Induction Of Immunogenic Cell Death Research Articles

Liposomal DQ in Combination with Copper Inhibits ARID1A Mutant Ovarian Cancer Growth.

Therapeutic strategies for ARID1A-mutant ovarian cancers are limited. Higher basal reactive oxygen species (ROS) and lower basal glutathione (GSH) empower the aggressive proliferation ability and strong metastatic property of OCCCs, indicated by the increased marker of epithelial-mesenchymal transition (EMT) and serving the immunosuppressive microenvironment. However, the aberrant redox homeostasis also empowers the sensitivity of DQ-Lipo/Cu in a mutant cell line. DQ, a carbamodithioic acid derivative, generates dithiocarbamate (DDC) in response to ROS, and the chelation of Cu and DDC further generates ROS and provides a ROS cascade. Besides, quinone methide (QM) released by DQ targets the vulnerability of GSH; this effect, plus the increase of ROS, destroys the redox homeostasis and causes cancer cell death. Also importantly, the formed Cu(DDC)2 is a potent cytotoxic anti-cancer drug that successfully induces immunogenic cell death (ICD). The synergistic effect of EMT regulation and ICD will contribute to managing cancer metastasis and possible drug resistance. In summary, our DQ-Lipo/Cu shows promising inhibitory effects in cancer proliferation, EMT markers, and "heat" the immune response.

Immunogenic sonodynamic therapy for inducing immunogenic cell death and activating antitumor immunity.

Immunotherapy is widely regarded as a promising treatment for cancer. However, the immune effector phase suppression of tumor microenvironment (TME) and the generation of immune-related adverse events limit its application. Research indicates that sonodynamic therapy (SDT) can effectively activate antitumor immunity while killing tumor cells. SDT produces cytotoxic substances of tumors, and then cell apoptosis and immunogenic death occur by selectively activating the sonosensitizer under ultrasound. In recent years, various SDT alone as well as SDT in combination with other therapies have been developed to induce immunogenic cell death (ICD) and enhance immunotherapy. This paper overviews the research progress of SDT and nanotechnology in recent years, including the strategies involving SDT alone, SDT-based synergistic induction of antitumor immunity, and immunotherapy based on SDT for multimodal immunotherapy. Finally, the prospects and challenges of these SDT-based therapies in cancer immunotherapy are discussed.

Chemotherapeutic and targeted drugs-induced immunogenic cell death in cancer models and antitumor therapy: An update review.

As traditional strategies for cancer treatment, some chemotherapy agents, such as doxorubicin, oxaliplatin, cyclophosphamide, bortezomib, and paclitaxel exert their anti-tumor effects by inducing immunogenic cell death (ICD) of tumor cells. ICD induces anti-tumor immunity through release of, or exposure to, damage-related molecular patterns (DAMPs), including high mobility group box 1 (HMGB1), calreticulin, adenosine triphosphate, and heat shock proteins. This leads to activation of tumor-specific immune responses, which can act in combination with the direct killing functions of chemotherapy drugs on cancer cells to further improve their curative effects. In this review, we highlight the molecular mechanisms underlying ICD, including those of several chemotherapeutic drugs in inducing DAMPs exposed during ICD to activate the immune system, as well as discussing the prospects for application and potential role of ICD in cancer immunotherapy, with the aim of providing valuable inspiration for future development of chemoimmunotherapy.

Enhancing anti-tumor immunity through liposomal oxaliplatin and localized immunotherapy via STING activation

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is a promising approach for anti-cancer immunotherapy by bridging innate and adaptive immunity. Recent evidence suggests that chemotherapy-induced DNA damage can directly induce dendritic cell (DC) maturation and recruitment, which synergizes with STING activation to enhance anti-tumor effects. As an immunogenic cell death (ICD) inducer, oxaliplatin generates massive double-stranded DNA (dsDNA) crosslinks, release of tumor-associated antigens and promoting the “eat me” signal. STING activation improves antigen immunogenicity, which can promote T cell activation and infiltration. In this study, we developed liposomes encapsulating oxaliplatin and combine this formulation with a STING agonist (ADU-S100) for treating colorectal cancer. The liposomes efficiently inhibited the proliferation of tumor cells while induced ICD in CT26 colorectal cancer cells, which enhanced dendritic cell maturation and phagocytosis in vitro. The liposome-based immunochemotherapy exhibited the strongest efficacy, resulting in complete remission upon tumor inoculation. Mechanistic studies showed this potent anti-cancer effect was related to the significant recruitment of infiltrating CD8 and CD4 T cells, reduction of suppressive Treg cells, and a shift in the phenotype of tumor-associated suppressive macrophages that promote cancer to immune stimulating macrophages. Thus, our study demonstrated the potential of combining oxaliplatin-loaded liposomes with a STING agonist to reduce tumor growth by regulating the immunosuppressive state in the tumor.

