our pre-clinical studies with the SODm GC4419 (AVA) indicated that increased inflammatory, TNFα, and apoptosis signaling contribute to treatment synergy that was most effective at hypofractionation (Sci Transl Med. 13:593). The analogue GC4711 (GC) is currently in clinical trials for SBRT against NSCLC and pancreatic cancer. However, optimal combination schedules and molecular mechanisms are largely unknown. Here, we present optimized combination schedules using human lung tumor xenografts regarding drug administration timing and dosage, as well as local and abscopal tumor control in a syngeneic lung tumor model. Further, we tested various cell stress and immune pathways to identify targets of synergistic IR-drug interaction. Methods: Female athymic nude and C57BL/6 mice were inoculated with H1299 and LLC, respectively. H1299 tumors were irradiated with 10-15 Gy and GC was given once or twice daily (24 or 2x20 mg/kg, respectively) over 5 days, including untreated controls. LLC tumors were set up as an abscopal model and mice received combination treatment with GC and 15 Gy, 15 Gy only, or GC only, including untreated controls. In vitro, lung cancer cell lines were pre-treated with AVA or GC 30 min prior to IR and assayed for various immune or DNA damage-related endpoints. Results: The anti-tumor efficacy of single or double GC administration showed nonlinear dose-dependence indicating complex drug-IR interplay. Optimal drug administration appears to be around 3 hours prior to irradiation while time-of-day of treatment has no observable effect in this model. In the LLC double tumor model, GC in combination with IR induced significant and pronounced abscopal tumor control. In vitro, analysis revealed GC action related to e.g. 53BP1, yH2AX, Akt, R-loop formation and replication stress, and interaction with various immune pathways. Discussion and Conclusions: The radiotherapeutic effect can be vastly increased with superoxide dismutase mimetics, both within and outside the treatment field. Combination therapy requires screening of schedules regarding timing, drug dosage, and IR dose and fractionation to achieve optimal tumoricidal effects. SODm synergize with IR acting on various molecular targets that can be harnessed to overcome treatment resistance. Secondary tumor control is a promising new venue for IR-SODm combination therapy. Moreover, redox-immune interaction opens new therapeutic applications with combined immune checkpoint inhibitors for unprecedented tumor control and cure rate. Citation Format: Britta Langen, Laurentiu Pop, Zengfu Shang, Moito Iijima, James Nicholson, Mingming Yang, Michael D. Story. Novel SOD mimetics GC4419 & GC4711 induce synergistic tumoricidal effects combined with radiotherapy in lung cancer models [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 218.

The combination timing of radio-immunotherapy determines immune microenvironment remodeling and abscopal effect through eosinophils.

e14566 Background: Recently, several studies have confirmed the abscopal effect of tumor shrinkage outside the irradiated field induced by local radiotherapy (RT) combined with immunotherapy. The timing of the combination, including concurrent and sequential treatment, may affect the anti-tumor efficacy of radiotherapy and immune checkpoint inhibitors (ICIs). However, the optimal timing of RT combined with immunotherapy to enhance the abscopal effect and the underlying mechanism are still unknown. Methods: The animal model of bilateral subcutaneous tumor of MC38 in C57BL/6J mice were randomly divided into four groups: PD-1 therapy (P1) group, radiotherapy (unilateral irradiation, 8Gy × 3F, the same below) concurrent with anti-PD-1 therapy (Con.) group, anti-PD-1 therapy one week after radiotherapy (Seq.1) group and anti-PD-1 therapy two weeks after radiotherapy (Seq.2) group. RNA sequencing was employed to identify differential genes. The changes of the immune microenvironment of tumor-draining lymph nodes (TDLN) and tumors were detected by flow cytometry. The expression of chemokine receptors, ligands, and cytokines was detected by qPCR, western blot, and ELISA. Results: The results showed that the survival benefit of sequential PD-1 inhibitor after RT was higher than that of the Con. group and P1 group., the survival benefited most in Seq.1 group, particularly. Similarly, tumor growth on both sides was significantly inhibited in Seq.1 group compared with the Con. group, P1 group, and Seq2. group. Furthermore, a combination of RT with anti-PD-1 inhibitor induced changes of immune microenvironment in irradiated tumor, abscopal tumor and TDLN. In the Seq.1 group, the tumor immune microenvironment was reshaped, including increased eosinophils and CD8+T cells infiltration, while decreased Treg, MDSCs, and TAMs frequency. Correspondingly, the expression of crucial chemokine receptors and ligands involved in chemotaxis of eosinophils and CTL CD8+T cells was up-regulated in tumors of mice in the Seq.1 group. After eosinophil neutralization in vivo, the survival of mice in Seq.1 group was significantly shortened. Besides, the anti-tumor effect and abscopal effect were significantly weakened, accompanied by deduction of the infiltration of T cells, especially cytotoxicity CD8+T cells in the immune microenvironment. Conclusions: Our results showed that RT combined with PD-1 inhibitors could induce a synergistic anti-tumor effect. Sequential PD-1 inhibitor one week after RT could enhance the anti-tumor effect most, including the abscopal effect. The mechanism related to eosinophils recruitment, which established a tumor-suppressive immune microenvironment mainly through enrichment of anticancer T lymphocytes in abscopal tumors. This study provides an insight for clinical precision treatment in combination of RT and immunotherapy.

