Cristina Magi-Galluzzi

EZH2 Oncogenic Activity in Castration-Resistant Prostate Cancer Cells Is Polycomb-Independent

Alternative Role for EZH2 Epigenetic regulators are implicated in cancer progression and proposed as therapeutic targets. Xu et al. (p. 1465; see the Perspective by Cavalli) report that EZH2 (Enhancer of zeste homolog 2), a factor previously thought to exert its oncogenic function primarily as part of the polycomb repressive complex, acts through a distinct mechanism in cells of castration-resistant prostate cancer. Rather than exclusively silencing gene expression through histone methylation, EZH2 acts as a transcriptional coactivator. The activation function of EZH2 plays a critical role in the growth of castration-resistant prostate cancer cells, which could be relevant in future drug development. An epigenetic regulator positively regulates gene expression in cell-based models of hormone-resistant prostate cancer. Epigenetic regulators represent a promising new class of therapeutic targets for cancer. Enhancer of zeste homolog 2 (EZH2), a subunit of Polycomb repressive complex 2 (PRC2), silences gene expression via its histone methyltransferase activity. We found that the oncogenic function of EZH2 in cells of castration-resistant prostate cancer is independent of its role as a transcriptional repressor. Instead, it involves the ability of EZH2 to act as a coactivator for critical transcription factors including the androgen receptor. This functional switch is dependent on phosphorylation of EZH2 and requires an intact methyltransferase domain. Hence, targeting the non-PRC2 function of EZH2 may have therapeutic efficacy for treating metastatic, hormone-refractory prostate cancer.

A Contemporary Prostate Cancer Grading System: A Validated Alternative to the Gleason Score.

BACKGROUND Despite revisions in 2005 and 2014, the Gleason prostate cancer (PCa) grading system still has major deficiencies. Combining of Gleason scores into a three-tiered grouping (6, 7, 8-10) is used most frequently for prognostic and therapeutic purposes. The lowest score, assigned 6, may be misunderstood as a cancer in the middle of the grading scale, and 3+4=7 and 4+3=7 are often considered the same prognostic group. OBJECTIVE To verify that a new grading system accurately produces a smaller number of grades with the most significant prognostic differences, using multi-institutional and multimodal therapy data. DESIGN, SETTING, AND PARTICIPANTS Between 2005 and 2014, 20,845 consecutive men were treated by radical prostatectomy at five academic institutions; 5501 men were treated with radiotherapy at two academic institutions. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Outcome was based on biochemical recurrence (BCR). The log-rank test assessed univariable differences in BCR by Gleason score. Separate univariable and multivariable Cox proportional hazards used four possible categorizations of Gleason scores. RESULTS AND LIMITATIONS In the surgery cohort, we found large differences in recurrence rates between both Gleason 3+4 versus 4+3 and Gleason 8 versus 9. The hazard ratios relative to Gleason score 6 were 1.9, 5.1, 8.0, and 11.7 for Gleason scores 3+4, 4+3, 8, and 9-10, respectively. These differences were attenuated in the radiotherapy cohort as a whole due to increased adjuvant or neoadjuvant hormones for patients with high-grade disease but were clearly seen in patients undergoing radiotherapy only. A five-grade group system had the highest prognostic discrimination for all cohorts on both univariable and multivariable analysis. The major limitation was the unavoidable use of prostate-specific antigen BCR as an end point as opposed to cancer-related death. CONCLUSIONS The new PCa grading system has these benefits: more accurate grade stratification than current systems, simplified grading system of five grades, and lowest grade is 1, as opposed to 6, with the potential to reduce overtreatment of PCa. PATIENT SUMMARY We looked at outcomes for prostate cancer (PCa) treated with radical prostatectomy or radiation therapy and validated a new grading system with more accurate grade stratification than current systems, including a simplified grading system of five grades and a lowest grade is 1, as opposed to 6, with the potential to reduce overtreatment of PCa.

A 17-gene Assay to Predict Prostate Cancer Aggressiveness in the Context of Gleason Grade Heterogeneity, Tumor Multifocality, and Biopsy Undersampling

