The epidermal growth factor receptor is frequently overexpressed in penile squamous cell carcinomas: a tissue microarray and digital image analysis study of 112 cases

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.

Emerging Therapies in Penile Cancer

Advances in the treatment of rare tumors like penile cancer were always hampered by the lack of deep comprehension of the molecular biology and genomic and epigenomic alterations involved in carcinogenesis and tumor progression, as well as by the difficulty in recruitment of patients for prospective clinical trials. Despite the high rates of cure in early localized penile cancers with surgery or other local procedures, locally advanced and metastatic tumors require systemic treatment, with chemotherapy being the current standard, but with high toxicity and no proven real impact on survival. Recent important findings of frequent genomic alterations and mutation signatures in penile cancer have motivated several trials in new modalities of systemic treatments, especially immunotherapy. This review aims to present the most recent advances and the prospect of new modalities of systemic therapies with ongoing studies in penile cancer.

Disruption of miRNA-mRNA Networks Defines Novel Molecular Signatures for Penile Carcinogenesis

Penile cancer (PeC) carcinogenesis is not fully understood, and no biomarkers are reported in clinical practice. We aimed to investigate molecular signatures based on miRNA and mRNA and perform an integrative analysis to identify molecular drivers and pathways for PeC development. Affymetrix miRNA microarray was used to identify differentially expressed miRNAs (DEmiRs) comparing 11 tumoral tissues (TT) paired with non-neoplastic tissues (NNT) with further validation in an independent cohort (n = 13). We also investigated the mRNA expression of 83 genes in the total sample. Experimentally validated targets of DEmiRs, miRNA-mRNA networks, and enriched pathways were evaluated in silico. Eight out of 69 DEmiRs identified by microarray analysis were validated by qRT-PCR (miR-145-5p, miR-432-5p, miR-487b-3p, miR-30a-5p, miR-200a-5p, miR-224-5p, miR-31-3p and miR-31-5p). Furthermore, 37 differentially expressed genes (DEGs) were identified when comparing TT and NNT. We identified four downregulated DEmiRs (miR-30a-5p, miR-432-5p, miR-487b-3p, and miR-145-5p) and six upregulated DEGs (IL1A, MCM2, MMP1, MMP12, SFN and VEGFA) as potential biomarkers in PeC by their capacity of discriminating TT and NNT with accuracy. The integration analysis showed eight dysregulated miRNA-mRNA pairs in penile carcinogenesis. Taken together, our findings contribute to a better understanding of the regulatory roles of miRNAs and altered transcripts levels in penile carcinogenesis.

Penile Cancer-Derived Cells Molecularly Characterized as Models to Guide Targeted Therapies

Penile cancer (PeCa) is a common disease in poor and developing countries, showing high morbidity rates. Despite the recent progress in understanding the molecular events involved in PeCa, the lack of well-characterized in vitro models precludes new advances in anticancer drug development. Here we describe the establishment of five human primary penile cancer-derived cell cultures, including two epithelial and three cancer-associated fibroblast (CAF) cells. Using high-throughput genomic approaches, we found that the epithelial PeCa derived- cells recapitulate the molecular alterations of their primary tumors and present the same deregulated signaling pathways. The differentially expressed genes and proteins identified are components of key oncogenic pathways, including EGFR and PI3K/AKT/mTOR. We showed that epithelial PeCa derived cells presented a good response to cisplatin, a common therapeutic approach used in PeCa patients. The growth of a PeCa-derived cell overexpressing EGFR was inhibited by EGFR inhibitors (cetuximab, gefitinib, and erlotinib). We also identified CAF signature markers in three PeCa-derived cells with fibroblast-like morphology, indicating that those cells are suitable models for PeCa microenvironment studies. We thus demonstrate the utility of PeCa cell models to dissect mechanisms that promote penile carcinogenesis, which are useful models to evaluate therapeutic approaches for the disease.