Immunotherapeutic Hydrogel with Photothermal Induced Immunogenic Cell Death and STING Activation for Post‐Surgical Treatment

AbstractPost‐surgical tumor recurrence remains a major clinical concern for patients with malignant solid tumors. Herein, an immunotherapeutic hydrogel (SAPBA/ZMC/ICG) is developed by incorporating metal ion‐cyclic dinucleotide (CDN) nanoparticles (Zn‐Mn‐CDN, ZMC) and a photosensitizer (indocyanine green, ICG) into phenylboronic acid (PBA)‐conjugated sodium alginate (SAPBA) for photothermal therapy (PTT)‐triggered in situ vaccination to inhibit post‐surgical recurrence and metastasis of malignant tumors. The gelation of SAPBA/ZMC/ICG in the residual tumors can achieve accurate local PTT and the local sustained release of CDN and Mn2+ with minimal detrimental off‐target toxic effects. Furthermore, CDN, which is an agonist of the stimulator of interferon genes (STING), along with Mn2+ can activate the STING pathway and trigger type‐I‐IFN‐driven immune responses against tumors. Therefore, the immunotherapeutic hydrogel with enhanced immune response by STING agonist and PTT‐induced immunogenic cell death (ICD) reprograms the post‐surgical immunosuppressive microenvironment, substantially decreasing the post‐surgical recurrence and metastasis of solid tumors in multiple murine tumor models when administered during surgical resection. Taken together, PTT‐triggered and STING‐mediated in situ cancer vaccination is an effective therapeutic intervention for post‐surgical recurrence and metastasis of tumors.

Self-delivery photodynamic-hypoxia alleviating nanomedicine synergizes with anti-PD-L1 for cancer immunotherapy

The low level of T-lymphocyte infiltration in tumor is a key issue in cancer immunotherapy. Stimulating anti-tumor immune responses and improving the tumor microenvironment are essential for enhancing anti-PD-L1 immunotherapy. Herein, atovaquone (ATO), protoporphyrin IX (PpIX), and stabilizer (ATO/PpIX NPs) were constructed to self-assemble with hydrophobic interaction and passively targeted to tumor for the first time. The studies have indicated that PpIX-mediated photodynamic induction of immunogenic cell death combined with relieving tumor hypoxia by ATO, leading to maturation of dendritic cells, polarization of M2-type tumor-associated macrophages (TAMs) towards M1-type TAMs, infiltration of cytotoxic T lymphocytes, reduction of regulatory T cells, release of pro-inflammatory cytokines, resulting in an effective anti-tumor immune response synergized with anti-PD-L1 against primary tumor and pulmonary metastasis. Taken together, the combined nanoplatform may be a promising strategy to enhance cancer immunotherapy.

Molecular Engineering of NIR-II/IIb Emitting AIEgen for Multimodal Imaging-Guided Photo-Immunotherapy.

In view of the great challenges related to the complexity and heterogeneity of tumors, efficient combination therapy is an ideal strategy for eliminating primary tumors and inhibiting distant tumors. A novel aggregation-induced emission (AIE) phototherapeutic agent called T-TBBTD is developed, which features a donor-acceptor-donor (D-A-D) structure, enhanced twisted molecule conformation, and prolonged second near-infrared window (NIR-II) emission. The multimodal imaging function of the molecule has significance for its treatment time window and excellent photothermal/photodynamic performance for multimode therapy. The precise molecular structure and versatility provide prospects for molecular therapy for anti-tumor applications. Fluorescence imaging in the NIR-II window offers advantages with enhanced spatial resolution, temporal resolution, and penetration depth. The prepared AIE@R837 NPs also have controllable performance for antitumor photo-immunotherapy. Following local photo-irradiation, AIE@R837 NPs generate abundant heat, and 1 O2 directly kills tumor cells, induces immunogenic cell death (ICD) as a photo-therapeutic effect, and releases R837, which enhances the synergistic effect of antigen presentation and contributes to the long-lasting protective antitumor immunity. A bilateral 4T1 tumor model revealed that this photo-immunotherapy can eliminate primary tumors. More importantly, it has a significant inhibitory effect on distant tumor growth. Therefore, this method can provide a new strategy for tumor therapy.

Harnessing the Immunological Effects of Radiation to Improve Immunotherapies in Cancer.

