Inhibition Of Interleukin-6 Signaling Research Articles

Human Genetic Evidence to Inform Clinical Development of IL-6 Signaling Inhibition for Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) represents a significant cause of mortality, yet no medical therapies have proven efficacious. The aim of the current study was to leverage human genetic evidence to inform clinical development of IL-6 (interleukin-6) signaling inhibition for the treatment of AAA. Associations of rs2228145, a missense variant in the IL6R gene region, are expressed per additional copy of the C allele, corresponding to the genetically predicted effect of IL-6 signaling inhibition. We consider genetic associations with AAA risk in the AAAgen consortium (39 221 cases and 1 086 107 controls) and UK Biobank (1963 cases and 365 680 controls). To validate against known effects of IL-6 signaling inhibition, we present associations with rheumatoid arthritis, polymyalgia rheumatica, and severe COVID-19. To explore mechanism specificity, we present associations with thoracic aortic aneurysm, intracranial aneurysm, and coronary artery disease. We further explored genetic associations in clinically relevant subgroups of the population. We observed strong genetic associations with AAA risk in the AAAgen consortium, UK Biobank, and FinnGen (odds ratios: 0.91 [95% CI, 0.90-0.92], P=4×10-30; 0.90 [95% CI, 0.84-0.96], P=0.001; and 0.86 [95% CI, 0.82-0.91], P=7×10-9, respectively). The association was similar for fatal AAA but with greater uncertainty due to the lower number of events. The association with AAA was of greater magnitude than associations with coronary artery disease and even rheumatological disorders for which IL-6 inhibitors have been approved. No strong associations were observed with thoracic aortic aneurysm or intracranial aneurysm. Associations attenuated toward the null in populations with concomitant rheumatological or connective tissue disease. Inhibition of IL-6 signaling is a promising strategy for treating AAA but not other types of aneurysmal disease. These findings serve to help inform clinical development of IL-6 signaling inhibition for AAA treatment.

What have we learnt from the inhibition of IL-6 in RA and what are the clinical opportunities for patient outcomes?

Rheumatoid arthritis (RA) is an autoimmune disease characterised by persistent inflammation of the synovial joints as well as other tissues and organs. Left untreated, it can lead to joint damage, disability and even increased mortality. The disease is driven by inflammatory cytokines that contribute to the chronic inflammation seen in RA. Interleukin-6 (IL-6) is a key pathological cytokine and a target for treatments aiming to alleviate local and systemic inflammation. Despite advances in understanding RA and the introduction of new treatments, achieving sustained remission remains challenging. This review explores the role of IL-6 in RA pathogenesis, its potential as a treatment target and the significance of personalised medicine in RA management. IL-6 has a dual signalling mechanism, classical and trans-signalling, which influences various intracellular pathways. While several targeted therapies have emerged, no single mechanism-based therapy is universally effective due to the diversity and complexity of the disease. Different approaches to targeting IL-6 have been tested, including biologic blockade of receptors or ligands, and inhibition of IL-6 signalling. IL-6 receptor inhibitors have been validated as RA therapeutics, either alone or in combination with other treatments. Tocilizumab, the first approved IL-6 inhibitor, blocks both soluble and membrane-bound IL-6 receptors, reducing the inflammatory cascade. Clinical trials confirm the efficacy and safety of tocilizumab and its role as a treatment option for patients unresponsive to conventional therapies. The benefits of IL-6 inhibition extend beyond reduced joint inflammation to the amelioration of comorbidities like anaemia, cardiovascular disease, depression and osteoporosis. Tailoring treatment to patients' profiles and comorbidities is essential for optimal outcomes. A 'treat-to-profile' approach, focusing on a holistic view of the patient, could improve personalised medicine strategies. Biosimilars - lower-cost alternatives to biologics - further enhance the accessibility and cost-effectiveness of treatment. IL-6 inhibitors present a valuable treatment option for RA management, particularly for patients with specific comorbidities.

Differential Roles of Interleukin-6 in Severe Acute Respiratory Syndrome-Coronavirus-2 Infection and Cardiometabolic Diseases.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can lead to a cytokine storm, unleashed in part by pyroptosis of virus-infected macrophages and monocytes. Interleukin-6 (IL-6) has emerged as a key participant in this ominous complication of COVID-19. IL-6 antagonists have improved outcomes in patients with COVID-19 in some, but not all, studies. IL-6 signaling involves at least 3 distinct pathways, including classic-signaling, trans-signaling, and trans-presentation depending on the localization of IL-6 receptor and its binding partner glycoprotein gp130. IL-6 has become a therapeutic target in COVID-19, cardiovascular diseases, and other inflammatory conditions. However, the efficacy of inhibition of IL-6 signaling in metabolic diseases, such as obesity and diabetes, may depend in part on cell type-dependent actions of IL-6 in controlling lipid metabolism, glucose uptake, and insulin sensitivity owing to complexities that remain to be elucidated. The present review sought to summarize and discuss the current understanding of how and whether targeting IL-6 signaling ameliorates outcomes following SARS-CoV-2 infection and associated clinical complications, focusing predominantly on metabolic and cardiovascular diseases.