The Biomarker Potential of Caveolin-1 in Penile Cancer

Various types of human cancers were characterized by an altered expression of epithelial or stromal caveolin-1 (CAV1). However, the clinical significance of CAV1 expression in penile cancer remains largely unknown. Here the expression patterns of CAV1 were analyzed in a retrospective cohort (n=43) of penile squamous cell carcinomas (SCC). Upon penile cancer progression, significantly increased CAV1-levels were determined within the malignant epithelium, whereas within the tumor stroma, namely the fibroblastic tumor compartment harboring activated and/or cancer associated fibroblasts, CAV1 levels significantly decline. Concerning the clinicopathological significance of CAV1 expression in penile cancer as well as respective epithelial-stromal CAV1 distributions, high expression within the tumor cells as well as low expression of CAV1 within the stromal compartment were correlated with decreased overall survival of penile cancer patients. Herein, CAV1 expressions and distributions at advanced penile cancer stages were independent of the immunohistochemically proven tumor protein p53 status. In contrast, less differentiated p16-positive tumor epithelia (indicative for human papilloma virus infection) were characterized by significantly decreased CAV1 levels. Conclusively, we provide further and new evidence that the characteristic shift in stromal‐epithelial CAV1 being functionally relevant to tumor progression even occurs in penile SCC.

The HPV and p63 Status in Penile Cancer Are Linked with the Infiltration and Therapeutic Availability of Neutrophils

Squamous penile cancer displays a rare human papillomavirus (HPV)-associated tumor entity. Investigations on the molecular pathogenesis of HPV-driven penile cancer are impaired by the rareness of clinical specimens and, in particular, are missing relevant cell culture models. Here, we identified in HPV-positive penile cancer cell lines that HPV16 oncoproteins control TP63 expression by modulating critical regulators, while integration into the TP63 open reading frame facilitates oncogene expression. The resulting feed-forward loop leads to elevated p63 levels that in turn enhance the release of the neutrophil-recruiting chemokine CXCL8. Remarkably, elevated CXCL8 amounts lead to the increased surface exposition of the Fc receptor of human IgA antibodies, FcαRI, on neutrophils and correlated with a higher susceptibility to antibody-dependent neutrophil-mediated cytotoxicity (ADCC) using an EGFR-specific IgA2 antibody. IHC staining of tissue microarrays proved that elevated expression of p63 together with neutrophil infiltration were significantly more frequent in HPV-positive penile cancer displaying a higher tumor grade. In summary, we identified a promising marker profile of patients with penile cancer at higher risk for worse prognosis. However, these patients may benefit from immunotherapeutic approaches efficiently engaging neutrophils for tumor cell killing.

An update on systemic therapy for penile cancer

PURPOSE OF REVIEW

Whereas substantial advances have been made in systemic tumour therapy in the past decade, the prognosis of advanced squamous cell carcinoma (SCC) of the penis remains disproportionally poor. In this review, we aimed to present an update on systemic therapy of penile SCC highlighting the most recent data and future perspectives.

RECENT FINDINGS

Lymph node metastases play a key role in treating and assessing the prognosis of patients with penile SCC. Data show longer overall survival with the use of adjuvant chemotherapy in patients with pelvic lymph node metastases and recent analyses lead to the development of a nomogramm predicting overall survival in connection with the use of perioperative chemotherapy. There are two pathways in the pathogenesis of penile cancer, including human papilloma virus related and unrelated, leading to many possible novel therapeutic targets. Other targeted therapies have been evaluated, which show promising results with the use of tyrosine kinase inhibitors.

SUMMARY

Chemotherapy has shown moderate activity in advanced stages of the disease, however, the ideal timing of chemotherapy in patients with lymph node metastases is not entirely clear. Potential targets for future therapies exist, and are already being tested in other malignancies. Owing to the rarity of this condition, a robust evidence is lacking and it is of great importance to pursue further research to unveil several aspects of this disease, particularly in patients with recurrence, lymph node metastases or metastatic disease.

Potential Receptors for Targeted Imaging of Lymph Node Metastases in Penile Cancer

Imaging modalities using tumor-directed monoclonal antibodies may be of value to improve the pre- and intraoperative detection and resection of lymph node (LN) metastatic disease in penile squamous cell carcinoma (PSCC). We investigated the expression of prostate-specific membrane antigen (PSMA), vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) and epithelial cell adhesion molecule (EpCAM) to analyze their potency for diagnostic applications. Antigen expression was determined in primary tumors and LNs with and without metastases of 22 patients with PSCC. The total immunostaining score (TIS, 0–12) was determined as the product of a proportion score (PS, 0–4) and an intensity score (IS, 0–3). EGFR and VEGF expression were high in primary tumor (median TIS 8) and LN metastases (median TIS 6 and 8, respectively). No EGFR expression was seen in LNs without metastases. However, LNs without metastases did show VEGF expression (median TIS 6). No EpCAM or PSMA expression was seen in PSCC. This study shows that VEGF and EGFR expression is moderate to high in LN metastases of PSCC. Both VEGF and EGFR warrant further clinical evaluation to determine their value as a target for pre- and intraoperative imaging modalities in the detection of LN metastases in PSCC.