Multimodal Imaging‐Guided Photothermal Immunotherapy Based on a Versatile NIR‐II Aggregation‐Induced Emission Luminogen

Synergistic photothermal immunotherapy has captured great attention owing to the mutually strengthening therapeutic outcomes towards both original tumors and abscopal tumors. Herein, a versatile theranostic agent displaying aggregation-induced emission, namely TPA-BT-DPTQ, was designed and prepared based on benzo[c]thiophene unit as a building block; it can be used for simultaneous fluorescence imaging (FLI) in the second near-infrared (NIR-II) window, photoacoustic imaging (PAI), photothermal imaging (PTI), and thermal eradication of tumors. Further experiments validate that photothermal therapy (PTT) mediated by TPA-BT-DPTQ nanoparticles not only destroys the primary tumor but also enhances immunogenicity for further suppressing the growth of tumors at distant sites. Furthermore, PTT combining a programmed death-ligand 1 (PD-L1) antibody prevents the metastasis and recurrence of cancer by potentiating the effect of immunotherapy.

Multimodal Imaging‐Guided Photothermal Immunotherapy Based on a Versatile NIR‐II Aggregation‐Induced Emission Luminogen

AbstractSynergistic photothermal immunotherapy has captured great attention owing to the mutually strengthening therapeutic outcomes towards both original tumors and abscopal tumors. Herein, a versatile theranostic agent displaying aggregation‐induced emission, namely TPA‐BT‐DPTQ, was designed and prepared based on benzo[c]thiophene unit as a building block; it can be used for simultaneous fluorescence imaging (FLI) in the second near‐infrared (NIR‐II) window, photoacoustic imaging (PAI), photothermal imaging (PTI), and thermal eradication of tumors. Further experiments validate that photothermal therapy (PTT) mediated by TPA‐BT‐DPTQ nanoparticles not only destroys the primary tumor but also enhances immunogenicity for further suppressing the growth of tumors at distant sites. Furthermore, PTT combining a programmed death‐ligand 1 (PD‐L1) antibody prevents the metastasis and recurrence of cancer by potentiating the effect of immunotherapy.

Systemic nano-delivery of low-dose STING agonist targeted to CD103+ dendritic cells for cancer immunotherapy

Current methods of STING activation based on intra-tumoral injections of cyclic dinucleotides (CDNs) are not suitable for addressing tumor heterogeneity or for inaccessible, metastatic and abscopal tumors. In this study, we developed systemically administered CD103+ dendritic cell (DCs) targeted liposomal formulations and evaluated the anti-tumor efficacy with low dose. Liposomal CDN formulations were prepared using Clec9a targeting peptide and evaluated therapeutic efficacy in vitro and in vivo in subcutaneous MC38 and B16F10 tumor models. Targeted delivery of CDNs is expected to enhance anti-tumor immune response as well as reduce off-target toxicities. With intravenous 0.1mg/kg systemic CDN dose of the targeted liposomal formulation, our results showed robust immune response with significant antitumor efficacy both as a monotherapy and in combination with anti-PD-L1 antibody. These results show that a CD103+ DC targeted CDN formulation can lead to potent immune stimulation upon systemic administration even in relatively "cold" tumors such as B16F10.

High Dose Local Photon Irradiation Is Crucial in Anti-CTLA-4 Antibody Therapy to Enhance the Abscopal Response in a Murine Pancreatic Carcinoma Model.