Efficacy and safety of selective JAK 1 inhibitor filgotinib in active rheumatoid arthritis patients with inadequate response to methotrexate: comparative study with filgotinib and tocilizumab examined by clinical index as well as musculoskeletal ultrasound assessment (TRANSFORM study): study protocol for a randomized, open-label, parallel-group, multicenter, and non-inferiority clinical trial

BackgroundAdministration of Janus kinase (JAK) inhibitors and biological disease-modifying antirheumatic drugs has dramatically improved even the clinical outcomes in patients with rheumatoid arthritis (RA) and an inadequate response to methotrexate (MTX). Dysregulation of JAK-STAT pathways via overproduction of cytokines, such as interleukin-6, is involved in the pathogenesis of RA. Filgotinib is a selective JAK1 inhibitor pending approval for use in RA. By inhibition of the JAK-STAT pathway, filgotinib is effective in suppressing disease activity and preventing the progression of joint destruction. Similarly, interleukin-6 inhibitors such as tocilizumab also inhibit the JAK-STAT pathways by inhibition of interleukin-6 signaling. We present the protocol for a study that will evaluate whether the effectiveness of filgotinib monotherapy is non-inferior to that of tocilizumab monotherapy in RA patients with an inadequate response to MTX.MethodsThis study is an interventional, multicenter, randomized, open-label, parallel-group, and non-inferiority clinical trial with a 52-week follow-up. Study participants will be 400 RA patients with at least moderate disease activity during treatment with MTX. Participants will be randomized in a 1:1 ratio to administer filgotinib monotherapy or subcutaneous tocilizumab monotherapy switched from MTX. We will evaluate disease activity by measuring clinical disease activity indices and by using musculoskeletal ultrasound (MSUS). The primary endpoint is the proportion of patients who achieve an American College of Rheumatology 50 response at week 12. Secondary endpoints are changes from baseline in the MSUS scores. We will also comprehensively analyze serum levels of multiple biomarkers, such as cytokines and chemokines.DiscussionThe study results are expected to show the non-inferiority of the effectiveness of filgotinib monotherapy to that of tocilizumab monotherapy in RA patients with inadequate response to MTX. The strength of this study is its prospective evaluation of therapeutic efficacy using not only clinical disease activity indices, but also MSUS, which accurately and objectively evaluates disease activity at the joint level among patients drawn from multiple centers with a standardized evaluation by MSUS. We will evaluate the effectiveness of both drugs by integrating multilateral assessments—clinical disease activity indices, MSUS findings, and serum biomarkers.Trial registrationJapan Registry of Clinical Trials (https://jrct.niph.go.jp) jRCTs071200107. Registered on March 3, 2021. ClinicalTrials.gov NCT05090410. Registered on October 22, 2021.

Inhibition of IL-6 signaling prevents serum-induced umbilical cord artery dysfunction from patients with severe COVID-19.

Coronavirus disease 2019 (COVID-19) infection has a negative impact on the cytokine profile of pregnant women. Increased levels of proinflammatory cytokines seem to be correlated with the severity of the disease, in addition to predisposing to miscarriage or premature birth. Proinflammatory cytokines increase the generation of reactive oxygen species (ROS). It is unclear how interleukin-6 (IL-6) found in the circulation of patients with severe COVID-19 might affect gestational health, particularly concerning umbilical cord function. This study tested the hypothesis that IL-6 present in the circulation of women with severe COVID-19 causes umbilical cord artery dysfunction by increasing ROS generation and activating redox-sensitive proteins. Umbilical cord arteries were incubated with serum from healthy women and women with severe COVID-19. Vascular function was assessed using concentration-effect curves to serotonin in the presence or absence of pharmacological agents, such as tocilizumab (antibody against the IL-6 receptor), tiron (ROS scavenger), ML171 (Nox1 inhibitor), and Y27632 (Rho kinase inhibitor). ROS generation was assessed by the dihydroethidine probe and Rho kinase activity by an enzymatic assay. Umbilical arteries exposed to serum from women with severe COVID-19 were hyperreactive to serotonin. This effect was abolished in the presence of tocilizumab, tiron, ML171, and Y27632. In addition, serum from women with severe COVID-19 increased Nox1-dependent ROS generation and Rho kinase activity. Increased Rho kinase activity was abolished by tocilizumab and tiron. Serum cytokines in women with severe COVID-19 promote umbilical artery dysfunction. IL-6 is key to Nox-linked vascular oxidative stress and activation of the Rho kinase pathway.