Leveraging innovative therapies with an evolving understanding of the molecular pathogenesis of penile squamous cell carcinoma

Penile squamous cell carcinoma is a rare condition that is associated with significant morbidity and mortality in its advanced stages. In today's rapidly evolving field of oncology, physicians and scientists are learning to harness the power of genomics to drive innovative targeted, immunotherapeutic, and multimodal strategies across different cancer types; however, there remains a pressing need for a deeper understanding of the molecular pathways of penile carcinogenesis in order to help direct individualized therapy for patients with this disease. In this article, we will review our current understanding of some of the biologic mechanisms, including virally and nonvirally based pathways, which are thought to drive the development and progression of penile cancer.

[Systemic treatment of locally advanced or metastatic penile cancer]

Penile cancers are rare, the vast majority is represented by squamous cell carcinoma, with HPV virus being found in 30 to 40% of cases. At a locally advanced or metastatic stage, first-line treatment relies on platinum and taxane based polychemotherapy. The prognosis for advanced or metastatic penile cancer remains poor, with overall survival ranging from 13.9 to 17.1 months. After the first line, guidelines recommend various chemotherapy treatments or targeted anti-EGFR therapies whose results as well as the level of evidence are limited. A better understanding of the oncogenic pathways involved in penile cancer and a frequent expression of PD-L1 are the rationale for the elaboration of new strategies. This review article presents the data, guidelines and ongoing studies in locally advanced or metastatic penile cancer.

A phase II trial of cabazitaxel as second line chemotherapy in relapsed locally advanced and/or metastatic carcinoma of the penis

Objectives

To assess the efficacy and tolerability of cabazitaxel in relapsed penile cancer.

Methods

This Phase II single-arm trial was designed to recruit 17 patients with relapsed penile cancer. The primary endpoint was objective (complete + partial) response rate (ORR; Response Evaluation Criteria in Solid Tumours [RECIST] v1.1). Treatment comprised six 21-day cycles of cabazitaxel with restaging after cycles 2 and 4. The planned interim analysis was based upon the premise that if none of the first nine patients achieved ORR, trial would be stopped (α = 0.05, Simon’s 2-stage design).

Results

Nine patients were recruited from four UK centres between December 2014 and August 2016. The median age was 61 (range, 27–73.6) years, and seven patients had metastases. Patients received a median of two chemotherapy cycles (range, 2–5). None of the nine patients achieved ORR and the trial was stopped. Cabazitaxel was well tolerated with no dose reductions or delays. Three patients had grade 3/4 adverse events (anaemia, vomiting, or neutropenic sepsis). The median progression-free and overall survival were 1.3 and 5.6 months, respectively.

Conclusions

The trial did not reach the threshold for further continuation of single-agent cabazitaxel. However, the observed tolerability profile supports its further investigation in combination with other agents to improve patient outcomes.

Beyond chemotherapy for advanced disease-the role of EGFR and PD-1 inhibitors

Penile squamous cell carcinoma (SCC) is a rare malignancy with limited treatment options when the tumor is unresectable and/or chemorefractory. Triplet systemic chemotherapy regimens including taxane and cisplatin are recommended, but the response duration can be short and the treatment-related toxicity high. Only a small proportion of patients survive 1 year or longer with the current standard treatment paradigm. Beyond chemotherapy, the use of novel targeted agents, either alone or in combination with traditional chemotherapeutic agents, has appeared to have promising efficacy in patients with platinum-refractory penile cancer. The frequent overexpression of PD-L1 in advanced penile SCC indicates the potential efficacy of PD-1 inhibitors. Upcoming clinical trials using the immune check-point inhibitors may provide exciting landscape and change the paradigm for patients in the future.

Advances in Understanding of Penile Carcinogenesis: The Search for Actionable Targets

Penile cancer (PeCa) is a rare malignancy with potentially devastating effects. Squamous cell carcinoma is the most common variant with distinct precancerous lesions before development into invasive disease. Involvement of the inguinal lymph nodes is the most important prognostic factor in PeCa, and once disease is present outside the groin, prognosis is poor. Metastatic PeCa is challenging to treat and often requires multidisciplinary approaches in management. Due to its rarity, molecular understanding of the disease continues to be limited with most studies based on small, single center series. Thus far, it appears PeCa has diverse mechanisms of carcinogenesis affecting similar molecular pathways. In this review, we evaluate the current landscape of the molecular carcinogenesis of PeCa and explore ongoing research on potential actionable targets of therapy. The emergence of anti-epidermal growth factor receptor (EGFR) and other immunotherapeutic strategies may improve outcomes for PeCa patients.

