Hallmarks Of Immunogenic Cell Death Research Articles

Optimizing high-intensity focused ultrasound-induced immunogenic cell-death using passive cavitation mapping as a monitoring tool

Over the past decade, ultrasound (US) has gathered significant attention and research focus in the realm of medical treatments, particularly within the domain of anti-cancer therapies. This growing interest can be attributed to its non-invasive nature, precision in delivery, availability, and safety. While the conventional objective of US-based treatments to treat breast, prostate, and liver cancer is the ablation of target tissues, the introduction of the concept of immunogenic cell death (ICD) has made clear that inducing cell death can take different non-binary pathways through the activation of the patient's anti-tumor immunity. Here, we investigate high-intensity focused ultrasound (HIFU) to induce ICD by unraveling the underlying physical phenomena and resulting biological effects associated with HIFU therapy using an automated and fully controlled experimental setup. Our in-vitro approach enables the treatment of adherent cancer cells (B16F10 and CT26), analysis for ICD hallmarks and allows to monitor and characterize in real time the US-induced cavitation activity through passive cavitation detection (PCD). We demonstrate HIFU-induced cell death, CRT exposure, HMGB1 secretion and antigen release. This approach holds great promise in advancing our understanding of the therapeutic potential of HIFU for anti-cancer strategies.

Natural compound Alternol actives multiple endoplasmic reticulum stress-responding pathways contributing to cell death.

Background: Alternol is a small molecular compound isolated from the fermentation of a mutant fungus obtained from Taxus brevifolia bark. Our previous studies showed that Alternol treatment induced reactive oxygen species (ROS)-dependent immunogenic cell death. This study conducted a comprehensive investigation to explore the mechanisms involved in Alternol-induced immunogenic cell death. Methods: Prostate cancer PC-3, C4-2, and 22RV1 were used in this study. Alternol interaction with heat shock proteins (HSP) was determined using CETSA assay. Alternol-regulated ER stress proteins were assessed with Western blot assay. Extracellular adenosine triphosphate (ATP) was measured using ATPlite Luminescence Assay System. Results: Our results showed that Alternol interacted with multiple cellular chaperone proteins and increased their expression levels, including endoplasmic reticulum (ER) chaperone hypoxia up-regulated 1 (HYOU1) and heat shock protein 90 alpha family class B member 1 (HSP90AB1), as well as cytosolic chaperone heat shock protein family A member 8 (HSPA8). These data represented a potential cause of unfolded protein response (UPR) after Alternol treatment. Further investigation revealed that Alternol treatment triggered ROS-dependent (ER) stress responses via R-like ER kinase (PERK), inositol-requiring enzyme 1α (IRE1α). The double-stranded RNA-dependent protein kinase (PKR) but not activating transcription factor 6 (ATF6) cascades, leading to ATF-3/ATF-4 activation, C/EBP-homologous protein (CHOP) overexpression, and X-box binding protein XBP1 splicing induction. In addition, inhibition of these ER stress responses cascades blunted Alternol-induced extracellular adenosine triphosphate (ATP) release, one of the classical hallmarks of immunogenic cell death. Conclusion: Taken together, our data demonstrate that Alternol treatment triggered multiple ER stress cascades, leading to immunogenic cell death.

Disulfiram/Copper Activates ER Stress to Promote Immunogenic Cell Death of Oral Squamous Cell Carcinoma.

Disulfiram/copper complex (DSF/Cu) was found to have anti-tumor effects in a range of malignancies, including oral squamous cell carcinoma (OSCC), yet its precise mechanism remains unknown. It has been shown that ER stress enhances immunogenic cell death (ICD) in tumor cells, as it can influence the anti-cancer immune system favorably. In this study, we reported that DSF/Cu exhibited a marked inhibitory effect on the growth of OSCC cells, accompanied by cell apoptosis. OSCC cells treated with DSF/Cu showed the hallmarks of immunogenic cell death (ICD), including surface expression of calreticulin (CRT), heat shock protein 70 (HSP70), high mobility-group box 1 (HMGB-1) and adenosine triphosphate (ATP), thus, eliciting the maturation and activation of dendritic cells. Furthermore, we showed DSF/Cu-induced endoplasmic reticulum (ER) stress in OSCC cells. In vivo, results demonstrate that DSF/Cu inhibits tumor growth locally and alters the intratumoral immune cell infiltration and response. In conclusion, DSF/Cu suppresses OSCC development by inducing ICD and ER stress. DSF/Cu has the potential to be a new anti-tumor immunotherapy concept because of its ability to elicit ICD.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot.

