The Prognostic Role of Human Papillomavirus and p16 Status in Penile Squamous Cell Carcinoma-A Systematic Review

New Therapeutic Horizons for Advanced or Metastatic Penile Cancer

Penile cancer is a rare malignancy with a poor prognosis. Studies with single-agent immune checkpoint inhibitors (ICIs) have demonstrated efficacy, but response rates are low. Studies combining ICIs with both chemotherapy and targeted therapy are ongoing. Up to 50% of penile cancer cases are associated with human papillomavirus (HPV). HPV-targeting therapies, such as HPV-targeting vaccines and T-cell receptor therapies, are an area of active investigation. Penile cancer cells also express cell surface antigens that may be targeted by the emerging class of antibody-drug conjugates.

Single-cell Atlas of Penile Cancer Reveals TP53 Mutations as a Driver of an Aggressive Phenotype, Irrespective of Human Papillomavirus Status, and Provides Clues for Treatment Personalization

BACKGROUND AND OBJECTIVE

TP53 loss-of-function (TP53LOF) mutations might be a driver of poor prognosis and chemoresistance in both human papillomavirus (HPV)-independent (HPV-) and HPV-associated (HPV+) penile squamous cell carcinoma (PSCC). Here, we aim to describe transcriptomic differences in the PSCC microenvironment stratified by TP53LOF and HPV status.

METHODS

We used single-cell RNA sequencing (scRNA-seq) and T-cell receptor sequencing to obtain a comprehensive atlas of the cellular architecture of PSCC. TP53LOF and HPV status were determined by targeted next-generation sequencing and sequencing HPV-DNA reads. Six HPV+ TP53 wild type (WT), six HPV- TP53WT, and four TP53LOF PSCC samples and six controls were included. Immunohistochemistry and hematoxylin-eosin confirmed the morphological context of the observed signatures. Prognostic differences between patient groups were validated in 541 PSCC patients using Kaplan-Meier survival estimates.

KEY FINDINGS AND LIMITATIONS

Patients with aberrant p53 staining fare much worse than patients with either HPV- or HPV+ tumors and WT p53 expression. Using scRNA-seq, we revealed 65 cell subtypes within 83 682 cells. TP53LOF tumors exhibit a partial epithelial-to-mesenchymal transition, immune-excluded, angiogenic, and morphologically invasive environment, underlying their aggressive phenotype. HPV- TP53WT tumors show stemness and immune exhaustion. HPV+ TP53WT tumors mirror normal epithelial maturation with upregulation of antibody-drug-conjugate targets and activation of innate immunity. Inherent to the scRNA-seq analysis, low sample size is a limitation and validation of signatures in large PSCC cohorts is needed.

CONCLUSIONS AND CLINICAL IMPLICATIONS

This first scRNA-seq atlas offers unprecedented in-depth insights into PSCC biology underlying prognostic differences based on TP53 and HPV status. Our findings provide clues for testing novel biomarker-driven therapies in PSCC.

PATIENT SUMMARY

Here, we analyzed tissues of penile cancer at the level of individual cells, which helps us understand why patients who harbor a deactivating mutation in the TP53 gene do much worse than patients lacking such a mutation. Such an analysis may help us tailor future therapies based on TP53 gene mutations and human papillomavirus status of these tumors.

Immune-based Therapies for Penile Cancer

This article reviews penile squamous cell carcinoma (PSCC), a rare genitourinary cancer that has been increasing in prevalence. It discusses emerging therapies, focusing on immunotherapy, vaccine therapy, and cell-based treatments, especially in the context of human papillomavirus-related PSCC. Factors influencing these therapies are discussed. These include the immune microenvironment, programmed cell death ligand-1 expression, and tumor immune cell infiltration. This article also highlights immune checkpoint inhibitors and related clinical trials. This review supports the use of personalized medicine in treating PSCC. It stresses the need for collaborative studies and data sharing to create specific treatment plans and achieve better outcomes.