Ionizing radiation (IR) is used to treat 50% of cancers. While the cytotoxic effects related to DNA damage with IR have been known since the early 20th century, the role of the immune system in the treatment response is still yet to be fully determined. IR can induce immunogenic cell death (ICD), which activates innate and adaptive immunity against the cancer. It has also been widely reported that an intact immune system is essential to IR efficacy. However, this response is typically transient, and wound healing processes also become upregulated, dampening early immunological efforts to overcome the disease. This immune suppression involves many complex cellular and molecular mechanisms that ultimately result in the generation of radioresistance in many cases. Understanding the mechanisms behind these responses is challenging as the effects are extensive and often occur simultaneously within the tumor. Here, we describe the effects of IR on the immune landscape of tumors. ICD, along with myeloid and lymphoid responses to IR, are discussed, with the hope of shedding light on the complex immune stimulatory and immunosuppressive responses involved with this cornerstone cancer treatment. Leveraging these immunological effects can provide a platform for improving immunotherapy efficacy in the future.

Nanodrug Inducing Autophagy Inhibition and Mitochondria Dysfunction for Potentiating Tumor Photo-Immunotherapy.

Anticancer immunotherapy is hampered by the poor tumor immunogenicity and immunosuppressive tumor microenvironment (TME). Herein, a liposome nanodrug co-encapsulating doxycycline hydrochloride (Doxy) and chlorin e6 (Ce6) to simultaneously induce autophagy inhibition and mitochondria dysfunction for potentiating tumor photo-immunotherapy is developed. Under near infrared laser irradiation, Ce6 generates cytotoxic reactive oxygen species (ROS) and elicits robust photodynamic therapy (PDT)-induced immunogenic cell death (ICD) for immunosuppressive TME remodeling. In addition, Doxy induced mitochondria dysfunction, which increases ROS generation and enhances PDT to exert more potent killing effect and more powerful ICD. Meanwhile, Doxy increases MHC-I expression on tumor cells surface by efficient autophagy inhibition, leading to more efficient antigen presentation and CTLs recognition to increase tumor immunogenicity. The nanodrugs elicit remarkable antitumor therapy by combining Ce6-mediated PDT and Doxy-induced autophagy inhibition and mitochondria dysfunction. The developed nanodrugs represent a highly efficient strategy for improving cancer immunotherapy.

Doxorubicin Detoxification in Healthy Organs Improves Tolerability to High Drug Doses for Enhanced Antitumor Therapy.

With its well-documented toxicity, the use of doxorubicin (Dox) for cancer treatment requires trade-offs between safety and effectiveness. This limited use of Dox also hinders its functionality as an immunogenic cell death inducer, thus impeding its usefulness for immunotherapeutic applications. Here, we develop a biomimetic pseudonucleus nanoparticle (BPN-KP) by enclosing GC-rich DNA within erythrocyte membrane modified with a peptide to selectively target healthy tissue. By localizing treatment to organs susceptible to Dox-mediated toxicity, BPN-KP acts as a decoy that prevents the drug from intercalating into the nuclei of healthy cells. This results in significantly increased tolerance to Dox, thereby enabling the delivery of high drug doses into tumor tissue without detectable toxicity. By lessening the leukodepletive effects normally associated with chemotherapy, dramatic immune activation within the tumor microenvironment was also observed after treatment. In three different murine tumor models, high-dose Dox with BPN-KP pretreatment resulted in significantly prolonged survival, particularly when combined with immune checkpoint blockade therapy. Overall, this study demonstrates how targeted detoxification using biomimetic nanotechnology can help to unlock the full potential of traditional chemotherapeutics.

Abstract 4892: MMAE drives immunomodulatory changes in a preclinical xenograft model that are distinct from other clinical-stage ADC payloads

