BackgroundA major barrier to achieving effective therapies for patients with glioblastoma multiforme (GBM) is the phenotypic heterogeneity seen both between patients and within individual tumors, the ...later creating multiple cell subpopulations contributing to disease recurrence. One strategy for creating more efficacious therapies is to design novel immunotherapies targeting higher proportions of tumors and tumor cells than current options. Chlorotoxin (CLTX) is a 36-amino acid peptide component of scorpion venom that selectively binds to glioma cells of all malignancy grades while sparing normal brain cells and non-malignant tissues.1 2 With this understanding, we developed chimeric antigen receptor (CAR) T cells incorporating the CLTX peptide as a tumor-recognizing ligand, thereby redirecting T cells to target GBM cells and tumors.3 Preclinical studies suggested broad yet specific CLTX binding to patient-derived GBM cells. Preclinical data also suggested a role for cell surface matrix metalloproteinase-2 (MMP-2) in CLTX-CAR T cell activation.MethodsWe designed a non-randomized and dose escalating phase 1 trial evaluating intracavity/intratumoral (ICT) delivery of CLTX-CAR T cells to patients with recurrent/progressing GBM (NCT04214392; approved by the City of Hope National Medical Center protocol review committee, written consent obtained for leukapheresis and treatment), with the primary objectives of feasibility and safety.ResultsHere we report clinical outcomes and correlative observations for four lead-in research participants, all of whom had a histopathological diagnosis of glioblastoma, idh wild type, grade 4, and who had received prior temozolomide as well as radiation and other treatments. The key enrollment criterion was MMP-2 expression in tissue biopsies at levels greater than 20% (moderate and/or high expression) as assessed by immunochemistry. Participants received three infusions of 4, 20, and 20 x 10^6 CLTX-CAR T cells at weekly intervals. There were no CRS events or DLTs observed. Three of the four participants (75%) achieved stable disease. Participants survived a median of 5.75 months (min = 2.4, max = 20.5) after CAR T cell infusion. The presence of CLTX-CAR T cells in tumor fluid collected before and one day after each infusion indicated persistence of CLTX-CAR T cells. IgG1 was absent in these samples, suggesting non-immunogenicity of CLTX-CAR T cells despite the presence of the exogenous CLTX peptide.ConclusionsPhase 1 clinical observations to date confirm the feasibility and safety of CLTX-CAR T cell immunotherapy for patients with GBM. These studies will lead to determination of a maximum tolerated dose/maximum feasible dose.ReferencesLyons SA, O’Neal J, Sontheimer H. Chlorotoxin, a scorpion-derived peptide, specifically binds to gliomas and tumors of neuroectodermal origin. Glia. 2022;39:162–173.Veiseh M, Gabikian P, Bahrami SB, Veiseh O, Zhang M, Hackman RC, Ravanpay AC, Stroud MR, Kusuma Y, Hansen SJ, Kwok D, Munoz NM, Sze RW, Grady WM, Greenberg NM, Ellenbogen RG, Olson JM. Tumor paint: a chlorotoxin:Cy5.5 bioconjugate for intraoperative visualization of cancer foci, Cancer Res. 2007;67:6882–6888.Wang D, Starr R, Chang WC, Aguilar B, Alizadeh D, Wright SL, Yang X, Brito A, Sarkissian A, Ostberg JR, Li L, Shi Y, Gutova M, Aboody K, Badie B, Forman SJ, Barish ME, Brown CE. Chlorotoxin-directed CAR T cells for specific and effective targeting of glioblastoma. Sci Transl Med. 2020;12.Ethics ApprovalWe designed a non-randomized and dose escalating phase 1 trial evaluating intracavity/intratumoral (ICT) delivery of CLTX-CAR T cells to patients with recurrent/progressing GBM (NCT04214392; approved by the City of Hope National Medical Center protocol review committee, written consent obtained for leukapheresis and treatment), with the primary objectives of feasibility and safety.