The effects of HIV and oncogenic human papillomavirus on the tumor immune microenvironment of penile squamous cell carcinoma

Penile squamous cell carcinoma (PSCC) occurs more frequently in some developing countries compared to developed countries. Infection with HIV and/or high-risk human papillomavirus (hrHPV) are risk factors for penile cancer development. The tumor microenvironment of PSCC may predict prognosis and may inform on the best targets for immunotherapy. We evaluated the immune microenvironment of penile tumors histologically, and determined whether and/or how HIV and/or hrHPV infections affect this tumor microenvironment. We conducted a prospective analytical cross-sectional study in which penile cancer tumors from 35 patients presenting at the University Teaching Hospital in Lusaka, Zambia were histologically staged and assessed for presence of tumor infiltrating immune cells and expression of immune checkpoints. Immunohistochemistry was used to evaluate immune checkpoints and infiltrating immune cells, while multiplex real-time polymerase chain reaction was used for hrHPV genotyping. The median age of all participants was 55 years. About 24% had advanced histological stage, 83% were HIV+, and 63% had hrHPV detected in their tumors using multiplex real-time polymerase chain reaction. PDL1 expression was significantly higher in HIV- participants than HIV+ participants (p = 0.02). Tumors with multiple hrHPV infections had a significantly higher number of cells expressing TIM3 than those with one hrHPV (p = 0.04). High grade tumors had a significantly higher infiltrate of FoxP3+ cells (p = 0.02), CD68+ cells (p = 0.01), CD163+ cells (p = 0.01), LAG3+ cells (p = 0.01), PD1+ cells (p = 0.01) and TIM3+ cells (p = 0.03) when compared with low grade tumours. There was significant moderate to strong positive correlation of cells expressing PD1 and LAG3 (⍴ = 0.69; p = 0.0001), PD1 and TIM3 (⍴ = 0.49; p = 0.017) and TIM3 and LAG3 PDL1 (⍴ = 0.61; p = 0.001). In conclusion, the tumor microenvironment of penile squamous cell carcinoma seems to be affected by both HIV and HPV infections. TIM3 appears to be a potential therapeutic target in PSCC patients with hrHPV infections.

Surveillance or Dynamic Sentinel Lymph-Node Biopsy in Low-Risk Clinically N0 Penile Squamous Cell Carcinoma: Single-Institution Real World Data

INTRODUCTION

Surveillance is the standard management in low-risk cN0 penile squamous cell carcinoma (peSCC) patients. However, no previous analysis focused on early and long-term outcomes of these patients. We report on main oncological outcomes of a large series of low-risk cN0 peSCC patients.

PATIENTS AND METHODS

Between 1980 and 2017 included, 93 evaluable consecutive low-risk (ie, pT1a G1 cN0M0) peSCC patients underwent primary tumor surgery and either observation (74) or dynamic sentinel node biopsy (DSNB) (19) following a clinical diagnosis of T1 in 66 (71%), T2 in 15 (16.1%) and Tx in 12 (12.9%) patients, respectively. The statistical significance of differences in medians and proportions was tested with the Kruskal-Wallis and chi-square tests. Kaplan-Meier plots illustrated 5-year inguinal relapse (IR)-free survival rates.

RESULTS

Median age was 60 years (IQR: 50-69 years). Median follow-up was 92 months (IQR 54-133 months). Surveillance was more frequently adopted in clinical (c)T1 than in cT2 tumors (79.7% vs. 36.8%). None of 19 patients who had DSNB had nodal metastasis. Overall, 7 (7.5%) out of 93 pT1aG1cN0 peSCC patients had IR after a median interval of 9 months. Of note, 1 patient only relapsed after 12 months of surveillance. After stratification according to IR, relapses occurred more frequently in younger patients (59 vs. 64 years, P < .001). The 5-year IR-free survival rates for the entire cohort was 92% (95% Confidence interval [CI] 87-98%).

CONCLUSIONS

Observation is a safe and effective management for low-risk peSCC patients. Younger patients may be offered a mini-invasive staging as an alternative.

