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ATIM-15. SUSTAINED COMPLETE RADIOGRAPHIC RESPONSE AND PROLONGED SYSTEMIC IMMUNE ACTIVATION IN A PATIENT WITH MGMT UNMETHYLATED MIDLINE GLIOBLASTOMA RECEIVING CMV pp65-LAMP RNA-PULSED DENDRITIC CELL VACCINES

ABSTRACT: 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.

SUBMITTER: Rahman M

PROVIDER: S-EPMC6846973 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Project description: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.

Project description:Abstract BACKGROUND Most patients with GBM & an unmethylated O-6-methylguanine-DNA methylase (MGMT) gene promoter, have a poor prognosis with approximately 20% of patients surviving to 2 years. Poor prognosis is likely related to factors including a highly immunosuppressive tumor microenvironment (TME). The TME in GBM is mainly composed of tumor associated macrophages (TAMs) & microglia. A subset of tumor-infiltrating macrophages characterized by expression of the angiopoietin receptor Tie2 (TEMs) have features of M2-TAMs, promote tumor angiogenesis & are infrequently found in normal organs. Tie2 is significantly upregulated upon homing to tumors. Gene therapy technology has allowed TEMs to be used as carriers for the local and tumor restricted release of interferon-α (IFN). IFN has antitumor effects, inhibits angiogenesis & modulates the immune system. Cell-based delivery of IFN into the TME by TEMs is expected to provide efficacy, taking advantage of pleiotropic anti-tumor effects & avoiding tolerability issues associated with systemic IFN treatment. We are currently conducting a Phase I/IIa clinical study in Milan (INCB & OSR) to evaluate this therapeutic approach (Temferon) in 21 patients with GBM & unmethylated MGMT promoter (EudraCT Number 2018-001404-11). Eligible patients are identified immediately after first surgical resection. After screening, harvesting of HSPCs occurs followed by 6 weeks of radiotherapy. Non-myeloablative conditioning consists of BCNU & thiotepa followed by administration of non-manipulated HSPCs and Temferon. RESULTS In Part A of the study, 3 cohorts of 3 patients will receive escalating doses of Temferon. After Part A, a single dose of Temferon will be studied in a further 12 patients (Part B). Criteria for study eligibility are the same for both Part A and Part B. Part A is ongoing with the first 2 patients recruited (June 2019) and Temferon is scheduled for administration. An update on the status and progress of the study will be provided.

Project description:Abstract Glioblastoma (GBM) is the most common and aggressive primary brain cancer. Current standard-of-care includes surgery, radiation and treatment with temozolomide (TMZ), however nearly all tumors recur and the prognosis for recurrent GBM is dismal. Resistance to TMZ is correlated with expression of the DNA repair enzyme O6-methylguanine-DNA-methyltransferase (MGMT), which is highly expressed in a majority of GBM tumors. Dianhydrogalactitol (VAL-083) is a first-in-class bi-functional DNA-targeting agent that exhibited activity against GBM in NCI-sponsored clinical trials both as a single agent and in combination with radiotherapy. VAL-083 readily crosses the blood-brain barrier and accumulates in brain tumor tissue. We have demonstrated that VAL-083 targets N7-Guanine and rapidly induces interstrand DNA cross-links, leading to DNA double-strand breaks, S/G2 cell-cycle arrest and cell death in GBM cell lines and GBM cancer stem cells (CSCs) in vitro. This unique N7-guanine targeting mechanism not only circumvents MGMT-mediated chemo-resistance but also maintains cytotoxic activity in cancer cells deficient in mismatch repair (MMR). These data suggest VAL-083 may offer a superior chemotherapeutic alternative in the treatment of MGMT-unmethylated or MMR deficient GBM. Here, we provide an update of ongoing clinical trials with VAL-083 in MGMT-unmethylated GBM: i) a single-arm, biomarker-driven, Phase II study to determine if VAL-083 treatment of MGMT-unmethylated adult GBM patients at first recurrence/progression, prior to bevacizumab improves survival compared to historical lomustine control (clinicaltrials.gov identifier: NCT02717962); ii) a single-arm, biomarker-driven, Phase II study to confirm the tolerability and efficacy of VAL-083 in combination with radiotherapy in newly diagnosed MGMT-unmethylated GBM patients (clinicaltrials.gov identifier: NCT03050736). The results of these studies may support a new treatment paradigm in for the treatment of MGMT-unmethylated GBM.

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ATIM-15. SUSTAINED COMPLETE RADIOGRAPHIC RESPONSE AND PROLONGED SYSTEMIC IMMUNE ACTIVATION IN A PATIENT WITH MGMT UNMETHYLATED MIDLINE GLIOBLASTOMA RECEIVING CMV pp65-LAMP RNA-PULSED DENDRITIC CELL VACCINES

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