BACKGROUND Prostate tumor heterogeneity and biopsy undersampling pose challenges to accurate, individualized risk assessment for men with localized disease. OBJECTIVE To identify and validate a biopsy-based gene expression signature that predicts clinical recurrence, prostate cancer (PCa) death, and adverse pathology. DESIGN, SETTING, AND PARTICIPANTS Gene expression was quantified by reverse transcription-polymerase chain reaction for three studies-a discovery prostatectomy study (n=441), a biopsy study (n=167), and a prospectively designed, independent clinical validation study (n=395)-testing retrospectively collected needle biopsies from contemporary (1997-2011) patients with low to intermediate clinical risk who were candidates for active surveillance (AS). OUTCOME MEASURES AND STATISTICAL ANALYSIS The main outcome measures defining aggressive PCa were clinical recurrence, PCa death, and adverse pathology at prostatectomy. Cox proportional hazards regression models were used to evaluate the association between gene expression and time to event end points. Results from the prostatectomy and biopsy studies were used to develop and lock a multigene-expression-based signature, called the Genomic Prostate Score (GPS); in the validation study, logistic regression was used to test the association between the GPS and pathologic stage and grade at prostatectomy. Decision-curve analysis and risk profiles were used together with clinical and pathologic characteristics to evaluate clinical utility. RESULTS AND LIMITATIONS Of the 732 candidate genes analyzed, 288 (39%) were found to predict clinical recurrence despite heterogeneity and multifocality, and 198 (27%) were predictive of aggressive disease after adjustment for prostate-specific antigen, Gleason score, and clinical stage. Further analysis identified 17 genes representing multiple biological pathways that were combined into the GPS algorithm. In the validation study, GPS predicted high-grade (odds ratio [OR] per 20 GPS units: 2.3; 95% confidence interval [CI], 1.5-3.7; p<0.001) and high-stage (OR per 20 GPS units: 1.9; 95% CI, 1.3-3.0; p=0.003) at surgical pathology. GPS predicted high-grade and/or high-stage disease after controlling for established clinical factors (p<0.005) such as an OR of 2.1 (95% CI, 1.4-3.2) when adjusting for Cancer of the Prostate Risk Assessment score. A limitation of the validation study was the inclusion of men with low-volume intermediate-risk PCa (Gleason score 3+4), for whom some providers would not consider AS. CONCLUSIONS Genes representing multiple biological pathways discriminate PCa aggressiveness in biopsy tissue despite tumor heterogeneity, multifocality, and limited sampling at time of biopsy. The biopsy-based 17-gene GPS improves prediction of the presence or absence of adverse pathology and may help men with PCa make more informed decisions between AS and immediate treatment. PATIENT SUMMARY Prostate cancer (PCa) is often present in multiple locations within the prostate and has variable characteristics. We identified genes with expression associated with aggressive PCa to develop a biopsy-based, multigene signature, the Genomic Prostate Score (GPS). GPS was validated for its ability to predict men who have high-grade or high-stage PCa at diagnosis and may help men diagnosed with PCa decide between active surveillance and immediate definitive treatment.

Saturation Technique Does Not Improve Cancer Detection as an Initial Prostate Biopsy Strategy

PURPOSE We reported on the results of a sequential cohort study comparing office based saturation prostate biopsy to traditional 10-core sampling as an initial biopsy. MATERIALS AND METHODS Based on improved cancer detection of office based saturation prostate biopsy repeat biopsy, we adopted the technique as an initial biopsy strategy to improve cancer detection. Two surgeons performed 24-core saturation prostate biopsies in 139 patients undergoing initial biopsy under periprostatic local anesthesia. Indication for biopsy was an increased PSA of 2.5 ng/dl or greater in all patients. Results were compared to those of 87 patients who had previously undergone 10-core initial biopsies. RESULTS Cancer was detected in 62 of 139 patients (44.6%) who underwent saturation biopsy and in 45 of 87 patients (51.7%) who underwent 10-core biopsy (p >0.9). Breakdown by PSA level failed to show benefit to the saturation technique for any degree PSA increase. Men with PSA 2.5 to 9.9 ng/dl were found to have cancer in 53 of 122 (43.4%) saturation biopsies and 26 of 58 (44.8%) 10-core biopsies. Complications included 3 cases of prostatitis in each group. Rectal bleeding was troublesome enough to require evaluation only in 3 men in the saturation group and 1 in the 10-core group. CONCLUSIONS Although saturation prostate biopsy improves cancer detection in men with suspicion of cancer following a negative biopsy, it does not appear to offer benefit as an initial biopsy technique. These findings suggest that further efforts at extended biopsy strategies beyond 10 to 12 cores are not appropriate as an initial biopsy strategy.

TMPRSS2–ERG gene fusion prevalence and class are significantly different in prostate cancer of caucasian, african‐american and japanese patients

Prostate cancer (PCa) exhibits significant differences in prevalence and mortality among different ethnic groups. The underlying genetics is not well understood. TMPRSS2–ERG fusion is a common recurrent chromosomal aberration in PCa and is however not studied among different ethnic groups. We examined the prevalence and class of TMPRSS2–ERG gene fusion in PCa from Caucasian, African‐American, and Japanese patients.