Inhibition of Interleukin-6 signaling: A novel therapeutic approach to necrotizing enterocolitis

ObjectivesThis study investigated the effects of tocilizumab on the prevention and treatment of experimental necrotizing enterocolitis (NEC) in newborn rats. MethodsForty-two newborn Sprague-Dawley rats were randomly separated into three groups: NEC + placebo, NEC + tocilizumab, and the control group. NEC + placebo and NEC + tocilizumab groups were given 1 mg/kg lipopolysaccharide intraperitoneally once only on the first day, were fed with a special rodent formula every 3 h, inhaled 100% CO2 for 10 min, were exposed to cold stress at + 4 °C for 5 min, and 97% O2 for 5 min twice a day for 3 days. NEC + tocilizumab group was treated with 8 mg/kg/day tocilizumab (Actemra®) intraperitoneally, while NEC + placebo group was given intraperitoneal 0.9% saline at a dose of 2 mL/kg/day from the first day to the end of the study. All newborn rats were sacrificed on day 4. Specimens were taken for histopathologic, immunohistochemical and biochemical evaluation from the ileum and proximal colon. ResultsNEC + tocilizumab group had higher weight gain and survival rate compared to NEC + placebo group and clinical sickness score was reduced in NEC + tocilizumab group (p < 0.05). Lower tissue damage and apoptosis were found in the NEC + tocilizumab group compared to the NEC + placebo group (p < 0.01). Tissue Interleukin-6, Interleukin-1β, TNF-α, myeloperoxidase and caspase-3 levels were significantly decreased in the NEC + tocilizumab group (p < 0.01). ConclusionsTocilizumab could be a potential option in the prevention and treatment of NEC.

Endothelial SOCS3 maintains homeostasis and promotes survival in endotoxemic mice

SOCS3 is the main inhibitor of the JAK/STAT3 pathway. This pathway is activated by interleukin 6 (IL-6), a major mediator of the cytokine storm during shock. To determine its role in the vascular response to shock, we challenged mice lacking SOCS3 in the adult endothelium (SOCS3iEKO) with a nonlethal dose of lipopolysaccharide (LPS). SOCS3iEKO mice died 16–24 hours postinjection after severe kidney failure. Loss of SOCS3 led to an LPS-induced type I IFN–like program and high expression of prothrombotic and proadhesive genes. Consistently, we observed intraluminal leukocyte adhesion and neutrophil extracellular trap–osis (NETosis), as well as retinal venular leukoembolization. Notably, heterozygous mice displayed an intermediate phenotype, suggesting a gene dose effect. In vitro studies were performed to study the role of SOCS3 protein levels in the regulation of the inflammatory response. In human umbilical vein endothelial cells, pulse-chase experiments showed that SOCS3 protein had a half-life less than 20 minutes. Inhibition of SOCS3 ubiquitination and proteasomal degradation led to protein accumulation and a stronger inhibition of IL-6 signaling and barrier function loss. Together, our data demonstrate that the regulation of SOCS3 protein levels is critical to inhibit IL-6–mediated endotheliopathy during shock and provide a promising therapeutic avenue to prevent multiorgan dysfunction through stabilization of endothelial SOCS3.

Activated IL-6 signaling contributes to the pathogenesis of, and is a novel therapeutic target for, CALR-mutated MPNs