Simple SummaryPancreatic cancer is an extremely treatment-resistant neoplasm to chemotherapy and immunotherapy. The combination of photon beam irradiation and anti-CTLA-4 antibody (C4) for the anti-tumor effect enhancement at local and distant tumors (abscopal tumors) was investigated using a pancreatic ductal adenocarcinoma (PDAC) mouse model. Monotherapy with C4 was not effective for PDAC. The high dose irradiation to local tumors produced significant shrinkage of irradiated tumors but did not induce the abscopal responses. In contrast, the combination therapy of high dose radiation and C4 enhanced the abscopal responses with significantly prolonged overall survival. The combination therapy dramatically decreased the regulatory T cell infiltration while increasing the cytotoxic T lymphocytes in the irradiated and abscopal tumors. These results suggest that high dose photon beam irradiation plays an important role in C4 therapy to enhance the abscopal response in PDAC.Pancreatic cancer is an extremely treatment-resistant neoplasm to chemotherapy and immunotherapy. The combination of photon beam irradiation and anti-CTLA-4 antibody (C4) for the anti-tumor effect enhancement at local and distant tumors (abscopal tumors) was investigated using the pancreatic ductal adenocarcinoma (PDAC) mouse model. Pan02 cells were bilaterally inoculated to both legs of C57BL/6 mice. High dose photon beams in a hypofractionation or a single fraction were delivered to the tumors on one leg. Monotherapy with C4 via i.p. was not effective for PDAC. The high dose irradiation to the local tumors produced significant shrinkage of irradiated tumors but did not induce the abscopal responses. In contrast, the combination therapy of high dose photon beam irradiation in both hypofractionation and a single fraction with C4 enhanced the anti-tumor effect for abscopal tumors with significantly prolonged overall survival. The flow cytometric analysis revealed that the combination therapy dramatically decreased the regulatory T cell (Treg) proportion while increasing the cytotoxic T lymphocytes in both local and abscopal tumors. These results suggest that high dose photon beam irradiation plays an important role in C4 therapy to enhance the abscopal response with immune microenvironment changes in PDAC, regardless of the fractionation in radiation therapy.

ATP-exhausted nanocomplexes for intratumoral metabolic intervention and photoimmunotherapy

Tumor cells reprogram the metabolic pathways to acquire abundant nutrients and sustain malignant proliferation. This fierce metabolic competition in tumor ecosystem has been uncovered to be associated with tumor microenvironmental immunosuppression. Here we develop an adenosine triphosphate (ATP)-exhausted nanocomplex (IR@ZIF-RGD) to intervene in tumor energy metabolism and regulate tumor immune microenvironment. IR@ZIF-RGD could effectively deplete intracellular ATP and inhibit ATP synthesis by ATP-responsive ZIF-90 and siRNA targeting thioredoxin reductase-2, respectively, thus leading to tumor metabolism disorders and immunosuppressive reversion. Meanwhile, IR@ZIF-RGD induced oxidative stress and ICG triggered photothermal therapy could provoke potent immunogenic cell death to enhance antitumor immunogenicity. Such a photo-immunometabolic nanocomplex has been demonstrated to be an efficient vaccine to elicit protective anticancer immune response in vivo, achieving suppressed growth of both primary and abscopal tumors, as well as inhibited tumor metastasis.

Nanoplatform Self-Assembly from Small Molecules of Porphyrin Derivatives for NIR-II Fluorescence Imaging Guided Photothermal-Immunotherapy.

Combinatorial photothermal and immunotherapy have demonstrated great potential to remove primary tumors, suppress metastases, and prevent tumor recurrence. However, this strategy still confronts patients with many limitations, such as complex components, sophisticated construction, and inadequate therapeutic efficacy. In this work, small molecules of porphyrin derivatives (PPor) which can self-assemble into monodispersed nanoparticles without supplement of any other ingredients or surfactants are developed. The formed PPor nanoparticles (PPor NPs) exhibit highly photothermal conversion efficiency of 70% and NIR-II luminous abilities originate from the strong intramolecular charge transfer (ICT) effect of D-A structure under 808nm laser irradiation, thus achieving NIR-II fluorescence imaging guided photothermal therapy (PTT) against primary tumors with a high cure rate. More importantly, tumor-associated antigens (TAAs), together with damage-associated molecular patterns (DAMPs) released from PTT-treated cancer cells, are proved to elicit immune responses to some degree. After combination with programmed cell death-1 (PD-1) antibodies, a robust systematic antitumor immunity is generated to restrain both primary and abscopal tumors growth, prolong survival, and prevent pulmonary metastasis on an aggressive 4T1 murine breast tumor model. Thus, this study provides a promising therapeutic paradigm with porphyrin derivatives nano-assembly as phototheranostic agents for the treatment of aggressive tumors with high efficiency.

ER-Targeting Cyanine Dye as an NIR Photoinducer to Efficiently Trigger Photoimmunogenic Cancer Cell Death.

