Daniel Krell

Screen for IDH1, IDH2, IDH3, D2HGDH and L2HGDH Mutations in Glioblastoma

Isocitrate dehydrogenases (IDHs) catalyse oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG). IDH1 functions in the cytosol and peroxisomes, whereas IDH2 and IDH3 are both localized in the mitochondria. Heterozygous somatic mutations in IDH1 occur at codon 132 in 70% of grade II–III gliomas and secondary glioblastomas (GBMs), and in 5% of primary GBMs. Mutations in IDH2 at codon 172 are present in grade II–III gliomas at a low frequency. IDH1 and IDH2 mutations cause both loss of normal enzyme function and gain-of-function, causing reduction of α-KG to D-2-hydroxyglutarate (D-2HG) which accumulates. Excess hydroxyglutarate (2HG) can also be caused by germline mutations in D- and L-2-hydroxyglutarate dehydrogenases (D2HGDH and L2HGDH). If loss of IDH function is critical for tumourigenesis, we might expect some tumours to acquire somatic IDH3 mutations. Alternatively, if 2HG accumulation is critical, some tumours might acquire somatic D2HGDH or L2HGDH mutations. We therefore screened 47 glioblastoma samples looking for changes in these genes. Although IDH1 R132H was identified in 12% of samples, no mutations were identified in any of the other genes. This suggests that mutations in IDH3, D2HGDH and L2HGDH do not occur at an appreciable frequency in GBM. One explanation is simply that mono-allelic IDH1 and IDH2 mutations occur more frequently by chance than the bi-allelic mutations expected at IDH3, D2HGDH and L2HGDH. Alternatively, both loss of IDH function and 2HG accumulation might be required for tumourigenesis, and only IDH1 and IDH2 mutations have these dual effects.

microRNAs with prognostic significance in pancreatic ductal adenocarcinoma: A meta-analysis.

BACKGROUND Reports have described the prognostic relevance of microRNAs (miRNAs) in patients treated for pancreatic ductal adenocarcinoma (PDAC). However, many of these include small numbers of patients. To increase statistical power and improve translation, we performed a systematic review and meta-analysis to determine a pooled conclusion. We examined the impact of miRNAs on overall survival (OS) and disease-free survival (DFS) in PDAC. METHODS Eligible studies were identified and quality assessed using multiple search strategies (last search December 2014). Data were collected from studies correlating clinical outcomes with dysregulated tumoural or blood miRNAs. Studies were pooled, and combined hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate strength of the associations. RESULTS Twenty studies involving 1525 patients treated for PDAC were included. After correcting for publication bias, OS was significantly shortened in patients with high tumoural miR-21 (adjusted HR = 2.48; 1.96-3.14). This result persisted when only studies adjusting for adjuvant chemotherapy were combined (adjusted HR = 2.72; 1.91-3.89). High miR-21 also predicted reduced DFS (adjusted HR = 3.08; 1.78-5.33). Similarly, we found significant adjusted HRs for poor OS for high miR-155, high miR-203, and low miR-34a; and unadjusted HRs for high miR-222 and high miR-10b. The small number of studies, limited number of miRNAs and paucity of multivariate analyses are the limitations of our study. CONCLUSIONS This is the first rigorous pooled analysis assessing miRNAs as prognostic biomarkers in PDAC. Tumoural miR-21 overexpression emerged as an important predictor of poor prognosis after PDAC resection independent of other clinicopathologic factors, including adjuvant chemotherapy use.

IDH mutations in tumorigenesis and their potential role as novel therapeutic targets

Isocitrate dehydrogenases (IDHs) catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG). Somatic mutations in genes encoding IDH1 and IDH2 were first identified in glioma and subsequently in acute myeloid leukemia and other solid tumors. These heterozygous point mutations occur at the arginine residue of the enzymes active site and cause both loss of normal enzyme function and gain of function, causing reduction of α-KG to D-2-hydroxyglutarate, which accumulates. D-2-hydroxyglutarate may act as an oncometabolite through the inhibition of various α-KG-dependent enzymes, stimulating angiogenesis, histone modifications and aberrant DNA methylation. Possibly, IDH mutations may also cause oncogenic effects through dysregulation of the tricarboxylic acid cycle, or by increasing susceptibility to oxidative stress. Clinically, IDH mutations may be useful diagnostic, prognostic and predictive biomarkers, and it is anticipated that a better understanding of the pathogenesis of IDH mutations will enable IDH-directed therapies to be developed in the future.