Calreticulin (CALR), an endoplasmic reticulum–associated chaperone, is frequently mutated in myeloproliferative neoplasms (MPNs). Mutated CALR promotes downstream JAK2/STAT5 signaling through interaction with, and activation of, the thrombopoietin receptor (MPL). Here, we provide evidence of a novel mechanism contributing to CALR-mutated MPNs, represented by abnormal activation of the interleukin 6 (IL-6)-signaling pathway. We found that UT7 and UT7/mpl cells, engineered by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) to express the CALR type 1–like (DEL) mutation, acquired cytokine independence and were primed to the megakaryocyte (Mk) lineage. Levels of IL-6 messenger RNA (mRNA), extracellular-released IL-6, membrane-associated glycoprotein 130 (gp130), and IL-6 receptor (IL-6R), phosphorylated JAK1 and STAT3 (p-JAK1 and p-STAT3), and IL-6 promoter region occupancy by STAT3 all resulted in increased CALR DEL cells in the absence of MPL stimulation. Wild-type, but not mutated, CALR physically interacted with gp130 and IL-6R, downregulating their expression on the cell membrane. Agents targeting gp130 (SC-144), IL-6R (tocilizumab [TCZ]), and cell-released IL-6 reduced proliferation of CALR DEL as well as CALR knockout cells, supporting a mutated CALR loss-of-function model. CD34+ cells from CALR-mutated patients showed increased levels of IL-6 mRNA and p-STAT3, and colony-forming unit–Mk growth was inhibited by either SC144 or TCZ, as well as an IL-6 antibody, supporting cell-autonomous activation of the IL-6 pathway. Targeting IL-6 signaling also reduced colony formation by CD34+ cells of JAK2V617F-mutated patients. The combination of TCZ and ruxolitinib was synergistic at very low nanomolar concentrations. Overall, our results suggest that target inhibition of IL-6 signaling may have therapeutic potential in CALR, and possibly JAK2V617F, mutated MPNs.

Macrophage activation syndrome in patients with adult-onset Still's disease under tocilizumab treatment: A single-center observational study.

Macrophage activation syndrome (MAS) developed under tocilizumab treatment poses a diagnostic challenge. This study aims to demonstrate the frequency and the clinical features of MAS developed in patients with adult-onset Still's disease (AOSD) receiving tocilizumab. The consecutive AOSD patients treated with tocilizumab in our institution from April 2008 to March 2020 were studied. The frequency of clinically diagnosed MAS during tocilizumab treatment, their conformity to the several criteria relevant for MAS, and laboratory characteristics compared to AOSD flare were investigated. Of the 20 AOSD patients treated with tocilizumab, six developed clinically diagnosed MAS, four immediately after starting tocilizumab and two after long-term treatment. Some of them had already met the MAS criteria before starting tocilizumab. At MAS diagnosis, although some did not meet the MAS criteria due to lack of fever and/or the lower ferritin levels, all consistently showed sharp increases in ferritin along with marked abnormal changes in two or more different markers of organ damage, unlike the AOSD flares. MAS is not a rare complication in AOSD patients receiving tocilizumab. The clinical similarities between systemic AOSD and MAS, and substantial alterations in MAS features by inhibition of interleukin-6 signaling may limit the utility of the existing diagnostic/classification criteria in diagnosing MAS under tocilizumab treatment. The emergence of abnormalities in MAS-related organ damage markers with a rapid elevation of ferritin should be considered as MAS development in AOSD patients receiving tocilizumab even if the patients are afebrile or have relatively low ferritin levels.

Inhibition of interleukin 6 signalling and renal function: A Mendelian randomization study.

Inhibition of interleukin 6 (IL‐6) signalling has been proposed as a potential cardioprotective strategy for patients with chronic kidney disease (CKD), but the direct effects of IL‐6 inhibition on renal function are not known. A Mendelian randomization (MR) study was performed to investigate the association of genetically proxied inhibition of IL‐6 signalling with estimated glomerular filtration rate (eGFR), CKD and blood urea nitrogen (BUN). Inverse‐variance weighted MR was used as the main analysis, with sensitivity analyses performed using simple median, weighted median and MR‐Egger methods. There was no evidence for an association of genetically proxied inhibition of IL‐6 signalling (scaled per standard deviation unit decrease in C‐reactive protein) with log eGFR (0.001, 95% confidence interval −0.004‐0.007), BUN (0.009, 95% confidence interval −0.003‐0.021) and CKD (odds ratio 0.948, 95% confidence interval 0.822‐1.094). These findings do not raise concerns for IL‐6 signalling having large adverse effects on renal function.

Role of Interleukin-6 in Lung Complications in Patients With COVID-19: Therapeutic Implications.

COVID-19 is viral respiratory infection with frequently fatal lung complications in the elderly or in people with serious comorbidities. Lung destruction appears to be associated with a cytokine storm related to an increased level of interleukin-6 (IL6). Therapeutic targeting of the interleukin-6 signaling pathway can attenuate such a cytokine storm and can be beneficial for patients with COVID-19 in danger of pulmonary failure. This article demonstrates the importance of IL6 in progression of disease and the possibility of inhibition of IL6 signaling in COVID-19 therapy.

Is there a role for prostanoid-mediated inhibition of IL-6 trans-signalling in the management of pulmonary arterial hypertension?