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Abstract 7144: BR0L075 (SCB01A), a microtubule inhibitor targeting the colchicine binding site, induces immunogenic cell death

Abstract BPR0L075 (also known as SCB01A in phase II clinical trial) is a novel anti-microtubule drug with potent anti-tumor and anti-angiogenic activity in vitro and in vivo. BPR0L075 inhibits tubulin polymerization (microtubule de-stabilizer) by binding to the colchicine-binding site of tubulin. We previously reported that BPR0L075 overcomes paclitaxel (microtubule stabilizer) resistance and induces vascular-disruption in vitro and in vivo. We observed that breast and ovarian cancer cells treated with BPR0L075 in vitro induced key hallmarks of immunogenic cell death (ICD). In both human and murine, ovarian (OVCAR3, ID8) and breast cancer (MDA-MB-231, 4T1) cell lines, treatment with low nanomolar concentration of BPR0L075 significantly decreased the viability of cells evidenced by SRB assay. Using a known ICD inducer mitoxantrone as a positive control, both flow cytometric analysis and immunofluorescence staining assays demonstrated that BPR0L075 treatment led to a time- and dose-dependent translocation of calreticulin, an endoplasmic reticulum chaperone protein, on the plasma membrane of dying cells which sends an “eat me” signal. The BPR0L75 treatment also led to secretion of High Mobility Group Box 1 (HMGB1), a non-histone chromatin-binding nuclear protein, as well as adenosine triphosphate (ATP) from the cell into the extracellular space using ELISA assay. These damage-associated molecular patterns (DAMPs) are known to lead to antigen-presenting cell recruitment, phagocytosis, maturation of dendritic cells, and chemotaxis. The appearance of the ICD biomarkers (calreticulin exposure, HMGB1 and ATP release) supports BPR0L075 as an ICD-inducing antimitotic agent. Further in vivo studies are warranted to delineate the effect of BPR0L075 on immune activation and recruitment of immune cells to the tumor microenvironment. Citation Format: Ayesha Bano, Xinli Liu. BR0L075 (SCB01A), a microtubule inhibitor targeting the colchicine binding site, induces immunogenic cell death [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 7144.

Abstract C115: Preclinical characterization of STRO-002, a clinical-stage anti-FolRα antibody-drug conjugate

Abstract STRO-002 is a novel folate receptor alpha (FolRα)-targeting antibody-drug conjugate (ADC) currently undergoing evaluation in clinical trials at various phases of development in ovarian and endometrial cancer and pediatric AML. Here, we describe the favorable properties of the STRO-002 ADC and summarize its activity in preclinical models. STRO-002 is an ADC composed of an anti-FolRα antibody conjugated to four tubulin-targeting hemiasterlin warheads. Incorporation of non-natural amino acids, using Sutro’s XpressCF® and XpressCF+® cell-free expression and conjugation systems, allows for site-specific conjugation of the hemiasterlin payload, yielding a homogenous and high-fidelity ADC. As an ADC, STRO-002 internalizes rapidly into FolRα+ tumor cells and exhibits potent target-dependent cell killing on xenograft tumor cell lines. Further characterization of STRO-002 and the hemiasterlin payload reveals significant ADC bystander activity and a lower sensitivity to drug efflux via the P-gp drug pump compared to other microtubule-targeting warheads. In addition to robust direct and bystander cell killing, STRO-002 is also capable of triggering immunogenic cell death (ICD). In in vitro cell killing assays, STRO-002 induces all three hallmarks of ICD—HMGB1 and ATP release and surface exposure of calreticulin—and in in vivo vaccination studies, injection of STRO-002-killed tumor cells was effective at establishing a protective immune response against subsequent tumor challenge, identifying STRO-002 as a bonafide ICD inducer.In vivo, STRO-002 treatment demonstrates robust efficacy in ovarian xenograft models, even when treatment is initiated in large, established tumors. In addition, combination therapy with STRO-002 and carboplatin, anti-VEGF, or anti-PD-L1 results in greater efficacy than treatment with single agents alone, demonstrating combination benefit with current standard-of-care therapies. To better understand the activity of STRO-002 in more-translatable preclinical models, we turned to patient-derived xenografts (PDX) and found that STRO-002 exhibits good anti-tumor activity in endometrial cancer and non-small cell lung cancer PDX studies, suggesting potential clinical benefit in these indications. In conclusion, STRO-002 exhibits multiple advantageous properties as an ADC and shows good anti-tumor activity, either in combination or as a single agent, in both cell-derived xenograft and PDX models. Citation Format: Robert Yuan, Andrew McGeehan, Sihong Zhou, Jennifer Smith, Dayson Moreira, Krishna Bajjuri, Cuong Tran, Gang Yin, Alice Yam, Helena Kiefel, Xiaofan Li. Preclinical characterization of STRO-002, a clinical-stage anti-FolRα antibody-drug conjugate [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C115.

