Sequential evaluation of MUC promoter methylation using next-generation sequencing-based custom-made panels in liquid-based cytology specimens of pancreatic cancer.

BACKGROUND: As liquid-based cytology (LBC) specimens preserve high-quality DNA, clinical sequencing of LBC specimens using next-generation sequencing (NGS) is becoming a common strategy. This study aimed to evaluate the feasibility of NGS-based custom-made panels for evaluating MUC promoter methylation in LBC specimens. METHODS: Thirty-one patients with pancreatic cancer were enrolled in the study. Cancer tissue samples were obtained using endoscopic ultrasound-guided fine-needle aspiration/biopsy (EUS-FNA/FNB). LBC, formalin-fixed paraffin-embedded (FFPE), and fresh frozen specimens were prepared for DNA extraction after pathological diagnosis. These specimens were then subjected to NGS analysis using custom-made cancer gene screening and methylation panels comprising 28 cancer-related genes and 13 gene promoter regions, including MUC1, MUC2, and MUC4. RESULTS: The success rate of NGS using the cancer gene panel was comparable among the LBC, FFPE, and frozen specimens, and the presence of cancer cell-derived somatic mutations in each specimen was confirmed. The specimens were then tested using a methylation panel that revealed the sequential methylation status of CpG islands located in the promoter regions of MUC genes. The methylation status results obtained from LBC specimens were almost comparable with those from FFPE and frozen specimens. CONCLUSIONS: MUC and other gene methylation analyses using an NGS-based panel were successfully performed in residual LBC specimens obtained by EUS-FNA/FNB. Therefore, this approach provides an alternative source of molecular tests for gene mutations and methylation, especially in the pancreatic cancers, which are often unresectable and unsuitable for obtaining FFPE specimens.

Triage performance and predictive value of the human gene methylation panel among women positive on self-collected HPV test: Results from a prospective cohort study.

Triaging of women positive for high-risk human papillomavirus (hrHPV) on self-collected samples requires a molecular reflex test to avoid recall for cytology or visual tests. We assessed triage performance and predictive value of human gene methylation panel (ZNF671/ASTN1/ITGA4/RXFP3/SOX17/DLX1) alone and with combination of HPV16/18 genotyping in a longitudinal screening study. Out of 9526 women at baseline, 1758 women positive for hrHPV on self-collected samples followed up yearly were included in the current analysis. Satisfactory risk stratification to detect cervical intraepithelial neoplasia grade 2 or worse (CIN2+) was demonstrated by the methylation panel with an odds ratio (OR) of 11.3 among methylation-positive women compared to methylation-negative counterparts. Triaging with methylation panel reduced colposcopy referral rate by 67.2% with sensitivity and specificity of 83.0% and 69.9% to detect CIN2+. The corresponding values for the combining methylation and HPV 16/18 were 96.6% and 58.3%. The cumulative 3-year incident CIN2+ risk was 6.8% (95% CI: 4.9%-8.6%) for hrHPV positive women, which was reduced to 4.5% (95% CI: 2.7%-6.3%) and 2.9% (95% CI: 1.2%-4.5%) for women negative on methylation triaging alone and negative on the combined strategy. The corresponding risk for women positive for both methylation and HPV 16/18 reached 33.7% (95% CI: 19.0%-45.8%). Our study demonstrated the satisfactory triage performance and predictive value of the methylation panel, especially in combination with HPV 16/18 genotyping. The substantially lower risk of CIN2+ among the triage negative women over the next 3 years suggests that the interval for repeat HPV test can be safely extended to at least 2 years.