Endoplasmic reticulum (ER) stress, caused by overproduction of reactive oxygen species (ROS), has been shown to be responsible for immunogenic cell death (ICD). Seeking ROS generator targeting ER is an optimal solution to efficiently induce ER stress. Despite clear indications of demand for ER-targeting photosensitizer, the alternative chemical tools remain limited. Herein, the first ER-localizable ICD photoinducer using thio-pentamethine cyanine dye (TCy5) to induce ER stress under mild near-infrared (NIR) irradiation has been developed. Within the ICD photoinducer design, polyfluorinated TCy5-Ph-3F possesses a selective tropism to ER accumulation and superior ROS generation capability in both normoxia and hypoxia conditions, which benefit from its low singlet-triplet gaps. Under NIR irradiation, cancer cells stained by TCy5-Ph-3F will lead to ER stress and induce massive emission of damage-associated molecular patterns, including calreticulin and heat-shock protein 70 exposure, high mobility group box 1 efflux, and adenosine triphosphate secretion. Dendritic cells maturation and CD8+ T cells activation in vivo also highlight the effectiveness. Therefore, the growth of abscopal tumors was substantially suppressed by the primary tumor treated with TCy5-Ph-3F and NIR irradiation. These results confer practical applicability that could provide a guideline for designing efficient ICD photoinducers, which will enable expanding organic molecular applications for cancer immunotherapy.

Engineered Mesenchymal Stem Cells as a Biotherapy Platform for Targeted Photodynamic Immunotherapy of Breast Cancer.

Interleukin-12 (IL12) is a pleiotropic cytokine with promising prospects for cancer immunotherapy. Though IL12 gene-based therapy can overcome the fatal hurdle of severe systemic toxicity, targeted delivery and tumor-located expression of IL12 gene remain the challenging issues yet to be solved. Photo-immunotherapy emerging as a novel and precise therapeutic strategy, which elaborately combines immune-activating agents with light-triggered photosensitizers for potentiated anticancer efficacy. Herein, an engineered stem cell-based biotherapy platform (MB/IL12-MSCs) incorporating immune gene plasmid IL12 (pIL12) and photosensitizer methylene blue (MB) is developed to realize tumor-homing delivery of therapeutic agents and photo-immunotherapy efficacy enhancement. The biotherapy platform retained tumor-tropic migration and penetration functions, which improved the intratumoral distribution of therapeutic agents, thereby promoting photodynamic effects and reinforcing immune responses. Importantly, MB/IL12-MSCs restricted the expression and distribution of IL12 at tumor site, which minimized potential toxicity while eliciting sufficient anticancer immunity. In noteworthy, activation of immunity induced by MB/IL12-MSCs established long-term systemic immunologic memory to prevent tumor relapse. The MB/IL12-MSCs outperform their monotherapy counterparts in breast tumor models, and the growth of tumor significantly arrested as well as re-challenging abscopal tumor growth slowdown. Collectively, this work reveals that MSCs-based strategy may advance more efficient, durable, and safer cancer photo-immunotherapy.

Nanoscale CaH2 materials for synergistic hydrogen-immune cancer therapy

<h2>Summary</h2> Herein, we prepared CaH₂ nanoparticles through liquid-phase exfoliation and first applied them as an antitumor therapeutic agent. Being dispersed in low-molecular-weight polyethylene glycol (PEG) and injected into the tumor, nano-CaH₂ would react with water to generate abundant hydrogen gas (H₂), calcium ions (Ca²⁺), and hydroxyl ions (OH⁻), enabling hydrogen therapy, tumor calcification, and neutralization of acidic tumor microenvironment (TME), respectively. The injectable nano-CaH₂ dispersion could lead to significant tumor growth inhibition. In addition, the local nano-CaH₂-induced tumor cell apoptosis and TME modulation would activate the immune system and promote tumor infiltration of immune cells, which, working together with immune checkpoint blockade, could elicit robust immune responses to inhibit abscopal distant tumors without direct nano-CaH₂ injection. Furthermore, nano-CaH₂ could be dispersed in lipiodol to obtain CaH₂-lipiodol dispersion for interventional transarterial embolization (TAE) therapy, and they showed obviously improved TAE therapeutic outcome on orthotopic rabbit liver cancer model compared with lipiodol alone.

