PIK3CA copy number aberration and activation of the PI3K-AKT-mTOR pathway in varied disease states of penile cancer.

BACKGROUND: Therapeutic targeting of the PI3K-AKT-mTOR pathway may benefit patients with advanced penile squamous cell carcinoma (PSCC). OBJECTIVES: To determine the prevalence of PIK3CA copy number gain and correlate this with the activity status of PI3K-AKT-mTOR pathway in pre-malignant penile intraepithelial neoplasia (PeIN) and invasive PSCC. MATERIALS AND METHODS: Archival tissue blocks were obtained from 58 PeIN and 244 primary PSCC patients treated at St George's Hospital. PIK3CA copy number status (CNS) was assessed by fluorescence in-situ hybridisation. High-risk HPV DNA was detected with INNO-LiPA assay. p16INK4A, p-AKT and p-mTOR protein expression were assessed using immunohistochemistry (IHC). RESULTS: Increased prevalence of PIK3CA copy number gain was seen in PSCC in comparison to PeIN (84/199 (42%) vs. 10/58 (17%); p = 0.0009). Analysis of the p-AKT and p-mTOR revealed a tendency to a more common expression of cytoplasmic p-AKT (p = 0.1318), nuclear p-AKT (p<0.0001) and cytoplasmic mTOR (p = 0.0006) in PeIN than PSCC. A significant association between p-AKT cytoplasmic immunoexpression and PIK3CA CNS (p = 0.0404) was found in PeIN. CONCLUSION: Overall, PIK3CA copy number gain correlated with activation of the PI3K-AKT-mTOR pathway in PeIN and activation of this pathway is primarily involved in early penile carcinogenesis. Based on these results therapeutic targeting of this pathway in advanced PSCC is unlikely to produce significant clinical benefit. Future studies will need to focus on alternative therapeutic targets.

DNA Copy Number Aberrations, and Human Papillomavirus Status in Penile Carcinoma. Clinico-Pathological Correlations and Potential Driver Genes.

Penile squamous cell carcinoma is a rare disease, in which somatic genetic aberrations have yet to be characterized. We hypothesized that gene copy aberrations might correlate with human papillomavirus status and clinico-pathological features. We sought to determine the spectrum of gene copy number aberrations in a large series of PSCCs and to define their correlations with human papillomavirus, histopathological subtype, and tumor grade, stage and lymph node status. Seventy formalin-fixed, paraffin embedded penile squamous cell carcinomas were centrally reviewed by expert uropathologists. DNA was extracted from micro-dissected samples, subjected to PCR-based human papillomavirus assessment and genotyping (INNO-LiPA human papillomavirus Genotyping Extra Assay) and microarray-based comparative genomic hybridization using a 32K Bacterial Artificial Chromosome array platform. Sixty-four samples yielded interpretable results. Recurrent gains were observed in chromosomes 1p13.3-q44 (88%), 3p12.3-q29 (86%), 5p15.33-p11 (67%) and 8p12-q24.3 (84%). Amplifications of 5p15.33-p11 and 11p14.1-p12 were found in seven (11%) and four (6%) cases, respectively. Losses were observed in chromosomes 2q33-q37.3 (86%), 3p26.3-q11.1 (83%) and 11q12.2-q25 (81%). Although many losses and gains were similar throughout the cohort, there were small significant differences observed at specific loci, between human papillomavirus positive and negative tumors, between tumor types, and tumor grade and nodal status. These results demonstrate that despite the diversity of genetic aberrations in penile squamous cell carcinomas, there are significant correlations between the clinico-pathological data and the genetic changes that may play a role in disease natural history and progression and highlight potential driver genes, which may feature in molecular pathways for existing therapeutic agents.

Dynamic sentinel lymph node biopsy in patients with invasive squamous cell carcinoma of the penis: a prospective study of the long-term outcome of 500 inguinal basins assessed at a single institution.

BACKGROUND: Dynamic sentinel node biopsy (DSNB) in combination with ultrasound scan (USS) has been the technique of choice at our centre since 2004 for the assessment of nonpalpable inguinal lymph nodes (cN0) in patients with squamous cell carcinoma of the penis (SCCp). Sensitivity and false-negative rates may vary depending on whether results are reported per patient or per node basin, and with or without USS. OBJECTIVE: To determine the long-term outcome of patients undergoing DSNB and USS-guided fine-needle aspiration cytology (FNAC) in our cohort of newly diagnosed cN0 SCCp patients, as well as to analyse any variation in sensitivity of the procedure. DESIGN, SETTING, AND PARTICIPANTS: A series of consecutive patients with newly diagnosed SCCp, over a 6-yr period (2004-2010), were analysed prospectively with a minimum follow-up period of 21 mo. All patients had definitive histology of ≥ T1G2 and nonpalpable nodes in one or both inguinal basins. Patients with persistent or untreated local disease were excluded from the study. INTERVENTION: All eligible patients had DSNB and USS with or without FNAC of cN0 groins. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary end point was no nodal disease recurrence on follow-up. The secondary end point was complications after DSNB. Sensitivity of the procedure was calculated per node basin, per patient, with DSNB alone, and with USS with DSNB combined. RESULTS AND LIMITATIONS: Five hundred inguinal basins in 264 patients underwent USS with or without FNAC and DSNB. Seventy-three positive inguinal basins (14.6%) in 59 patients (22.3%) were identified. Four inguinal basins in four patients were confirmed false negative at 5, 8, 12, and 18 mo. Two inguinal basins had positive USS and FNAC and negative DSNB results. Sensitivity of DSNB with USS, with and without FNAC, per inguinal basin was 95% and per patient was 94%. Sensitivity of DSNB alone per inguinal basin and per patient was 92% and 91%, respectively. The DSNB morbidity rate was 7.6%. CONCLUSIONS: DSNB in combination with USS has excellent performance characteristics to stage patients with cN0 SCCp, with a 5% false-negative rate per node basin and a 6% false-negative rate per patient.