Benedikt Wiestler

A vaccine targeting mutant IDH1 induces antitumour immunity

Monoallelic point mutations of isocitrate dehydrogenase type 1 (IDH1) are an early and defining event in the development of a subgroup of gliomas and other types of tumour. They almost uniformly occur in the critical arginine residue (Argu2009132) in the catalytic pocket, resulting in a neomorphic enzymatic function, production of the oncometabolite 2-hydroxyglutarate (2-HG), genomic hypermethylation, genetic instability and malignant transformation. More than 70% of diffuse grade II and grade III gliomas carry the most frequent mutation, IDH1(R132H) (ref. 3). From an immunological perspective, IDH1(R132H) represents a potential target for immunotherapy as it is a tumour-specific potential neoantigen with high uniformity and penetrance expressed in all tumour cells. Here we demonstrate that IDH1(R132H) contains an immunogenic epitope suitable for mutation-specific vaccination. Peptides encompassing the mutated region are presented on major histocompatibility complexes (MHC) class II and induce mutation-specific CD4+ T-helper-1 (TH1) responses. CD4+ TH1 cells and antibodies spontaneously occurring in patients with IDH1(R132H)-mutated gliomas specifically recognize IDH1(R132H). Peptide vaccination of mice devoid of mouse MHC and transgenic for human MHC class I and II with IDH1(R132H) p123-142 results in an effective MHC class II-restricted mutation-specific antitumour immune response and control of pre-established syngeneic IDH1(R132H)-expressing tumours in a CD4+ T-cell-dependent manner. As IDH1(R132H) is present in all tumour cells of these slow-growing gliomas, a mutation-specific anti-IDH1(R132H) vaccine may represent a viable novel therapeutic strategy for IDH1(R132H)-mutated tumours.

ATRX loss refines the classification of anaplastic gliomas and identifies a subgroup of IDH mutant astrocytic tumors with better prognosis

Mutation/loss of alpha-thalassemia/mental retardation syndrome X-linked (ATRX) expression has been described in anaplastic gliomas. The present study explored the role of ATRX status in the molecular classification of anaplastic gliomas and its impact on survival in the biomarker cohort of the NOA-04 anaplastic glioma trial. Patients (nxa0=xa0133) of the NOA-04 trial were analyzed for ATRX expression using immunohistochemistry. ATRX status was correlated with age, histology, isocitrate dehydrogenase (IDH), 1p/19q, alternative lengthening of telomeres (ALT) and O6-methylguanine-DNA methyltransferase (MGMT) status, and the trial efficacy endpoints. Loss of ATRX expression was detected in 45xa0% of anaplastic astrocytomas (AA), 27xa0% of anaplastic oligoastrocytomas (AOA) and 10xa0% of anaplastic oligodendrogliomas (AO). It was mostly restricted to IDH mutant tumors and almost mutually exclusive with 1p/19q co-deletion. The ALT phenotype was significantly correlated with ATRX loss. ATRX and 1p/19q status were used to re-classify AOA: AOA harboring ATRX loss shared a similar clinical course with AA, whereas AOA carrying 1p/19q co-deletion shared a similar course with AO. Accordingly, in a Cox regression model including ATRX and 1p/19q status, histology was no longer significantly associated with time to treatment failure. Survival analysis showed a marked separation of IDH mutant astrocytic tumors into two groups based on ATRX status: tumors with ATRX loss had a significantly better prognosis (median time to treatment failure 55.6 vs. 31.8xa0months, pxa0=xa00.0168, log rank test). ATRX status helps better define the clinically and morphologically mixed group of AOA, since ATRX loss is a hallmark of astrocytic tumors. Furthermore, ATRX loss defines a subgroup of astrocytic tumors with a favorable prognosis.