BackgroundChimeric antigen receptor (CAR) T cell therapy is being explored in early-stage clinical trials as a strategy to improve treatment outcomes for high-grade gliomas (HGGs). We report here, a ...completed phase I trial (NCT02208362) evaluating locoregionally delivered IL13Rα2-targeted CAR T cells in 65 patients with recurrent HGG (rHGG), the majority being recurrent glioblastoma (rGBM).MethodsThis five-arm trial evolved to evaluate three routes of locoregional CAR T cell administration: (i) intratumoral (ICT) following tumor biopsy (Arm 1) or resection (Arm 2); (ii) intraventricular (ICV; Arm 3); and (iii) dual ICT/ICV (Arm 4). The final treatment arm (Arm 5) evaluated dual ICT/ICV delivery with a modified manufacturing process. Primary objectives were feasibility and safety. Secondary objectives evaluated therapy-related cytokine dynamics by cytometric bead array, CAR T cell persistence by flow cytometry and PCR, and clinical outcomes by radiographic imaging and survival. The pretreatment tumor immune landscape was evaluated by immunohistochemistry.ResultsFeasibility and safety were established for all three routes of locoregional CAR T cell delivery (ICT, ICV and dual ICT/ICV). IL13Rα2-CAR T cells were well-tolerated with clinically manageable adverse events at all dose levels, and no dose limiting toxicities observed. Stable disease or better was achieved in 50% of patients, with two partial responses, one complete response (CR), and a second CR after additional CAR T cycles off protocol therapy. Median overall survival (OS) for rGBM patients (68% treated at 2nd recurrence or later) was 7.7 mo. Post-hoc analysis revealed that Arm 5 rGBM patients exhibited the best median OS of 10.2 months, compared to 6.1 months for other treatment arms (Arms 1–4). Increase in inflammatory cytokines, including IFNγ, CXCL9, and CXCL10, was observed in the cerebrospinal (CSF) and tumor fluid after each infusion. Further, pre-treatment intratumoral CD3 T cell levels were positively associated with survival.ConclusionsWe report the largest CAR T cell clinical trial in brain tumors to date, assessing the feasibility, safety, and bioactivity of IL13Rα2-CAR T cells in rHGG. Key findings include: (1) repetitive locoregional administration of IL13Rα2-CAR T cells is feasible and safe, with clinical benefit observed in a subset of patients; (2) elevations in IFNγ-related chemokines in the CSF was associated with CAR T cell administration and bioactivity; and (3) tumor immune contexture was identified as a determinant of patient outcome to CAR T cell therapy. These findings advance our understanding of CAR T cell immunotherapy for malignant brain tumors.Ethics ApprovalThis study was conducted I accordance with the Institutional Review Board and Independent Ethics Committee at The City of Hope National Medical Center as well as the U.S. Food and Drug Administration (FDA). All subjects provided written informed consent.
Chimeric antigen receptor T cell (CAR-T) therapy is an emerging strategy to improve treatment outcomes for recurrent high-grade glioma, a cancer that responds poorly to current therapies. Here we ...report a completed phase I trial evaluating IL-13Rα2-targeted CAR-T cells in 65 patients with recurrent high-grade glioma, the majority being recurrent glioblastoma (rGBM). Primary objectives were safety and feasibility, maximum tolerated dose/maximum feasible dose and a recommended phase 2 dose plan. Secondary objectives included overall survival, disease response, cytokine dynamics and tumor immune contexture biomarkers. This trial evolved to evaluate three routes of locoregional T cell administration (intratumoral (ICT), intraventricular (ICV) and dual ICT/ICV) and two manufacturing platforms, culminating in arm 5, which utilized dual ICT/ICV delivery and an optimized manufacturing process. Locoregional CAR-T cell administration was feasible and well tolerated, and as there were no dose-limiting toxicities across all arms, a maximum tolerated dose was not determined. Probable treatment-related grade 3+ toxicities were one grade 3 encephalopathy and one grade 3 ataxia. A clinical maximum feasible dose of 200 × 10
CAR-T cells per infusion cycle was achieved for arm 5; however, other arms either did not test or achieve this dose due to manufacturing feasibility. A recommended phase 2 dose will be refined in future studies based on data from this trial. Stable disease or better was achieved in 50% (29/58) of patients, with two partial responses, one complete response and a second complete response after additional CAR-T cycles off protocol. For rGBM, median overall survival for all patients was 7.7 months and for arm 5 was 10.2 months. Central nervous system increases in inflammatory cytokines, including IFNγ, CXCL9 and CXCL10, were associated with CAR-T cell administration and bioactivity. Pretreatment intratumoral CD3 T cell levels were positively associated with survival. These findings demonstrate that locoregional IL-13Rα2-targeted CAR-T therapy is safe with promising clinical activity in a subset of patients. ClinicalTrials.gov Identifier: NCT02208362 .
