Prognostic implications of p16 and HPV discordance in oropharyngeal cancer (HNCIG-EPIC-OPC): a multicentre, multinational, individual patient data analysis

BACKGROUND

p16^INK4a (p16) immunohistochemistry is the most widely used biomarker assay for inferring HPV causation in oropharyngeal cancer in clinical and trial settings. However, discordance exists between p16 and HPV DNA or RNA status in some patients with oropharyngeal cancer. We aimed to clearly quantify the extent of discordance, and its prognostic implications.

METHODS

In this multicentre, multinational individual patient data analysis, we did a literature search in PubMed and Cochrane database for systematic reviews and original studies published in English between Jan 1, 1970, and Sept 30, 2022. We included retrospective series and prospective cohorts of consecutively recruited patients previously analysed in individual studies with minimum cohort size of 100 patients with primary squamous cell carcinoma of the oropharynx. Patient inclusion criteria were diagnosis with a primary squamous cell carcinoma of oropharyngeal cancer; data on p16 immunohistochemistry and on HPV testing; information on age, sex, tobacco, and alcohol use; staging by TNM 7th edition; information on treatments received; and data on clinical outcomes and follow-up (date of last follow-up if alive, date of recurrence or metastasis, and date and cause of death). There were no limits on age or performance status. The primary outcomes were the proportion of patients of the overall cohort who showed the different p16 and HPV result combinations, as well as 5-year overall survival and 5-year disease-free survival. Patients with recurrent or metastatic disease or who were treated palliatively were excluded from overall survival and disease-free survival analyses. Multivariable analysis models were used to calculate adjusted hazard ratios (aHR) for different p16 and HPV testing methods for overall survival, adjusted for prespecified confounding factors.

FINDINGS

Our search returned 13 eligible studies that provided individual data for 13 cohorts of patients with oropharyngeal cancer from the UK, Canada, Denmark, Sweden, France, Germany, the Netherlands, Switzerland, and Spain. 7895 patients with oropharyngeal cancer were assessed for eligibility. 241 were excluded before analysis, and 7654 were eligible for p16 and HPV analysis. 5714 (74·7%) of 7654 patients were male and 1940 (25·3%) were female. Ethnicity data were not reported. 3805 patients were p16-positive, 415 (10·9%) of whom were HPV-negative. This proportion differed significantly by geographical region and was highest in the areas with lowest HPV-attributable fractions (r=-0·744, p=0·0035). The proportion of patients with p16+/HPV- oropharyngeal cancer was highest in subsites outside the tonsil and base of tongue (29·7% vs 9·0%, p<0·0001). 5-year overall survival was 81·1% (95% CI 79·5-82·7) for p16+/HPV+, 40·4% (38·6-42·4) for p16-/HPV-, 53·2% (46·6-60·8) for p16-/HPV+, and 54·7% (49·2-60·9) for p16+/HPV-. 5-year disease-free survival was 84·3% (95% CI 82·9-85·7) for p16+/HPV+, 60·8% (58·8-62·9) for p16-/HPV-; 71·1% (64·7-78·2) for p16-/HPV+, and 67·9% (62·5-73·7) for p16+/HPV-. Results were similar across all European sub-regions, but there were insufficient numbers of discordant patients from North America to draw conclusions in this cohort.

INTERPRETATION

Patients with discordant oropharyngeal cancer (p16-/HPV+ or p16+/HPV-) had a significantly worse prognosis than patients with p16+/HPV+ oropharyngeal cancer, and a significantly better prognosis than patients with p16-/HPV- oropharyngeal cancer. Along with routine p16 immunohistochemistry, HPV testing should be mandated for clinical trials for all patients (or at least following a positive p16 test), and is recommended where HPV status might influence patient care, especially in areas with low HPV-attributable fractions.

FUNDING

European Regional Development Fund, Generalitat de Catalunya, National Institute for Health Research (NIHR) UK, Cancer Research UK, Medical Research Council UK, and The Swedish Cancer Foundation and the Stockholm Cancer Society.