Strong association of insulin-like growth factor 1 receptor expression with histologic grade, subtype, and HPV status in penile squamous cell carcinomas: a tissue microarray study of 112 cases

Insulin-like growth factor-1 receptor (IGF1R) plays a key role in cell growth and transformation. It is overexpressed in several solid tumors. This study evaluates IGF1R immunoexpression in penile squamous cell carcinoma (SCC). Four tissue microarrays were built from formalin-fixed, paraffin-embedded blocks of 112 penile SCC from Paraguay. Membranous IGF1R expression was evaluated by immunohistochemistry using two different approaches. An H-score was calculated in each spot (stain intensity by extent), and a median score per tumor was obtained. The second approach consisted of a score similar to the scoring system that was used for evaluating HER2 immunoexpression. For each case, the highest category obtained at any spot was used for statistical analyses. IGF1R expression was compared by histologic subtype, grade, and human papillomavirus (HPV) status. Median H-score was 22.5. The distribution of IGF1R expression by HER2 approach was as follows: 0 in 33.0% cases, 1+ in 46.4%, 2+ in 14.3%, and 3+ in 6.2%. IGF1R H-scores were associated with basaloid and warty/basaloid subtypes (p = 0.0026) and higher grade (p = 0.00052). Although weaker when using the HER2 approach, the association of IGF1R expression with subtype (p = 0.015) and grade (p = 0.015) remained significant. Furthermore, there was an association between IGF1R expression by HER2 approach and HPV status (p = 0.012). IGF1R was expressed in about two thirds of penile SCC cases, showing a strong positive association with histologic grade, subtype, and HPV status. Considering that grade is a predictor of outcome IGF1R expression may have prognostic relevance and could point to a potential role for IGF1R inhibitors in treating penile SCC.

New Developments and Challenges in Rare Genitourinary Tumors: Non-Urothelial Bladder Cancers and Squamous Cell Cancers of the Penis

The diagnosis and treatment of rare genitourinary tumors is inherently challenging. The Rare Diseases Act of 2002 initially defined a rare disorder as one that affects fewer than 200,000 Americans. The lack of widely available clinical guidelines, limited research funding, and inaccessible clinical trials often lead to difficulty with treatment decisions to guide practitioners in rendering effective care for patients with rare genitourinary cancers. This article will discuss basic tenets of diagnosis and treatment as well as recent developments and clinical trials in rare non-urothelial bladder cancers and penile squamous cell cancers.

Epidermal growth factor receptor as an adverse survival predictor in squamous cell carcinoma of the penis

Penile carcinoma (PC) is more frequent in underdeveloped countries, generally is diagnosed at an advanced stage when therapeutic options are restricted, and thus is associated with high morbidity/mortality rates. Recent studies have demonstrated clinical benefits with epidermal growth factor receptor (EGFR)-targeted therapy in patients with PC, although there is no test that provides accurate patient selection. The aim of the present study was to evaluate the prognostic value of EGFR gene and protein status in tumor samples from patients with primary penile squamous cell carcinoma. We assessed the expression of wild-type and 2 mutant EGFR isoforms (delA746-E750 and mL858R) by immunohistochemistry in 139 samples, of which 49 were also evaluated for EGFR copy number by fluorescence in situ hybridization (FISH). Positive immunohistochemical staining of wild-type and mutant EGFR was evidenced by complete and strong membranous staining. For FISH analysis, cases were considered unaltered, polysomic, or amplified, as determined by signals of the EGFR gene and chromosome 7. An independent cohort of 107 PC samples was evaluated for mutations in EGFR, KRAS, and BRAF. Protein overexpression was noted in nearly half of the cases and was associated with cancer recurrence (P=.004) and perineural invasion (P=.005). Expression of the 2 mutated EGFR isoforms was not observed. The FISH status was not associated with protein expression. Altered FISH (polysomy and gene amplification) was an independent risk factor for dying of cancer. Only 1 patient of 107 presented KRAS mutations, and no mutations of EGFR or BRAF were observed.