Abstract Monomethyl auristatin E (MMAE), the payload delivered by vedotin ADCs, exerts its cytotoxic effects via microtubule disruption and induction of ER stress, leading to apoptosis and tumor cell death. In addition, MMAE also has the ability to induce immunogenic cell death (ICD) and immune modulation in the tumor microenvironment (TME) (Liu, 2020; Gray, 2020). Other clinical-stage and approved ADCs incorporate payloads that also cause microtubule disruption (DM1, DM4), or that drive DNA damage through topoisomerase I inhibition (exatecan) as the primary mechanism of action (MOA). While ADCs with different linker payloads produce clinical benefit, their long-term impact on survival and how they pair with PD(L)1 agents may differ based on their ability to elicit immune modulation. In this study we have investigated how these payloads compare to MMAE in their ability to drive immune changes in the TME and describe how these changes could support anti-tumor immunity and improve outcomes in the clinic.Building upon an initial in vitro assessment in which we observed superior induction of ICD markers and underlying ER stress with an MMAE ADC, we utilized a B7H4-expressing MDA-MB-468 xenograft model of triple-negative breast cancer to further characterize the ICD properties of ADC payloads. Tumor-bearing mice were treated with a single dose of B7H4-targeted antibody conjugated to either MMAE, DM1, DM4 or exatecan. Tumors were harvested seven days after treatment and processed for immunohistochemistry (IHC) to assess changes in immune cell infiltration and analyzed by RNA-seq to determine alterations in gene expression. Payload-driven anti-tumor activity was observed with all ADC treatments, each leading to a similar reduction in tumor volume compared to vehicle or unconjugated antibody. IHC staining of tumor sections for F4/80, a mouse macrophage marker, revealed that of the microtubule-disrupting agents, only MMAE significantly increased F4/80+ macrophage infiltration in both the tumor nests and stroma. Increased F4/80+ macrophages in tumor nests and stroma was also observed as a result of B7H4-exatecan ADC treatment. RNA-seq analysis revealed a unique profile for the MMAE conjugate, with an increase in human transcripts encoding cytokine and type I interferon response genes. In summary, the anti-tumor activity of the B7H4-MMAE ADC resulted in recruitment of mouse innate immune cells to the xenograft tumors. Importantly, immune response genes related to ICD were increased following B7H4-MMAE treatment compared to DM1, DM4, and exatecan conjugates. Together, these data suggest that treatment with vedotin ADCs results in robust immunomodulatory changes in vivo that are distinct from other clinical ADC payloads. Citation Format: Michelle Ulrich, Kerry Klussman, John J. Gosink, Sean Allred, Kelly Hensley, Piper M. Treuting, Nikhil J. Parekh, Elizabeth E. Gray, Shyra J. Gardai. MMAE drives immunomodulatory changes in a preclinical xenograft model that are distinct from other clinical-stage ADC payloads. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4892.

Abstract 5946: OBI-999, an anti-Globo H antibody drug conjugate, exhibits synergistic anti-tumor effect in combination with pembrolizumab

Abstract Background: Globo H (GH) is highly expressed in a variety of epithelial tumors with a limited expression in normal tissues rendering it a novel therapeutic target. OBI-999 is an antibody drug conjugate (ADC) consisting of a GH-specific monoclonal antibody conjugated with monomethyl auristatin E (MMAE) through a cathepsin B cleavable linker. MMAE is known to induce immunogenic cell death (ICD) which involves in the activation of cytotoxic T lymphocyte-driven adaptive immunity with long-term immunological memory. Aim: The aim of this study was to evaluate the synergistic effects of OBI-999 + pembrolizumab on tumor growth suppression in several xenograft tumor models. Methods: OBI-999-induced ICD was examined in vitro by the detection of damaging-associated molecular patterns (DAMPs) such as calreticulin (CRT), HMGB1, and ATP in incubated Globo H expressing cells. The synergistic effects with the combination of OBI-999 and pembrolizumab as well as the ICD-related immunity were assessed in vivo using advanced severe immunodeficient mice that were reconstituted with human peripheral blood mononuclear cells (PBMCs). Results: Incubation of OBI-999 with high GH expression cancer cell lines (HCC-1428, NCI-N87 and NCI-H526) and mid GH expression cancer cell line (SW-480) induced the release of DAMPs including CRT, HMGB1, and ATP, in a dose- and time-dependent manner, indicating that OBI-999 is capable of inducing ICD in vitro. In the high GH expression human breast cancer cell line HCC-1428 xenograft model, OBI-999+pembrolizumab exhibited significantly stronger inhibition of tumor growth compared to either OBI-999 or pembrolizumab alone. Similar synergistic effects were observed in other xenograft tumor models including gastric (NCI-N87), small cell lung (NCI-H526), and colorectal (SW-480) cancers. Analysis of tumor-infiltrating lymphocytes (TILs) in HCC-1428 humanized mice showed that OBI-999 + pembrolizumab induced populations of activated cytotoxic CD8 T-cells and mature dendritic cells. Pembrolizumab decreased PD-1 expression on CD8 and CD4 cells, and OBI-999 decreased PD-L1 expression on tumor cells, which reversed the exhausted status of immune cells and alleviated immunosuppression in the tumor microenvironment. Conclusion: We demonstrated significant synergistic effects of OBI-999 and pembrolizumab in several animal models. These synergistic effects may be attributed to the ability of OBI-999 to induce ICD, as demonstrated by the release of DAMPs in vitro and tumor-specific immunity in vivo, suggesting that OBI-999 can create a tumor microenvironment that enhances the function of pembrolizumab. The results suggest that combination therapy with OBI-999 and immune checkpoint inhibitors is warranted in human clinical studies. OBI-999 is currently in Phase 1/2 clinical trials for the treatment of advanced solid tumors with high GH expression (NCT04084366). Citation Format: Chun-Chung Wang, Chi-Huan Lu, Jhih-Jie Yang, Wan-Fen Li, Ming-Tain Lai. OBI-999, an anti-Globo H antibody drug conjugate, exhibits synergistic anti-tumor effect in combination with pembrolizumab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5946.