Distribution of TERT promoter mutations in pediatric and adult tumors of the nervous system

Hot spot mutations in the promoter region of telomerase reverse transcriptase (TERT) have recently been described in several human tumor entities. These mutations result in an upregulation of the telomerase complex activity and thus constitute a relevant mechanism for immortalization of tumor cells. Knowledge of the TERT promoter status in tumors is likely to be of interest for molecular classification and as a potential target for therapy. We, therefore, performed a systematic analysis of TERT promoter mutations in 1,515 tumors of the human nervous system and its coverings including 373 pediatric and 1,142 adult patients. We detected a total of 327 mutations. TERT promoter mutations were exceedingly rare in tumors typically encountered in pediatric patients. In entities typically encountered in adult patients TERT promoter mutations were strongly associated with older age (pxa0<xa00.0001). Highest mutation frequencies were detected in gliosarcomas (81xa0%), oligodendrogliomas (78xa0%), oligoastrocytomas (58xa0%), primary glioblastomas (54xa0%), and solitary fibrous tumors (50xa0%). Related to other molecular alterations, TERT promoter mutations were strongly associated with 1p/19q loss (pxa0<xa00.0001), but inversely associated with loss of ATRX expression (pxa0<xa00.0001) and IDH1/IDH2 mutations (pxa0<xa00.0001). TERT promoter mutations are typically found in adult patients and occur in a highly tumor type-associated distribution.

A Phase II, Randomized, Study of Weekly APG101+Reirradiation versus Reirradiation in Progressive Glioblastoma

Purpose: Preclinical data indicate anti-invasive activity of APG101, a CD95 ligand (CD95L)–binding fusion protein, in glioblastoma. Experimental Design: Patients (N = 91) with glioblastoma at first or second progression were randomized 1:2 between second radiotherapy (rRT; 36 Gy; five times 2 Gy per week) or rRT+APG101 (400 mg weekly i.v.). Patient characteristics [N = 84 (26 patients rRT, 58 patients rRT+APG101)] were balanced. Results: Progression-free survival at 6 months (PFS-6) rates were 3.8% [95% confidence interval (CI), 0.1–19.6] for rRT and 20.7% (95% CI, 11.2–33.4) for rRT+APG101 (P = 0.048). Median PFS was 2.5 (95% CI, 2.3–3.8) months and 4.5 (95% CI, 3.7–5.4) months with a hazard ratio (HR) of 0.49 (95% CI, 0.27–0.88; P = 0.0162) adjusted for tumor size. Cox regression analysis adjusted for tumor size revealed a HR of 0.60 (95% CI, 0.36–1.01; P = 0.0559) for rRT+APG101 for death of any cause. Lower methylation levels at CpG2 in the CD95L promoter in the tumor conferred a stronger risk reduction (HR, 0.19; 95% CI, 0.06–0.58) for treatment with APG101, suggesting a potential biomarker. Conclusions: CD95 pathway inhibition in combination with rRT is an innovative concept with clinical efficacy. It warrants further clinical development. CD95L promoter methylation in the tumor may be developed as a biomarker. Clin Cancer Res; 20(24); 6304–13. ©2014 AACR.

Association of overall survival in patients with newly diagnosed glioblastoma with contrast‐enhanced perfusion MRI: Comparison of intraindividually matched T1‐ and T2*‐based bolus techniques

To compare intraindividual dynamic susceptibility contrast (DSC) and dynamic contrast enhanced (DCE) MR perfusion parameters and determine the association of DCE parameters with overall survival (OS) with the established predictive DSC parameter cerebral blood volume (CBV) in patients with newly diagnosed glioblastoma.

