HPV circulating tumoral DNA quantification by droplet‐based digital PCR: A promising predictive and prognostic biomarker for HPV‐associated oropharyngeal cancers

Abstract

We aimed to determine whether pretherapeutic assessment of HPV circulating tumoral DNA (HPV ctDNA) by droplet‐based digital PCR (ddPCR) could constitute a predictive and prognostic biomarker for HPV‐associated oropharyngeal squamous cell carcinoma (OPSCC). A mono‐institutional prospective biomarker study on 66 patients with p16+/HPV16‐positive oropharyngeal squamous cell carcinoma (OPSCC) was conducted in European Georges Pompidou Hospital, Paris, France. Blood samples were collected at the time of diagnosis before any treatment. Optimized digital PCR assays were used to quantify HPV16 ctDNA. Forty‐seven (71%) patients showed a positive pretherapeutic HPV ctDNA at time of diagnosis. Interestingly, the quantity of HPV16 ctDNA at baseline, as assessed by ddPCR, was significantly correlated with the T/N/M status or OPSCC stages according to the 2018 new staging criteria for high‐risk human papillomavirus (HR HPV) related OPSCC from American Joint Committee on Cancer (AJCC). Moreover, all recurrences and the majority (83%) of death reported events occurred in patients with positive HPV16 ctDNA at baseline. Finally, when posttreatment blood samples were available (n = 6), the kinetic of pretreatment/posttreatment HPV16 ctDNA was clearly associated with treatment success or failure. HPV ctDNA monitoring by ddPCR could constitute a useful and noninvasive dynamic biomarker to select HR HPV‐related OPSCC patients eligible for potential treatment de‐escalation and to monitor treatment response.

Cell-Free HPV-DNA as a Biomarker for Oropharyngeal Squamous Cell Carcinoma—A Step Towards Personalized Medicine?

“…According to collection of data/samples, five studies had a prospective design [ 24 , 27 , 28 , 30 , 37 ], whereas four studies were purely retrospective [ 23 , 25 , 29 , 33 ]. Seven studies did not report how data/samples were collected [ 22 , 26 , 31 , 32 , 34 , 35 , 36 ] ( Table 1 , Table S1 ).…”

“…One study [ 27 ] used “HPV16-detect” and compared sensitivity and specificity via real-time PCR. Additionally, eight studies [ 25 , 28 , 29 , 30 , 33 , 35 , 36 , 37 ] used droplet digital PCR (ddPCR). Damerla et al [ 29 ] and Jeannot et al [ 33 ] compared ddPCR with qPCR and they reported more sensitive values by using ddPCR at lower cfHPV-DNA concentrations.…”

“…Probes and primers used in the 16 studies included in the review are displayed in Table S3 . Thirteen studies extracted cfHPV-DNA from plasma [ 22 , 23 , 25 , 27 , 28 , 29 , 30 , 31 , 32 , 34 , 35 , 36 , 37 ], whereas two other studies extracted DNA from serum [ 24 , 26 ] and Jeannot et al used both plasma and serum [ 33 ].…”

“…In the study by Cao et al [ 22 ], a significant correlation of nodal classification and metabolically active nodal volume with HPV-DNA copy number was observed (N1-N2a: 225.5 copies/mL, N2b-N2c: 1026.1 copies/mL, N3: 5500 copies/mL). Five studies [ 24 , 31 , 32 , 33 , 36 ] observed that higher T- and N-stage resulted in higher rates of cfHPV-DNA in pre-treatment samples. In contrast to this, Chera et al [ 28 ] reported that patients with larger tumors may be associated with less release of cfHPV-DNA and, therefore, tumor burden alone may not clarify the variability in the level of pre-treatment cfHPV-DNA in OPSCC patients.…”

Molecular Diagnostics in Human Papillomavirus-Related Head and Neck Squamous Cell Carcinoma

“…In contrast, when using quantitative reverse transcription PCR to detect HPV16 E6/E7 expression, the presence of circulating HPV16 E6/E7 mRNA at baseline, prior to treatment, was associated with worse progression-free survival and overall survival [56]. This was similarly true of different individual studies, which found that increased levels of pre-treatment HPV16 ctDNA were correlated with worse prognosis [57], and in one study, worse TNM staging as well [58].…”