IL-6R Antagonist Research Articles

Chemical Synthesis and Antitumor Evaluation of Chikusetsusaponin IVa Butyl Ester and Its Analogues

AbstractChikusetsusaponin IVa butyl ester (CS-IVa-Be) is a triterpene saponin that acts as a novel IL6R antagonist for inducing breast cancer cell apoptosis. However, the structure–activity relationship for this class of saponins remains unclear. Here, we report a gram-scale synthesis of CS-IVa-Be and the efficient preparation of eight of its analogues. CS-IVa-Be was demonstrated to have significant antitumor activities against MDA-MB-231, HepG2, and A549 cells. When one of the sugar residues at either the 3-OH or 28-COOH position of CS-IVa-Be was cleaved, or the length of the alkyl chain on the d-glucuronic acid residue of CS-IVa-Be was changed, these analogues showed varied inhibitory activities against the cancer cell lines. Notably, the carboxylic acid form of CS-IVa-Be exhibited a stronger antitumor activity against MDA-MB-231 cells. Furthermore, the carboxylic acid form of CS-IVa-Be inhibited MDA-MB-231 cell proliferation in a dose-dependent manner by arresting the cell cycle at the G2/M phase.

Interleukin 6 exacerbates the progression of warm autoimmune hemolytic anemia by influencing the activity and function of B cells

To explore the effect of IL-6 on the activity and secretory function of B cells and analyze its effect on clinical indicators and efficacy in wAIHA patients. This study included 25 hemolytic wAIHA patients, 13 remission patients, and 10 HCs. Plasma levels of various cytokines were detected using CBA. PBMCs were extracted from 12 hemolytic wAIHA patients and divided into three wells, stimulation with IL-6 and IL-6 + tocilizumab, the blank control wells were also set. After 48 h of in vitro cell culture, percentage of CD5+CD80+, CD5–CD80+,CD5+CD86+,CD5–CD86+,CD5+IL-10+,CD5–IL-10+B cells were determined by flow-cytometry. Plasma levels of IL-6 and IL-10 in hemolytic episode group were significantly higher than that in HCs group (p = 0.0243; p = 0.0214). RBC and Hb levels were negatively correlated with IL-6 levels in wAIHA patients, while LDH levels were positively correlated.Therapeutic effects of glucocorticoid and duration of efficacy were also significantly correlated with IL-6 levels in wAIHA patients. After 48 h in vitro cell culture, percentages of CD80+/CD5+CD19+and CD80+/CD5–CD19+ cells in the IL-6 stimulation group were higher than those in blank control group (p = 0.0019; p = 0.0004), while CD86+/CD5+ CD19+ and CD86+/CD5–CD19+ cells were not statistically different before and after IL-6 stimulation. Percentage of IL-10+/CD5+ CD19+ cells in IL-6 stimulation group was lower than that in blank control (p = 0.0017) and IL-6 + toc (p = 0.0117) group. Percentage of IL-10+/CD5– CD19+cells in the IL-6 stimulation group was lower than that in the blank control group (p = 0.0223). Plasma levels of IL-6 were significantly elevated in hemolytic wAIHA patients and correlated with clinical indicators and efficacy. IL-6 promotes the activation of B cells. Although the results were not statistically significant, IL-6R antagonist tocilizumab may hopefully become a targeted therapy for wAIHA patients.

Targeting DCLK1 attenuates tumor stemness and evokes antitumor immunity in triple-negative breast cancer by inhibiting IL-6/STAT3 signaling

Triple-negative breast cancer (TNBC) exhibits the poorest outcomes among breast cancer subtypes due to the high heterogeneity and a lasting scarcity of effectual treatments. Targeted therapies based on molecular subtypes of TNBC are critical step toward tailoring treatments to improve clinical outcomes. Gastrointestinal cancer stem cell (CSC) marker DCLK1 was reported to be highly expressed in stem cell-rich subtype of TNBC. Here, we firstly explored the impacts of DCLK1 on tumor cells as well as their immune microenvironment in TNBC and potential therapeutic strategies for TNBC patients with high DCLK1 expression. Our results disclosed that DCLK1 overexpression promoted, while knockout of DCLK1 suppressed the CSC-like traits of TNBC cells and resistance to chemotherapeutics. Besides, DCLK1 supported immune escape by inhibiting intratumoral cytotoxic T cell infiltration in TNBC and hence limited immune checkpoint inhibitors efficacy. Mechanistically, bioinformatics analysis revealed that IL-6/STAT3 signaling was significantly enriched in high DCLK1-expressing patients, and our results further revealed that DCLK1 enhanced IL-6 expression and STAT3 activation in TNBC cells, which finally gave rise to upregulated CSC traits and suppressed CD8+ T-cell activity. Inhibiting IL-6/STAT3 pathway by IL-6R antagonist, Tocilizumab or STAT3 inhibitor, S31-201 could abolish DCLK1-promoted malignant phenotypes of TNBC cells. Finally, DCLK1 was identified to be specifically and highly expressed in the mesenchymal-like subtype of TNBC and targeting DCLK1 could improve chemotherapy efficacy and activate antitumor immunity. Overall, our study revealed the potential clinical benefits of targeting DCLK1 in TNBC treatment.

