Dataset Information

EPCT-14. GD2 CAR T-CELLS MEDIATE CLINICAL ACTIVITY AND MANAGEABLE TOXICITY IN CHILDREN AND YOUNG ADULTS WITH H3K27M-MUTATED DIPG AND SPINAL CORD DMG

ABSTRACT: Abstract

Background

We previously discovered high expression of the disialoganglioside GD2 on H3K27M+ gliomas and demonstrated preclinical efficacy of intravenous (IV) GD2-targeted chimeric antigen receptor (CAR) T-cells in preclinical models of H3K27M-mutated diffuse intrinsic pontine glioma (DIPG) and diffuse midline gliomas (DMGs). We are now conducting a Phase I clinical trial (NCT04196413) of autologous GD2-targeting CAR T-cells for H3K27M+ DIPG and spinal cord DMG. Here we present the results of subjects treated at dose level 1 (DL1; 1 million GD2-CAR T-cells/kg IV).

Methods

Four patients (3 DIPG, 1 spinal DMG; ages 4–25; 1M/3F) were enrolled at DL1. Three subjects with H3K27M+ DIPG received 1e6 GD2-CAR T-cells/kg IV on study. One patient with spinal DMG enrolled but became ineligible after manufacturing and was treated on an eIND at DL1. An Ommaya reservoir was placed in all subjects for therapeutic monitoring of intracranial pressure. Subjects underwent lymphodepletion with fludarabine/cyclophosphamide and remained inpatient for at least two weeks post-infusion.

Results

All subjects developed cytokine release syndrome (Grade 1–3) manifested by fever, tachycardia and hypotension. Other toxicities included ICANS (Grade 1–2) and neurological symptoms/signs mediated by intratumoral inflammation which we have termed Tumor Inflammation-Associated Neurotoxicity (TIAN). No evidence of on-target, off-tumor toxicity was observed in any patients. No dose-limiting toxicities occurred. CAR T cells trafficked to the CNS and were detected in CSF and blood. 3/4 patients exhibited marked improvement or resolution of neurological deficits and radiographic improvement. The patient treated on an eIND exhibited >90% reduction in spinal DMG volume but progressed by month 3. Re-treatment of this subject via intracerebroventricular administration resulted in a second reduction in spinal DMG volume by ~80%.

Conclusions

GD2-CAR T-cells at DL1 demonstrate a tolerable safety profile in patients with H3K27M+ DIPG/DMG with clear signs of T-cell expansion and activity including clinical responses.

SUBMITTER: Majzner R

PROVIDER: S-EPMC8168142 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Abstract Introduction We are conducting a Phase I clinical trial utilizing chimeric antigen receptor (CAR) T-cells targeting GD2 (NCT04196413) for H3K27M-mutant diffuse intrinsic pontine glioma (DIPG) and spinal cord diffuse midline glioma (DMG). Cerebrospinal fluid (CSF) is collected for correlative studies at the time of routine intracranial pressure monitoring via Ommaya catheter. Here we present single cell RNA-sequencing results from the first 3 subjects. Methods Single cell RNA-sequencing was performed utilizing 10X Genomics on cells isolated from CSF at various time points before and after CAR T-cell administration and on the CAR T-cell product. Output was aligned with Cell Ranger and analyzed in R. Results As detailed in the Majzner et al. abstract presented at this meeting, three of four subjects treated at dose-level one exhibited clear radiographic and/or clinical benefit. We have to date completed single cell RNA-sequencing for three of these four subjects (two with benefit, one without). After filtering out low-quality signals and doublets, 89,604 cells across 3 subjects were analyzed. Of these, 4,122 cells represent cells isolated from CSF and 85,482 cells represent CAR T-cell product. Two subjects who demonstrated clear clinical and radiographic improvement exhibited fewer S100A8+S100A9+ myeloid suppressor-cells and CD25+FOXP3+ regulatory T-cells in the CSF pre-infusion compared to the subject who did not derive a therapeutic response. In one subject with DIPG who demonstrated improvement, polyclonal CAR T-cells detectable in CSF at Day +14 demonstrated enrichment of CD8A, GZMA, GNLY and PDCD1 compared to the pre-infusion CAR T-cells by trajectory analysis, suggesting differentiation toward a cytotoxic phenotype; the same subject exhibited increasing numbers of S100A8+S100A9+ myeloid cells and CX3CR1+P2RY12+ microglia over time. Further analyses will be presented as data become available. Conclusions The presence of immunosuppressive myeloid populations, detectable in CSF, may correlate to clinical response in CAR T cell therapy for DIPG/DMG.