Expression of Idh1R132H in the Murine Subventricular Zone Stem Cell Niche Recapitulates Features of Early Gliomagenesis.

Summary Isocitrate dehydrogenase 1 mutations drive human gliomagenesis, probably through neomorphic enzyme activity that produces D-2-hydroxyglutarate. To model this disease, we conditionally expressed Idh1R132H in the subventricular zone (SVZ) of the adult mouse brain. The mice developed hydrocephalus and grossly dilated lateral ventricles, with accumulation of 2-hydroxyglutarate and reduced α-ketoglutarate. Stem and transit amplifying/progenitor cell populations were expanded, and proliferation increased. Cells expressing SVZ markers infiltrated surrounding brain regions. SVZ cells also gave rise to proliferative subventricular nodules. DNA methylation was globally increased, while hydroxymethylation was decreased. Mutant SVZ cells overexpressed Wnt, cell-cycle and stem cell genes, and shared an expression signature with human gliomas. Idh1R132H mutation in the major adult neurogenic stem cell niche causes a phenotype resembling gliomagenesis.

Defining a prognostic molecular profile for ductal adenocarcinoma of the pancreas highlights known key signaling pathways.

There has been very little progress in improving outcomes for patients with pancreatic ductal adenocarcinoma (PDAC) over the past few decades. High-throughput array profiling has made it possible to discover new assays to diagnose or prognose PDAC more accurately based on the genetic profile of an individual tumor. To improve patient survival, there is a need to extract the most practical data to define tumor subgroups and personalize anticancer therapy. In the evaluated study, a multiplatform, survival-based analysis of molecular changes was performed for PDAC to discover clinically useful biomarkers. A composite score predictive for survival was calculated for individual genes, taking into account the DNA copy-number and any regulation by miRNAs. Several genes involved in the PI3K/AKT and SRC signaling pathways were identified and further investigated.

Multi-Center Randomized Phase II Study Comparing Cediranib plus Gefitinib with Cediranib plus Placebo in Subjects with Recurrent/Progressive Glioblastoma

Background Cediranib, an oral pan-vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor, failed to show benefit over lomustine in relapsed glioblastoma. One resistance mechanism for cediranib is up-regulation of epidermal growth factor receptor (EGFR). This study aimed to determine if dual therapy with cediranib and the oral EGFR inhibitor gefitinib improved outcome in recurrent glioblastoma. Methods and Findings This was a multi-center randomized, two-armed, double-blinded phase II study comparing cediranib plus gefitinib versus cediranib plus placebo in subjects with first relapse/first progression of glioblastoma following surgery and chemoradiotherapy. The primary outcome measure was progression free survival (PFS). Secondary outcome measures included overall survival (OS) and radiologic response rate. Recruitment was terminated early following suspension of the cediranib program. 38 subjects (112 planned) were enrolled with 19 subjects in each treatment arm. Median PFS with cediranib plus gefitinib was 3.6 months compared to 2.8 months for cediranib plus placebo (HR; 0.72, 90% CI; 0.41 to 1.26). Median OS was 7.2 months with cediranib plus gefitinib and 5.5 months with cediranib plus placebo (HR; 0.68, 90% CI; 0.39 to 1.19). Eight subjects (42%) had a partial response in the cediranib plus gefitinib arm versus five patients (26%) in the cediranib plus placebo arm. Conclusions Cediranib and gefitinib in combination is tolerated in patients with glioblastoma. Incomplete recruitment led to the study being underpowered. However, a trend towards improved survival and response rates with the addition of gefitinib to cediranib was observed. Further studies of the combination incorporating EGFR and VEGF inhibition are warranted. Trial Registration ClinicalTrials.gov NCT01310855