COVID-19 acute respiratory distress syndrome: A simulation study of the effects of combination therapy with tocilizumab and siltuximab.

AimsTo assess the potential of interleukin‐6 (IL‐6) signalling blockade in the lung to treat SARS‐CoV‐2 infection via model‐based simulation by exploring soluble IL‐6 receptor (sIL‐6R) sequestration by tocilizumab (TCZ) and IL‐6 sequestration by siltuximab (SIL).MethodsLiterature values of IL‐6, IL‐6 antagonist SIL, sIL‐6R, IL‐6R antagonist TCZ and their respective binding constants were used to develop a model to predict the impact of treatment on IL‐6 signalling. Models were used to generate simulated bronchoalveolar lavage fluid concentrations for normal subjects, subjects at risk of developing acute respiratory distress syndrome (ARDS), and subjects with ARDS under 4 conditions: without treatment; treatment with TCZ; treatment with SIL; and treatment with TCZ + SIL.ResultsWith TCZ intervention, IL‐6 levels are unaffected and sIL‐6R is reduced somewhat below the Normal case. IL‐6:sIL‐6R complex only slightly decreased relative to the no‐intervention case. With SIL intervention, sIL‐6R levels are unaffected and IL‐6 is greatly reduced below the Normal case. IL‐6:sIL‐6R complex is greatly decreased relative to the no‐intervention case. With TCZ + SIL intervention, IL‐6 and sIL‐6R levels are reduced below the Normal case and achieve suppression equivalent to monotherapy results for their respective targets. IL‐6:sIL‐6R complex reduction is predicted to be greater than that achieved with monotherapy. This reflects sequestration of both components of the complex and the nonlinear binding equilibrium.ConclusionCoadministration of both IL‐6 and IL‐6R sequestering products such as SIL and TCZ may be necessary to effectively treat COVID‐19 patients who have or are at risk of developing ARDS.

Sarilumab (IL-6R antagonist) in critically ill patients with cytokine release syndrome by SARS-CoV2.

Blocking IL-6 pathways with sarilumab, a fully human anti–IL-6R antagonist may potentially curb the inflammatory storm of SARS-CoV2. In the present emergency scenario, we used “off-label” sarilumab in 5 elderly patients in life-threatening condition not candidates to further active measures. We suggest that sarilumab can modulate severe COVID-19-associated Cytokine Release Syndrome.

Abstract 4231: Factors predictive of CAR T cell associated hemophagocytic lymphohistiocytosis (HLH)

Introduction: HLH is a T cell mediated inflammatory syndrome associated with immune activation and NK cell dysfunction. In the context of CAR T cells, HLH occurs in a subset of those with cytokine release syndrome (CRS), yet predisposing factors are not yet well established. Utilizing our ongoing phase I study of CD22/4-1BB CAR T cells in children and young adults with CD22+ B cell malignancies (NCT02315612), we evaluated patient and product characteristics to elucidate factors associated with HLH. Methods: We retrospectively reviewed multiple variables to identify correlates of HLH in those infused. Definitions for CRS and HLH are in Table 1. Multiple univariate analyses were performed to identify risk factors for HLH; variables with significance were incorporated into a multiple logistic regression model to predict those at risk of HLH-like CRS. Results: 52 of 60 (86.7%) treated subjects developed CRS; 21 (40.4%) of whom subsequently developed HLH. The following factors were associated with HLH: lower baseline blood and marrow NK% and higher CD3% cells; CD4/CD8 T cell selection (TCS) of the apheresis product (which increased CD3 and reduced NK cell populations); and higher IL18. Following infusion, distinct cytokine profiles and prolonged predominance of CD8 T cells distinguished those with HLH from those without it. Multiple logistic regression identified a) use of TCS, b) higher grade CRS and c) high baseline bone marrow T/NK ratio as most predictive of HLH; leading to a model with 75% sensitivity and 80% specificity. Conclusion: Our results provide novel insights into factors associated with CAR T cell related HLH and implicate preexisting T and NK cell populations, baseline cytokines, apheresis selection methodologies and CAR T cell expansion parameters in the pathophysiology. With a goal of earlier intervention to prevent HLH, the predictive model will be prospectively evaluated. Biologic correlative studies and assessment of generalizability in alternate CAR T cell constructs are planned. Citation Format: Daniel A. Lichtenstein, Seth M. Steinberg, Steven L. Highfill, Bonnie Yates, Ping Jin, Jianjian Jin, Sandhya Panch, Haneen Shalabi, David F. Stroncek, Terry J. Fry, Nirali N. Shah. Factors predictive of CAR T cell associated hemophagocytic lymphohistiocytosis (HLH) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4231.

GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts

AbstractChimeric antigen receptor T (CAR-T) cell therapy is a new pillar in cancer therapeutics; however, its application is limited by the associated toxicities. These include cytokine release syndrome (CRS) and neurotoxicity. Although the IL-6R antagonist tocilizumab is approved for treatment of CRS, there is no approved treatment of neurotoxicity associated with CD19-targeted CAR-T (CART19) cell therapy. Recent data suggest that monocytes and macrophages contribute to the development of CRS and neurotoxicity after CAR-T cell therapy. Therefore, we investigated neutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) as a potential strategy to manage CART19 cell–associated toxicities. In this study, we show that GM-CSF neutralization with lenzilumab does not inhibit CART19 cell function in vitro or in vivo. Moreover, CART19 cell proliferation was enhanced and durable control of leukemic disease was maintained better in patient-derived xenografts after GM-CSF neutralization with lenzilumab. In a patient acute lymphoblastic leukemia xenograft model of CRS and neuroinflammation (NI), GM-CSF neutralization resulted in a reduction of myeloid and T cell infiltration in the central nervous system and a significant reduction in NI and prevention of CRS. Finally, we generated GM-CSF–deficient CART19 cells through CRISPR/Cas9 disruption of GM-CSF during CAR-T cell manufacturing. These GM-CSFk/o CAR-T cells maintained normal functions and had enhanced antitumor activity in vivo, as well as improved overall survival, compared with CART19 cells. Together, these studies illuminate a novel approach to abrogate NI and CRS through GM-CSF neutralization, which may potentially enhance CAR-T cell function. Phase 2 studies with lenzilumab in combination with CART19 cell therapy are planned.

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.

IL6 blockade potentiates the anti-tumor effects of γ-secretase inhibitors in Notch3-expressing breast cancer.

Notch pathways have important roles in carcinogenesis including pathways involving the Notch1 and Notch2 oncogenes. Pan-Notch inhibitors, such as gamma secretase inhibitors (GSIs), have been used in the clinical trials, but the outcomes of these trials have been insufficient and have yielded unclear. In the present study, we demonstrated that GSIs, such as MK-0752 and RO4929097, inhibit breast tumor growth, but increase the breast cancer stem cell (BCSC) population in Notch3-expressing breast cancer cells, in a process that is coupled with IL6 induction and is blocked by the IL6R antagonist Tocilizumab (TCZ). IL6 induction results from inhibition of Notch3-Hey2 signaling through MK-0752. Furthermore, HIF1α upregulates Notch3 expression via direct binding to the Notch3 promoter and subsequently downregulates BCSCs by decreasing the IL6 levels in Notch3-expressing breast cancer cells. Utilizing both breast cancer cell line xenografts and patient-derived xenografts (PDX), we showed that the combination of MK-0752 and Tocilizumab significantly decreases BCSCs and inhibits tumor growth and thus might serve as a novel therapeutic strategy for treating women with Notch3-expressing breast cancers.

T-Cell Subsets in Rheumatoid Arthritis Patients on Long-Term Anti-TNF or IL-6 Receptor Blocker Therapy.

Data on the impact of biological therapies on the T-cell phenotype in rheumatoid arthritis are limited. Here, we prospectively measured the percentages of 15 circulating T-cell subtypes using flow cytometry. We obtained transversal and longitudinal data in 30 anti-TNF responders, 19 secondary anti-TNF nonresponders, and 43 IL-6R antagonist responders, before, 8 weeks and at least 6 months after biological therapy. Untreated RA patients and healthy controls were also included. The important findings are the following: (1) the proportion of regulatory T-cells (Tregs) which are decreased in untreated RA patients becomes normal in all long-term-treated groups; (2) in anti-TNF responders as well as in nonresponders, the frequencies of naïve CD4+ and CD8+ cells are lower, whereas those of proinflammatory Th1, Th2, and Th17 cells and HLA-DR+-activated cells are higher than those in untreated RA or healthy controls; (3) in IL-6R responders, Th1 proportion is decreased, while that of Th2 and Th17 is increased as compared to that in anti-TNF-treated patients and controls; (4) pending confirmation, a CD4CD69 ratio < 2.43 at baseline, could be useful to predict a good therapeutic response to anti-TNF therapy. This study provides comprehensive information regarding the long-term impacts of those biological therapies on the ecotaxis of T-cells in RA. The ClinicalTrials.gov registration number of our study is NCT03266822.

