Combined CADM1 and MAL promoter methylation analysis to detect (pre-)malignant cervical lesions in high-risk HPV-positive women^†

Given the lower specificity for high-grade cervical lesions of high-risk human papillomavirus (hrHPV) testing compared to cytology, additional triage testing for hrHPV test-positive women is needed to detect high-grade cervical lesions. Here, we tested whether combined methylation analysis for cell adhesion molecule 1 (CADM1) and T-lymphocyte maturation associated protein (MAL), both functionally involved in cervical carcinogenesis, could serve as such a triage marker. Four quantitative methylation-specific PCRs (qMSP), two for CADM1 (regions M12 and M18) and MAL (regions M1 and M2) each, were applied to 261 cervical tissue specimens ranging from no neoplasia to carcinoma. When qMSPs were combined and positivity for at least one of the qMSPs in the combination was taken into account, the highest positivity rates for cervical intraepithelial neoplasia grade 3 (CIN3) lesions (97%) and squamous cell- and adeno-carcinomas (99%) were obtained by combining a single CADM1 marker with a single MAL marker. Subsequent qMSP analysis of 70 GP5+/6+-PCR hrHPV-positive scrapings revealed that a two-marker panel consisting of CADM1-M18 and MAL-M1 was most discriminative, detecting 90% of women with CIN3 (n = 30), whereas it showed a positive result in only 13.5% of women without cervical disease (n = 40). Finally, we applied hrHPV GP5+/6+-PCR testing followed by CADM1-M18/MAL-M1 methylation analysis to a cohort of 79 women visiting the outpatient colposcopy clinic. hrHPV testing revealed a sensitivity of 97% and a specificity of 33% for CIN3+. Additional CADM1-M18/MAL-M1 methylation analysis on the hrHPV-positive women increased the specificity to 78% with a sensitivity of 70%. In conclusion, the methylation marker panel CADM1-M18 and MAL-M1 may serve as an alternative molecular triage tool for hrHPV-positive women.