Brentuximab Vedotin-Driven Microtubule Disruption Results in Endoplasmic Reticulum Stress Leading to Immunogenic Cell Death and Antitumor Immunity.

Brentuximab vedotin, a CD30-directed antibody-drug conjugate (ADC), is approved for clinical use in multiple CD30-expressing lymphomas. The cytotoxic payload component of brentuximab vedotin is monomethyl auristatin E (MMAE), a highly potent microtubule-disrupting agent. Preclinical results provided here demonstrate that treatment of cancer cells with brentuximab vedotin or free MMAE leads to a catastrophic disruption of the microtubule network eliciting a robust endoplasmic reticulum (ER) stress response that culminates in the induction of the classic hallmarks of immunogenic cell death (ICD). In accordance with the induction of ICD, brentuximab vedotin-killed lymphoma cells drove innate immune cell activation in vitro and in vivo. In the "gold-standard" test of ICD, vaccination of mice with brentuximab vedotin or free MMAE-killed tumor cells protected animals from tumor rechallenge; in addition, T cells transferred from previously vaccinated animals slowed tumor growth in immunodeficient mice. Immunity acquired from killed tumor cell vaccination was further amplified by the addition of PD-1 blockade. In a humanized model of CD30+ B-cell tumors, treatment with brentuximab vedotin drove the expansion and recruitment of autologous Epstein-Barr virus-reactive CD8+ T cells potentiating the activity of anti-PD-1 therapy. Together, these data support the ability of brentuximab vedotin and MMAE to drive ICD in tumor cells resulting in the activation of antigen-presenting cells and augmented T-cell immunity. These data provide a strong rationale for the clinical combination of brentuximab vedotin and other MMAE-based ADCs with checkpoint inhibitors.

Aspirin induces immunogenic cell death and enhances cancer immunotherapy in colorectal cancer.

The use of aspirin is associated with reduced incidence of colorectal cancer (CRC). However, the detailed mechanism remains unclear. In this study, we reported that colon cancer cells treated with aspirin showed the hallmarks of immunogenic cell death (ICD), including surface expression of calreticulin (CRT) and heat shock protein 70 (HSP70). Mechanistically, aspirin induced endoplasmic reticulum (ER) stress in colon cancer cells. In addition, aspirin decreased the expression of the glucose transporters, GLUT3, and reduced the key enzyme of glycolysis, including HK2, PFKM, PKM2 and LDHA. The changes of tumor glycolysis after aspirin treatment were associated with c-MYC downregulation. Moreover, aspirin potentiated the antitumor efficacy of anti-PD-1 antibody and anti-CTLA-4 antibody in CT26 tumors. However, this antitumor activity of aspirin in combination with anti-PD-1 antibody was abolished by the depletion of CD8+ T cells. Vaccination with tumor antigens is one of the strategies for activating T-cell response against tumors. Here, we demonstrated that aspirin-treated tumor cells in combination with tumor antigens (AH1 peptide) or protective substituted peptide (A5 peptide) could be served as a potent vaccine to eradicate tumors. Overall, our data indicated that aspirin can be used as an inducer of ICD for CRC therapy.

A Half-sandwich Ru(II) (N^N) Complex: Inducing Immunogenic Cell Death of Melanoma In vitro and In vivo.