Abstract 4894: The anti-ROR1 ADC STRO-003 demonstrates immune-modulating properties that may enhance checkpoint blockade

Abstract There is growing evidence that tumor-targeted cytotoxins can also enhance anti-tumor immunity by inducing immunogenic cell death (ICD) in tumor cells and promoting recruitment of immune effector cells. We sought to investigate the immune stimulating potential of STRO-003, an antibody drug conjugate (ADC) composed of an anti-Receptor Orphan Receptor Kinase 1 (ROR1) antibody conjugated to a topoisomerase I targeted exatecan warhead via a cleavable linker. ROR1 is an oncofetal transmembrane receptor with restricted expression in normal tissues. Its overexpression in several cancer indications has been described, including in ovarian, non-small cell lung carcinoma (NSCLC), triple negative breast cancer (TNBC), and hematological malignancies, thus making it an ideal ADC target. We have previously demonstrated potent in vivo activity of STRO-003 in a panel of ROR1-expressing lung cancer patient-derived xenograft (PDX) models. Here we show that the exatecan warhead, SC3386, and STRO-003 ADC induced ICD in vitro as evidenced by presentation of cell-surface calreticulin and release of HMGB1. Consistent with this finding, STRO-003-treated cells elicited monocyte activation in a PBMC co-culture assay. To determine if these immunogenic properties could improve therapeutic efficacy, we evaluated STRO-003 in combination with an immune checkpoint inhibitor in a mouse syngeneic model expressing ROR1. We have demonstrated that STRO-003 in combination with checkpoint inhibition significantly enhances efficacy in a syngeneic mouse model and supports durable anti-tumor immunity. Follow-up vaccination studies were performed to further explore the significance of STRO-003-induced ICD and protective immunity in vivo. These results demonstrate that tumor cells pre-treated with STRO-003 or SC3386 undergo potent immunogenic cell damage which can, in turn, mount protective immunity in vivo. Citation Format: Alice Yam, Helena Kiefel, Andrew McGeehan, Robert Yuan, Sihong Zhou, Dayson Moreira, Indrani Dutta, Xiaofan Li, Cuong Tran, Gang Yin, Kristin Bedard, Trevor Hallam. The anti-ROR1 ADC STRO-003 demonstrates immune-modulating properties that may enhance checkpoint blockade. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4894.

Abstract 2259: Novel metallotherapeutic BOLD-100 induces circulating cytokine changes when administered in combination with FOLFOX in advanced gastrointestinal cancer patients

Abstract Proven metallotherapeutics, such as cisplatin and oxaliplatin, alter immune responses as part of their multimodal mechanisms-of-action. These immune responses can drive efficacy in specific patient populations and/or in combination with other oncology drugs. BOLD-100, currently in a multinational Phase 2 trial, is a first-in-class metallotherapeutic that (1) alters the unfolded protein response (UPR) through selective GRP78 inhibition, and (2) induces reactive oxygen species (ROS), leading to DNA damage and cell cycle arrest. Collectively, these pathways result in cell death in both sensitive and resistant cancers, giving BOLD-100 the potential to significantly improve outcomes in a wide range of both solid and liquid tumors in combination with other anticancer therapies. BOLD-100 can also alter immune responses, including through induction of immunogenic cell death, but these responses have not been investigated in a clinical population. A recently completed Phase 1b trial investigating BOLD-100 in combination with FOLFOX demonstrated a 3X improvement in progression-free survival (PFS) in 3rd line or later metastatic colorectal cancer patients compared to existing therapies, with a favorable safety profile. In this Phase 1b study, BOLD-100 was administered via IV infusion for 60-90 minutes immediately prior to FOLFOX on a 2-week cycle. To investigate the pharmacodynamics of immune markers, plasma samples were collected at baseline and 1, 6, 24, and 48 hours after initiation of BOLD-100 plus FOLFOX treatment for each of the first 4 cycles, and then at baseline for all subsequent cycles. In 326 samples collected from 15 patients, 48 cytokines were measured via multiplex. Multiple cytokines showed short-term (1 to 48 hours) transient increases in plasma concentration levels, including IL-10, IL-27, G-CSF, MIP-1β, IP-10, IL-2, IL-18 and TNFα. IL-10, a cytokine previously investigated as an anticancer therapeutic, increased significantly by 1 hour (6.7X increase) and by 6 hours (84.5X increase) after treatment, before reverting to baseline levels by 48 hours. Despite large acute increases in specific cytokines, no changes to baseline levels over multiple treatment cycles were observed. Correlation analysis showed that baseline MCP-1 and MIP-1α levels were negatively correlated with overall survival; and the maximum change in concentration over the first dosage cycle of RANTES, IL-17F, Eotaxin, TGFα and MDC were positively correlated with overall survival. These results show that BOLD-100 in combination with FOLFOX can induce immune responses, and that these immune responses may predict clinical outcome. Analysis of additional patient samples from the Phase 2 trial is ongoing. Citation Format: Mark Bazett, Brian Park, E Russell McAllister, Jim Pankovich. Novel metallotherapeutic BOLD-100 induces circulating cytokine changes when administered in combination with FOLFOX in advanced gastrointestinal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2259.