IL-34 Upregulated Th17 Production through Increased IL-6 Expression by Rheumatoid Fibroblast-Like Synoviocytes.

Rheumatoid arthritis (RA) is a chronic autoimmune disease which is characterized by synovial inflammation and cartilage damage for which causes articular dysfunction. Activation of fibroblast-like synoviocytes (FLS) is a critical step that promotes disease progression. In this study, we aimed to explore the effect of interleukin-34 (IL-34) on RA FLS as a proinflammatory factor and IL-34-stimulated FLS on the production of Th17. We found that serum IL-34 levels were increased compared to those of the healthy controls and had positive correlations with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), and anticyclic citrullinated peptide (CCP) antibody accordingly. CSF-1R was also highly expressed on RA FLS. The interaction of IL-34 and CSF-1R promoted a dramatic production of IL-6 by FLS through JNK/P38/NF-κB signaling pathway. Further, the IL-34-stimulated IL-6 secretion by RA FLS was found to upregulate the number of Th17. The treatment of IL-6R antagonist could attenuate the production of Th17 mediated by IL-34-stimulated RA FLS. Our results suggest that the increased IL-34 levels were closely related to the disease activity of RA. Additionally, the overexpression of IL-6 in the IL-34-stimulated FLS promoted the generation of Th17. Therefore, IL-34 was supposed to be involved in the pathogenesis of RA. The inhibition of IL-34 might provide a novel target for therapies of RA.

Interleukin 6 Is Not Made By Chimeric Antigen Receptor T Cells and Does Not Impact Their Function

Introduction:Anti-CD19 chimeric antigen receptor T cells (CART19) generate unprecedented complete response rates of up to 90% in relapsing/refractory acute lymphoblastic leukemia. Associated with this therapy is a multi-symptom toxicity known as cytokine release syndrome (CRS). Clinically CRS resembles macrophage activation syndrome (MAS), with a pattern of cytokines in serum coupled with other biomarkers (such as ferritin) and physical findings (fever, sudden organomegaly, confusion). Clinical interest has focused on interleukin-6 (IL-6), as blocking this pathway with tocilizumab (an IL-6R antagonist) has relieved the most life-threatening aspects of CRS in patients. Nothing is known, however, about the mechanism behind the triggering of CAR associated CRS/MAS nor the cellular sources of the toxic cytokines. This is a critical lack of knowledge, as each CAR product may result in a different CRS resulting in different clinical outcomes and management strategies. We sought to identify the cellular source of IL-6 and other MAS cytokines specifically during a 41BB CAR mediated CRS, and cross validate with investigations into patient peripheral blood PBMCs during CRS.Results: Using a xenograft model of a primary patient leukemia and CART19 from a patient that experienced Grade 4 CRS, we measured cytokine production in the serum of animals 3 and 7 days post CART19. While we could detect GMCSF, IL-2 and IFNg easily, IL-6 was not detected and the animals did not appear ill during this phase despite disease response. Given the clinical similarities of CRS to MAS, we performed co-culture of CART19 T cells, Nalm-6 leukemia and cells derived in vitro from peripheral blood monocytes (which were autologous to the CAR T cells) including immature dendritic cells (iDC), mature dendritic cells (mDC) and macrophages. Similar to the in vivo results, coculture of CART19 and Nalm-6 produced high levels of GMCSF, IFNg, IL-2 and IL-10 but no detectable IL-6 or IL-8. Only in the presence of the monocyte lineage antigen presenting cells (APCs) did we observe IL-6 and IL-8 release (more than 100 fold increase over controls). Transwell in vitro experiments separating CART19/Nalm-6 from the APCs showed the same pattern, indicating the CART19 mediated killing of target cells induces the IL-6 release from APCs in a contact independent manner. Nanostring RNA analysis of separated cell populations indicated that IL-6 and IL-8 are exclusively produced by APCs, not CART19 or Nalm-6 (Figure 1). Both CD107a degranulation and the total Nanostring RNA profile of CART19 was not different in the presence or absence of APCs, indicating that an MAS-like CRS is likely not part of CART19 efficacy. Finally, we analyzed the peripheral blood mononuclear cells of 18 patients receiving CART19 for pediatric ALL by Nanostring. Patients with Grade 4 CRS and only circulating T cells showed no IL-6 or IL-8 RNA, confirming in vivo that CART19 cells are not the cellular source of IL-6 during CRS. Unsupervised clustering of the Nanostring profiles also revealed four distinct gene signatures: one for patients with only circulating leukemic blasts, two for Grade 2-3 CRS that clustered separately and one for Grade 4 CRS (Figure 2).Conclusions: Here we demonstrate that IL-6 as part of CRS is produced by APCs and not T cells in response to CART19 mediated killing of leukemia, and that CART19 cells do not seem affected by the presence of CRS cytokines either in transcriptional profile or killing potential. This data provides the rationale for blocking this toxic cytokine before symptoms appear without changing CART19 efficacy, in addition to supporting a rapid Nanostring based profile to identify prospectively the patients at risk for Grade 4 CRS. [Display omitted] [Display omitted] DisclosuresBarrett:Novartis: Research Funding. Grupp:Novartis: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Pfizer: Consultancy.