Efficacy of clinical chemotherapeutic agents depends not only on direct cytostatic and cytotoxic effects but also involves in eliciting (re)activation of tumour immune effects. One way to provoke long-lasting antitumour immunity is coined as immunogenic cell death (ICD). Although metal-based antitumour complexes hold promise as potential chemotherapeutic agents, ruthenium (Ru)-based ICD inducers remain sparse. Herein, we report a half-sandwich complex Ru(Ⅱ) bearing aryl-bis(imino) acenaphthene chelating ligand with ICD inducing properties for melanoma in vitro and in vivo. Complex Ru(Ⅱ) displays strong anti-proliferative potency and potential cell migration inhibition against melanoma cell lines. Importantly, complex Ru(Ⅱ) drives the multiple biochemical hallmarks of ICD in melanoma cells. In vivo the inhibition of tumour growth in prophylactic tumour vaccination model further confirms that mice with complex Ru(Ⅱ)-treated dying cells lead to activate adaptive immune responses and anti-tumour immunity by the activation of ICD in melanoma cells. Mechanisms of action studies show that complex Ru(Ⅱ)-induced ICD could be associated with mitochondrial damage, ER stress and impairment of metabolic status in melanoma cells. We believe that the half-sandwich complex Ru(Ⅱ) as an ICD inducer in this work will help to design new half-sandwich Ru-based organometallic complexes with immunomodulatory response in melanoma treatments.

Platinum(IV) Derivatives of [Pt(1S,2S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)] with Diclofenac Ligands in the Axial Positions: A New Class of Potent Multi-action Agents Exhibiting Selectivity to Cancer Cells.

The platinum(II) complex [Pt(1S,2S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)]2+ (PtII56MeSS, 1) exhibits high potency across numerous cancer cell lines acting by a multimodal mechanism. However, 1 also displays side toxicity and in vivo activity; all details of its mechanism of action are not entirely clear. Here, we describe the synthesis and biological properties of new platinum(IV) prodrugs that combine 1 with one or two axially coordinated molecules of diclofenac (DCF), a non-steroidal anti-inflammatory cancer-selective drug. The results suggest that these Pt(IV) complexes exhibit mechanisms of action typical for Pt(II) complex 1 and DCF, simultaneously. The presence of DCF ligand(s) in the Pt(IV) complexes promotes the antiproliferative activity and selectivity of 1 by inhibiting lactate transporters, resulting in blockage of the glycolytic process and impairment of mitochondrial potential. Additionally, the investigated Pt(IV) complexes selectively induce cell death in cancer cells, and the Pt(IV) complexes containing DCF ligands induce hallmarks of immunogenic cell death in cancer cells.

Immunogenic cell death after combined treatment with radiation and ATR inhibitors is dually regulated by apoptotic caspases.

Inhibitors of the ATR kinase act as radiosensitizers through abrogating the G2 checkpoint and reducing DNA repair. Recent studies suggest that ATR inhibitors can also increase radiation-induced antitumor immunity, but the underlying immunomodulating mechanisms remain poorly understood. Moreover, it is poorly known how such immune effects relate to different death pathways such as caspase-dependent apoptosis. Here we address whether ATR inhibition in combination with irradiation may increase the presentation of hallmark factors of immunogenic cell death (ICD), and to what extent caspase activation regulates this response. Human lung cancer and osteosarcoma cell lines (SW900, H1975, H460, U2OS) were treated with X-rays and ATR inhibitors (VE822; AZD6738) in the absence and presence of a pan-caspase inhibitor. The ICD hallmarks HMGB1 release, ATP secretion and calreticulin surface-presentation were assessed by immunoblotting of growth medium, the CellTiter-Glo assay and an optimized live-cell flow cytometry assay, respectively. To obtain accurate measurement of small differences in the calreticulin signal by flow cytometry, we included normalization to a barcoded control sample. Extracellular release of HMGB1 was increased in all the cell lines at 72 hours after the combined treatment with radiation and ATR inhibitors, relative to mock treatment or cells treated with radiation alone. The HMGB1 release correlated largely - but not strictly - with loss of plasma membrane integrity, and was suppressed by addition of the caspase inhibitor. However, one cell line showed HMGB1 release despite caspase inhibition, and in this cell line caspase inhibition induced pMLKL, a marker for necroptosis. ATP secretion occurred already at 48 hours after the co-treatment and did clearly not correlate with loss of plasma membrane integrity. Addition of pan-caspase inhibition further increased the ATP secretion. Surface-presentation of calreticulin was increased at 24-72 hours after irradiation, but not further increased by either ATR or caspase inhibition. These results show that ATR inhibition can increase the presentation of two out of three ICD hallmark factors from irradiated human cancer cells. Moreover, caspase activation distinctly affects each of the hallmark factors, and therefore likely plays a dual role in tumor immunogenicity by promoting both immunostimulatory and -suppressive effects.