Treatment of anaplastic glioma

Anaplastic gliomas have received increasing attention over the past years. As opposed to glioblastoma, where the focus has been on the evaluation of novel compounds (with mainly disappointing results), in anaplastic gliomas relevant progress was generated with genotoxic therapies and translational work on biomarkers. Anaplastic gliomas are classified using single biomarkers, namely isocitrate dehydrogenase (IDH) or the related CpG island methylator phenotype (CIMP), alpha-thalassemia/mental retardation syndrome X-linked (ATRX), telomerase reverse transcriptase (TERT), p53, 1p/19q, and O(6)-methylguanine DNA-methyltransferase (MGMT). With these molecular biomarkers, three main prognostically distinct groups have been defined: (i) CIMP-negative anaplastic gliomas, which have a similar prognosis as glioblastoma, (ii) CIMP-positive 1p/19q intact, and (iii) CIMP-positive 1p/19q codeleted gliomas. In the CIMP-negative, mainly IDH wild-type group, MGMT promoter methylation may be used to identify patients who benefit from alkylating chemotherapy. The mutually exclusive ATRX losses and 1p/19q codeletions are used to subcategorize anaplastic tumors with a mixed histology according to microscopic features. This eliminates the biological basis and clinical necessity for the diagnosis of mixed gliomas (anaplastic oligoastrocytomas). Retrospective long-term analysis of the EORTC 26951 and RTOG 9402 trials revealed that patients with tumors harboring 1p/19q codeletions benefit from addition of procarbazine, lomustine, and vincristine (PCV) chemotherapy to primary radiotherapy. RTOG 9402 suggests that this may be the case also for patients with 1p/19q intact tumors, but IDH mutation. Future developments in addition to the ongoing CATNON and CODEL trials, will focus on further refinement of the molecular predictors and development of treatments that not only increase survival but also maintain neurological function, cognition, and health-related quality of life.

Towards optimizing the sequence of bevacizumab and nitrosoureas in recurrent malignant glioma

AbstractnStudies on the monoclonal VEGF-A antibody bevacizumab gave raise to questions regarding the lack of an overall survival benefit, the optimal timing in the disease course and potential combination and salvage therapies. We retrospectively assessed survival, radiological progression type on bevacizumab and efficacy of salvage therapies in 42 patients with recurrent malignant gliomas who received bevacizumab and nitrosourea sequentially. 15 patients received bevacizumab followed by nitrosourea at progression and 27 patients vice versa. Time to treatment failure, defined as time from initiation of one to failure of the other treatment, was similar in both groups (9.6 vs. 9.2xa0months, log rank pxa0=xa00.19). Progression-free survival on nitrosoureas was comparable in both groups, while progression-free survival on bevacizumab was longer in the group receiving bevacizumab first (5.3 vs. 4.1xa0months, log rank pxa0=xa00.03). Survival times were similar for patients with grade III (nxa0=xa09) and grade IV (nxa0=xa033) tumors. Progression-free survival on bevacizumab for patients developing contrast-enhancing T1 progression was longer than for patients who displayed a non-enhancing T2 progression. However, post-progression survival times after bevacizumab failure were not different. Earlier treatment with bevacizumab was not associated with better outcome in this series. The fact that earlier as compared to later bevacizumab treatment does not result in a different time to treatment failure highlights the challenge for first-line or recurrence trials with bevacizumab to demonstrate an overall survival benefit if crossover of bevacizumab-naïve patients after progression occurs.

Inhibition of CD95/CD95L (FAS/FASLG) Signaling with APG101 Prevents Invasion and Enhances Radiation Therapy for Glioblastoma

CD95 (Fas/APO-1), a death receptor family member, activity has been linked to tumorigenicity in multiple cancers, including glioblastoma multiforme (GBM). A phase II clinical trial on relapsed glioblastoma patients demonstrated that targeted inhibition of CD95 signaling via the CD95 ligand (CD95L) binding and neutralizing Fc-fusion protein APG101 (asunercept) prolonged patient survival. Although CD95 signaling may be relevant for multiple aspects of tumor growth, the mechanism of action of APG101 in glioblastoma is not clear. APG101 action was examined by in vitro proliferation, apoptosis, and invasion assays with human and murine glioma and human microglial cells, as well as in vivo therapy studies with orthotopic gliomas and clinical data. APG101 inhibits CD95L-mediated invasion of glioma cells. APG101 treatment was effective in glioma-bearing mice, independently of the presence or absence of CD4 and CD8 T lymphocytes, which should be sensitive to CD95L. Combined with radiotherapy, APG101 demonstrated a reduction of tumor growth, fewer tumor satellites, reduced activity of matrix metalloproteinases (MMP) as well as prolonged survival of tumor-bearing mice compared with radiotherapy alone. Inhibiting rather than inducing CD95 activity is a break-of-paradigm therapeutic approach for malignant gliomas. Evidence, both in vitro and in vivo, is provided that CD95L-binding fusion protein treatment enhanced the efficacy of radiotherapy and reduced unwanted proinfiltrative effects by reducing metalloproteinase activity by directly affecting the tumor cells. Implications: APG101 (asunercept) successfully used in a controlled phase II glioblastoma trial (NCT01071837) acts anti-invasively by inhibiting matrix metalloproteinase signaling, resulting in additive effects together with radiotherapy and helping to further develop a treatment for this devastating disease. Mol Cancer Res; 16(5); 767–76. ©2018 AACR.

