Interleukin-13 Receptor Alpha2 Research Articles

Identification and characterisation of novel CAR-T cells to target IL13Rα2 positive human glioma in vitro and in vivo.

Previously, we discovered that human solid tumours, but not normal human tissues, preferentially overexpress interleukin-13Receptor alpha2, a high binding receptor for IL-13. To develop novel anti-cancer approaches, we constructed a chimeric antigen receptor construct using a high binding and codon optimised scFv-IL-13Rα2 fragment fused with CD3ζ and co-stimulatory cytoplasmic domains of CD28 and 4-1BB. We developed a scFv clone, designated 14-1, by biopanning the bound scFv phages using huIL-13Rα2Fc chimeric protein and compared its binding with our previously published clone 4-1. We performed bioinformatic analyses for complementary determining regions (CDR) framework and residue analyses of the light and heavy chains. This construct was packaged with helper plasmids to produce CAR-lentivirus and transduced human Jurkat T or activated T cells from peripheral blood mononuclear cells (PBMCs) to produce CAR-T cells and tested for their quality attributes in vitro and in vivo. Serum enzymes including body weight from non-tumour bearing mice were tested for assessing general toxicity of CAR-T cells. The binding of 14-1 clone is to IL-13Rα2Fc-chimeric protein is ∼5 times higher than our previous clone 4-1. The 14-1-CAR-T cells grew exponentially in the presence of cytokines and maintained phenotype and biological attributes such as cell viability, potency, migration and T cell activation. Clone 14-1 migrated to IL-13Rα2Fc and cell free supernatants only from IL-13Rα2+ve confluent glioma tumour cells in a chemotaxis assay. scFv-IL-13Rα2-CAR-T cells specifically killed IL-13Rα2+ve but not IL-13Rα2-ve tumour cells in vitro and selectively caused significant release of IFN-γ only from IL-13Rα2+ve co-cultures. These CAR-T cells regressed IL-13Rα2+ve glioma xenografts in vivo without any general toxicity. In contrast, the IL-13Rα2 gene knocked-down U251 and U87 xenografts failed to respond to the CAR-T therapy. Taken together, we conclude that the novel scFv-IL-13Rα2 CAR-T cell therapy may offer an effective therapeutic option after designing a careful pre-clinical and clinical study.

EXTH-10. QUAD-DM1: A HIGHLY POTENT DRUG CONJUGATE FOR BREAST CANCER AND BREAST CANCER BRAIN METASTASIS TREATMENT

Abstract Triple-negative breast cancer (TNBC) remains an unmet need in medicine. Previously, we and others found that interleukin 13 receptor alpha 2 (IL-13RA2), EphA2, EphA3 and EphB2 receptors are over-expressed in almost all patients with glioblastoma (GBM). We performed a first-of-a-kind Phase I clinical trial in dogs with spontaneous gliomas using a cocktail of cytotoxins targeting IL-13RA2 and EphA2 receptor. The majority of dogs experienced >50% of tumor regression; four dogs exhibited >92% tumor shrinkage and several dogs became long-term survivors. Next, we pursued the novel idea of targeting four tumor-associated receptors, instead of two, with one pharmaceutical compound. To this end, we produced a multivalent ligand, termed QUAD. More recently, we found that a conjugate of QUAD with emtansine (DM1), a microtubule-disrupting agent, demonstrated a specific killing potency on GBM cells, in low picomolar range. Unexpectedly, we observed that human breast cancer cells are also highly responsive to this drug candidate. We thus examined the presence of the four receptors in breast cancer cells and tissue micro-arrays, including involved lymph nodes, and in paired primary tumor - brain metastases, spanning two molecular subtypes of breast cancer: TNBC and HER2+. We found that the four targeted receptors are expressed in almost all breast cancer and related metastases to brain specimens, based on the expression levels for the genes and the gene products. Furthermore, the breast cancer cell lines like HC1806, MDA-MB-468, MDA-MB-231, BT549, and the breast metastatic cell line MDA-MB-231-BRM cells are killed at up to picomolar concentrations of QUAD-DM1. MDA-MB-231 tumors growing in mammary pads of athymic mice responded significantly to QUAD-DM1 given intravenously; QUAD recognizes murine receptors similarly to human. Thus, QUAD-DM1 is a novel type of a multivalent drug conjugate for the treatment of breast cancer and its brain metastases, which is applicable, but not exclusively, to TNBC.