Inflammation has been highlighted as a key factor in pulmonary arterial hypertension (PAH) development, particularly interleukin-6 (IL-6). IL-6 activates JAK-STAT signalling to induce transcription of pro-inflammatory and pro-angiogenic genes, enabling PAH progression, as well as the transcription of suppressor of cytokine signalling 3 (SOCS3) which limits IL-6 signalling. Current PAH therapies include prostanoid drugs which induce vasodilation via stimulating intracellular 3',5'-cyclic adenosine monophosphate (cAMP) levels. cAMP can also inhibit IL-6-mediated endothelial dysfunction via the induction of SOCS3. Thus, we propose that an important mechanism by which cAMP-mobilising prostanoid drugs limit PAH is by inhibiting IL-6-mediated pulmonary inflammation and remodelling via SOCS3 inhibition of IL-6 signalling. Further clarification may result in effective strategies with which to target the IL-6/JAK-STAT signalling pathway in PAH.

Abstract 128: Amelioration of Ischemic Stroke Damage Through Inhibition of Interleukin-6 Signaling With Tocilizumab Requires Sex Specific Dosing

Introduction: Interleukin 6 (IL-6) is a proinflammatory cytokine. Higher plasma IL-6 levels in stroke patients are correlated with increased stroke severity and poor prognosis. Our work has shown that tocilizumab, an FDA approved drug that blocks the IL-6 receptor (IL-6R) significantly reduced acute and long-term brain infarct and atrophy in aged male mice after stroke. At the same dose, tocilizumab had no significant effect on stroke outcome in aged females. Methods: We utilized aged (18-20 month) C57BL/6J male (N= 27) and female (N= 30) mice to examine neuroprotection and behavioral deficits with treatment. Mice were randomly assigned into 4 groups of either stroke or sham and drug or IgG control treatment. Stroke was induced by 1 hour of transient right middle cerebral artery occlusion followed by reperfusion for 35 days. Four hours after the onset of ischemia mice were given an intraperitoneal injection of either tocilizumab (20mg/1kg) or an IgG control. Tests were conducted to evaluate motor, sensory and cognitive deficits. Another aged female cohort (N= 15) was used to assess tocilizumab efficacy at reducing infarct 3 days post stroke with a higher dose (100mg/1kg). Results: Soluble IL-6R expression, while equivalent at baseline, is significantly higher after stroke in aged female mice compared to males (P= 0.0070). Tocilizumab treatment reduced brain atrophy (P= 0.0120), mortality (P= 0.0239) and behavioral deficits in aged males on multiple behavior tests (P&lt; 0.05). Females did not show similar benefits at the same dose (20mg/1kg). A higher dose of tocilizumab (100mg/1kg) reduced brain infarct acutely in aged females 3 days post stroke (P= 0.0005). This affect at only the higher dose in females is likely related to the higher level of soluble IL-6R seen post stroke compared to males. Testing in human stroke patient plasma revealed that women, as in mice, had significantly higher soluble IL-6R level compared to men after stroke (P= 0.0047). Conclusion: These results support our hypothesis that inhibition of the IL-6 receptor can be a novel therapeutic approach for stroke treatment. The neuroprotective dose of tocilizumab is different in males and females, which helps to emphasize the importance of determining dosage efficacy in a sex-specific manner.

Abstract 1972: Targeting the IL-6 signaling pathway overcomes cetuximab resistance in head and neck squamous cell carcinoma