Efficacy of Humanized CD19-Targeted Chimeric Antigen Receptor (CAR)-Modified T Cells in Children and Young Adults with Relapsed/Refractory Acute Lymphoblastic Leukemia

▪BackgroundTargeted immunotherapy with CTL019, CD19-specific chimeric antigen receptor (CAR)-modified T cells, can produce potent and sustained responses in children with relapsed/refractory acute lymphoblastic leukemia (ALL). However, a subset of patients has limited persistence, which can increase the risk of relapse. Most CAR single chain variable fragment (scFv) domains, including that of CTL019, are of murine origin; therefore, anti-mouse reactivity is one potential cause of immune-mediated rejection that may be overcome by fully human or humanized CAR designs. We developed a humanized anti-CD19 scFv domain and now report on treatment with humanized CD19-directed CAR T cells (CTL119).DesignA pilot/phase 1 study of CAR-modified T cells containing a humanized anti-CD19 scFv domain (CTL119) enrolled children and young adults with relapsed/refractory B-ALL with or without prior exposure to a CAR T cell product. Patients previously treated with CD19-specific CAR-modified T cells were eligible if they met 1 of 3 criteria: 1) CD19+ relapse 2) no response to prior CAR T cell therapy or 3) early B cell recovery indicating poor persistence of CAR T cells. Patient-derived T cells were transduced ex vivo with a lentiviral vector encoding a CAR composed of CD3z, 4-1BB, and humanized anti-CD19 scFv domains and activated/expanded with anti-CD3/CD28 beads. The humanized scFv domain was developed by grafting the complementary determining regions of both the heavy and light chains onto human germline acceptor frameworks. Patients received lymphodepletion with cyclophosphamide and fludarabine 1 week prior to infusion with CTL119.ResultsThirty children and young adults aged 29 mo-24 yr were infused with CTL119. Eighteen patients had received prior allogeneic stem cell transplant (SCT). Eleven patients who previously received murine-derived CD19-specific CAR-modified T cells (CTL019, n=7; other, n=4) were retreated for B cell recovery (n=5), CD19+ relapse (n=5), or no response to prior CAR T cells (n=1). CNS disease or other extramedullary disease was the indication for enrollment in 6 and 3 patients, respectively.At assessment 1 month after infusion, 26/30 patients (87%) achieved a complete response (CR), defined as morphologic remission with B cell aplasia. Of 11 patients previously treated with murine CD19-specific CAR-modified T cells, 7 (64%) achieved a CR at 1 month, 4 demonstrated no response. Multiparameter flow cytometry for minimal residual disease (MRD) was negative at a detection level of 0.01% in 5/7 responding patients. Two responding patients with positive MRD progressed to CD19+ relapse at 1.6 and 3 mo.In patients with no prior exposure to a CD19 CAR T cell product, MRD-negative CR was achieved in 19/19 patients (100%). One patient relapsed with CD19+ extramedullary disease at 2.8 mo. With a median follow-up of 4.2 mo (range, 1.0-14.1 mo) for all responding patients in both cohorts, 23/26 remain in remission with 1 proceeding to SCT in remission.B cell aplasia, a functional marker of CD19-targeted CAR T cell persistence, continued for 3 months or more in 11/18 patients with adequate follow-up: 1/6 retreatment, 10/12 CAR-naïve. Cytokine release syndrome (CRS) was observed in 28/30 patients and mild in most patients (grade 1, n=6; grade 2, n=18). Three patients experienced grade 3 CRS requiring supplemental oxygen or low-dose vasopressor support and 1 experienced grade 4 CRS requiring high-dose vasopressor and ventilatory support. Severe CRS was successfully managed with the IL6R antagonist tocilizumab in 3 patients. Neurologic toxicity included encephalopathy (n=5) and seizure (n=4) and was fully reversible.ConclusionIn the first study of humanized anti-CD19 CAR T cells, CTL119 induced remissions in children and young adults with relapsed/refractory B-ALL, including 64% of patients previously treated with murine CD19-directed CAR T cells and 100% of CAR-naïve patients. Further investigation into CAR T cell persistence and anti-CAR responses will be vital to improve durable remission rates in this highly refractory population. DisclosuresMaude:Novartis: Consultancy. Barrett:Novartis: Research Funding. Teachey:Novartis: Research Funding. Shaw:Novartis: Research Funding; Vitality Institute: Research Funding. Brogdon:Novartis: Employment. Scholler:Novartis: Patents & Royalties: Royalties, Research Funding. Marcucci:Novartis: Research Funding. Levine:GE Healthcare Bio-Sciences: Consultancy; Novartis: Patents & Royalties, Research Funding. Frey:Amgen: Consultancy; Novartis: Research Funding. Porter:Novartis: Patents & Royalties, Research Funding; Genentech: Employment. Lacey:Novartis: Research Funding. Melenhorst:Novartis: Research Funding. June:Novartis: Honoraria, Patents & Royalties, Research Funding; Celldex: Consultancy, Equity Ownership; Pfizer: Honoraria; Immune Design: Consultancy, Equity Ownership; Johnson & Johnson: Honoraria; Novartis: Honoraria, Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership. Grupp:Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy; Novartis: Consultancy, Research Funding.