Analytical validation of the Oncotype DX prostate cancer assay – a clinical RT-PCR assay optimized for prostate needle biopsies

BackgroundThe Oncotype DX® Prostate Cancer Assay is a multi-gene RT-PCR expression assay that was developed for use with fixed paraffin-embedded (FPE) diagnostic prostate needle biopsies containing as little as 1 mm of prostate tumor in the greatest dimension. The assay measures expression of 12 cancer-related genes representing four biological pathways and 5 reference genes which are algorithmically combined to calculate the Genomic Prostate Score (GPS). This biopsy-based assay has been analytically and subsequently clinically validated as a predictor of aggressive prostate cancer. The aim of this study was to validate the analytical performance of the Oncotype DX Prostate Cancer Assay using predefined acceptance criteria.ResultsThe lowest quartile of RNA yields from prostate needle biopsies (six 5 μm sections) was between 19 and 34 ng. Analytical validation of the process requiring as little as 5 ng of RNA met all pre-defined acceptance criteria. Amplification efficiencies, analytical sensitivity, and accuracy of gene assays were measured by serially diluting an RNA sample and analyzing features of the linear regression between RNA expression measured by the crossing point (Cp) versus the log2 of the RNA input per PCR assay well. Gene assays were shown to accurately measure expression over a wide range of inputs (from as low as 0.005 ng to 320 ng). Analytical accuracy was excellent with average biases at qPCR inputs representative of patient samples <9.7% across all assays while amplification efficiencies were within ±6% of the median. Assessments of reproducibility and precision were performed by testing 10 prostate cancer RNA samples over multiple instruments, reagent lots, operators, days (precision), and RNA input levels (reproducibility) using appropriately parameterized linear mixed models. The standard deviations for analytical precision and reproducibility were 1.86 and 2.11 GPS units (100-unit scale) respectively.ConclusionsThe Oncotype DX Prostate Cancer Assay, a clinical RT-PCR assay specifically designed for use with prostate needle biopsies, has been analytically validated using very limited RNA inputs. The assay requirements and analytical performance will provide physicians with test results from a robust and reliable assay which will enable improved treatment decisions for men diagnosed with early-stage prostate cancer.

Renal angiomyolipoma: clinicopathologic study of 194 cases with emphasis on the epithelioid histology and tuberous sclerosis association.

The majority of renal angiomyolipoma (AML) is sporadic and occasionally it occurs as part of tuberous sclerosis complex (TSC). Epithelioid AML (EAML), an uncommon variant, is considered potentially malignant based on anecdotal case reports. The prognostic significance of epithelioid component in an otherwise typical AML is uncertain. We studied 194 AMLs for the clinicopathologic features of epithelioid and TSC-associated AMLs. Epithelioid component was present in 15 cases (7.7%) with an average amount of 51% (range: 10% to 100%). Histologically, the epithelioid tumor cells were categorized into small, intermediate, and large cell type based on the cell size. Worrisome histologic features were seen in many EAMLs, including coagulative tumor necrosis in 27% (4/15), nuclear atypia in 93% (14/15), mitosis in 47% (7/15), and atypical mitosis in 1 case. All 15 EAML patients had a mean follow-up time of 5.1 years and none had local recurrence or distant metastasis. Sixteen (8.2%) AMLs occurred in patients with definitive TSC. Three histologic features, namely microscopic AML foci, epithelioid component, and epithelial cysts, were present in 10 (62.5%), 4 (25%), and 44% (7/16), respectively, of TSC-associated AMLs, compared with 11 (6.2%), 11 (6.2%), and 6 (3.4%), respectively, in non–TSC-associated AMLs (P value all <0.01). In summary, all 15 cases of EAMLs in our study had benign clinical outcomes despite adverse pathologic features. Epithelioid component, epithelial cysts, and microscopic AML foci are strongly associated with TSC and the presence of all 3 features should raise strong suspicion for TSC.

International Society of Urological Pathology (ISUP) Consensus Conference on Handling and Staging of Radical Prostatectomy Specimens. Working group 3: extraprostatic extension, lymphovascular invasion and locally advanced disease.

The International Society of Urological Pathology Consensus Conference on Handling and Staging of Radical Prostatectomy Specimens in Boston made recommendations regarding the standardization of pathology reporting of radical prostatectomy specimens. Issues relating to extraprostatic extension (pT3a disease), bladder neck invasion, lymphovascular invasion and the definition of pT4 were coordinated by working group 3. It was agreed that prostate cancer can be categorized as pT3a in the absence of adipose tissue involvement when cancer bulges beyond the contour of the gland or beyond the condensed smooth muscle of the prostate at posterior and posterolateral sites. Extraprostatic extension can also be identified anteriorly. It was agreed that the location of extraprostatic extension should be reported. Although there was consensus that the amount of extraprostatic extension should be quantitated, there was no agreement as to which method of quantitation should be employed. There was overwhelming consensus that microscopic urinary bladder neck invasion by carcinoma should be reported as stage pT3a and that lymphovascular invasion by carcinoma should be reported. It is recommended that these elements are considered in the development of practice guidelines and in the daily practice of urological surgical pathology.

