Validation of targeted next-generation sequencing of cell-free DNA from archival cerebrospinal fluid specimens for the detection of somatic variants in cancer involving the leptomeninges: Cytopathologic and radiographic correlation.

BACKGROUND: Leptomeningeal metastases occur across multiple solid and lymphoid cancers, and patients typically undergo cytopathologic assessment of cerebrospinal fluid (CSF) in this setting. For patients diagnosed with metastatic cancer, the detection of actionable somatic mutations in CSF can provide clinically valuable information for treatment without the need for additional tissue collection. METHODS: The authors validated a targeted next-generation sequencing assay for the detection of somatic variants in cancer (OncoPanel) on cell-free DNA (cfDNA) isolated from archival CSF specimens in a cohort of 25 patients who had undergone molecular testing of a prior tumor specimen. RESULTS: CSF storage time and volume had no impact on cfDNA concentration or mean target coverage of the assay. Previously identified somatic variants in CSF cfDNA were detected in 88%, 50%, and 27% of specimens diagnosed cytologically as positive, suspicious/atypical, and negative for malignancy, respectively. Somatic variants were identified in 81% of CSF specimens from patients who had leptomeningeal enhancement on magnetic resonance imaging compared with 31% from patients without such enhancement. CONCLUSIONS: These data highlight the stability of cfDNA in CSF, which allows for cytopathologic evaluation before triage for next-generation sequencing assays. For a subset of cases in which clinical suspicion is high but cytologic or radiographic studies are inconclusive, the detection of pathogenic somatic variants in CSF cfDNA may aid in the diagnosis of leptomeningeal metastases.

Risk of leakage and tissue dissemination with various contained tissue extraction (CTE) techniques: an in vitro pilot study.

STUDY OBJECTIVE: To evaluate risk of leakage and tissue dissemination associated with various contained tissue extraction (CTE) techniques. DESIGN: In vitro study (Canadian Task Force classification: II-1). SETTING: Academic hospital simulation laboratory. INTERVENTION: Beef tongue specimens weighing 400 to 500 g were stained using 5 mL indigo carmine dye and morcellated under laparoscopic guidance within a plastic box trainer. CTE was performed via 3 different techniques: a stitch-sealed rip-stop nylon bag and multi-port approach; a one-piece clear plastic 50 × 50-cm isolation bag and multi-port approach; or a 1-piece clear plastic 50 × 50-cm isolation bag and single-site approach. Four trials of each CTE method were performed and compared with an open morcellation control. All bags were insufflated to within 10 to 25 mmHg pressure with a standard CO2 insufflator. Visual evidence of spilled tissue or dye was recorded, and fluid washings of the box trainer were sent for cytologic analysis. MEASUREMENTS AND MAIN RESULTS: Blue dye spill was noted in only 1 of 12 CTE trials. Spillage was visualized from a seam in 1 of the 4 stitch-sealed rip-stop nylon bags before morcellation of the specimen. The only trial in which gross tissue chips were visualized in the box trainer after morcellation was the open morcellation control. However, cytologic examination revealed muscle cells in the open morcellation washings and in the washings from the trial with dye spill. Muscle cells were not observed at cytologly in any of the other samples. CONCLUSION: CTE did not result in any leakage or tissue dissemination with use of the single-site or multi-port approach when using a 1-piece clear plastic 50 × 50-cm isolation bag. Further studies are needed to corroborate these findings in an in vivo context and to evaluate use of alternate bag options for specimen containment.

A non-genetic route to aneuploidy in human cancers.

Aneuploidy is common in human tumours and is often indicative of aggressive disease. Aneuploidy can result from cytokinesis failure, which produces binucleate cells that generate aneuploid offspring with subsequent divisions. In cancers, disruption of cytokinesis is known to result from genetic perturbations to mitotic pathways or checkpoints. Here we describe a non-genetic mechanism of cytokinesis failure that occurs as a direct result of cell-in-cell formation by entosis. Live cells internalized by entosis, which can persist through the cell cycle of host cells, disrupt formation of the contractile ring during host cell division. As a result, cytokinesis frequently fails, generating binucleate cells that produce aneuploid cell lineages. In human breast tumours, multinucleation is associated with cell-in-cell structures. These data define a previously unknown mechanism of cytokinesis failure and aneuploid cell formation that operates in human cancers.