Phase 1/2 study of intratumoral G100 (TLR4 agonist) with or without pembrolizumab in follicular lymphoma

Intratumoral injection of G100, a toll-like receptor 4 (TLR4) agonist, was shown pre-clinically to stimulate anti-tumor immune responses and tumor regression. This open-label, multicenter, phase 1/2 trial evaluated the safety, tolerability, and preliminary efficacy of intratumoral G100 injections following localized low-dose radiation in patients with follicular lymphoma (ClinicalTrials.gov #NCT02501473). The study was comprised of a G100 dose escalation (5 or 10 µg/dose, or 20 µg/dose for large tumors); a randomized component comparing G100 to G100 plus pembrolizumab; and G100 20 µg/dose expansion. Adverse events grade ≥3 were uncommon in patients treated with G100, and no unexpected toxicities were observed when combined with pembrolizumab. G100 20 µg (n = 18) resulted in an overall response rate of 33.3% and abscopal tumor regression in 72.2% of patients. This early-phase study provides a foundation for combining an intratumoral TLR4 agonist with agents to produce immune-mediated responses in follicular lymphoma with limited added toxicity.

In Situ Vaccination with IL-12Fc and TLR Agonist - a Crucial Role for B Cells in Generating Anti-Tumor T Cell Immunity

Interleukin 12 (IL-12) is a potent proinflammatory cytokine that plays a central role in regulating both innate and adaptive immune responses. This cytokine has been tested as a cancer immunotherapy agent based on its impressive anti-tumor effects in animal models. Clinically, systemic delivery of IL-12 incurred dose-limiting toxicities because of its pharmaco-kinetic extremes of peaks and troughs, a result of its short serum half-life. Here, we evaluated mDF6006, a mouse IL-12 Fc-fusion protein which was designed to have a prolonged half-life with equivalent potency to recombinant mouse IL-12.We hypothesized that local intra-tumoral (IT) delivery of low doses IL-12Fc would lead to immune-therapeutic potential.To screen candidates for in situ vaccination, we have employed a preclinical strategy whereby the same syngeneic tumor is implanted at two separate sites in the body. One tumor is then injected with the test agents and the resulting immune response is detected by the regression of the distant, untreated tumor.Using this assay for abscopal therapeutic effects we have tested a variety of immune stimulatory ligands and antibodies against immune checkpoints and T cell co-stimulatory targets, alone and in multiple combinations.Among these, the combination of unmethylated CG-enriched oligodeoxynucleotide (CpG), a TLR9 ligand, and IL-12Fc has provided the most impressive results. TLRs, expressed in antigen-presenting cells and are components of the innate immune system that recognize molecular patterns on bacterial, fungal, or viral pathogens.In a mouse model of lymphoma, IT injection of CpG and IL-12Fc, combined to cause tumor eradication at both the injected site and the untreated tumor. All these results were dependent on T cells in the animal.During this therapy we observed a significant increase in activated B cells within the treated tumor and especially in its draining lymph nodes (dLN). This B cell stimulation was contributed by both the CpG and the IL12-Fc. Surprisingly, depletion of the animals of B cells by an anti-CD20 antibody completely ablated the abscopal therapeutic effect.B cells function as antigen-presenting cells, secrete cytokines and are precursors of antibody producing plasma cells. To evaluate which of these roles B cells play in the therapeutic efficacy of CpG and IL-12Fc we isolated B cells from the LN of the treated mice and co-cultured them with T cells. These B cells activated T cells in an antigen-specific manner that was MHC dependent. No such T cell activation occurred when MHC molecules were blocked with anti-MHC antibodies or when the cells were physically separated by a semi-permeable membrane. Thus, local CpG and IL12-Fc directly activated B cells to present tumor antigens to specific T cells in the tumor microenvironment, resulting ultimately in an abscopal tumor response.IL-12Fc and CpG are both currently in phase-1/2 trials as single agents and in combinations with checkpoint antibodies. Our results provide strong rationale for using low doses of IL-12Fc with CpG as an in situ therapeutic vaccine for lymphoma. DisclosuresLevy: Virsti: Membership on an entity's Board of Directors or advisory committees; Khloris: Membership on an entity's Board of Directors or advisory committees; Abintus Bio: Membership on an entity's Board of Directors or advisory committees; Kira: Membership on an entity's Board of Directors or advisory committees; Walking Fish: Membership on an entity's Board of Directors or advisory committees; Immunocore: Membership on an entity's Board of Directors or advisory committees; Spotlight: Membership on an entity's Board of Directors or advisory committees; Viracta: Membership on an entity's Board of Directors or advisory committees; Apexigen: Membership on an entity's Board of Directors or advisory committees; Dragonfly: Membership on an entity's Board of Directors or advisory committees; Nurix: Membership on an entity's Board of Directors or advisory committees; Teneobio: Membership on an entity's Board of Directors or advisory committees; GigaGen: Membership on an entity's Board of Directors or advisory committees; BeiGene: Membership on an entity's Board of Directors or advisory committees; BiolineRx: Membership on an entity's Board of Directors or advisory committees; Quadriga: Membership on an entity's Board of Directors or advisory committees.