Deep Learning Predicts HPV Association in Oropharyngeal Squamous Cell Carcinomas and Identifies Patients with a Favorable Prognosis Using Regular H&E Stains

PURPOSE

Human papillomavirus (HPV) in oropharyngeal squamous cell carcinoma (OPSCC) is tumorigenic and has been associated with a favorable prognosis compared with OPSCC caused by tobacco, alcohol, and other carcinogens. Meanwhile, machine learning has evolved as a powerful tool to predict molecular and cellular alterations of medical images of various sources.

EXPERIMENTAL DESIGN

We generated a deep learning-based HPV prediction score (HPV-ps) on regular hematoxylin and eosin (H&E) stains and assessed its performance to predict HPV association using 273 patients from two different sites (OPSCC; Giessen, n = 163; Cologne, n = 110). Then, the prognostic relevance in a total of 594 patients (Giessen, Cologne, HNSCC TCGA) was evaluated. In addition, we investigated whether four board-certified pathologists could identify HPV association (n = 152) and compared the results to the classifier.

RESULTS

Although pathologists were able to diagnose HPV association from H&E-stained slides (AUC = 0.74, median of four observers), the interrater reliability was minimal (Light Kappa = 0.37; P = 0.129), as compared with AUC = 0.8 using the HPV-ps within two independent cohorts (n = 273). The HPV-ps identified individuals with a favorable prognosis in a total of 594 patients from three cohorts (Giessen, OPSCC, HR = 0.55, P < 0.0001; Cologne, OPSCC, HR = 0.44, P = 0.0027; TCGA, non-OPSCC head and neck, HR = 0.69, P = 0.0073). Interestingly, the HPV-ps further stratified patients when combined with p16 status (Giessen, HR = 0.06, P < 0.0001; Cologne, HR = 0.3, P = 0.046).

CONCLUSIONS

Detection of HPV association in OPSCC using deep learning with help of regular H&E stains may either be used as a single biomarker, or in combination with p16 status, to identify patients with OPSCC with a favorable prognosis, potentially outperforming combined HPV-DNA/p16 status as a biomarker for patient stratification.

HPV16 increases the number of migratory cancer stem cells and modulates their miRNA expression profile in oropharyngeal cancer

Human papillomavirus type 16 (HPV16) is a major risk for development of oropharyngeal squamous-cell-carcinoma (OPSCC). Although HPV⁺ OPSCC metastasize faster than HPV^- tumors, they have a better prognosis. The molecular and cellular alterations underlying this pathobiology of HPV⁺ OPSCC remain elusive. In this study, we examined whether expression of HPV16-E6E7 targets the number of migratory and stationary cancer stem cells (CSC). Furthermore, we wanted to elucidate if aberrantly expressed miRNAs in migratory CSC may be responsible for progression of OPSCCs and whether they may serve as potential novel biomarkers for increased potential of metastasis. Our studies revealed that HPV16-E6E7 expression leads to an increase in the number of stationary (CD44^high /EpCAM^high ) stem cells in primary keratinocyte cultures. Most importantly, expression of E6E7 in the cell line H357 increased the migratory (CD44^high /EpCAM^low ) CSC pool. This increase in migratory CSCs could also be confirmed in HPV⁺ OPSCC. Differentially expressed miRNAs from HPV16-E6E7 positive CD44^high /EpCAM^low CSCs were validated by RT-qPCR and in situ hybridization on HPV16⁺ OPSCCs. These experiments led to the identification of miR-3194-5p, which is upregulated in primary HPV16⁺ OPSCC and matched metastasis. MiR-1281 was also found to be highly expressed in HPV⁺ and HPV^- metastasis. As inhibition of this miRNA led to a markedly reduction of CD44^high /EpCAM^low cells, it may prove to be a promising drug target. Taken together, our findings highlight the capability of HPV16 to modify the phenotype of infected stem cells and that miR-1281 and miR3194-5p may represent promising targets to block metastatic spread of OPSCC.