ALK-1 expression in inflammatory myofibroblastic tumor of the urinary bladder.

Inflammatory myofibroblastic tumor (IMT) of the bladder is an uncommon myofibroblastic spindle cell proliferation. Because of its cytologic features and infiltrative nature, it may be difficult to distinguish histologically from sarcomatous proliferations such as sarcomatoid urothelial carcinoma, leiomyosarcoma, and embryonal rhabdomyosarcoma. Recently, anaplastic lymphoma kinase (ALK) gene translocations or ALK protein expression in IMT has been reported, especially in patients of relatively young ages. However, there are only a few reports mentioning IMT of the bladder. We sought to determine the frequency of ALK expression among IMTs of the urinary bladder. We examined 16 cases of IMTof the bladder in 14 patients to elucidate the incidence of ALK-1 expression by immunohistochemistry and its diagnostic usefulness. The age of patients with IMT ranged from 18 to 76 years, with an average age of 42.8 years. The tumors from 10 of 14 patients (12 of 16 cases) were positive for ALK-1. ALK-1-positive cases ranged in age from 18 to 73 years (mean, 39.2 years; median, 38 years) and ALK-1-negative cases from 41 to 76 years (mean, 41.5 years; median, 44.5 years). Two locally recurrent cases were positive for ALK-1 in both the primary and recurrent lesion. ALK-1 immunostaining was detected only in the cytoplasm, with granular or subplasmalemmal linear features, suggesting ALK gene translocation. ALK-1 immunostaining was also performed in 8 sarcomatoid urothelial carcinomas, 5 genitourinary leiomyosarcomas, and 2 stromal tumors of uncertain malignant potential of the prostate, all of which were negative. These results support that ALK-1 immunostaining is useful to differentiate IMT from other malignant spindle cell neoplasms of the bladder. There were no histologic differences between ALK-1 positive and negative IMTs.

Clear cell tubulopapillary renal cell carcinoma: A study of 36 distinctive low-grade epithelial tumors of the kidney

Recently several low-grade renal cell tumors, distinct from those recognized by the 2004 World Health Organization classification of renal tumors, have been described. These tumors had similar clinicopathologic features, being low-stage tumors with cystic, tubuloacinar, and/or papillary architecture. The tumor cells were low grade with variable amounts of clear cytoplasm that was positive for cytokeratin 7 (CK7), but negative for CD10. Genetic changes characteristic of clear cell or papillary renal cell carcinoma were not seen in these tumors. We investigated the morphologic, immunohistochemical, and genetic features of 36 additional tumors. Immunohistochemistry was carried out for CK7, carbonic anhydrase 9, α-methylacyl-CoA racemase, CD10, TFE-3, and desmin. Interphase fluorescence in situ hybridization was carried out with centromeric probes for chromosomes 3, 7, 17, and a subtelomeric probe for 3p25. Sequencing of von Hippel-Lindau gene and analysis of the methylation status of the promoter region was also carried out in 2 tumors. Thirty-six tumors from 33 patients (mean age: 60.4 , range: 26 to 88; 17 men and 16 women) were studied. Three patients had bilateral tumors and 1 patient had von Hippel-Lindau disease. Follow-up was available in 60% (20/33) of the patients for a mean of 27.4 (range 1 to 85) months. No patient had evidence of the disease after surgery except for the patient with von Hippel-Lindau disease, who was alive with stable disease in the contralateral kidney. All 36 tumors were small (mean size 2.4 cm; range 0.9 to 4.5 cm) and low stage (pT1). The majority was cystic and had prominent fibrous capsule and stroma. The tumors were composed of variable amount of cysts, papillae, tubules, acini, and solid nests. The most characteristic histologic features were branching tubules and acini and anastomosing clear cell ribbons with low-grade nuclei. All tumors were strongly positive for CK7 and variably positive for CA9, but largely negative for CD10, and negative for α-methylacyl-CoA racemase and TFE-3. All but 1 tumor had no gains of chromosomes 7 and 17 and deletion of 3p. Only 1 tumor had low copy number gains of chromosomes 7 and 17. VHL gene mutation and promoter methylation were negative in 2 tumors analyzed. We show that these tumors, which we term as “clear cell tubulopapillary renal cell carcinoma,” constitute a unique subtype in the spectrum of renal epithelial neoplasia based on their characteristic morphologic and immunohistochemical features.