Bi-Specific Killer Cell Engager Enhances NK Cell Activity against Interleukin-13 Receptor Alpha-2 Positive Gliomas.

Glioblastoma (GBM) is a lethal brain tumor with limited therapeutic options. Bi-specific killer cell engagers (BiKEs) are novel immunotherapies designed to engage natural killer (NK) cells against cancer. We designed a BiKE molecule consisting of a single-domain CD16 antibody, an interleukin-15 linker, and a single-chain variable antibody against the glioma-associated antigen interleukin 13 receptor alpha 2 (IL13Rα2). Recombinant BiKE protein was expressed in HEK cells and purified. Flow cytometric analysis of co-cultures of peripheral blood-derived NK cells with GBM6 and GBM39 patient-derived xenograft lines revealed significantly increased activation of NK cells (CD25+CD69+) and increased glioma cell killing following BiKE treatment compared to controls (n = 4, p < 0.01). Glioma cell killing was also confirmed via immunofluorescence staining for cleaved caspase-3 (p < 0.05). In vivo, intracranial delivery of NK cells with BiKE extended median survival in mice bearing GBM6 (p < 0.01) and GBM12 (p < 0.01) tumors compared to controls. Finally, histological analysis of brain tissues revealed a higher frequency of peritumoral NK cells in mice treated with BiKE than with NK cells alone (p < 0.05). In conclusion, we demonstrate that a BiKE generated in a mammalian expression system is functional in augmenting NK cell targeting of IL13Rα2-positive gliomas.

205 Liquid Biopsy Biomarker for Differentiating Neurofibroma/Schwannoma From Other Solid Mass Mimics

INTRODUCTION: Interleukin13 receptor alpha 2 (IL13Ra2) is a high-affinity receptor for the interleukin 13 (IL13) cytokine. With the exception of the testes, in normal conditions, IL13Ra2 demonstrates little normal cell expression. Prior work in our laboratory has demonstrated that IL13Ra2 is expressed on benign and malignant peripheral nerve sheath tumors in sporadic and syndromic cases. We have shown in in vitro and in murine MPST models that the receptor can be utilized to facilitate the treatment of malignant peripheral nerve sheath tumors. While mice have membrane-bound and soluble forms of IL13Ra2, humans lack the soluble form. We have previously shown the detection of IL13Ra2 exosomes in the cerebrospinal fluid and plasma of patients with glioblastoma. METHODS: IL13Ra2 levels were obtained from plasma and tumor specimens of 17 patients with diagnoses of Schwannoma/Neurofibroma (n = 13) and Lipoma/AVM (n = 4). Plasma and Tumor specimens were collected pre-operatively on the day of tumor resection. Plasma levels of IL13Ra2 were measured with ELISA. The tumor specimen was placed in NP40 buffer for extraction then levels were measured with ELISA. RESULTS: The plasma level of IL13Ra2 is significantly elevated in patients with schwannoma/neurofibroma compared to patients with lipomas/AVMs. Increased level of IL13Ra2 in tumors correlates with the increased levels of IL13Ra2 in the plasma. CONCLUSIONS: Plasma level of IL13Ra2 has the potential for diagnosis and may serve as a liquid biopsy biomarker to help differentiate solid tumors like neurofibroma/schwannoma from lipomas /arteriovenous malformations.

Development of Nodular Lesions after Dupilumab Therapy in Erythrodermic Mycosis Fungoides with Interleukin-13 Receptor alpha2 Expression.