Pathophysiological basis of human papillomavirus in penile cancer: Key to prevention and delivery of more effective therapies

Answer questions and earn CME/CNE Squamous cell carcinoma (SCC) of the penis is a rare malignancy in the United States, with a significantly higher incidence-up to 20 to 30 times greater-in areas of Africa and South America. This can be explained in part by the significantly greater prevalence of sexually transmitted diseases among high-risk males often having unprotected sex with multiple sexual partners. Human papillomavirus (HPV) has been implicated as the infectious pathway by which several these penile neoplasms originate from precursor lesions. In this regard, a fundamental understanding of HPV in penile carcinogenesis can have meaningful implications in understanding 1) the diagnosis of HPV-related precursor penile lesions, 2) targeting HPV-specific molecular pathways, and 3) cancer prevention. Using vaccination programs not only may improve patient outcomes but also may minimize the need for highly aggressive and often debilitating surgical resection. CA Cancer J Clin 2016;66:481-495. © 2016 American Cancer Society.

Emerging Systemic Therapies for the Management of Penile Cancer

Penile squamous cell carcinoma (PSCC) is a rare cancer, but is more common in developing countries. Locally advanced and metastatic PSCC is associated with significant morbidity and mortality, with the prognosis remaining extremely poor. The authors searched PubMed and published abstracts for metastatic PSCC studies to describe emerging therapies. Multimodality treatment using chemotherapy, radiation, and consolidative surgery are standard of care. Utilizing anti-EGFR therapies and novel immunotheraputic approaches may help improve outcomes in PSCC.

Genomic Profiling of Penile Squamous Cell Carcinoma Reveals New Opportunities for Targeted Therapy

Penile squamous cell carcinoma (PeSCCA) is a rare malignancy for which there are limited treatment options due to a poor understanding of the molecular alterations underlying disease development and progression. Therefore, we performed comprehensive, targeted next-generation sequencing to identify relevant somatic genomic alterations in a retrospective cohort of 60 fixed tumor samples from 43 PeSCCA cases (including 14 matched primary/metastasis pairs). We identified a median of two relevant somatic mutations and one high-level copy-number alteration per sample (range, 0-5 and 0-6, respectively). Expression of HPV and p16 was detectable in 12% and 28% of patients, respectively. Furthermore, advanced clinical stage, lack of p16 expression, and MYC and CCND1 amplifications were significantly associated with shorter time to progression or PeSCCA-specific survival. Notably, four cases harbored EGFR amplifications and one demonstrated CDK4 amplification, genes for which approved and investigational targeted therapies are available. Importantly, although paired primary tumors and lymph node metastases were largely homogeneous for relevant somatic mutations, we identified heterogeneous EGFR amplification in primary tumor/lymph node metastases in 4 of 14 cases, despite uniform EGFR protein overexpression. Likewise, activating HRAS mutations occurred in 8 of 43 cases. Taken together, we provide the first comprehensive molecular PeSCCA analysis, which offers new insight into potential precision medicine approaches for this disease, including strategies targeting EGFR.

A next-generation tissue microarray (ngTMA) protocol for biomarker studies

Biomarker research relies on tissue microarrays (TMA). TMAs are produced by repeated transfer of small tissue cores from a ‘donor’ block into a ‘recipient’ block and then used for a variety of biomarker applications. The construction of conventional TMAs is labor intensive, imprecise, and time-consuming. Here, a protocol using next-generation Tissue Microarrays (ngTMA) is outlined. ngTMA is based on TMA planning and design, digital pathology, and automated tissue microarraying. The protocol is illustrated using an example of 134 metastatic colorectal cancer patients. Histological, statistical and logistical aspects are considered, such as the tissue type, specific histological regions, and cell types for inclusion in the TMA, the number of tissue spots, sample size, statistical analysis, and number of TMA copies. Histological slides for each patient are scanned and uploaded onto a web-based digital platform. There, they are viewed and annotated (marked) using a 0.6-2.0 mm diameter tool, multiple times using various colors to distinguish tissue areas. Donor blocks and 12 ‘recipient’ blocks are loaded into the instrument. Digital slides are retrieved and matched to donor block images. Repeated arraying of annotated regions is automatically performed resulting in an ngTMA. In this example, six ngTMAs are planned containing six different tissue types/histological zones. Two copies of the ngTMAs are desired. Three to four slides for each patient are scanned; 3 scan runs are necessary and performed overnight. All slides are annotated; different colors are used to represent the different tissues/zones, namely tumor center, invasion front, tumor/stroma, lymph node metastases, liver metastases, and normal tissue. 17 annotations/case are made; time for annotation is 2-3 min/case. 12 ngTMAs are produced containing 4,556 spots. Arraying time is 15-20 hr. Due to its precision, flexibility and speed, ngTMA is a powerful tool to further improve the quality of TMAs used in clinical and translational research.