Abstract Head and neck squamous cell carcinoma (HNSCC), the sixth most common cancer worldwide, has a five-year survival rate of 50%. The last few decades have seen only marginal improvements to the survival rate due to high rates of resistance to currently available treatments. The only oncogene-targeted agent that has been FDA approved for the treatment of HNSCC is cetuximab, a monoclonal antibody directed against the epidermal growth factor receptor (EGFR). The response rate for single-agent cetuximab is below 20%, and both intrinsic and acquired resistance to cetuximab remain major obstacles in the treatment of HNSCC. Identification and targeting of mediators that confer cetuximab resistance are needed to improve patient outcomes in HNSCC and in other cancers in which cetuximab is employed. To address this unmet need, we generated cetuximab-resistant variants of the human HNSCC cell lines PE/CA-PJ49 and FaDu. Because secretion of interleukin 6 (IL-6) has been proposed as a mechanism of cetuximab resistance in HNSCC, we assessed IL-6 levels in these models of acquired resistance. IL6 mRNA expression was increased in PE/CA-PJ49 and FaDu cells that have acquired resistance to cetuximab compared to the parental cells from which they were derived. In addition, cetuximab-resistant PE/CA-PJ49 variants exhibited increased levels of glycoprotein 130 (gp130), a molecule that oligomerizes with IL-6R alpha (IL-6Rα) to form the IL-6 receptor. Since IL-6 is known to promote tumor cell proliferation and survival, we hypothesized that cetuximab-resistant PE/CA-PJ49 and FaDu variants would be sensitive to inhibition of components of the IL-6 signaling pathway. To test this hypothesis, we treated PE/CA-PJ49 parental cells and cetuximab-resistant variants with cetuximab and/or inhibitors of the IL-6 pathway. Colony formation assays revealed that cetuximab-treated parental cells formed fewer colonies than vehicle-treated cells, while cetuximab treatment did not affect the ability of cetuximab-resistant PE/CA-PJ49 variants to form colonies. In contrast, siRNA-mediated knockdown of IL6 or IL6R (encoding IL-6Rα) markedly reduced the colony-forming ability of the cetuximab-resistant variants, but not parental cells. These results suggest that targeted inhibition of IL-6 signaling inhibits proliferation and/or survival in cetuximab-resistant PE/CA-PJ49 cells. Ongoing studies are testing our hypothesis using small-molecule and antibody-based inhibitors of the IL-6 pathway in our cell line models and in cetuximab-resistant patient-derived xenografts. By conducting these experiments, we aim to assess the therapeutic potential of targeting the IL-6 pathway in cetuximab-resistant HNSCC. Citation Format: Rachel A. O'Keefe, Neil E. Bhola, David S. Lee, Daniel E. Johnson, Jennifer R. Grandis. Targeting the IL-6 signaling pathway overcomes cetuximab resistance in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1972.

Abstract 5611: Inhibition of IL-6 trans-signaling in HNSCC

Abstract Various types of cancers including head and neck squamous cell carcinomas (HNSCCs) are highly inflammatory, and the cytokine interleukin-6 (IL-6) is believed to be associated with this inflammatory phenotype. Unfortunately, global inhibition of IL-6 signaling has demonstrated little to no clinical efficacy in various types of cancers. Previous studies in the field have reported major differences between IL-6 classical signaling through the membrane bound IL-6R (mIL-6R) and IL-6 trans-signaling through the soluble IL-6R (sIL-6R), and the idea that these 2 pathways may have vastly different functions. Recent studies in models of inflammation have proposed that IL-6 classical signaling serves an anti-inflammatory/homeostatic role while IL-6 trans-signaling stimulates proinflammatory events. Therefore, IL-6 trans-signaling (and not classical signaling) may be associated with the proinflammatory phenotype observed in HNSCCs and may also be responsible for the increased tumor progression and treatment resistance frequently encountered with this disease. The goal of this work is to investigate if selective inhibition of IL-6 trans-signaling will demonstrate superior antitumor efficacy compared to global inhibition of IL-6 signaling in HNSCC cells and if selective inhibition of IL-6 trans-signaling will enhance the antitumor efficacy of chemo/radiotherapy in HNSCC cells. We observed that the HNSCC cell lines SQ20B, SCC-25, FaDu and Cal-27 all express mIL-6R and secrete IL-6, sIL-6R, and the natural inhibitor of sIL-6R signaling–soluble glycoprotein 130 (sgp130)–at varying levels. Simultaneous inhibition of IL-6 classical and trans-signaling using the IL-6R antagonist tocilizumab, and selective inhibition of IL-6 trans-signaling using the extracellular portion of gp130 fused to the Fc portion of human IgG1 (sgp130-Fc), showed no significant effects on cell survival in vitro. However, sgp130-Fc significantly suppressed SQ20B tumor growth in athymic nude mice while tocilizumab had no effect. Significant antitumor effects of sgp130-Fc were also observed in a murine SCCVII/C3H syngeneic mouse model. Cell lines treated with cisplatin and/or X-ray radiation (0-4 Gy) increased IL-6, sIL-6R and sgp130 in a dose-dependent manner and sgp130-Fc significantly increased SQ20B tumor response to chemo/radiotherapy in vivo. Altogether, this work suggests that selective inhibition of IL-6 trans-signaling using sgp130-Fc may be more effective than global IL-6 inhibition with respect to suppressing HNSCC tumor growth and warrants further study as an adjuvant to standard HNSCC therapy. Citation Format: Andrean L. Simons, Rachel A. Dahl, Madelyn Espinosa-Cotton, Samuel N. Rodman, Stefan Rose-John. Inhibition of IL-6 trans-signaling in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5611.