Abstract is missing (Short communication)

IMMU-06. COMBINATORIAL IMMUNE CHECKPOINT INHIBITORS FOR TARGETED INTRATUMORAL DELIVERY IN GBM

Abstract Glioblastoma (GBM) is an immunologically cold tumor. Using single cell sequencing of CD45+ cells we confirmed that T cells are present within GBM samples. These T cells are positive for exhaustion markers such as LAG3 and TIGIT, as well as CTLA4 and PD1 checkpoint receptors. Modulating T cell activity through use of immune checkpoint inhibitors (ICIs) has shown efficacy in the treatment of a variety of solid tumors, and the combination of anti-CTLA4 and anti-PD1 ICIs has shown increased efficacy over use of a single therapeutic. Additionally, targeting ICIs to the tumor cells may increase efficacy of this treatment. We therefore constructed a combinatorial ICI redirected to GBM via interleukin 13 receptor alpha 2 (IL13RA2), a receptor over-expressed on the majority of GBM cells but not normal brain. The first component of the construct, labeled with a histidine tag, targets CTLA4 while the second component, tagged with a StrepII tag, targets PD1. The tags added to the constructs will allow for purification of a combinatorial heterodimer simultaneously targeting PD1, CTLA4 and IL13RA2. We purified individual components via fast protein liquid chromatography (FPLC) using a proteinG column followed by a HisTrap or StrepTrap column. We obtained a recombinant, targeted multivalent ICI at &amp;gt; 95% purity. We found that these constructs are able to bind their target receptors via ELISA in which the Kd values ranged from picomolar to low nanomolar range. Additionally, our constructs bind their target on live cells by flow cytometry. We next designed a heterodimeric construct which can combinatorially target CTLA4 and PD1 while also directing the ICI therapy to GBM. These constructs in conjunction with other immune stimulants like cytotoxic therapies are intended to facilitate the interaction between T cells and GBM tumor cells directly in a tumor microenvironment.

EXTH-34. PHASE I TRIAL OF CONVECTION-ENHANCED DELIVERY OF IL13RA2 AND EPHA2 RECEPTOR TARGETED CYTOTOXINS IN DOGS WITH SPONTANEOUS INTRACRANIAL GLIOMAS

Abstract The interleukin 13 receptor alpha 2 (IL13RA2) and ephrin type-A receptor 2 (EPHA2) receptors are attractive therapeutic targets, being expressed in ~90% of canine and human gliomas, and absent in normal brain. Clinical trials using an earlier generation IL-13 based cytotoxin showed encouraging clinical effects in human glioma, but met with technical barriers associated with the convection enhanced delivery (CED) method. In this study, IL-13 mutant and Ephrin-A1 (EFNA1)-based bacterial cytotoxins targeted to IL13RA2 and EPHA2 receptors, respectively, were administered locoregionally by CED to dogs with intracranial gliomas to evaluate their safety and preliminary efficacy. In this Phase I, 3 + 3 dose escalation trial, cytotoxins were infused by CED in 17 dogs with gliomas expressing IL13RA2 or EPHA2 receptors. CED was performed using a shape-fitting therapeutic planning algorithm, reflux-preventing catheters, and real-time intraoperative MRI-monitoring. The primary end point was to determine the maximum tolerated dose of the cytotoxic cocktail in dogs with gliomas. Consistent intratumoral delivery of the cytotoxic cocktail was achieved, with a median target coverage of 70% (range, 40–94%). Cytotoxins were well tolerated over a dose range of 0.012–1.278 mg/mL delivered to the target volume (median, 0.099 mg/mL), with no dose limiting toxicities observed. Objective tumor responses, up to 94% tumor volume reduction, were observed in 50% (8/16) of dogs, including at least one dog in each dosing cohort &amp;gt;0.05 mg/mL. This study provides pre-clinical data fundamental to the translation of this multi-receptor targeted therapeutic approach to the human clinic.

A Novel Role of Interleukin 13 Receptor alpha2 in Perineural Invasion and its Association with Poor Prognosis of Patients with Pancreatic Ductal Adenocarcinoma.