Enfortumab vedotin (EV) with or without pembrolizumab (P) in patients (pts) who are cisplatin-ineligible with previously untreated locally advanced or metastatic urothelial cancer (la/mUC): Additional 3-month follow-up on cohort K data.

4568 Background: There is a high unmet need for effective and durable first-line (1L) treatment options in cisplatin-ineligible la/mUC. EV and P have shown survival benefit as monotherapies in 2L+ la/mUC, and preclinical studies demonstrate that EV induces hallmarks of immunogenic cell death, which may be further augmented by PD-1 inhibitors (e.g., P). Promising results from EV-103 dose escalation/Cohort A (DE/A) provided rationale for this randomized Cohort K for which we are disclosing additional follow-up to previous reports (Rosenberg, ESMO 2022) on efficacy and safety. Methods: Untreated cisplatin-ineligible pts with la/mUC were randomized 1:1 to EV (1.25 mg/kg, day 1, day 8) as monotherapy (EV mono) or in combination with P (200 mg, day 1) using 3-week cycles. The primary endpoint was confirmed objective response rate (cORR) per RECIST v1.1 by blinded independent central review (BICR). Secondary endpoints included duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. No formal statistical comparisons were planned between treatment arms. Results: 149 pts were treated; EV+P, n=76; EV, n=73. Median follow-up (95% CI) for EV+P, 17.6 (16.03, 20.37) months; EV+P cORR (95% CI), 64.5% (52.7, 75.1); median DOR not reached; DCR, 86.6% (77.1, 93.5); median PFS, and OS not reached. PFS rate at 6 and 12 months (95% CI), 73.8% (62.01, 82.42) and 54.5% (41.74, 65.61); OS rate at 6 and 12 months (95% CI), 88.2% (78.48, 93.65) and 81.5% (70.78, 88.61). Median follow-up (95% CI) for EV mono, 18.2 (15.90, 20.07) months; cORR (95% CI), 45.2% (33.5, 57.3); median DOR, 13.2 months (6.14, -); DCR, 79.5% (68.4, 88.0); median PFS and OS, 8.2 (6.05, 15.28) and 21.7 (15.47, -) months; PFS rate at 6 and 12 months, 64.2% (51.09, 74.69) and 40.3% (26.62, 53.60); OS rate at 6 and 12 months, 83.6% (72.87, 90.31) and 69.7% (57.68, 78.87). EV treatment-related adverse events of special interest (AESIs) include skin reactions (EV+P, 67.1%; EV mono, 45.2%), peripheral neuropathy (EV+P, 63.2%; EV mono, 54.8%), and hyperglycemia (EV+P, 14.5%; EV mono, 11.0%). In EV+P, the most frequent (any grade) P treatment-emergent adverse events of special interest were severe skin reactions (27.6%), hypothyroidism (13.2%), and pneumonitis (9.2%). Conclusions: With an additional 3 months of follow-up, EV+P continues to show a high cORR with rapid and durable responses as 1L treatment in cisplatin-ineligible pts with la/mUC, including a manageable safety profile with no new safety concerns after extended treatment exposure. DOR, PFS and OS will evolve with further follow-up and continue to trend similarly to those of DE/A; EV monotherapy was consistent with prior results. Clinical trial information: NCT03288545 .

Abstract LB246: Enfortumab vedotin, a nectin-4-directed antibody-drug conjugate, demonstrates compelling antitumor activity in non-muscle invasive bladder cancer models which predicts minimal systemic exposure when administered by intravesical instillation in patients