HOT mutation screening in human glioblastomas

Aims: Somatic mutations in IDH1 and IDH2 are described in glioblastomas (GBMs). Mutant IDH1 and IDH2 reduce α-KG to D-2HG which accumulates, and is proposed to promote tumorigenesis. HOT catalyzes the conversion of γ-hydroxybutyrate to succinic semialdehyde in a reaction that produces D-2HG. Since increased HOT enzyme activity could lead to an accumulation of D-2HG, coupled with the fact that only a minority of GBMs carry IDH1/2 mutations and 2HG accumulation has recently been described in IDH wild-type tumors, we analyzed a set of GBM samples for mutations in the HOT gene. Materials & methods: We screened 42 human GBM samples for mutations in HOT. Results: No mutations in HOT were identified in the 42 GBM samples screened. Conclusion: Mutations in the coding regions of HOT do not occur at an appreciable frequency in GBM.

Audit of Ca125 Follow-up After First-line Therapy for Ovarian Cancer.

Aims The Medical Research Council OVO5/EORTC 55955 trial showed that patients in remission after first-line therapy for ovarian cancer did not benefit from routine measurement of CA125 during follow-up. Since the presentation of these results, we have counseled patients about the options for follow-up and provided them with an information leaflet about the trial results and the symptoms that should prompt an early appointment and CA125 measurement. We present an audit of practice after the presentation of those results. Methods The medical records of 143 consecutive patients completing first-line therapy for epithelial ovarian, fallopian tube, or primary peritoneal cancer in our unit between July 2009 and December 2013 were analyzed. Results An agreed plan of CA125 follow-up was recorded in 69 (79%) of 87 eligible patients on completion of first-line therapy. No routine CA125 follow-up was selected by 55 (80%) patients, and routine CA125 follow-up was selected by 14 (20%), of whom 3 wished not to be informed of the results. CA125 levels were checked in 28 (51%) patients in the no routine CA125 follow-up group, in 26 cases because of the development of symptoms. Relapse was confirmed in 22. Median follow-up was 360 days (range, 100–836). CA125 levels were checked in all 14 patients who had requested routine CA125 follow-up. Relapse has been confirmed in 2 patients. Median follow-up was 560 days (range, 500–620). Conclusions If patients are given sufficient information about the role of routine CA125 measurements during follow-up, the majority decide against CA125 monitoring and hence, avoid these blood tests.

Ongoing Adjuvant/Neoadjuvant Trials in Resectable Metastatic Colorectal Cancer

The treatment of patients with colorectal cancer with colorectal liver metastases remains an exciting challenge for the multidisciplinary team. The role and choice of induction chemotherapy, the timing of surgery in resectable disease and the prioritisation of resection of the primary or the metastases are all still controversial. A true multidisciplinary approach and individualisation of treatment strategies are recommended.

Single-agent capecitabine use in patients age 70 or older with colorectal cancer.

764 Background: Colorectal cancer (CRC) is primarily a disease of the elderly, with a median age at diagnosis of 71. Administration of chemotherapy treatment in elderly patients with CRC is challenging due to multiple factors, including co-morbidities and a decline in organ function and is often associated with more toxicities and hospitalisations. Capecitabine monotherapy is an effective treatment in CRC but is associated with toxicities, commonly necessitating dose reduction (DR) in elderly patients. We present an audit of capecitabine prescribing in patients with CRC over the age of 70. Methods: The medical records of 43 patients over 70 receiving capecitabine monotherapy for CRC in our unit between November 2012 and August 2014 were analysed. The starting dose of capecitabine was established, and dose reductions prior to initial treatment were noted. Subsequent dose reductions, and toxicities necessitating such reductions were recorded. Results: 74 patients (37 male;37 female) were treated, 47 adjuvan...