Perineural invasion (PNI) is one of the major pathological characteristics of pancreatic ductal adeno-carcinoma (PDAC), which is mediated by invading cancer cells into nerve cells. Herein, we identify the overexpression of Interleukin-13 Receptor alpha2 (IL-13Rα2) in the PNI from 236 PDAC samples by studying its expression at the protein levels by immunohistochemistry (IHC) and the RNA level by in situ hybridization (ISH). We observe that ≥75% samples overexpressed IL-13Rα2 by IHC and ISH in grade 2 and 3 tumors, while ≥64% stage II and III tumors overexpressed IL-13Rα2 (≥2+). Interestingly, ≥36 % peripancreatic neural plexus (PL) and ≥70% nerve endings (Ne) among PNI in PDAC samples showed higher levels of IL-13Rα2 (≥2+). IL-13Rα2 +ve PL and Ne subjects survived significantly less than IL-13Rα2 –ve subjects, suggesting that IL-13Rα2 may have a unique role as a biomarker of PNI-aggressiveness. Importantly, IL-13Rα2 may be a therapeutic target for intervention, which might not only prolong patient survival but also help alleviate pain attributed to perineural invasion. Our study uncovers a novel role of IL-13Rα2 in PNI as a key factor of the disease severity, thus revealing a therapeutically targetable option for PDAC and to facilitate PNI-associated pain management.

Silencing of IL13RA2 promotes partial epithelial-mesenchymal transition in hepatocellular carcinoma via ERK signaling pathway activation.

Lack of insight into the mechanisms underlying hepatocellular carcinoma (HCC) metastasis has hindered the development of curative treatments. Overexpression of interleukin‐13 receptor alpha 2 (IL13RA2) has been reported to contribute to invasion and metastasis in several tumors. However, the role of IL13RA2 in HCC remains to be characterized. In this study, we identified that low expression of IL13RA2 is associated with poor survival of patients with HCC, and demonstrated that IL13RA2 knockdown endows HCC cells with invasive potential. Mechanistically, silencing of IL13RA2 promotes partial epithelial‐mesenchymal transition via increasing extracellular signal‐regulated kinase phosphorylation in HCC. Collectively, our results suggest that IL13RA2 may have potential as a prognostic biomarker for HCC.

B7-H3 as a Novel CAR-T Therapeutic Target for Glioblastoma

Glioblastoma (GBM) remains one of the most malignant primary tumors in adults, with a 5-year survival rate less than 10% because of lacking effective treatment. Here, we aimed to explore whether B7-H3 could serve as a novel therapeutic target for GBM in chimeric antigen receptor (CAR) T cell therapy. In this study, a CAR targeting B7-H3 was constructed and transduced into T cells by lentivirus. Antitumor effects of B7-H3-specific CAR-T cells were assessed with primary and GBM cell lines both in vitro and in vivo. Our results indicated that B7-H3 was positively stained in most of the clinical glioma samples, and its expression levels were correlated to the malignancy grade and poor survival in both low-grade glioma (LGG) and GBM patients. Specific antitumor functions of CAR-T cells were confirmed by cytotoxic and ELISA assay both in primary glioblastoma cells and GBM cell lines. In the orthotropic GBM models, the median survival of the CAR-T-cell-treated group was significantly longer than that of the control group. In conclusion, B7-H3 is frequently overexpressed in GBM patients and may serve as a therapeutic target in CAR-T therapy.

IL13RA2 Is Differentially Regulated in Papillary Thyroid Carcinoma vs Follicular Thyroid Carcinoma.

The interleukin-13 receptor alpha2 (IL13RA2), which is known to be overexpressed in glioblastoma multiforme, plays a role in various cellular processes such as cell migration that may contribute to tumor progression. Studies have attributed IL13RA2 to invasion and metastasis in cancers of the ovary, breast, and pancreas, but the pathological role of IL13RA2 in thyroid cancer is still unclear. This study aims to evaluate IL13RA2 expression in thyroid carcinomas and to examine the role of IL13RA2 in the progression of papillary thyroid carcinoma (PTC). IL13RA2 immunochemical staining was performed on tissue microarrays of 137 thyroid carcinomas from patients, and the differential profile of IL13RA2 was validated in thyroid cancer cell lines. In PTC cell lines, we functionally assessed the effects of IL13RA2 underexpression and overexpression on cell proliferation, cell migration, and epithelial-mesenchymal transition (EMT) by using CCK-8, transwell migration assay, quantitative RT-PCR, and Western blot analysis. IL13RA2 expression was significantly correlated with advanced tumor T stage (pT3 or pT4; P = 0.001) and regional lymph node metastasis (pN1; P < 0.001). The staining scores of IL13RA2 were significantly higher in PTC compared with follicular subtypes (P < 0.001) and correlated with advanced tumor stage among PTC samples (pT3 or pT4; P = 0.028). Knockdown of IL13RA2 in B-CPAP cells significantly reduced cell viability, cell migration, and EMT markers including N-cadherin, Vimentin, and Snail. Exogenous overexpression of IL13RA2 in K1 cells increased cell migration and EMT, although cell proliferation was not affected. IL13RA2 is differentially regulated in PTC and is involved in cell migration by enhancing EMT.

