Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Randomized Phase III Trial of Erlotinib versus Docetaxel in Patients with Advanced Squamous Cell Non–Small Cell Lung Cancer Failing First-Line Platinum-Based Doublet Chemotherapy Stratified by VeriStrat Good versus VeriStrat Poor. The European Thoracic Oncology Platform (ETOP) EMPHASIS-lung Trial

Introduction Docetaxel and erlotinib are registered second-line treatments for wild-type EGFR NSCLC. Previous studies suggested a predictive value of the VeriStrat test in second-line therapy of NSCLC, classifying patients as either VeriStrat good or VeriStrat poor. EMPHASIS-lung aimed at exploring this predictive effect in patients with squamous cell NSCLC. The trial closed prematurely because of low accrual and results from other trials. Our analysis includes an exploratory combined analysis with results from the PROSE trial. Methods EMPHASIS-lung was a randomized phase III multicenter trial exploring the differential effect of second-line erlotinib versus docetaxel on progression-free survival (PFS) in VeriStrat good versus VeriStrat poor patients with squamous cell NSCLC. Results A total of 80 patients were randomized, with 72.5% categorized as VeriStrat good. Patient characteristics were balanced between VeriStrat status and treatment groups. The median PFS times with docetaxel and erlotinib treatment in the VeriStrat good cohort were 4.1 and 1.6 months, respectively, versus 1.9 and 2.1 months, respectively, in the VeriStrat poor cohort. The median overall survival (OS) times with docetaxel and erlotinib treatment in the VeriStrat good cohort were 7.8 and 8.4 months, respectively, and 4.4 and 5.2 months, respectively, in the VeriStrat poor cohort. An additional exploratory analysis was performed; in it, 47 patients from the squamous cell subgroup of PROSE were included in a combined analysis, contributing with 45 PFS and 41 OS events. Conclusions The final analysis of EMPHASIS-lung did not show a differential effect on PFS for erlotinib versus docetaxel stratified by VeriStrat status. Similarly, in the combined analysis, no significant treatment by VeriStrat status interaction was observed (interaction p = 0.24 for PFS and 0.45 for OS, stratified by study). © 2017 International Association for the Study of Lung Cance

NMDA receptor gene variations as modifiers in Huntington disease: a replication study.

Several candidate modifier genes which, in addition to the pathogenic CAG repeat expansion, influence the age at onset (AO) in Huntington disease (HD) have already been described. The aim of this study was to replicate association of variations in the N-methyl D-aspartate receptor subtype genes GRIN2A and GRIN2B in the “REGISTRY” cohort from the European Huntington Disease Network (EHDN). The analyses did replicate the association reported between the GRIN2A rs2650427 variation and AO in the entire cohort. Yet, when subjects were stratified by AO subtypes, we found nominally significant evidence for an association of the GRIN2A rs1969060 variation and the GRIN2B rs1806201 variation. These findings further implicate the N-methyl D-aspartate receptor subtype genes as loci containing variation associated with AO in HD