Dataset Information

CTIM-29. CRUCIAL APPLICATION OF SINGLE CELL GENE EXPRESSION FOR MONITORING CHANGES IN GLIOBLASTOMA PATIENTS WITH SUSTAINED RADIOGRAPHIC RESPONSE TO CMV pp65-LAMP RNA-PULSED DENDRITIC CELL-BASED VACCINES

ABSTRACT: Abstract

BACKGROUND

The application of single cell sequencing as a novel immune monitoring platform can be used to identify the molecular mechanisms of immune response to dendritic cell- based vaccines, trace the cell types and states involved, and uncover novel biomarkers for immunotherapy. We applied single-cell RNA Seq analysis of longitudinal peripheral blood mononuclear cells (PBMCs) in patients with newly-diagnosed GBM enrolled on the ATTAC II clinical trial (FDA IND BB-16530; Clinicaltrials.gov # NCT02465268) who experienced a sustained radiographic response to autologous CMV pp65-LAMP RNA-pulsed DC vaccines plus GM-CSF and tetanus-diphtheria booster administered during adjuvant cycles of dose-intensified temozolomide.

METHODS

We constructed 5’ gene expression libraries and T cell receptor enriched libraries for 10x Genomics single-cell 5’ and VDJ sequencing, generated from PBMCs collected prior to and during patient immunization using dendritic cells loaded with messenger ribonucleic acid encoding the human cytomegalovirus (CMV) matrix protein pp65 conjugated with the lysosomal associated membrane protein (LAMP) sequence.

RESULTS

Overall, we sequenced a total of 189,808 single-cell transcriptomes from 5 patients. We leveraged these transcriptome-wide features to distinguish 15 peripheral immune cell subtypes in tested PBMCs. Analysis revealed dynamic changes in immune cell subsets over the course of first three vaccines, including increases in cytotoxic CD8 T cells, CD4 T cells, and NK cell subsets. Increased markers of T cell activation were observed during vaccination. Surprisingly, we observed a very high-level frequency of natural killer T (NKT) cells in the patient with a complete durable response compared to other patients. After three DC vaccines, the level of NKT cells in PBMC of this patient increased up to 10%.

CONCLUSIONS

These results emphasize the importance of subset specific profiling to achieve higher resolution in monitoring immune responses compared with bulk expression profiling in patients receiving immunotherapeutic treatment.

SUBMITTER: Yegorov O

PROVIDER: S-EPMC7650444 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Abstract BACKGROUND We initiated a Phase 2, randomized, placebo-controlled, clinical trial evaluating the efficacy of autologous CMV pp65-LAMP RNA pulsed dendritic cell vaccines mixed with GM-CSF and administered during cycles of adjuvant dose-intensified temozolomide (ATTAC II, NCT02465268). STUDY OBJECTIVE A patient with partially resected GBM experienced a sustained complete radiographic response after receiving five DC vaccines. Peripheral blood responses were characterized to examine possible immunologic biomarkers concordant with a sustained clinical response. METHODS Patients with newly diagnosed glioblastoma undergoing surgical resection are eligible and randomized 2:1 to DC vaccine arms vs placebo (PBMCs in saline). DC vaccines consist of CMV pp65 RNA conjugated either to the full-length lysosomal associated membrane protein (LAMP) or to the short LAMP signal sequence. Patients undergo leukapheresis for DC generation prior to standard chemoradiation and receive cycle 1 of dose-intensified temozolomide (100 mg/m^2 x 21 days) before first three biweekly intradermal DC vaccines admixed with GM-CSF. Subsequent DC vaccines (total of 10) are given monthly with each diTMZ cycle with an intradermal tetanus-diphtheria booster given 6-24hrs before the third, fifth, seventh, and ninth DC vaccines. PBMCs and serum are collected for immune monitoring. RESULTS A 58-year old white male with partially-resected, MGMT-unmethlyated, p53 mutant, H3.3 mutant, midline glioblastoma was enrolled on the ATTAC II study and experienced a complete radiographic response after the fifth DC vaccine that has been sustained > 10 months. Immune monitoring by Elispot, cytokine array, and single-cell RNA sequencing have revealed significant expansion of CMV pp65-specific immune responses, increased circulating IFNg, and marked systemic expansion of cytotoxic T cells and iNKT cells during vaccination. These responses were sustained through cycles of diTMZ despite profound lymphopenia. CONCLUSIONS CMV pp65-LAMP RNA-pulsed DC vaccination was associated with profound immunologic and clinical response in a patient with MGMT unmethylated midline glioblastoma.

Project description:Abstract INTRODUCTION The cytomegalovirus (CMV) antigen, pp65, is ubiquitously expressed in malignant glioma and medulloblastoma but not in healthy brain. The objective of this Phase I trial (NCT03299309) was to assess the safety and feasibility of a novel pp65 peptide vaccine (PEP-CMV) in children and young adults with recurrent medulloblastoma and malignant glioma. METHODS Vaccines contain a synthetic long peptide (SLP) of 26 amino acids encoding multiple potential class I, class II, and antibody epitopes of CMV pp65 across several haplotypes. This SLP is administered as an emulsion in Montanide ISA 51. Patients receive a single course of temozolomide to induce lymphopenia, tetanus/diphtheria toxoid site preconditioning, then vaccines administered intradermally every two weeks for 3 doses, then monthly. RESULTS To date, 17 patients have been enrolled. Diagnoses include medulloblastoma (n=1), glioblastoma (n=9), anaplastic oligodendroglioma (n=2), anaplastic astrocytoma (n=2), and malignant glioma NOS (n=3). Mean number of prior treatment regimens is 4.9 (range 1–12). Mean age is 22yo (range 6–35) and 41% of patients are male. The median KPS is 80. The median number of vaccines given at time of analysis is 3.3 (range 1–12). There have been no ? 3 Grade toxicities related to the vaccine. One patient developed nausea, vomiting, palpitations, and tachycardia after vaccination and had elevated inflammatory cytokines consistent with cytokine release syndrome. Median PFS is 2.5 months (95% CI: 0.8, not estimable) and median OS is 6.5 months (95% CI 1.8, not estimable). Interim analysis of immune monitoring bloodwork and perfusion MRI to quantify responses to PEP-CMV has been delayed due to COVID-19. However, adults with GBM who received PEP-CMV (NCT02864368) had significant (p?0.05) increases in GCSF, GM-CSF, IFN-?, IL-10, IL-2, IL-8, MIP1-?, and TNF-? levels. CONCLUSIONS Preliminary results demonstrate that PEP-CMV is feasible and well-tolerated in heavily pretreated, multiply recurrent patients.