The randomised thoracoscopic talc poudrage+indwelling pleural catheters versus thoracoscopic talc poudrage only in malignant pleural effusion trial (TACTIC): study protocol for a randomised controlled trial

INTRODUCTION: Malignant pleural effusion (MPE) is common, with 50 000 new cases per year in the UK. MPE causes disabling breathlessness and indicates advanced disease with a poor prognosis. Treatment approaches focus on symptom relief and optimising quality of life (QoL). Patients who newly present with MPE commonly require procedural intervention for both diagnosis and therapeutic benefit.Thoracoscopic pleural biopsies are highly sensitive in diagnosing pleural malignancy. Talc poudrage may be delivered at thoracoscopy (TTP) to prevent effusion recurrence by effecting pleurodesis. Indwelling pleural catheters (IPCs) offer an alternative strategy for fluid control, enabling outpatient management and are often used as 'rescue' therapy following pleurodesis failure or in cases of 'trapped lung'. It is unknown whether combining a TTP with IPC insertion will improve patient symptoms or reduce time spent in the hospital.The randomised thoracoscopic talc poudrage + indwelling pleural catheters versus thoracoscopic talc poudrage only in malignant pleural effusion trial (TACTIC) is the first randomised controlled trial (RCT) to examine the benefit of a combined TTP and IPC procedure, evaluating cost-effectiveness and patient-centred outcomes such as symptoms and QoL. The study remains in active recruitment and has the potential to radically transform the pathway for all patients presenting with MPE. METHODS AND ANALYSIS: TACTIC is an unblinded, multicentre, RCT comparing the combination of TTP with an IPC to TTP alone. Co-primary outcomes are time spent in the hospital and mean breathlessness score over 4 weeks postprocedure. The study will recruit 124 patients and aims to define the optimal pathway for patients presenting with symptomatic MPE. ETHICS AND DISSEMINATION: TACTIC is sponsored by North Bristol NHS Trust and has been granted ethical approval by the London-Brent Research Ethics Committee (REC ref: 21/LO/0495). Publication of results in a peer-reviewed journal and conference presentations are anticipated. TRIAL REGISTRATION: ISRCTN 11058680

DNaseI hypersensitivity at gene-poor, FSH dystrophy-linked 4q35.2

A subtelomeric region, 4q35.2, is implicated in facioscapulohumeral muscular dystrophy (FSHD), a dominant disease thought to involve local pathogenic changes in chromatin. FSHD patients have too few copies of a tandem 3.3-kb repeat (D4Z4) at 4q35.2. No phenotype is associated with having few copies of an almost identical repeat at 10q26.3. Standard expression analyses have not given definitive answers as to the genes involved. To investigate the pathogenic effects of short D4Z4 arrays on gene expression in the very gene-poor 4q35.2 and to find chromatin landmarks there for transcription control, unannotated genes and chromatin structure, we mapped DNaseI-hypersensitive (DH) sites in FSHD and control myoblasts. Using custom tiling arrays (DNase-chip), we found unexpectedly many DH sites in the two large gene deserts in this 4-Mb region. One site was seen preferentially in FSHD myoblasts. Several others were mapped >0.7 Mb from genes known to be active in the muscle lineage and were also observed in cultured fibroblasts, but not in lymphoid, myeloid or hepatic cells. Their selective occurrence in cells derived from mesoderm suggests functionality. Our findings indicate that the gene desert regions of 4q35.2 may have functional significance, possibly also to FSHD, despite their paucity of known genes

Gene expression during normal and FSHD myogenesis

<p>Abstract</p> <p>Background</p> <p>Facioscapulohumeral muscular dystrophy (FSHD) is a dominant disease linked to contraction of an array of tandem 3.3-kb repeats (D4Z4) at 4q35. Within each repeat unit is a gene, <it>DUX4</it>, that can encode a protein containing two homeodomains. A <it>DUX4 </it>transcript derived from the last repeat unit in a contracted array is associated with pathogenesis but it is unclear how.</p> <p>Methods</p> <p>Using exon-based microarrays, the expression profiles of myogenic precursor cells were determined. Both undifferentiated myoblasts and myoblasts differentiated to myotubes derived from FSHD patients and controls were studied after immunocytochemical verification of the quality of the cultures. To further our understanding of FSHD and normal myogenesis, the expression profiles obtained were compared to those of 19 non-muscle cell types analyzed by identical methods.</p> <p>Results</p> <p>Many of the ~17,000 examined genes were differentially expressed (> 2-fold, <it>p </it>< 0.01) in control myoblasts or myotubes vs. non-muscle cells (2185 and 3006, respectively) or in FSHD vs. control myoblasts or myotubes (295 and 797, respectively). Surprisingly, despite the morphologically normal differentiation of FSHD myoblasts to myotubes, most of the disease-related dysregulation was seen as dampening of normal myogenesis-specific expression changes, including in genes for muscle structure, mitochondrial function, stress responses, and signal transduction. Other classes of genes, including those encoding extracellular matrix or pro-inflammatory proteins, were upregulated in FSHD myogenic cells independent of an inverse myogenesis association. Importantly, the disease-linked <it>DUX4 </it>RNA isoform was detected by RT-PCR in FSHD myoblast and myotube preparations only at extremely low levels. Unique insights into myogenesis-specific gene expression were also obtained. For example, all four Argonaute genes involved in RNA-silencing were significantly upregulated during normal (but not FSHD) myogenesis relative to non-muscle cell types.</p> <p>Conclusions</p> <p><it>DUX4</it>'s pathogenic effect in FSHD may occur transiently at or before the stage of myoblast formation to establish a cascade of gene dysregulation. This contrasts with the current emphasis on toxic effects of experimentally upregulated <it>DUX4 </it>expression at the myoblast or myotube stages. Our model could explain why <it>DUX4</it>'s inappropriate expression was barely detectable in myoblasts and myotubes but nonetheless linked to FSHD.</p