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Improved efficacy against malignant brain tumors with EGFRwt/EGFRvIII targeting immunotoxin and checkpoint inhibitor combinations.

ABSTRACT: BACKGROUND:D2C7-IT is a novel immunotoxin (IT) targeting wild-type epidermal growth factor receptor (EGFRwt) and mutant EGFR variant III (EGFRvIII) proteins in glioblastoma. In addition to inherent tumoricidal activity, immunotoxins induce secondary immune responses through the activation of T cells. However, glioblastoma-induced immune suppression is a major obstacle to an effective and durable immunotoxin-mediated antitumor response. We hypothesized that D2C7-IT-induced immune response could be effectively augmented in combination with ?CTLA-4/?PD-1/?PD-L1 therapies in murine models of glioma. METHODS:To study this, we overexpressed the D2C7-IT antigen, murine EGFRvIII (dmEGFRvIII), in established glioma lines, CT-2A and SMA560. The reactivity and therapeutic efficacy of D2C7-IT against CT-2A-dmEGFRvIII and SMA560-dmEGFRvIII cells was determined by flow cytometry and in vitro cytotoxicity assays, respectively. Antitumor efficacy of D2C7-IT was examined in immunocompetent, intracranial murine glioma models and the role of T cells was assessed by CD4+ and CD8+ T cell depletion. In vivo efficacy of D2C7-IT/?CTLA-4/?PD-1 monotherapy or D2C7-IT+?CTLA-4/?PD-1 combination therapy was evaluated in subcutaneous unilateral and bilateral CT-2A-dmEGFRvIII glioma-bearing immunocompetent mice. Further, antitumor efficacy of D2C7-IT+?CTLA-4/?PD-1/?PD-L1/?Tim-3/?Lag-3/?CD73 combination therapy was evaluated in intracranial CT-2A-dmEGFRvIII and SMA560-dmEGFRvIII glioma-bearing mice. Pairwise differences in survival curves were assessed using the generalized Wilcoxon test. RESULTS:D2C7-IT effectively killed CT-2A-dmEGFRvIII (IC50 =?0.47?ng/mL) and SMA560-dmEGFRvIII (IC50 =?1.05?ng/mL) cells in vitro. Treatment of intracranial CT-2A-dmEGFRvIII and SMA560-dmEGFRvIII tumors with D2C7-IT prolonged survival (P =?0.0188 and P =?0.0057, respectively), which was significantly reduced by the depletion of CD4+ and CD8+ T cells. To augment antitumor immune responses, we combined D2C7-IT with ?CTLA-4/?PD-1 in an in vivo subcutaneous CT-2A-dmEGFRvIII model. Tumor-bearing mice exhibited complete tumor regressions (4/10 in D2C7-IT+?CTLA-4 and 5/10 in D2C7-IT+?PD-1 treatment groups), and combination therapy-induced systemic antitumor response was effective against both dmEGFRvIII-positive and dmEGFRvIII-negative CT-2A tumors. In a subcutaneous bilateral CT-2A-dmEGFRvIII model, D2C7-IT+?CTLA-4/?PD-1 combination therapies showed dramatic regression of the treated tumors and measurable regression of untreated tumors. Notably, in CT-2A-dmEGFRvIII and SMA560-dmEGFRvIII intracranial glioma models, D2C7-IT+?PD-1/?PD-L1 combinations improved survival, and in selected cases generated cures and protection against tumor re-challenge. CONCLUSIONS:These data support the development of D2C7-IT and immune checkpoint blockade combinations for patients with malignant glioma.

SUBMITTER: Chandramohan V

PROVIDER: S-EPMC6542114 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Improved efficacy against malignant brain tumors with EGFRwt/EGFRvIII targeting immunotoxin and checkpoint inhibitor combinations.

Chandramohan Vidyalakshmi V Bao Xuhui X Yu Xin X Parker Scott S McDowall Charlotte C Yu Yen-Rei YR Healy Patrick P Desjardins Annick A Gunn Michael D MD Gromeier Matthias M Nair Smita K SK Pastan Ira H IH Bigner Darell D DD

Journal for immunotherapy of cancer 20190529 1

<h4>Background</h4>D2C7-IT is a novel immunotoxin (IT) targeting wild-type epidermal growth factor receptor (EGFRwt) and mutant EGFR variant III (EGFRvIII) proteins in glioblastoma. In addition to inherent tumoricidal activity, immunotoxins induce secondary immune responses through the activation of T cells. However, glioblastoma-induced immune suppression is a major obstacle to an effective and durable immunotoxin-mediated antitumor response. We hypothesized that D2C7-IT-induced immune response ...[more]