Chikusetsusaponin IVa Butyl Ester (CS-IVa-Be), a Novel IL6R Antagonist, Inhibits IL6/STAT3 Signaling Pathway and Induces Cancer Cell Apoptosis.

The activation of IL6/STAT3 signaling is associated with the pathogenesis of many cancers. Agents that suppress IL6/STAT3 signaling have cancer-therapeutic potential. In this study, we found that chikusetsusaponin IVa butyl ester (CS-IVa-Be), a triterpenoid saponin extracted from Acanthopanas gracilistylus W.W.Smith, induced cancer cell apoptosis. CS-IVa-Be inhibited constitutive and IL6-induced STAT3 activation, repressed STAT3 DNA-binding activity, STAT3 nuclear translocation, IL6-induced STAT3 luciferase reporter activity, IL6-induced STAT3-regulated antiapoptosis gene expression in MDA-MB-231 cells, and IL6-induced TF-1 cell proliferation. Surprisingly, CS-IVa-Be inhibited IL6 family cytokines rather than other cytokines induced STAT3 activation. Further studies indicated that CS-IVa-Be is an antagonist of IL6 receptor via directly binding to the IL6Rα with a Kd of 663 ± 74 nmol/L and the GP130 (IL6Rβ) with a Kd of 1,660 ± 243 nmol/L, interfering with the binding of IL6 to IL6R (IL6Rα and GP130) in vitro and in cancer cells. The inhibitory effect of CS-IVa-Be on the IL6-IL6Rα-GP130 interaction was relatively specific as CS-IVa-Be showed higher affinity to IL6Rα than to LIFR (Kd: 4,910 ± 1,240 nmol/L) and LeptinR (Kd: 4,990 ± 915 nmol/L). We next demonstrated that CS-IVa-Be not only directly induced cancer cell apoptosis but also sensitized MDA-MB-231 cells to TRAIL-induced apoptosis via upregulating DR5. Our findings suggest that CS-IVa-Be as a novel IL6R antagonist inhibits IL6/STAT3 signaling pathway and sensitizes the MDA-MB-231 cells to TRAIL-induced cell death. Mol Cancer Ther; 15(6); 1190-200. ©2016 AACR.

Abstract 12186: Therapeutic Effects of Blockade of IL-6/gp130 Signaling in Pulmonary Arterial Hypertension

Background: Interleukin (IL)-6 has been linked to the prognosis of pulmonary arterial hypertension (PAH). However, precise contributions of IL-6 and its signaling system to PAH progression is still obscure. Objectives: To study pathogenic roles of IL-6 cis- and trans-signaling in experimental and human PAH and to evaluate the translational potential of IL-6 signaling inhibition. Methods: We examined the global expression pattern of key actors of the IL-6 signaling in human lung tissues, blood samples and cultured pulmonary artery-smooth muscle cells (PA-SMCs) of 10 controls and 10 idiopathic PAH (IPAH) patients. In addition, two complementary animal models of pulmonary hypertension (PH) have been studied: the monocrotaline and SU5416 plus chronic hypoxia rat models. Results: In IPAH, serum levels of IL-6 and soluble IL-6 receptors (sIL-6R) proteins were higher than in control subjects. We also found stronger immunoreactivity for IL-6R, p-STAT3 and myeloid leukemia-cell protein 1 (Mcl-1, a downstream target of IL-6) in the media of remodeled pulmonary arteries and cultured PA-SMCs of IPAH patients compared with controls. These abnormalities in the IL-6/IL-6R signaling were also histologically found in the two rat models. Consistent with these findings, we also found that IL-6 with or without sIL-6R could substantially increase p-STAT3 and the anti-apoptotic Mcl-1 protein in cultured IPAH PA-SMCs compared with control cells. These effects were totally abolished in the presence of IL-6R neutralizing antibodies and an IL-6R antagonist. Finally, we found that daily treatment with IL-6R antagonist started 1 week after a subcutaneous monocrotaline injection substantially attenuates the abnormal increase in p-STAT3 and Mcl-1 and regresses established PH. Conclusions: We demonstrate here that anti-IL-6R strategies may represent promising novels anti-proliferative and anti-inflammatory approaches for treatment of PAH.