Interleukin-6 receptor inhibitor suppresses bone metastases in a breast cancer cell line

Interleukin-6 (IL-6) is a potent inflammatory cytokine that appears to play a key role in cancer growth and metastasis. In the present study, the effects of IL-6 receptor (IL-6R) on breast cancer aggressiveness and bone metastases were investigated. MDA-MB-231 (MDA-231) cells were treated in the presence or absence of anti-human IL-6 receptor (IL-6R) monoclonal antibody and examined with respect to cell survival. The expressions of signal transducer and activator of transcription 3 (Stat3), vascular endothelial growth factor (VEGF), and receptor activator of NF-κB (RANK) were analyzed by SDS-PAGE and immunoblotting. MDA-231 cells were injected into the left ventricle of mice, and then anti-human IL-6R monoclonal antibody or saline was administered intraperitoneally for 28days. After 28days, the incidence of bone metastases was evaluated in the hind limbs by radiography and histology. Anti-human IL-6R monoclonal antibody reduced bone metastases in an animal model injected with MDA-231 cells on radiological and histomorphometric analyses. The mechanism of bone metastasis inhibition involved inhibited cell proliferation and decreased expressions of phospho-Stat3, VEGF, and RANK in MDA-231 cells. The results of the present study suggest that inhibition of IL-6 signaling may become a preventive therapeutic option for breast cancer and bone metastases.

Abstract 28: Inhibition of Interleukin-6 Signaling With Tocilizumab Ameliorates Ischemic Stroke Damage in Aged Male and Female Mice

Introduction: In stroke patients higher plasma IL-6 levels are correlated with increased stroke severity and poor long-term prognosis. Preliminary work in our lab has shown that tocilizumab, an FDA approved drug that blocks IL-6 receptors inhibiting the effects of IL-6, reduced infarct size and behavior deficits in young male mice following MCAO. Due to this promising preliminary data we hypothesized that tocilizumab will ameliorate injury in aged male and female mice. Testing both sexes and aged mice is important because the majority of stroke occurs in patients over 65 in both sexes. Methods: Aged (18-20month) C57BL/6J male (n=42) and female mice (n=45) were used to examine neuroprotection and behavioral deficits with treatment. Mice were randomly separated into 4 groups, stroke or sham then subdivided into drug or control treatment. Stroke was induced by 1 hour of transient MCAO followed by reperfusion for either 3 or 35 days. Four hours after the onset of ischemia mice were intraperitoneally injected with tocilizumab (20mg/1kg) or an IgG control. Behavior tests evaluated motor/sensory deficits, anxiety and locomotor activity. Depression and memory formation was also tested in the 35 day cohort. Results: Tocilizumab reduced mortality in aged male mice and significantly reduced anxiety levels in aged female mice 20 days after stroke (p=0.04). Treatment also led to a significant reduction (p=0.04) in infarct size 3 days post-ischemia. The corner test showed improved sensorimotor function in males on all testing days 3, 7 and 14 after stroke but was only significant for females on post stroke day 3 (p&lt;0.05). Direct revisit error on the Y-maze was significantly reduced in tocilizumab treated aged male mice on day 7 after stroke (p=0.04) and aged female mice on day 3 after stroke (p=0.032) showing an improved spatial learning. Time to discover the escape hole in the Barnes maze 31 days post stroke was improved in aged male mice (p=0.05) conveying benefit to new memory formation post stroke by tocilizumab. Conclusion: This study showed that tocilizumab treatment reduced stroke damage and decreased behavioral deficits in both sexes. Therefore, this study concludes that inhibition of the IL-6 receptor may be a potential therapeutic approach for stroke treatment.

Disease modifying actions of interleukin-6 blockade in a rat model of bone cancer pain.