Abstract Enfortumab vedotin (EV) is a monomethyl auristatin E (MMAE)-containing antibody-drug conjugate directed to Nectin-4, which is highly expressed in bladder cancers. Preclinically, EV has demonstrated tumor cell killing by direct cytotoxicity and bystander effect and can induce the hallmarks of immunogenic cell death. EV improves survival in adults with previously treated locally advanced or metastatic urothelial carcinoma (la/mUC) and is approved in the US, Europe, Japan, and others. Most newly diagnosed bladder cancer cases are non-muscle invasive (NMIBC). Standard treatment of high-risk NMIBC involves transurethral resection followed by intravesical Bacillus Calmette-Guerin (BCG) or chemotherapy. Although response to BCG is high, recurrence is common, and treatment options for patients with BCG-unresponsive tumors are limited, underscoring the significant unmet need. Previously, we demonstrated compelling preclinical antitumor activity of EV in NMIBC models with a favorable safety profile and minimal systemic exposure. EV-mediated antitumor activity was confirmed in a mouse model of NMIBC by both bioluminescence imaging and IHC for hNectin-4-expressing cancer cells. Following intravesical administration of EV, tumor growth inhibition ranged 46-96% across the dose range tested. Colocalization of EV to Nectin-4-positive tumor tissues was confirmed by IHC in the engrafted tumor cells. Systemic EV exposure in tumor-bearing mice was low, consistent with previous nonclinical studies, supporting that the antitumor activity is driven by local exposure within the bladder. In a repeat-dose GLP toxicology study in rats, no systemic toxicities were observed at intravesical doses up to 6-fold higher than the maximum tolerated IV dose. This lack of systemic toxicities that can occur with IV administration in rats was likely due to minimal systemic exposure of both EV and unconjugated MMAE. Currently, the safety, tolerability, and antitumor activity of intravesical EV are being evaluated in a Phase 1 study in adults with high-risk, BCG-unresponsive NMIBC (EV-104, NCT05014139). The initial dose level for EV-104 was selected to be active and predicted to have minimal systemic absorption based on preclinical and known clinical IV data. Here, we present confirmatory clinical data demonstrating that EV and unconjugated MMAE are undetectable in the bloodstream at the starting dose. These findings confirm the translatability of our nonclinical models and provide evidence that intravesical administration of EV in NMIBC is a promising approach that limits systemic exposure. These data support the potential for a favorable safety and activity profile and warrant continued investigation of intravesical EV in patients with NMIBC. Citation Format: Devra Olson, Yen Lin Chia, Enaharo Iboi, Lauren Farr, Maddy Burcher, Anthony Lee, Kelly Hensley, Sean Allred, Abbie Wong, Masashi Shimazaki, Masamichi Mori, Sharsti Sandall, Christopher Carosino. Enfortumab vedotin, a nectin-4-directed antibody-drug conjugate, demonstrates compelling antitumor activity in non-muscle invasive bladder cancer models which predicts minimal systemic exposure when administered by intravesical instillation in patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB246.

Necrocide 1 mediates necrotic cell death and immunogenic response in human cancer cells

Many anticancer agents induce apoptosis, mitotic catastrophe or cellular senescence. Here, we report the functional characterization of an experimental inducer of tumor necrosis factor (TNF)-independent necrosis, necrocide-1 (NC1). NC1 (but not its stereoisomer) killed a panel of human cancer cells (but not normal cells) at nanomolar concentrations and with a non-apoptotic, necrotic morphotype, both in vitro and in vivo. NC1-induced killing was not inhibited by caspase blockers, anti-apoptotic BCL2 overexpression or TNFα neutralization, suggesting that NC1 elicits a bona fide necrotic pathway. However, pharmacological or genetic inhibition of necroptosis, pyroptosis and ferroptosis failed to block NC1-mediated cell death. Instead, NC1 elicited reactive oxygen species (ROS) production by mitochondria, and elimination of mitochondrial DNA, quenching of mitochondrial ROS, as well as blockade of mitochondrial permeability transition with cyclosporine A, interfered with NC1-induced cell death. NC1 induced hallmarks of immunogenic cell death incurring calreticulin (CALR) exposure, ATP secretion and high mobility group box 1 (HMGB1) release. Taken together, these data identify a previously uncharacterized signaling cascade leading to an immunogenic variant of mitochondrion-regulated necrosis, supporting the notion that eliciting regulated necrosis may constitute a valid approach for anticancer therapy.