CD19-Targeted 19-28z CAR Modified Autologous T Cells Induce High Rates of Complete Remission and Durable Responses in Adult Patients with Relapsed, Refractory B-Cell ALL

Background: Relapsed adult acute lymphoblastic leukemia (ALL) is associated with high reinduction mortality, chemotherapy resistance, and dismal prognosis with a median overall survival (OS) < 6 months and 5-year OS ≤10%. We have previously reported a high anti-tumor activity of autologous T cells genetically modified to express 19-28z chimeric antigen receptor (19-28z CAR) targeting CD19 in adult patients with CLL and ALL (Brentjens R et al. Blood 2011; Davila M et al. Sci Transl Med2014). Herein, for the first time, we further report the long-term outcome of our phase I clinical trial in adults with relapsed/refractory (R/R) ALL (NCT01044069) with analysis on potential predictive markers of response and neurological toxicities.Patients and Methods: Adult patients with R/R B-ALL were enrolled. Eligible patients underwent leukapheresis, and T cells were transduced with a retrovirus encoding a CAR construct composed of anti-CD19 scFV linked to CD28 and CD3ζ signaling domains (19-28z). All patients received lymphodepleting chemotherapy followed 2 days later by 1x106 – 3x10619-28z CAR T cells/kg. The primary objective of the study was to evaluate the safety and anti-tumor activity of 19-28z CAR T cells in ALL. Post-treatment minimal residual disease (MRD) was assessed at day 14-28 by multiparameter flow cytometry and deep sequencing in the bone marrow (BM) samples (Adaptive Biotech Corp.)Results: 24 patients have been treated. The median age was 56 years (range, 23-74). 6 patients (25%) had Ph+ B-ALL (T315I mutation in 2 patients), 6 patients (25%) had prior allogeneic hematopoietic stem cell transplant (allo-HSCT), and 11 patients (46%) had 3 or more prior lines of ALL therapy before receiving the 19-28z CAR T cell therapy.Of the 24 patients, 22 patients were evaluable for response. At the time of 19-28z CAR T cell infusion, 12 of 22 patients had morphologic disease (6 to 97% blasts in the BM) and the remaining 10 patients had MRD. Twenty out of 22 patients (91%) were in complete remission (CR) after 19-28z CAR T-cell infusion, and 18 of these 20 patients (90%) achieved an MRD-negative CR. Ten of the 13 transplant eligible patients (77%) successfully underwent allo-HSCT following the 19-28z CAR T cell therapy. As of July 1, 2014, the median follow-up was 7.4 months (range 1-34), with 13 patients having at least 6 months of follow-up. Responses appear durable with 6 patients remaining disease-free beyond 1 year (range 12.6 – 34 months). Median overall survial (OS) is 9 months. 5 patients relapsed during the follow-up, including 1 patient with CD19 negative relapse. Three of the relapsed patients were treated again with the 19-28z CAR T cells, and two patients achieved a second CR.Comparing responders to non-responders, no association was observed between response and age (<60 vs. ≥60), prior allo-HSCT, number of prior therapies, or pre-treatment blast percentage.While none of the 10 patients with MRD at the time of T cell infusion developed cytokine release syndrome (CRS), 9 of 13 patients with morphologic disease at the time of the T cell infusion developed CRS with or without neurological symptoms that required intervention with an IL-6R antagonist or corticosteroid. A detailed analysis of serum cytokines demonstrated a consistent peak of IL-6 (22.2 to 553-fold increase) immediately prior to the development of neurological toxicities. Based on these data, we have developed a multi-disciplinary CRS management algorithm for patients at high risk in order to reduce the severity of CRS and improve safety of the 19-28z CAR T cell therapy.Conclusions: While longer follow-up is needed to confirm the durability of the observed responses, the potent induction of MRD-negative responses and successful long-term outcomes, including subsequent allo-HSCT without apparent additional post-transplant toxicities, strongly support the use of 19-28z CAR T cells in adult patients with B-ALL. A temporal relationship between serum IL-6 levels and neurological toxicities indicates that early intervention with IL-6 directed therapy may be more effective in ameliorating neurological toxicities in patients with morphologic disease at the time of T-cell infusion. These findings will need to be evaluated systematically and confirmed in a larger phase 2 trial. DisclosuresPark:Juno Therapeutics: Research Funding. Riviere:Juno Therapeutics: Consultancy, scientific co-founders Other. Sadelain:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Brentjens:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other.