Abstract 2780: IL13RA2 is differentially regulated in papillary thyroid carcinoma versus follicular thyroid carcinoma

Abstract The interleukin-13 receptor alpha2 (IL13RA2), which is known to overexpressed in glioblastoma multiforme, plays a role in various cellular processes such as cell migration that may contribute to tumor progression. Studies have attributed IL13RA2 to invasion and metastasis in cancers of the ovary, breast, and pancreas but the pathological role of IL13RA2 in thyroid cancer is still unclear. This study aims to evaluate the expression of IL13RA2 in thyroid carcinomas and examine the role of IL13RA2 in progression of papillary thyroid cancer (PTC). We performed IL13RA2 immunochemical staining on tissue microarrays of 137 thyroid carcinomas and observed that IL13RA2 expression was significantly correlated with advanced tumor stage (pT3 / pT4; p=0.001) and regional lymph node metastasis (pN1; p&amp;lt;0.001). Moreover, the staining scores of IL13RA2 were significantly higher in PTC compared to follicular and anaplastic subtypes (p&amp;lt;0.02) and correlated with advanced tumor stage amongst PTC samples (pT3 / pT4; p=0.028). This differential profile of IL13RA2 in PTC was further validated in thyroid cancer cell lines overexpressing IL13RA2 to assay the effects on cell proliferation, cell migration and epithelial-mesenchymal transition (EMT) using CCK-8, transwell migration assay, qRT-PCR and western blot analyses. Knockdown of IL13RA2 in the PTC subtype B-CPAP cell line showed significantly reduced cell viability, cell migration and EMT markers including N-cadherin, Vimentin and Snail. Exogenous overexpression of IL13RA2 in another PTC cell line, K1 increased cell migration and EMT although cell proliferation was not affected. In summary, we demonstrated that IL13RA2 is differentially regulated in PTC and is involved in cell migration by enhancing EMT. The underlying molecular mechanisms on how IL13RA2 drives progression of thyroid cancer remains to be further investigated. Citation Format: Siao Ting Chong, Catherine Y. Kok, Khee Ming Tan, Shou Ping Guan, Siang Hui Lai, Cindy Lim, Jiancheng Hu, Charles Sturgis, Charis Eng, Paula Y. Lam, Joanne Ngeow. IL13RA2 is differentially regulated in papillary thyroid carcinoma versus follicular thyroid carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2780.

Receptor-Targeted Glial Brain Tumor Therapies.

Among primary brain tumors, malignant gliomas are notably difficult to manage. The higher-grade tumors represent an unmet need in medicine. There have been extensive efforts to implement receptor-targeted therapeutic approaches directed against gliomas. These approaches include immunotherapies, such as vaccines, adoptive immunotherapy, and passive immunotherapy. Targeted cytotoxic radio energy and pro-drug activation have been designed specifically for brain tumors. The field of targeting through receptors progressed significantly with the discovery of an interleukin 13 receptor alpha 2 (IL-13RA2) as a tumor-associated receptor over-expressed in most patients with glioblastoma (GBM) but not in normal brain. IL-13RA2 has been exploited in novel experimental therapies with very encouraging clinical responses. Other receptors are specifically over-expressed in many patients with GBM, such as EphA2 and EphA3 receptors, among others. These findings are important in view of the heterogeneity of GBM tumors and multiple tumor compartments responsible for tumor progression and resistance to therapies. The combined targeting of multiple receptors in different tumor compartments should be a preferred way to design novel receptor-targeted therapeutic approaches in gliomas.