Metastasis of cancer to the skeleton represents a debilitating turning point in the lives of patients. Skeletal metastasis leads to moderate to severe ongoing pain along with bone remodeling that can result in fracture, events that dramatically diminish quality of life. Interleukin-6 (IL-6) levels are elevated in patients with metastatic breast cancer and are associated with a lower survival rate. We therefore determined the consequences of inhibition of IL-6 signaling using a novel small molecule antagonist, TB-2-081, on bone integrity, tumor progression, and pain in a rodent model of breast cancer. Rat MAT B III mammary adenocarcinoma cells were injected and sealed within the tibia of female Fischer rats. Growth of these cells within the rat tibia elicited increased IL-6 levels both within the bone exudate and in the plasma, produced ongoing pain and evoked hypersensitivity, and bone fracture that was observed by approximately day 12. Systemic TB-2-081 delivered by subcutaneous osmotic minipumps starting at tumor implantation prevented tumor-induced ongoing bone pain and evoked hypersensitivity without altering tumor growth. Remarkably, TB-2-081 infusion significantly reduced osteolytic and osteoblastic bone remodeling and time to fracture likely by decreasing osteoclastogenesis and associated increase in bone resorption. These findings indicate that blockade of IL-6 signaling may represent a viable, disease-modifying strategy to prevent tumor-induced bone remodeling allowing for stabilization of bone and decreased fractures as well as diminished ongoing pain that may improve quality of life of patients with skeletal metastases. Notably, anti-IL-6 antibodies are clinically available allowing for rapid testing of these possibilities in humans.

Abstract 4108: Targeting IL-6 signaling overcomes cetuximab resistance in head and neck squamous cell carcinoma

Abstract Head and neck squamous cell carcinoma (HNSCC), the sixth most common cancer worldwide, has a five-year survival rate of only 50%. The first targeted agent FDA approved for treatment of HNSCC was cetuximab, a monoclonal antibody targeting the epidermal growth factor receptor (EGFR). Despite EGFR overexpression in up to 90% of HNSCC tumors and ample evidence supporting EGFR as a therapeutic target in HNSCC, the response rate for single-agent cetuximab is below 20%, and resistance to cetuximab-containing therapy remains a major obstacle in the effective treatment of HNSCC. Identification and targeting of mediators of cetuximab resistance is needed to improve patient outcomes. Secretion of the cytokine interleukin 6 (IL-6) has been proposed as a mechanism of resistance to cetuximab in HNSCC, and inhibition of signal transducer and activator of transcription 3 (STAT3), a downstream mediator of IL-6 signaling, has been shown to overcome cetuximab resistance in preclinical HNSCC models. Thus, we hypothesize that IL-6 signaling mediates resistance to cetuximab and that co-treatment with agents targeting the IL-6 pathway will enhance the therapeutic efficacy of cetuximab in HNSCC. We have generated cetuximab-resistant variants of the cetuximab-sensitive HNSCC cell lines Cal33 and PE/CA-PJ49. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis indicated that IL6 expression is increased 3.5- to 8-fold in cetuximab-resistant variants compared to the parental cells from which they were derived. In addition, a colony formation assay revealed that, as expected, cetuximab-treated parental cells formed fewer colonies than vehicle-treated cells, while cetuximab treatment had no effect on the ability of cetuximab-resistant PE/CA-PJ49 variants to form colonies. In contrast, treatment with tocilizumab, an IL-6 receptor-neutralizing monoclonal antibody, markedly reduced the colony-forming ability of the cetuximab-resistant variants, but not parental cells. These results suggest that targeted inhibition of IL-6 signaling may effectively inhibit proliferation in cetuximab-refractory HNSCC cells. Citation Format: Rachel A. O'Keefe, Neil Bhola, Toni M. Brand, Yan Zeng, Daniel E. Johnson, Jennifer R. Grandis. Targeting IL-6 signaling overcomes cetuximab resistance in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4108. doi:10.1158/1538-7445.AM2017-4108

Monocyte lineage–derived IL-6 does not affect chimeric antigen receptor T-cell function

Background aimsChimeric antigen receptor (CAR) T-cell therapy targeting CD19 has demonstrated remarkable success in targeting B-cell malignancies but is often complicated by serious systemic toxicity in the form of cytokine release syndrome (CRS). CRS symptoms are primarily mediated by interleukin 6 (IL-6), and clinical management has focused on inhibition of IL-6 signaling. The cellular source and function of IL-6 in CRS remain unknown. MethodsUsing co-culture assays and data from patients on our clinical CAR T-cell trials, we investigated the cellular source of IL-6, as well as other CRS-associated cytokines, during CAR T-cell activation. We also explored the effect that IL-6 has on T-cell function. ResultsWe demonstrated that IL-6 is secreted by monocyte-lineage cells in response to CAR T-cell activation in a contact-independent mechanism upon T-cell engagement of target leukemia. We observed that the presence of antigen-presenting cell–derived IL-6 has no impact on CAR T-cell transcriptional profiles or cytotoxicity. Finally, we confirm that CAR T cells do not secrete IL-6 in vivo during clinical CRS. DiscussionThese findings suggest that IL-6 blockade will not affect CD19 CAR T-cell-driven anti-leukemic cytotoxicity, permitting enhanced control of CRS while maintaining CAR T-cell efficacy.