Project description:Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal central nervous system (CNS) tumors that occur most commonly in children and young adults1. Average life expectancy is ten months from diagnosis, and 5-year survival is less than 1%2. Palliative radiotherapy is the only established treatment3, and neither cytotoxic nor targeted pharmacological approaches have demonstrated anti-tumor responses or improved prognosis to date3,4. We previously discovered that the disialoganglioside GD2 is highly and uniformly expressed on H3K27M+ DMG cells and demonstrated that intravenously (IV) administered GD2.4-1BB.z chimeric antigen receptor (CAR) T-cells eradicated established DMGs in patient-derived orthotopic murine models5, thereby providing the rationale for a first-in-human/first-in-child Phase 1 clinical trial (NCT04196413). Because CAR T-cell-induced inflammation and edema of the brainstem can result in obstructive hydrocephalus, increased intracranial pressure, and dangerous tissue shifts, a number of neurocritical care precautions were incorporated in the clinical trial design and management plan. Here we present the clinical experience from the first four patients with H3K27M+ DMG treated with GD2-CAR T-cells at dose level 1 (DL1; 1e6 GD2-CAR T-cells/kg administered IV). Patients who exhibited clinical benefit were eligible for subsequent administrations of GD2-CAR T-cells. Given preclinical evidence for increased CAR T-cell potency6, and the potential for diminished immunogenicity with locoregional administration, second doses were administered intracerebroventricularly (ICV) through an Ommaya catheter to three patients. As predicted from preclinical models, toxicity was largely related to the neuroanatomical location of the tumors and was reversible with intensive supportive care. Although GD2 is expressed at low levels in normal neural tissue, no evidence of on-target, off-tumor toxicity was observed. Three of four patients exhibited clinical and radiographic improvement, underscoring the promise of this approach for H3K27M+ DMG therapy. Correlative studies of serum and CSF revealed marked proinflammatory cytokine production following GD2 CAR T cell administration and single cell transcriptomic analysis of 65,598 single cells from CAR T cell products and patient CSF has begun to reveal differences that correlate with the heterogeneity between subjects and routes of administration.

Project description:Abstract Effective treatments are urgently needed for the incurable paediatric brainstem tumour Diffuse Midline Glioma (DMG). Most DMGs contain Histone H3 mutations (H3K27M), which produce extensive epigenetic dysregulation by inhibiting EZH2-mediated trimethylation of H3K27 (H3K27me3). Global depletion of the repressive H3K27me3 modification results in aberrantly open chromatin and is central to DMG tumorigenesis. Thus, targeting the epigenome is a promising avenue of treatment for DMG. We found that targeting the histone chaperone complex Facilitates Chromatin Transcription (FACT) with the curaxin drug CBL0137 to have potent pre-clinical efficacy against DMG, leading to a paediatric Phase I/II clinical trial for CBL0137 which includes a DMG/DIPG cohort (NCT04870944). In this project we aim to elucidate CBL0137’s molecular mechanism in DMG. FACT is critical for maintaining chromatin homeostasis during DNA replication, transcription, and repair. We therefore hypothesised that FACT maintains the aberrant epigenetic landscape resulting from H3K27M. Consistently, we found CBL0137 to be more cytotoxic against H3K27M-mutant, compared to H3-WT or isogenic DMG cells lacking the mutation. Furthermore, FACT directly interacts with H3K27M, and FACT inhibition increases both EZH2 catalytic activity and global H3K27me3 levels. We are now using ChIP-seq to discover the genome-wide distribution of FACT and H3K27M, and will interrogate the consequence of CBL0137 treatment on the epigenome and transcriptome. Preliminary results suggest that FACT is located at certain genes co-occupied by H3K27M, the active histone mark H3K27ac, and the BET protein BRD4. This implies that FACT is involved in maintaining open chromatin and perhaps transcription at these regions. Combining CBL0137 with other epigenetic drugs, such as BET inhibitors, could therefore represent a rational therapeutic opportunity for DMG. This work will ultimately inform mechanism-based targeted therapies to combine with CBL0137 to improve its efficacy and uncover valuable new insights into DMG epigenetics and pathobiology.