Regression of Glioblastoma after Chimeric Antigen Receptor T-Cell Therapy

Abstract

A patient with recurrent multifocal glioblastoma received chimeric antigen receptor (CAR)-engineered T cells targeting the tumor-associated antigen interleukin-13 receptor alpha 2 (IL13Rα2). Multiple infusions of CAR T cells were administered over 220 days through two intracranial delivery routes - infusions into the resected tumor cavity followed by infusions into the ventricular system. Intracranial infusions of IL13Rα2-targeted CAR T cells were not associated with any toxic effects of grade 3 or higher. After CAR T-cell treatment, regression of all intracranial and spinal tumors was observed, along with corresponding increases in levels of cytokines and immune cells in the cerebrospinal fluid. This clinical response continued for 7.5 months after the initiation of CAR T-cell therapy. (Funded by Gateway for Cancer Research and others; ClinicalTrials.gov number, NCT02208362 .).

Figure 1. Local Tumor Control after Intracavitary Delivery of IL13BBζ–Chimeric Antigen Receptor (CAR) T Cells

Panel A shows an overview of the intracavitary administration of six cycles of IL13BBζ–CAR T cells according to dose schedule 1 (see Table S1 in the Supplementary Appendix). CAR T cells were delivered through a Rickham catheter device into the right temporal–occipital region (tumor 1; red arrow) from day 56 to day 98 after enrollment, with 1 week of rest after cycles 3 and 6 for evaluation of safety and disease. MRI denotes magnetic resonance imaging, and PET positron-emission tomography. Panel B shows axial MRI (T₁-weighted with gadolinium enhancement) of the brain highlighting the site of the resected tumor at which the catheter was placed for delivery of CAR T cells (tumor 1 [T1]; yellow circles), as well as the resected-only tumor sites in the frontal lobe (tumors 2 and 3 [T2 and T3]; yellow arrowheads) and the sites of tumors that developed during the intracavitary treatment period (tumors 6 and 7 [T6 and T7]; orange arrowheads). The CAR T-cell injection site (T1) remained stable without evidence of disease recurrence, whereas other disease foci, including T6 and T7, which were adjacent to resected T2 and T3 but distant from the CAR T-cell injection site, continued to progress.

Figure 2. Regression of Recurrent Multifocal Glioblastoma, Including Spinal Metastases, after Intraventricular Delivery of IL13Rα2-Targeted CAR T Cells

Panel A shows an overview of intraventricular delivery (through a Rickham catheter device) of 10 cycles of IL13BBζ–CAR T cells into the right lateral ventricle (red arrow) from day 112 to day 298 after enrollment. The first five weekly intraventricular infusions were interrupted for 1 week for assessment of safety and disease after the third infusion (cycle 9), a break of 6 weeks occurred during manufacture of the second product (between cycle 11 and cycle 12), and the remaining five intraventricular infusions were administered once every 3 weeks. CT denotes computed tomography. Panels B through D show MRI with gadolinium enhancement and ¹⁸F-fluorodeoxyglucose PET images before infusions of IL13BBζ–CAR T cells and after cycle 16 of intraventricular therapy. Panel B shows sagittal MRI (top) and PET images (bottom) of the brain (tumors 6 and 7 [T6 and T7]; yellow arrowheads and circles). Panel C shows axial MRI of the brain (tumors 4, 5, and 7 [T4, T5, and T7]; yellow arrowheads). Panel D shows sagittal MRI (top) and coronal PET-CT (bottom) images of the spine (tumor 8 [T8]; yellow circles). Panel E shows the maximum lesion area for nonresected tumors 4 through 8 (T4 through T8) with their respective decreases over time. These decreases indicate regression of all intracranial lesions (tumors 4 through 7 [T4 through T7]) and spinal lesions (T8) after intraventricular therapy.

Figure 3. Cerebrospinal Fluid (CSF) Analysis of Immune-Cell Populations, CAR T-Cell Persistence, and Inflammatory Cytokines during Intraventricular Therapy

The use of the catheter device enabled evaluation of the CSF during the intraventricular treatment course. Samples of CSF were obtained just before and 1 to 2 days after each intraventricular infusion during cycles 7 through 11, and additional samples were collected 8 days after the cycle 9 infusion and 44 days after the cycle 11 infusion. Panel A shows the cell counts in the CSF over the intraventricular treatment course. These counts were elevated after each infusion (P = 0.009 calculated with the use of a ratio paired t-test comparing the infusion values before [day 0] and after [day 1 or day 2] each cycle). Flow-cytometric analysis of cell populations on day 2 of cycle 9 show evidence of CD19+ B cells, both CAR+ (i.e., CD19t+) and nonengineered CD3+ T cells, CD11b+CD15+ granulocytes, and CD14+CD11b+HLA-DR+ mature myeloid populations. Panel B shows the results of serial evaluation of the CD3+ T-cell population in the CSF for the presence of IL13BBζ–CAR T cells (i.e., CD19t+). CD3-gated cells from the CSF samples obtained at the indicated day of cycles 9, 10, and 11 were costained with CD19 and CD8 (top histograms). Percentages of CD3 cells that were CAR+ (CD19t+) were as follows: day 0 of cycle 9, 9.4%; day 2 of cycle 9, 3.7%; day 8 of cycle 9, 2.1%; day 1 of cycle 10, 0.7%; and day 1 of cycle 11, 1.1%. Percentages of immunoreactive cells were then used to calculate the numbers of total CD3+ T cells and CD19+ CD3+ cells (IL13BBζ–CAR T cells) per cubic millimeter of CSF at each time point. Because of low cell recovery in the CSF, the persistence of CAR T cells could not be evaluated for cycles 7 and 8 and day 0 of cycles 10 and 11. Panel C shows the factor change in cytokine levels with intraventricular treatment during cycles 7 through 11. Only cytokines that were assessed with the use of a multiplex assay and that had a change by a factor of 10 or more as compared with pretreatment levels at one or more time points are shown. Baseline values (on day 0 of cycle 7) used to calculate factor changes were as follows: interferon-γ, 8.2 pg per milliliter; tumor necrosis factor α (TNF-α), 1.6 pg per milliliter; interleukin-1 receptor α, 50.1 pg per milliliter; interleukin-2, 0.6 pg per milliliter; interleukin-5, 0.5 pg per milliliter; interleukin-10, 4.4 pg per milliliter; interleukin-6, 56.5 pg per milliliter; interleukin-8, 226.2 pg per milliliter; C-X-C motif chemokine ligand 10 (CXCL10), 161.4 pg per milliliter; CCR2, 1660.6 pg per milliliter; and C-X-C motif chemokine ligand 9 (CXCL9), 82.9 pg per milliliter (Table S4A in the Supplementary Appendix). For all cytokines except interleukin-1 receptor α and CCR2, P<0.05, calculated with the use of a ratio paired t-test comparing the infusion values before (day 0) and after (day 1 or day 2) all cycles in which 10 × 10⁶ CAR+ T cells were infused (cycles 8 through 11).