Loss of PBRM1 and BAP1 expression is less common in non-clear cell renal cell carcinoma than in clear cell renal cell carcinoma.

Recurrent mutations in polybromo-1 (PBRM1, ~40%) and BRCA1-associated protein-1 (BAP1, ~10%) occur in clear cell renal cell carcinoma (ccRCC), but their prevalence in non-ccRCC or renal oncocytoma (RO) is unknown. We evaluated loss of PBRM1 and BAP1 staining in ccRCC, papillary RCC (pRCC), chromophobe RCC (chRCC), and RO tumors using an immunohistochemistry assay in which negative staining was associated with loss-of-function mutations. We identified 458 patients treated surgically for ccRCC, pRCC, chRCC, and RO between 2004 and 2012. We performed immunohistochemistry assays to evaluate PBRM1 and BAP1 protein expression to classify tumors as PBRM1 or BAP1 negative. We compared loss of staining of these 2 proteins in ccRCC and non-ccRCC using the Fisher exact test. For the total cohort of 458 patients, we successfully stained both PBRM1 and BAP1 in 408 tumor samples. Consistent with the mutation rate, loss of PBRM1 and BAP1 staining occurred in 43% (80/187) and 10% (18/187) of ccRCC cases, respectively. However, loss of PBRM1 staining occurred in only 3% (2/59), 6% (1/17), and 0% (0/34) of pRCC, chRCC, and RO tumors, respectively (P<0.0001). BAP1 loss was not observed in any of the pRCC (n = 61), chRCC (n = 17), or RO (n = 34) tumors, (P = 0.00021). Our data suggest that biallelic inactivation of PBRM1 or BAP1 is less common in non-ccRCC when compared with ccRCC tumors. These findings suggest that loss of PBRM1 or BAP1 are key events in ccRCC, whereas other pathways may support tumorigenesis in non-ccRCC subtypes.

Ho TH ，Kapur P ，Joseph RW ，Serie DJ ，Eckel-Passow JE ，Parasramka M ，Cheville JC ，Wu KJ ，Frenkel E ，Rakheja D ，Stefanius K ，Brugarolas J ，Parker AS ... -  《-》

Adverse outcomes in clear cell renal cell carcinoma with mutations of 3p21 epigenetic regulators BAP1 and SETD2: a report by MSKCC and the KIRC TCGA research network.

Hakimi AA ，Ostrovnaya I ，Reva B ，Schultz N ，Chen YB ，Gonen M ，Liu H ，Takeda S ，Voss MH ，Tickoo SK ，Reuter VE ，Russo P ，Cheng EH ，Sander C ，Motzer RJ ，Hsieh JJ ，ccRCC Cancer Genome Atlas (KIRC TCGA) Research Network investigators ... -  《-》

BAP1 and PBRM1 in metastatic clear cell renal cell carcinoma: tumor heterogeneity and concordance with paired primary tumor.

Eckel-Passow JE ，Serie DJ ，Cheville JC ，Ho TH ，Kapur P ，Brugarolas J ，Thompson RH ，Leibovich BC ，Kwon ED ，Joseph RW ，Parker AS ... -  《BMC Urology》

Loss of BAP1 expression in metastatic tumor tissue is an event of poor prognosis in patients with metastatic clear cell renal cell carcinoma.

To evaluate the prognostic impact of the protein expression of both PBRM1 and BAP1 in metastatic tissue of patients with metastatic clear cell renal cell carcinoma (ccRCC). In all 124 consecutive cases of metastatic ccRCC, who underwent metastasectomy or biopsy of metastatic tumor tissue between 2007 and 2016 were selected from the medical records of our institution. Additionally, 38 paired cases with tissue from the primary tumor involving radical or partial nephrectomy for ccRCC were also selected. All cases were reviewed for uniform reclassification and the most representative tumor areas were selected for the construction of a tissue microarray. PBRM1 nuclear staining of the 124-immunostained metastases of ccRCC specimens showed that 98 (79.0%) had negative expression and 26 (21.0%) positive expression of PBRM1. Regarding BAP1 expression, we observed that 77 (62.1%) specimens were negative and 47 (37.9%) showed positive nuclear staining. When we compared the expression of both markers on primary tumor and tumor metastasis, we found disagreement in half of the cases. Five-year overall survival rates in patients with positive expression and negative expression of BAP1 were 53.2% and 35.1%, respectively (P = 0.004). Five-year progression-free survival rates in patients with positive expression and negative expression of BAP1 were 14.9% and 3.9%, respectively (P = 0.003). Conversely, PBRM1 expression did not significantly influence either overall survival or progression-free survival rates. In multivariate analysis, negative expression of BAP1 tumors also presented higher risks of death (hazard ratio (HR) = 1.913, P = 0.041) and disease progression (HR = 1.656, P = 0.021). The use of prognostic biomarkers identified in the primary tumor tissue might be not reliable in the metastatic disease scenario. Patients with metastatic ccRCC that present loss of BAP1 expression in metastatic tissue demonstrated poor survival rates and represent a relevant risk group for tumor recurrence and death.

da Costa WH ，Fares AF ，Bezerra SM ，Morini MA ，de Toledo Benigno LA ，Clavijo DA ，Fornazieri L ，Rocha MM ，da Cunha IW ，de Cassio Zequi S ... -  《-》

Expression and Mutation Patterns of PBRM1, BAP1 and SETD2 Mirror Specific Evolutionary Subtypes in Clear Cell Renal Cell Carcinoma.

Bi-allelic inactivation of the VHL gene on chromosome 3p is the characteristic feature in most clear cell renal cell carcinomas (ccRCC). Frequent gene alterations were also identified in SETD2, BAP1 and PBRM1, all of which are situated on chromosome 3p and encode histone/chromatin regulators. The relationship between gene mutation, loss of protein expression and the correlations with clinicopathological parameters is important for the understanding of renal cancer progression. We analyzed PBRM1 and BAP1 protein expression as well as the tri-methylation state of H3K36 as a surrogate marker for SETD2 activity in more than 700 RCC samples. In ccRCC loss of nuclear PBRM1 (68%), BAP1 (40%) and H3K36me3 (47%) expression was significantly correlated with each other, advanced tumor stage, poor tumor differentiation (P < .0001 each), and necrosis (P < .005) Targeted next generation sequencing of 83 ccRCC samples demonstrated a significant association of genetic mutations in PBRM1, BAP1, and SETD2 with absence of PBRM1, BAP1, and HEK36me3 protein expression (P < .05, each). By assigning the protein expression patterns to evolutionary subtypes, we revealed similar clinical phenotypes as suggested by TRACERx Renal. Given their important contribution to tumor suppression, we conclude that combined functional inactivation of PBRM1, BAP1, SETD2 and pVHL is critical for ccRCC progression.

Bihr S ，Ohashi R ，Moore AL ，Rüschoff JH ，Beisel C ，Hermanns T ，Mischo A ，Corrò C ，Beyer J ，Beerenwinkel N ，Moch H ，Schraml P ... -  《NEOPLASIA》