Pig Artery Patch Transplantation (Tx) as a Surrogate For Heart Tx in Baboons.

Background: Pig heart Tx in baboons is time-consuming, expensive, and associated with complications. Graft failure can result from the development of (i) elicited anti-pig antibodies or (ii) thrombotic microangiopathy in the graft. We have developed a simple substitute model of pig artery patch Tx and have compared the results with those following heart Tx. Methods: Baboons received artery patch Tx into the wall of the abdominal aorta) (Gp 1; n=28) or heterotopic heart Tx (Gp 2; n=17) from GTKO pigs (+/- transgenes aimed at complement or coagulation regulation [n=22] +/- T cell regulation [a human mutant MHC class II transactivator, CIITA, n=9]). Nine recipients (patch 4, heart 5) received no immunosuppressive therapy (IS). The remainder (patch 24, heart 12) received IS based on blockade of either the CD40:CD154 pathway (anti-CD154 or anti-CD40 mAbs) or the CD28:B7 pathway (CTLA4-Ig - abatacept or belatacept) or of both pathways (anti-CD40mAb+belatacept). Monitoring was by MLR, anti-pig IgM and IgG, histopathology, and various coagulation (platelet count, fibrinogen, D-dimer) and inflammatory (C-reactive protein, CRP) parameters. Results: In both models, (i) with no IS, grafts induced a significant T cell response; (ii) anti-CD154mAb prevented a T cell response, whereas CTLA4-Ig did not; and (iii) anti-CD40mAb+belatacept prevented T cell proliferative and elicited antibody responses and cellular infiltration of the graft. Expression of CIITA in a patch graft reduced the elicited antibody response. Despite heparin therapy, thrombocytopenia, fall in fibrinogen, and increases in D-dimer and CRP were documented in baboons with heart grafts that did not express a human coagulation-regulatory transgene, but only increases in D-dimer and CRP were seen after patch Tx. Treatment with anti-CD40mAb+belatacept did not prevent the rise of D-dimer or CRP in either model. An IL-6R antagonist prevented a rise in CRP after patch Tx. Conclusions: Outcomes of patch and heart Tx are similar. Expression of CIITA reduces the elicited antibody response to a patch graft. To replace anti-CD154mAb, blockade of both the CD28 and CD154 pathways is essential. Patch Tx provides some (but not all) information on the coagulation and inflammatory responses to a heart graft. IL-6R blockade may reduce the inflammatory response. DISCLOSURE:Ayares, D.: Employee, Revivicor.

Managing Cytokine Release Syndrome Associated With Novel T Cell-Engaging Therapies

Chimeric antigen receptor (CAR)-modified T cells and bispecific T cell-engaging antibodies have demonstrated dramatic clinical responses in recent clinical trials. The hallmark of these novel highly active immunotherapies is nonphysiologic T cell activation, which has correlated not only with greatly increased efficacy but also with notable toxicity in some cases. We and others have observed a cytokine release syndrome (CRS), which correlates with both toxicity and efficacy in patients receiving T cell-engaging therapies. In addition to elevations in effector cytokines, such as interferon-γ, cytokines associated with hemophagocytic lymphohistiocytosis or macrophage activation syndrome, such as interleukin (IL)-10 and IL-6, may also be markedly elevated. Whereas corticosteroids may control some of these toxicities, their potential to block T cell activation and abrogate clinical benefit is a concern. Detailed studies of T cell proliferation and the resultant immune activation produced by these novel therapies have led to more targeted approaches that have the potential to provide superior toxicity control without compromising efficacy. One approach we have developed targets IL-6, a prominent cytokine in CRS, using the IL-6R antagonist tocilizumab. We will review the pathophysiology and management options for CRS associated with T cell-engaging therapies.

THU0011 MIR-223 expression in serum and CD3+ peripheral cells of rheumatoid arthritis

BackgroundWe have recently demonstrated that miR-223 is up-regulated in peripheral blood and synovial CD3+T lymphocytes (TL) from Rheumatoid Arthritis (RA) patients compared to healthy controls (1,2) suggesting that miR-223 could...

Anti-IL-6 receptor antibody (tocilizumab): a B cell targeting therapy

Background and objectivesB cells function as regulatory cells by producing inhibitory cytokines such as transforming growth factor β (TGF-β) and interleukin 10 (IL-10). Human CD25high B cells were shown to...