PMID: 31142380

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Project description:Glioblastoma is the most aggressive malignant brain tumor among all primary brain and central nervous system tumors. The median survival time for glioblastoma patients given the current standard of care treatment (surgery, radiation, and chemotherapy) is less than 15 months. Thus, there is an urgent need to develop more efficient therapeutics to improve the poor survival rates of patients with glioblastoma. To address this need, we have developed a novel tumor-targeted immunotoxin (IT), D2C7-(scdsFv)-PE38KDEL (D2C7-IT), by fusing the single chain variable fragment (scFv) from the D2C7 monoclonal antibody (mAb) with the Pseudomonas Exotoxin (PE38KDEL). D2C7-IT reacts with both the wild-type epidermal growth factor receptor (EGFRwt) and EGFR variant III (EGFRvIII), two onco-proteins frequently amplified or overexpressed in glioblastomas. Surface plasmon resonance and flow cytometry analyses demonstrated a significant binding capacity of D2C7-IT to both EGFRwt and EGFRvIII proteins. In vitro cytotoxicity data showed that D2C7-IT can effectively inhibit protein synthesis and kill a variety of EGFRwt-, EGFRvIII-, and both EGFRwt- and EGFRvIII-expressing glioblastoma xenograft cells and human tumor cell lines. Furthermore, D2C7-IT exhibited a robust anti-tumor efficacy in orthotopic mouse glioma models when administered via intracerebral convection-enhanced delivery (CED). A preclinical toxicity study was therefore conducted to determine the maximum tolerated dose (MTD) and no-observed-adverse-effect-level (NOAEL) of D2C7-IT via intracerebral CED for 72 hours in rats. Based on this successful rat toxicity study, an Investigational New Drug (IND) application (#116855) was approved by the Food and Drug Administration (FDA), and is now in effect for a Phase I/II D2C7-IT clinical trial (D2C7 for Adult Patients with Recurrent Malignant Glioma, https://clinicaltrials.gov/ct2/show/NCT02303678). While it is still too early to draw conclusions from the trial, results thus far are promising.

Project description:PURPOSE:Lung cancer is one of the most common types of cancer, resulting in approximately 1.8 million deaths worldwide. Immunotherapy using checkpoint inhibitors has become standard of care in advanced non-small cell lung cancer (NSCLC), and there is increasing interest in further improving outcomes through combination with other therapeutics. This systematic review evaluates emerging phase III data on the efficacy and safety of checkpoint inhibitor combinations as first-line treatment for advanced NSCLC. MATERIALS AND METHODS:Published and presented literature was searched using the key search terms "non-small cell lung cancer" AND "checkpoint-inhibitors" (OR respective aliases) AND phase III trials. Seven randomized phase III clinical trials reporting outcomes on checkpoint inhibitor combinations in first-line advanced NSCLC were identified. RESULTS:Four first-line trials reported outcomes for checkpoint inhibitor combinations in nonsquamous NSCLC. Pembrolizumab-chemotherapy, atezolizumab-chemotherapy, and atezolizumab-bevacizumab-chemotherapy showed significantly improved overall survival compared with controls in patients with advanced nonsquamous epidermal growth factor receptor-negative (EGFR-)/ anaplastic lymphoma kinase gene (ALK)- NSCLC. Two trials reported outcomes for squamous NSCLC, with pembrolizumab-chemotherapy reporting significantly improved overall survival (OS) compared with chemotherapy. The combination of nivolumab-ipilimumab in all-comer histology failed to improve OS compared with histology appropriate chemotherapy in patients regardless of their tumor mutational burden status. Based on improved survival and safety, either pembrolizumab monotherapy or pembrolizumab-chemotherapy administered based on PD-L1 status and histology is a preferred treatment option. Outcomes for atezolizumab-bevacizumab-chemotherapy in EGFR+/ALK+ patients are promising and require further exploration. CONCLUSION:First-line checkpoint inhibitors added to standard therapies improve overall survival for nonsquamous EGFR-/ALK- and squamous advanced NSCLC. IMPLICATIONS FOR PRACTICE:Single-agent immune checkpoint inhibitors are now standard of care for advanced non-small cell lung cancer (NSCLC), and emerging data show that combining these agents with established chemotherapy further improves outcomes. The phase III KEYNOTE-189 and IMPower-130 trials showed significantly improved survival using this strategy for nonsquamous NSCLC, and the phase III KEYNOTE-407 trial showed similar results in squamous disease. Checkpoint inhibitor combinations are therefore an important new treatment option for first-line NSCLC. Programmed death ligand-1 expression may inform the use of checkpoint inhibitor combination therapy, and overall tumor mutation burden is also an emerging biomarker for this new treatment strategy.

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Improved efficacy against malignant brain tumors with EGFRwt/EGFRvIII targeting immunotoxin and checkpoint inhibitor combinations.

Publications

Improved efficacy against malignant brain tumors with EGFRwt/EGFRvIII targeting immunotoxin and checkpoint inhibitor combinations.

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