Transcriptomic, Proteomic, and Genomic Mutational Fraction Differences Based on HPV Status Observed in Patient-Derived Xenograft Models of Penile Squamous Cell Carcinoma

Metastatic penile squamous cell carcinoma (PSCC) has only a 50% response rate to first-line combination chemotherapies and there are currently no targeted-therapy approaches. Therefore, we have an urgent need in advanced-PSCC treatment to find novel therapies. Approximately half of all PSCC cases are positive for high-risk human papillomavirus (HR-HPV). Our objective was to generate HPV-positive (HPV+) and HPV-negative (HPV-) patient-derived xenograft (PDX) models and to determine the biological differences between HPV+ and HPV- disease. We generated four HPV+ and three HPV- PSCC PDX animal models by directly implanting resected patient tumor tissue into immunocompromised mice. PDX tumor tissue was found to be similar to patient tumor tissue (donor tissue) by histology and short tandem repeat fingerprinting. DNA mutations were mostly preserved in PDX tissues and similar APOBEC (apolipoprotein B mRNA editing catalytic polypeptide) mutational fractions in donor tissue and PDX tissues were noted. A higher APOBEC mutational fraction was found in HPV+ versus HPV- PDX tissues (p = 0.044), and significant transcriptomic and proteomic expression differences based on HPV status included p16 (CDKN2A), RRM2, and CDC25C. These models will allow for the direct testing of targeted therapies in PSCC and determine their response in correlation to HPV status.

Insights into the management of penile squamous cell carcinoma: from conventional approaches to emerging novel therapies

INTRODUCTION

Penile squamous cell carcinoma (PSCC), a rare genitourinary cancer, is associated with poor outcomes due to limited treatment effectiveness, especially in advanced stages.

AREAS COVERED

While chemotherapy and/or surgery remain the standard of care, emerging therapies like immunotherapy, targeted therapy, and human papillomavirus (HPV) directed therapies show promise. Key to advancing treatment is understanding the immune microenvironment to gain insights into tumor resistance mechanisms and potential therapeutic targets. The scarcity of data on PSCC is a major obstacle in advancing research for this rare cancer.

EXPERT OPINION

Future research should prioritize collaborative efforts across various research centers and countries. Enhancing data sharing and pooling resources can lead to a more comprehensive understanding of PSCC, ultimately supporting the development of precision medicine strategies tailored to this specific cancer type. This collaborative approach is essential for making significant strides in PSCC treatment and care.

Evaluation of Prognostic Parameters to Identify Aggressive Penile Carcinomas

BACKGROUND

Advanced penile carcinoma is characterized by poor prognosis. Most data on prognostic factors are based on small study cohorts, and even meta-analyses are limited in patient numbers. Therefore, there is still a lack of evidence for clinical decisions. In addition, the most recent TNM classification is questionable; in line with previous studies, we found that it has not improved prognosis estimation.

METHODS

We evaluated 297 patients from Germany, Russia, and Portugal. Tissue samples from 233 patients were re-analyzed by two experienced pathologists. HPV status, p16, and histopathological parameters were evaluated for all patients.

RESULTS

Advanced lymph node metastases (N2, N3) were highly significantly associated with reductions in metastasis-free (MFS), cancer-specific (CS), and overall survival (OS) rates (p = <0.001), while lymphovascular invasion was a significant parameter for reduced CS and OS (p = 0.005; p = 0.007). Concerning the primary tumor stage, a significant difference in MFS was found only between pT1b and pT1a (p = 0.017), whereas CS and OS did not significantly differ between T categories. In patients without lymph node metastasis at the time of primary diagnosis, lymphovascular invasion was a significant prognostic parameter for lower MFS (p = 0.032). Histological subtypes differed in prognosis, with the worst outcome in basaloid carcinomas, but without statistical significance. HPV status was not associated with prognosis, either in the total cohort or in the usual type alone.

CONCLUSION

Lymphatic involvement has the highest impact on prognosis in penile cancer, whereas HPV status alone is not suitable as a prognostic parameter. The pT1b stage, which includes grading, as well as lymphovascular and perineural invasion in the T stage, seems questionable; a revision of the TNM classification is therefore required.