Abstract 4883: Pan cancer transcriptomic response to tumor treating fields (TTFields)

Abstract Introduction: Tumor Treating Fields (TTFields) are electric fields that disrupt cellular processes critical for cancer cell viability and tumor progression, ultimately leading to cell death. TTFields therapy is versatile with multiple mechanisms of action, including: anti-mitotic effects, downregulation of DNA double strand break repair, generation of replication stress, upregulation of autophagy, and induction of immunogenic cell death. In this research we were interested in identifying common responses to TTFields across cancer types. We addressed this by integrating whole transcriptome analyses of cancers from various origins. Methods: Control and TTFields-treated samples examined included gastric, ovarian, pancreatic, non-small cell lung carcinoma, and glioblastoma cell lines, pleural mesothelioma patient-derived cell lines, and a hepatocellular carcinoma animal model. A list of differentially expressed genes (DEGs) was generated from transcriptomics analysis. Gene Set Enrichment Analysis (GSEA) was conducted with the MSigDB, and additional pathway databases. Significantly overlapping pathways were identified using ActivePathways package, and an enrichment map was created according to the number of datasets supporting each pathway. Results: The response to TTFields showed a positive correlation of expression across different cell lines and indications, including in an animal model. Downregulation was seen in cell cycle related pathways - E2F targets, Myc targets, G2M checkpoint, and mitotic spindle - indicative of cell cycle arrest, which was mediated by increased expression of tumor suppressors. Several DNA repair pathways were downregulated, including nucleotide excision repair, base excision repair, and the Fanconi Anemia-BRCA pathway. Downregulation was also evident in nuclear envelope, DNA and RNA synthesis, metabolism of amino acids, translation, organelle organization, and splicing. Upregulation was observed in genes associated with the cytoskeleton, adhesion, extracellular proteins and transporters. In the majority of comparisons, an upregulation in the immune response was also observed. Conclusions: Transcriptomic analysis of datasets from different tumor types revealed common expression patterns and pathways involved in the responses to TTFields. Some of the identified pathways corroborate previously described mechanisms, whereas some reveal new potential mechanisms that require further investigation. Citation Format: Kerem Wainer-Katsir, Gitit Lavy-Shahaf, Hila Fishman, Hila Ena, Roni Frechtel-Gerzi, Antonia Martinez-Conde, Eyal Dor-On, Shiri Davidi, Sara Jacobovitch, Itai Tzchori, Yaara Porat, Lianghao Ding, Michael Story, Renfei Du, Ulf Kahlert, Laura Mannarino, Federica Mirimao, Monica Lupi, Maurizio D’Incalci, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. Pan cancer transcriptomic response to tumor treating fields (TTFields). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4883.

Abstract 3228: Photodynamic priming enhances immunotherapy responses overcoming oncogenic drivers in pancreatic patient derived tumor organoids