Abstract 2633: Zanidatamab zovodotin (ZW49) induces hallmarks of immunogenic cell death and is active in patient-derived xenograft models of gastric cancer

Abstract Zanidatamab zovodotin (ZW49) is an antibody drug conjugate (ADC) comprised of a bispecific anti-HER2 IgG1 antibody (ZW25, zanidatamab) conjugated to a microtubule inhibitor auristatin payload (ZD02044) via a protease cleavable linker. Clinical studies of ZW49 in HER2-expressing advanced solid tumors are currently underway (NCT03821233). We have previously presented data illustrating the rapid internalization of ZW49 and the anti-tumor activity of ZW49 in multiple patient-derived xenograft models originating from breast carcinomas. Here we present ZW49’s ability to induce in vitro hallmarks of immunogenic cell death (ICD) including increased calreticulin exposure, increased high mobility group box-1 (HMGB1) exposure, and increased extracellular ATP secretion in a HER2 dependent manner. Additionally, we present the results from a study evaluating the anti-tumor activity of ZW49 in a panel of patient-derived xenografts of gastric cancer. HER2-positive SK-BR-3 and HER2-negative MDA-MB-468 tumor cell lines were treated with ZW49 and cell surface calreticulin was assessed by flow cytometry. ZW49 treatment of SKBR-3 cells induced a significantly higher percentage of cells staining positive for cell surface calreticulin compared to untreated cells. In contrast, ZW49 treatment of MDA-MB-468 cells resulted in no significant difference in the percentage of cells staining positive for calreticulin compared to untreated cells. ZW49 treated HER2-positive cancer cell lines SK-BR-3 and SK-OV-3 induced higher levels of extracellular ATP compared to untreated cells. In the HER2-negative cell line MDA-MB-468, treatment with ZW49 did not alter levels of extracellular ATP compared to untreated cells. ZW49 induced higher levels of HMGB1 in the HER2-positive cancer cell lines SKBR3 and N87 compared to untreated cells, whereas in the HER2-negative cell line MDA-MB-468, ZW49 induced similar levels of HMGB1 to untreated cells. Anti-tumor activity was observed in 5/7 (71%) PDX models of gastric cancer after a single i.v. dose of 6 mg/kg, including in models with moderate and weak HER2 expression. The strong anti-tumor activity of ZW-49 in vivo, together with its ability to induce ICD and potential adaptive immune responses, support ZW49 as a promising ADC for the treatment of HER2-expressing cancers warranting further investigation, including potential combination with checkpoint inhibitors. Citation Format: Stuart D. Barnscher, Andrea Hernández Rojas, Kevin J. Hamblett, Nichole Escalante. Zanidatamab zovodotin (ZW49) induces hallmarks of immunogenic cell death and is active in patient-derived xenograft models of gastric cancer [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 2633.

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.

Study on B16 Cell Cytotoxicity by High Frequency Reversible Electroporation With Bleomycin That Induces Hallmarks of Immunogenic Death.

Hundreds of high frequency bipolar pulse bursts with ∼1 μs have been suggested to alleviate muscle contractions and pain during the irreversible electroporation (IRE) tumor treatment. This study is performed to verify whether eight bursts of high frequency reversible electroporation pulses (HFREs) with bleomycin could be used for electrochemotherapy (ECT) tumor treatment. Firstly, in vitro experiments on B16 cells are performed to determine the cytotoxicity of the HFREs with bleomycin. The result indicates that the protocol of HFREs with bleomycin has a significant killing effect compared with only bleomycin, in which the used HFRE pulses are set to induce high membrane permeabilization while maintaining high cell viability. The immunogenic cell death (ICD) that generates danger associated molecular patterns (DAMPs) could trigger an adaptive immune response against tumors. We demonstrated that HFREs with bleomycin could trigger the hallmarks of ICD with obvious up-regulation of DAMPs, including ATP, HMGB1, and CRT. The ICD process may begin at 3 h but perform at 6 h after HFREs with bleomycin stimulation. The in vivo experiment on mice tumor treatment also showed that the protocol of HFREs with bleomycin could inhibit tumor growth with more cytotoxic CD8+ T cells infiltration. The results obtained from in vitro and in vitro experiments preliminary confirmed that the HFREs with bleomycin could be used for ECT tumor treatment associated with the hallmarks of ICD and preliminary trigger the adaptive immune response.

Amphipathic barbiturates as marine product mimics with cytolytic and immunogenic effects on head and neck squamous cell carcinoma cell lines.