Impact of tapering and discontinuation of bevacizumab in patients with progressive glioblastoma.

Bevacizumab is frequently used in patients with progressive glioblastoma raising questions regarding frequency of treatments, dosage, duration of therapy and the possibility of tapering and discontinuation for selected patient groups. We retrospectively assessed the safety and outcome of tapering and discontinuation of bevacizumab therapy for reasons other than disease progression and toxicity in 19 patients with progressive glioblastoma receiving bevacizumab for at least 6xa0months. In 10 of the 19 patients tapering bevacizumab resulted in complete discontinuation and reinitiation after disease progression during halted treatment. As a comparison group 33 patients with bevacizumab for at least 6xa0months continuously dosed at 10xa0mg/kg every 2xa0weeks were selected. Age and Karnofsky performance status at start of bevacizumab were similar in both groups. Influenced by the selection process, progression-free survival (PFS) and overall survival (OS) were longer in the group receiving a tapered and discontinued bevacizumab regimen (PFS 22.7 versus 11.2xa0months, HR 0.33, p-valueu2009=u20090.01; OS 29.9 versus 15.5xa0months, HR 0.22, p-valueu2009=u20090.001) with a median time of discontinuation of 4.5xa0months (range: 1.9–44.2xa0months). Stable disease or partial response according to RANO at ≥3xa0months was achieved in 89u2009% of patients with reinitiated bevacizumab therapy after discontinuation. These data indicate that tapering and discontinuation of bevacizumab therapy for other reasons than progression is feasible without an increased risk for tumor rebound or unresponsiveness to reinitiated bevacizumab therapy.

Abstract LB-80: ATRX loss refines the classification of anaplastic glioma and is a favorable prognostic marker.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DCnnMutation / loss of ATRX expression has been described in anaplastic gliomas. The present study explored the role for ATRX status in the molecular classification of anaplastic gliomas and the impact of ATRX status on survival in the biomarker cohort of the NOA-04 trial.nnPatients (n=123) of the NOA-04 trial were analyzed for ATRX expression using immunohistochemistry. ATRX status was correlated with age, reference histology, IDH, 1p/19q and MGMT status, and the efficacy endpoints of the NOA-04 trial.nnLoss of ATRX expression was detected in 42% of anaplastic astrocytomas, 24% of anaplastic oligoastrocytomas and 10% of anaplastic oligodendrogliomas. It was restricted to IDH mutated tumors and almost mutually exclusive with 1p/19q co-deletion. Anaplastic oligoastrocytoma harboring ATRX loss shared a similar clinical course with anaplastic astrocytoma. Survival analysis showed a separation of IDH mutant tumors into two groups based on ATRX status: Tumors with ATRX loss have a significantly better prognosis (median time to treatment failure 1758 days [95% CI 1316 days - to not reached] vs. 968 days [95% CI 496 days - to not reached], log rank test, p = 0.0044). Independent of histological subtype, patients whose tumors harbored ATRX loss had a longer overall survival when initially treated with radiotherapy rather than with chemotherapy (p = 0.03).nnATRX status helps to re-classify oligoastrocytomas, since ATRX loss is a hallmark of astrocytic tumors. Furthermore, ATRX loss defines a subgroup of tumors with a favorable prognosis and predicts benefit from radiotherapy.nnCitation Format: Benedikt Wiestler, David Capper, Tim Holland-Letz, Andreas von Deimling, Stefan M. Pfister, Michael Platten, Michael Weller, Wolfgang Wick. ATRX loss refines the classification of anaplastic glioma and is a favorable prognostic marker. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-80. doi:10.1158/1538-7445.AM2013-LB-80