Reduced expression of interleukin-13 receptor alpha2 promotes growth of hepatocellular carcinoma

Introduction: Interleukin-13 receptor alpha2 (IL13Rα2) has been reported to be associated with invasion and metastasis of digestive cancers including colorectal cancer and pancreatic cancer. However, little is known about its role on hepatocellular carcinoma (HCC). This study aims to investigate the effect of IL13Rα2 on the progression of HCC. Methods: Expression of IL13Rα2 was measured on 81 Human liver tissue samples, which were collected from patients received hepatectomy, by immunohistochemistry and on 14 HCC cell lines by western blot. Independents factors, overall survival (OS) and recurrence-free survival (RFS) of patients were compared between high-IL13Rα2 expression group and low-IL13Rα2 group.HepG2 and SMMC7721 HCC cell lines were selected to knock down IL13Rα2 expression by PLKO-Tet-On lentivirus. Cell Counting Kit-8 (CCK-8) assays and colony formation assays were performed on selected cell lines. HepG2-vector and HepG2-sh IL13Rα2 cells were used to perform in vivo tumorigenicity assay. Results: IL13Rα2 showed higher expression in adjacent-tumor tissues than tumor tissues (P< 0.001). Differentiation of HCC was the only independent factor associated with IL13Rα2 expression in tumor tissues (HR: 0.19, 95%CI: 0.067-0.538, P =0.002). No significant difference of OS and RFS were found between high-IL13Rα2 expression group and low-IL13Rα2 group. Knockdown of IL13Rα2 promoted growth of HepG2 and SMMC7721 cells. Subcutaneous tumors from HepG2-sh IL13Rα2 cells showed larger in volume and heavier in weight (P< 0.05), in comparison to their empty control. Conclusion: Our research clarified that reduced expression of IL13Rα2 promoted growth of hepatocellular carcinoma.

Abstract 1928: Identification of interleukin 13 receptor alpha 2 (IL-13Ra2) overexpression in LSL-KrasG12D/+, LSL-Try53R172H/+, and PDx-1-Cre (KPC) genetically engineered mouse model of pancreatic ductal adenocarcinoma as a target for receptor directed anticancer therapy

Abstract Pancreatic ductal adenocarcinoma (PDA) is a uniformly lethal disease because it escapes early diagnosis and at an advanced stage there are no effective therapies available. Previously, we have demonstrated that IL-13R α2 is overexpressed in 71% of human PDA specimens. We have targeted IL-13Rα2 in an orthotopic mouse model of human PDA and shown effectiveness of the receptor targeting agent, IL-13-PE, a recombinant immunotoxin comprised of IL-13 and Pseudomonas exotoxin. To determine the effectiveness of IL-13-PE and develop receptor targeting approaches, we used a LSL-KrasG12D/+, LSL-Try53R172H/+ and PDx-1-Cre (KPC) genetically engineered mouse model that spontaneously develops PDA in C57BL/6J immunocompetent mice and simulates human PDA disease. These spontaneous PDA tumors showed significant overexpression of IL-13R α2 mRNA compared to normal mouse pancreas and surrounding non-cancerous pancreatic tissues as determined by RT-qPCR. By in situ hybridization (ISH) and immunohistochemistry (IHC) analysis, we confirmed these results at mRNA and protein levels of tumor and non-tumor tissue specimens by hybridizing the tumor sections with biotinylated anti-sense riboprobe and immunostaining with anti-murine IL-13R α2 antibody. We established two tumor cell lines from KPC mice PDA, which maintained abundant expression of IL-13R α2 mRNA and protein levels. The overexpressed IL-13R α2 on PDA tumor cells is found biologically active, as it binds to IL-13-PE in a concentration dependent manner killing tumors cells at IC50 of ~25ng/ml (concentration of IL-13-PE that killed 50% of tumor cells). In a clonogenic assay, PDA tumor cells formed colonies, which were again sensitive to IL-13-PE in a concentration dependent manner with IC50 of ~28ng/ml. Based on these data, we have initiated assessment of anti-cancer activity of IL-13-PE against spontaneously developed PDA tumors developed in mice between the ages of 14-16 weeks. These mice were randomized to either receive excipient control i.p. or 50 µg/Kg IL-13-PE every alternate day for two weeks and then evaluated for general health and tumor growth by ultrasound technique. Five week follow up data reveal that mice treated with excipient alone developed larger tumors compared to treated mice and the general health of IL-13-PE treated mice was better compared to excipient-treated mice. These animals are being followed for their overall survival. Our studies indicate that IL-13R α2 is overexpressed in genetically engineered mouse model of PDA suggesting that IL-13R α 2 is a useful drug target not only in orthotopic mouse model but also in spontaneously developed PDA in mice, which may mimic its biological function more closely to human PDA. Citation Format: Akiko Suzuki, Pamela Leland, Bharat H. Joshi, Raj K. Puri. Identification of interleukin 13 receptor alpha 2 (IL-13Ra2) overexpression in LSL-KrasG12D/+, LSL-Try53R172H/+, and PDx-1-Cre (KPC) genetically engineered mouse model of pancreatic ductal adenocarcinoma as a target for receptor directed anticancer therapy [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 1928.