Abstract Photodynamic therapy (PDT) is an anti-cancer therapy that utilizes light, a photoresponsive photosensitizer (PS), and oxygen to confer direct cytotoxicity or vascular damage. PDT alters the tumor microenvironment (TME) transiently in a process termed photodynamic priming (PDP), making it more receptive to subsequent therapies. Previous studies reported that PDP exerts immune stimulatory effects via the release of damage associated molecular patterns (DAMPs) as a potent inducer of immunogenic cell death. Pancreatic cancer (PC) is a lethal human malignancy with no curable treatments available thus far. The desmoplastic stroma in PC limits the delivery of therapeutic agents contributing to treatment resistance. More, the stroma promotes an immunosuppressive TME that leads to immune exclusion, which is largely responsible for the immunotherapy failure in PC. Therefore, there is an unmet need to find more effective combination therapies against PC. In this work, we evaluated whether PDP enhances anti-PD1 therapy response by modulating immunogenicity in PC patient-derived organoids (PDOs). Visudyne (PS) and varied light doses of 25-100 J/cm2 were used for PDP treatments. Our data showed light dose dependent cytotoxicity and the expression of DAMPs including HSP60, calreticulin and HMGB1 in PDOs. Gene expression analysis of PDP treated PDOs showed increases in IFNγ, TNFα and CXCL12 while decreases in PDL1, TGFβ1 and FOXP1. Coculture of healthy donor (HD) monocyte-derived dendritic cells (mDCs) for 24 h with PDOs treated with a sublethal dose of PDP (25 J/cm2) showed increased CD40, CD86 and MHC11 activation markers on mDCs. Addition of matched HD naïve T cells 24 h post mDC-PDO coculture led to the excessive activation of CD4+ and CD8+ T cells highlighted by the PD1 expression on T cells from 0 h of initial T cell coculture to 48 h. This led us to treat PDO-mDC-T cell cocultures at 0 h to 48 h of initial T cell coculture with the anti-PD1 monoclonal antibody, Pembrolizumab. The treatment response was measured by live imaging of PDO growth followed by the analysis of changes in PDO diameter/area from day 0 of PDP to day 7 post-PDP. There were significant decreases in PDO growth in cultures treated with PDP followed by Pembrolizumab at different time points compared to untreated PDOs, untreated PDO-mDC-T cell cocultures, PDOs treated with PDP alone, PDO-mDC-T cell cocultures treated with PDP only or PDO-mDC-T cell cocultures treated with anti-PD1 alone. Also, we sorted T cells from the same cocultures at day 7 of PDP for gene expression analysis of T cell activation markers. There was enhanced expression of IFNγ, TNFα, FAS ligand, Granzyme B, IL2 and IL21 in T cells collected from combination therapy treated cocultures compared to others. Lastly, our data show that PDP can enhance anti-PD1 immunotherapy responses providing insights into a combination therapy option to treat PDAC. Citation Format: Pushpamali De Silva, Demi Wekking, Joanna Joeun Choe, Dario Missael Castellanos, Piotr Zelga, Russell Jenkins, Andrew Scott Liss, Tayyaba Hasan. Photodynamic priming enhances immunotherapy responses overcoming oncogenic drivers in pancreatic patient derived tumor organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3228.

Abstract 632: Exploiting pyroptosis in melanoma brain metastasis

Abstract Melanoma is the deadliest form of skin cancer due to its frequent metastasis to the brain. Melanoma brain metastases (MBM) are a significant clinical challenge, and current model systems and therapeutic strategies are poor. Inhibitors targeting the most common oncogenic driver of melanoma, BRAFV600E (BRAFi), disrupt mitogenic signaling and promote caspase-3 associated cell death. Though caspase-3 is a well-known apoptotic driver, it can also cleave Gasdermin E (GSDME) to create pore-forming N-terminal fragments that oligomerize at plasma and mitochondrial membranes and trigger pyroptosis - a form of immunogenic cell death (ICD). Our recent work illustrates the importance of GSDME mediated pyroptosis and associated immunogenicity in providing a durable therapeutic response against melanoma. Since pyroptosis can be activated by GSDME cleavage via caspase-3, and is prominent in various neuropathologies, a better understanding of the interplay between central nervous system (CNS) immune cells and BRAFi-mediated ICD is critical for designing more effective therapies against MBM. Here, we engineered a panel of inducible pyroptotic melanoma cells to model BRAFi-mediated pyroptosis. Using ex vivo CNS slice co-cultures, we found that inducible N-GSDME expression in human and murine melanoma cells drives propidium iodide uptake and release of inflammatory activators like HMGB1 and IL-1 - hallmarks of pyroptosis. Importantly, conditioned media from these pyroptotic cells stimulates a more robust phagocytic response from resident macrophages of the CNS and pyroptotic melanoma elicit stronger cytotoxicity from syngeneic CD8+ T cells, further highlighting the benefits of BRAFi-mediated ICD. Our findings provide evidence that resident CNS immune cells and peripheral T cells respond to pyroptotic melanoma, suggesting that induction of ICD should be a consideration in the development of anti-MBM therapies. Citation Format: Maria R. Cavallo. Exploiting pyroptosis in melanoma brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 632.

Induction of immunogenic cell death effect of licoricidin in cervical cancer cells by enhancing endoplasmic reticulum stress-mediated high mobility group box 1 expression.