The incidence of head and neck squamous cell carcinoma (HNSCC) is increasing and the conventional treatments for this form of cancer can be tough. Despite the success of existing immunotherapies in some HNSCC patients, many do not respond to this type of treatment. Thus, the development of novel anti-cancer therapies should be prioritized. In the current study, the anticancer activity of a panel of novel compounds, herein termed marine product mimics (MPMs), against HNSCC cell lines is explored. The previously reported compound MPM-1, which is structurally related to the novel MPMs, was shown to have promising effects on the HNSCC cell line HSC-3. The results from the current study indicate that the novel MPMs are more potent than MPM-1 but cause a similar type of cell death. The results indicated that the MPMs must cross through the cell membrane to exert their action and that they are lysosomotropic. Further experiments showed that some of the MPMs could induce phosphorylation of eukaryotic initiation factor 2α (eIF2α) in HSC-3 and UT-SCC-24A cells, which indicates that they can activate the integrated stress response that is strongly associated with immunogenic cell death. Cell surface expression of calreticulin and release of HMGB1 and ATP, which are all hallmarks of immunogenic cell death, was also demonstrated in HSC-3 and UT-SCC-24A cells treated with MPMs. This suggests that the MPMs are interesting candidates for future HNSCC cancer therapies.

Targeting endoplasmic reticulum associated degradation pathway combined with radiotherapy enhances the immunogenicity of esophageal cancer cells

ABSTRACT Immunogenic cell death (ICD) is essential for the activation of immune system against cancer. We aimed to investigate the efficacy of endoplasmic reticulum (ER)-associated protein degradation (ERAD) inhibitors (EerI and NMS-873) in enhancing radiation-induced ICD in esophageal cancer (EC). EC cells were administered with ERAD inhibitors, radiation therapy (RT), and the combination treatment. ICD hallmarks including calreticulin (CALR), adenosine triphosphate (ATP), and high mobility group protein B1 (HMGB1) were detected. The efficacy of ERAD inhibitors combined with RT in stimulating ICD was analyzed. Additionally, the role of ICD hallmarks in immune cell infiltration and patient survival was investigated. Inhibiting ERAD pathways was able to stimulate ICD component emission from dying EC cells in a dose-dependent pattern. Radiation-induced ICD was significantly increased after high doses RT (≥10 Gy). ERAD inhibitor combined with moderate dose RT (≥6 Gy) was capable of stimulating increased ICD in EC cells. Dual therapy could elicit the antitumor immune response by enhancing dendritic cells maturation and phagocytosis. Further investigation revealed a significant correlation between CALR and tumor-infiltrating immune cells. Low expression of ATP and HMGB1 and high expression of CALR were associated with favorable survival in patients with EC. The immunogenicityof EC can be enhanced by ERAD inhibitors combined with moderate doses of RT. ICD hallmark genes, especially CALR, are correlated to immune cell infiltration and clinical outcomes in EC. The present results demonstrated an important method to improve the immunogenicity of EC cells for enhanced antitumor immune response.

Immunostimulatory oncolytic activity of coxsackievirus A11 in human malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive solid cancer with a poor prognosis, whereas coxsackievirus A11 (CVA11) is a potential oncolytic virus for cancer treatment. We here investigated the oncolytic activity of CVA11 with human MPM cell lines. CVA11 infection was cytotoxic in all six MPM cell lines examined and showed no or minimal cytotoxicity toward normal human normal cell lines. MPM cells with a higher surface level of intercellular adhesion molecule-1 (ICAM-1) expression tended to be more susceptible to CVA11-induced cytotoxicity, and a neutralizing antibody to ICAM-1 attenuated such cytotoxicity. CVA11 infection activated signaling by Akt and extracellular signal-regulated kinase (ERK) pathways, and inhibitors of such signaling also abrogated CVA11-mediated cytotoxicity. Furthermore, CVA11 infection-triggered multiple modes of tumor cell death including apoptosis, pyroptosis, and necroptosis, and such death was accompanied by the release or exposure of the proinflammatory cytokine interleukin-1β and damage-associated molecular patterns such as calreticulin, high-mobility group box-1, annexin A1, and heat shock protein 70, which are hallmarks of immunogenic cell death. Notably, in vivo treatment of human MPM xenografts with intratumoral CVA11 injection resulted in significant suppression of tumor growth in SCID mice, and all mice infected with CVA11 showed no significant change in body weight. Our findings collectively suggest that the oncolytic activity of CVA11 for MPM is dependent on ICAM-1 as a virus receptor, as well as on Akt and ERK signaling, and that oncolytic virotherapy with CVA11 is a promising treatment modality with immunostimulatory activity for human MPM.