ADAR1 mRNA quantification for predicting HSIL in persons with HIV and abnormal anal cytology

Abstract

Anal squamous cell carcinoma is a significant concern among people with HIV (PWH), with high-grade squamous intraepithelial lesions (HSIL) as its precursor. Current screening, primarily based on abnormal anal cytology, often results in unnecessary high-resolution anoscopies (HRA) due to limited specificity. This study evaluates whether quantifying Adenosine Deaminase Acting on RNA-1 (ADAR1) mRNA in anal swabs improves HSIL prediction and optimizes HRA selection. In this prospective cohort, HIV-positive adults with abnormal anal cytology underwent HRA. ADAR1 mRNA levels were quantified from anal swabs, and human papillomavirus (HPV) genotyping was performed. The diagnostic performance of ADAR1 mRNA was assessed using receiver operating characteristic (ROC) curve analysis and compared with E6/E7 mRNA detection for high-risk HPV (HR-HPV). HSIL was confirmed by biopsy in 40 of 171 participants (23.4%). HSIL cases had significantly higher ADAR1 mRNA levels (median: 49.4 vs. 4.1 relative units [RU], p < .001) and a greater median number of HPV genotypes (5 vs. 3, p < .001). ROC analysis for ADAR1 mRNA yielded an area under the curve (AUC) of 0.83 (95% CI: 0.75-0.92). At a cut-off of ≥24.8 RU, it demonstrated 73% sensitivity, 92% specificity, 74% positive predictive value, and 92% negative predictive value. Compared to E6/E7 mRNA, ADAR1 mRNA improved screening accuracy (64%-88%) and reduced HRA referrals (77.2%-48.8%). ADAR1 mRNA quantification reliably predicts HSIL in PWH with abnormal anal cytology. Integrating ADAR1 mRNA measurement into anal cancer screening protocols may enhance diagnostic accuracy, reduce unnecessary invasive procedures, and alleviate the burden on limited HRA resources.

Keywords: ADAR1; HPV; alternative prediction method; anal HSIL.

FIGURE 1

mRNA expression levels of adenosine deaminase acting on RNA 1 (ADAR1 mRNA) across different anal histological categories. Total RNA was collected from anal swabs of participants with HIV and abnormal anal cytology. mRNAs of ADAR1 was quantified by RT‐qPCR using specific TaqMan assay. Relative mRNA levels were referred to expression of hydroxymethylbilane synthase (HMBS). HSIL, high‐grade squamous intraepithelial lesion; LSIL, low‐grade squamous intraepithelial lesion.

FIGURE 2

Receiver operating characteristic (ROC) curve of adenosine deaminase acting on RNA 1 (ADAR1 mRNA) for predicting high‐grade squamous intraepithelial lesions in anal biopsy. The numbers in parenthesis represent the specificity and sensitivity of the optimal cut‐off point of ADAR1 mRNA for predicting high‐grade squamous intraepithelial lesions in participants with abnormal anal cytology. Positive predictive value was 0.74 and negative predictive value was 0.92. AUC, area under the curve; CI, confidence interval.