Phase 2 trial of SL-701 in relapsed/refractory (r/r) glioblastoma (GBM): Correlation of immune response with longer-term survival.

2058Background: SL-701 is a novel immunotherapy comprised of synthetic peptides designed to elicit an anti-tumor immune response against GBM targets: interleukin-13 receptor alpha-2, EphrinA2 and S...

Interleukin-13 receptor alpha 2 cooperates with EGFRvIII signaling to promote glioblastoma multiforme

The interleukin-13 receptor alpha2 (IL-13Rα2) is a cancer-associated receptor overexpressed in human glioblastoma multiforme (GBM). This receptor is undetectable in normal brain which makes it a highly suitable target for diagnostic and therapeutic purposes. However, the pathological role of this receptor in GBM remains to be established. Here we report that IL-13Rα2 alone induces invasiveness of human GBM cells without affecting their proliferation. In contrast, in the presence of the mutant EGFR (EGFRvIII), IL-13Rα2 promotes GBM cell proliferation in vitro and in vivo. Mechanistically, the cytoplasmic domain of IL-13Rα2 specifically binds to EGFRvIII, and this binding upregulates the tyrosine kinase activity of EGFRvIII and activates the RAS/RAF/MEK/ERK and STAT3 pathways. Our findings support the “To Go or To Grow” hypothesis whereby IL-13Rα2 serves as a molecular switch from invasion to proliferation, and suggest that targeting both receptors with STAT3 signaling inhibitor might be a therapeutic approach for the treatment of GBM.

ATIM-10. PHASE 2 TRIAL OF SL-701, A NOVEL IMMUNOTHERAPY COMPRISED OF SYNTHETIC SHORT PEPTIDES AGAINST GBM TARGETS IL-13Rα2, EphA2, AND SURVIVIN, IN ADULTS WITH SECOND-LINE RECURRENT GBM

SL-701, a novel immunotherapy comprised of synthetic peptides elicits immune responses against overexpressed GBM targets: interleukin-13 receptor alpha-2 (IL-13Rα2), EphrinA2 (EphA2), and Survivin. Updated data reported from a multicenter, 2-stage Phase 2 clinical trial of SL-701 in HLA-A2+ adults with relapsed GBM. Patients enrolled had KPS > 60 and failure of standard RT/TMZ. Stage 1: SL-701 was administered with adjuvants GM-CSF and imiquimod biweekly for 6 months, then q28 days. Stage 2: SL-701 and adjuvant poly-ICLC were administered biweekly with bevacizumab (10 mg/kg). Primary objectives include: safety and tolerability, investigator assessed objective response rate (ORR) using RANO criteria and 12 month-survival rate. As of 16May2017, 74 patients (46 in Stage 1 and 28 in Stage 2) received SL-701. Accrual for Stage 1 and 2 is complete. Patients were 100% bevacizumab naïve, 65% male with a median age of 56 years (range: 24–79). Patients received a median of 8.5 doses. The most frequent grade 3–4 treatment-related adverse event was fatigue (n = 2; 2.7%). Among 46 evaluable Stage 1 patients, 1 partial response (PR; duration: 78 weeks) and 15 stable disease (SD; median duration: 16 weeks; range: 1.3 – 99 weeks) were observed. Of 28 evaluable Stage 2 patients, 21% ORR consisting of 2 complete response (CR; duration: 30 and 46 weeks, respectively) and 4 PR (median duration: 31 weeks; range: 12 – 47 weeks) was observed with 19 SD (median duration: 14 weeks; range: 0.1 - 41 weeks) achieved. Median overall survival (mOS) of 11.2 and 11.7 months was observed for Stage 1 and 2 patients, respectively with a 25% survival probability at 14 weeks. SL-701 plus adjuvants with or without bevacizumab have a manageable safety profile with anti-tumor activity, several CRs, and a preliminarily promising survival curve, warranting further study. Updated study data will be presented.