Licoricidin (LCD) is an activity compound of the roots of Glycyrrhiza uralensis, which has therapeutic efficacy, including anti-virus, anti-cancer, and enhanced immunity in Traditional Chinese Medicine. Herein, this study aimed to clarify the effect of LCD on cervical cancer cells. In the present study, we found that LCD significantly inhibited cell viability via inducing cell apoptosis and companies with cleaved-PARP protein expression and caspase-3/-9 activity. Cell viability was markedly reversed these effects by pan-caspase inhibitor Z-VAD-FMK treatment. Furthermore, we showed that LCD-induced ER (endoplasmic reticulum) stress triggers upregulating the protein level of GRP78 (Bip), CHOP, and IRE1α, and subsequently confirmed the mRNA level by quantitative real-time polymerase chain reaction. In addition, LCD exhibited the release of danger-associated molecular patterns from cervical cancer cells, such as the release of high-mobility group box 1 (HMGB1), secretion of ATP, and exposure of calreticulin (CRT) on the cell surface, which led to immunogenic cell death (ICD). These results provide a novel foundation that LCD induces ICD via triggering ER stress in human cervical cancer cells. LCD might be an ICD inducer of immunotherapy in progressive cervical cancer.

Abstract 2013: Oxidized anthracycline payloads induce anti-tumor immunogenic cell-death and show linker-dependent tolerability when delivered as ADCs

Abstract Novel payloads with orthogonal mechanisms of action (MOAs) to established ADC technologies are important for expanding the utility of antibody-drug conjugates (ADCs) in cancer treatment. Anthracyclines, a class of cytotoxic small molecules that include important clinical chemotherapeutics such as doxorubicin, have long been of interest to the ADC field due to their high potency and unique MOA. Interest in anthracyclines has increased in recent years due to their status as canonical inducers of immunogenic-cell death (ICD), a feature that may lead to more durable tumor regressions and increased synergy with immune checkpoint blockade. In this work, we investigate several drug-linkers based on oxidized derivatives of the highly potent anthracycline analogue PNU-159682. Resultant ADCs are potent and immunologically specific with linker-dependent bystander activity in co-culture cytotoxicity assays displaying heterogeneous antigen (Ag+/Ag-) expression. Rodent in vivo anti-tumor activity and tolerability are shown with significant differences emerging between the toxicity profile of the cleavable and non-cleavable analogues. In vitro, tumor cells treated with anthracycline ADCs showed key hallmarks of ICD including markers of endoplasmic reticulum (ER) stress and the induction of ICD damage-associated molecular patterns (DAMPs) such as HMGB1 and ATP. In vivo mouse xenograft studies show increased tumoral F4/80+ macrophage infiltration by IHC in anthracycline ADC treated animals relative to controls. ADCs delivering monomethyl auristatin E (MMAE) show comparable activity in ICD assays, confirming MMAE as an ICD inducing ADC payload alongside canonical inducers such as anthracyclines. Our results indicate there is a therapeutic window in rodents alongside ICD induction by anthracycline ADCs, positioning anthracyclines as a potentially impactful class of ADC payloads. Citation Format: Joseph Z. Hamilton, Kerry Klussman, Rebecca Mahzereh, Jessica Simmons, Michelle Ulrich, Shyra J. Gardai, Peter D. Senter, Patrick J. Burke. Oxidized anthracycline payloads induce anti-tumor immunogenic cell-death and show linker-dependent tolerability when delivered as ADCs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2013.

A Hierarchical Structured Fiber Device Remodeling the Acidic Tumor Microenvironment for Enhanced Cancer Immunotherapy.

The acidic microenvironment of tumors significantly reduces the anti-tumor effect of immunotherapy. Herein, a hierarchically structured fiber device is developed as a local drug delivery system for remodeling the acidic tumor microenvironment (TME) to improve the therapeutic effect of immunotherapy. Proton pump inhibitors in the fiber matrix can be sustainedly released to inhibit the efflux of intracellular H+ from tumor cells, resulting in the remodeling of the acidic TME. The targeted micelles and M1 macrophage membrane-coated nanoparticles in internal cavities of fiber can induce immunogenic cell death (ICD) of tumor cells and phenotypic transformation of tumor-associated macrophages (TAMs), respectively. The relief of the acidity in the TME further promotes ICD and the polarization of TAMs, alleviating the immunosuppressive microenvironment and synergistically enhancing the antitumor immune response. In vivo results reveal this local drug delivery system restores the pH value of TME from 6.8 to 7.2 and exhibit an excellent immunotherapeutic effect.