Lars Sivars

Human Papillomavirus Type and Viral Load in Relation to Circulating Cell-Free Tumour HPV DNA Level and Survival in Cervical Cancer

Human papillomavirus (HPV) is the cause of most cervical cancers and is released as circulating cell-free tumour HPV DNA (ctHPV DNA) into circulation. Earlier studies have indicated that ctHPV DNA is a promising biomarker for analysing treatment response and for recurrence surveillance. However, factors influencing the release of ctHPV DNA, including HPV type and HPV viral load, have not been extensively studied and additional biomarkers for prognosis are needed. Therefore, here we analysed ctHPV DNA, HPV type and viral load in relation to each other and to progression-free survival in patients with locally advanced or advanced cervical cancer. Pre-treatment biopsies and blood samples were collected from patients diagnosed with cervical cancer (Federation of Gynecology and Obstetrics [FIGO] stage IB-IV). One hundred and seventeen patients with HPV-positive tumours were included. Human papillomavirus type-specific, droplet digital polymerase chain reaction (ddPCR) assays were used to analyse previously genotyped biopsies for the viral load. Pre-treatment plasma from 92/117 patients were available and analysed for ctHPV DNA and total cell-free DNA levels. Results were related to patient and tumour characteristics and progression-free survival. Patients were grouped based on HPV species where alpha-9-species (including HPV16) and alpha-7-species (including HPV 18) constituted the majority of cases. Cell-free tumour HPV DNA was found in 83/92 (90.2%) of pre-treatment plasma samples. Higher biopsy viral load was significantly related to a higher ctHPV DNA level. Higher stage and larger primary tumour size were also associated with higher ctHPV DNA level. Alpha-9 species, including HPV16, had a significantly higher viral load (16×), a higher ctHPV DNA level (17×), and a higher detection rate in plasma than alpha-7 species, including HPV18. Alpha-9 species also had significantly better progression-free survival than alpha-7 species. Additional factors leading to better progression-free survival included a lower stage, a lower total cell-free DNA level, a viral load in the 90th percentile and, in the high-risk cervical cancer group, a higher pre-treatment ctHPV DNA level. Cell-free tumour HPV DNA, HPV type and viral load are promising biomarkers in cervical cancer. The lower sensitivity for ctHPV DNA detection for alpha-7 species, including HPV18, needs to be considered in future studies on ctHPV DNA, especially if used as a marker for relapse during surveillance when ctHPV DNA levels are very low.

Cell-Free Human Papillomavirus DNA Is a Sensitive Biomarker for Prognosis and for Early Detection of Relapse in Locally Advanced Cervical Cancer

Abstract Purpose: Human papillomavirus (HPV) is the cause of the majority of cervical cancer cases and has been showed to be released as cell-free tumor DNA (ctHPV DNA) into the circulation. Here, we analyze if ctHPV DNA could be used as a prognostic biomarker and/or to detect relapse earlier than traditional methods in locally advanced cervical cancer (LACC). Experimental Design: A total of 74 patients with LACC were included; 66of 74 were positive for 13 high-risk HPV types on a bead-based assay of tumor biopsy samples. HPV-type–specific droplet digital PCR assays were developed. Longitudinal plasma samples were then analyzed for the biopsy-verified HPV type for each patient. In total, 418 plasma samples were analyzed. Patients were followed for a median of 37 months. Results were correlated to tumor and clinical characteristics. Results: Of the pretreatment plasma samples, 92.4% were positive for ctHPV DNA. Persistent ctHPV DNA in end-of-treatment, early follow-up (1–2 months after end-of-treatment), or tumor evaluation (3–4 months after end-of-treatment) plasma was correlated with worse progression-free survival (P < 0.001) compared with if ctHPV DNA was not found. The positive predictive value of ctHPV status at early follow-up for predicting disease progression was 87.5%, and the negative predictive value was 89.3%. ctHPV DNA was found in plasma before relapse was diagnosed using radiology in all patients (n = 10) who experienced relapse after complete clinical response to treatment with a median 315 days lead time. Conclusions: ctHPV DNA in follow-up plasma is a promising prognostic biomarker in patients with LACC, useful for analysis of response to therapy and for early detection of relapse.

The current status of cell‐free human papillomavirus DNA as a biomarker in cervical cancer and other HPV‐associated tumors: A review

AbstractTumor cells release fragments of their DNA into the circulation, so called cell‐free tumor DNA (ctDNA), allowing for analysis of tumor DNA in a simple blood test, that is, liquid biopsy. Cervical cancer is one of the most common malignancies among women worldwide and high‐risk human papillomavirus (HR‐HPV) is the cause of the majority of cases. HR‐HPV integrates into the host genome and is often present in multiple copies per cell and should thus also be released as ctDNA. Such ctHPV DNA is therefore a possible biomarker in cervical cancer. In this review, we first give a background on ctDNA in general and then a comprehensive review of studies on ctHPV DNA in cervical cancer and pre‐malignant lesions that may develop in cervical cancer. Furthermore, studies on ctHPV DNA in other HPV related malignancies (eg, head‐and‐neck and anogenital cancers) are briefly reviewed. We conclude that detection of ctHPV DNA in plasma from patients with cervical cancer is feasible, although optimized protocols and ultra‐sensitive techniques are required for sufficient sensitivity. Results from retrospective studies in both cervical cancer and other HPV‐related malignancies suggests that ctHPV DNA is a promising prognostic biomarker, for example, for detecting relapses early. This paves the way for larger, preferably prospective studies investigating the clinical value of ctHPV DNA as a biomarker in cervical cancer. However, there are conflicting results whether ctHPV DNA can be found in blood from patients with pre‐malignant lesions and further studies are needed to fully elucidate this question.