IL13RA2 targeted alpha particle therapy against glioblastomas.

Glioblastoma (GBM) is the most aggressive primary malignant brain cancer that invariably results in a dismal prognosis. Chemotherapy and radiotherapy have not been completely effective as standard treatment options for patients due to recurrent disease. We and others have therefore developed molecular strategies to specifically target interleukin 13 receptor alpha 2 (IL13RA2), a GBM restricted receptor expressed abundantly on over 75% of GBM patients. In this work, we evaluated the potential of Pep-1L, a novel IL13RA2 targeted peptide, as a platform to deliver targeted lethal therapies to GBM. To demonstrate GBM-specificity, we radiolabeled Pep-1L with Copper-64 and performed in vitro cell binding studies, which demonstrated specific binding that was blocked by unlabeled Pep-1L. Furthermore, we demonstrated real-time GBM localization of [64Cu]Pep-1L to orthotopic GBMs using small animal PET imaging. Based on these targeting data, we performed an initial in vivo safety and therapeutic study using Pep-1L conjugated to Actinium-225, an alpha particle emitter that has been shown to potently and irreversibly kill targeted cells. We infused [225Ac]Pep-1L into orthotopic GBMs using convection-enhanced delivery and found no significant adverse events at injected doses. Furthermore, our initial data also demonstrated significantly greater overall, median and mean survival in treated mice when compared to those in control groups (p < 0.05). GBM tissue extracted from mice treated with [225Ac]Pep-1L showed double stranded DNA breaks, lower Ki67 expression and greater propidium iodide internalization, indicating anti-GBM therapeutic effects of [225Ac]Pep-1L. Based on our results, Pep-1L warrants further investigation as a potential targeted platform to deliver anti-cancer agents.

Expression of interleukin-13 and its receptors in mycosis fungoides

Objective To measure the expression of interleukin-13 (IL-13) and its receptors in mycosis fungoides (MF) lesions, and to investigate their clinical significance. Methods A total of 34 paraffin-embedded specimens of MF, which was confirmed by clinical and histopathological features, immunophenotyping and/or T-cell receptor gene rearrangements, were collected from Hangzhou Third People's Hospital between January 2010 and March 2016. According to the tumor-node-metastasis (TNM) staging system, 5 patients were at stageⅠA, 9 at stageⅠB, 17 at stageⅡA, and 3 at stageⅡB. Ten normal skin tissue specimens served as controls. Immunohistochemical study was conducted to measure the expression of IL-13, IL-13Rα1 and IL-13Rα2. Results IL-13, IL-13Rα1 and IL-13Rα2 were all expressed in atypical lymphoid cells and epidermotropic lymphoid cells in MF lesions at various stages. IL-13Rα2 was highly expressed in all the MF lesions. None of IL-13 and its receptors were expressed in normal skin tissues and lymphocytes. The expression rates of IL-13 and its receptors in MF lesions increased along with the progression of MF. Additionally, the expression rates of IL-13 (10.00% ± 3.14%) , IL-13Rα1 (21.43% ± 6.88%) and IL-13Rα2 (31.14% ± 6.38%) significantly decreased in MF lesions at stage Ⅰ compared with those at stageⅡ (27.50% ± 11.00%, 39.45% ± 9.43%, 44.40% ± 11.15%, respectively, all P 0.05) . Conclusion IL-13 and its receptors, especially IL-13Rα2, may be expected to serve as biomarkers for early diagnosis of MF and prediction of its biological behaviors. Key words: Mycosis fungoides; Cell transformation, neoplastic; Interleukin-13; Interleukin-13 receptor alpha1 subunit; Interleukin-13 receptor alpha2 subunit