644: Cathepsin D is a Marker for Early Stage Renal Cell Cancer and Predicts the Presence of Distant Metastases

516 Background: Transition from localized renal cell cancer (RCC) to metastatic disease is associated with an immense mortality. Beside clinicopathological risk estimation, a molecular prediction of metastatic risk from primary cancers with a sufficient diagnostic accuracy is not available. We biometrically identified a candidate metastasis associated methylation signature (MAMS) in a genome-wide in silico DNA methylation analysis of TCGA data and carried out a double evaluation study using tissues from localized RCC, primary metastatic RCC, and distant metastases. Methods: Candidate MAMS was identified by genome-wide random forest analyses of TCGA methylation level 3 data aiming for classification of 230 primary RCC without distant metastases and 52 metastasized tumors. Forty-nine pyrosequencing and/or quantitative methylation specific PCR analyses were established for a total of 20 candidate methylated loci. For evaluation of MAMS, DNA was isolated and bisulfite converted from the primary RCC tissue cohort (n=187) as well as 99 distant metastases. Localized RCCs consisted of 92 pT1a/b tumors (clear cell, 73; papillary, 16; chromophobe, 2; not classified, 1) without lymph node or distant metastases. RCC samples of primary metastatic disease were obtained from 31 patients. Results: Single candidate loci showed specific hypermethylation when metastatic tissues were compared to primary RCC samples. Random forest analysis showed that MAMS including nine methylation loci achieved a sensitivity of 93% and a specificity of 89% (AUC 0.95) for differentiation of localized RCC and metastases (chi square, p = 3.4*10-29). Positive, negative likelihood, and diagnostic odds ratios were 8.6, 0.08, and 108. Using this random forest model for prediction of primary RCCs associated with distant or lymph node metastases revealed a sensitivity of 58% and specificity of 94% (AUC 0.84, p = 1.0*10-9). Positive, negative likelihood, and diagnostic odds ratios were 9.2, 0.45, and 20.5. Conclusions: A negative MAMS test result retrospectively reduced the probability of metastasis 15-fold in the localized disease cohort, suggesting a prospective evaluation for a possible clinical translation of MAMS in handling RCC patients.

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Molecular profile of early-stage and advanced-stage of renal cell cancer in China.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.e16071 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. e16071-e16071

Author(s):

Jimin Chen ◽

Yanrui Zhang ◽

Tongtong Yang ◽

Huina Wang ◽

Jing Guo ◽

...

Keyword(s):

Renal Cell Cancer ◽

Renal Cell ◽

Early Stage ◽

Clinical Status ◽

Cell Cancer ◽

Genetic Alterations ◽

Molecular Profile ◽

Molecular Characteristics ◽

Advanced Stage ◽

Genomic Alterations

e16071 Background: The mutation spectrum has been extensively studied in Renal Cell Cancer (RCC), a heterogeneous disease. While major investigations have focused on metastatic RCC (mRCC). This study intended to explore the molecular characteristics between early-stage (stage I/Ⅱ) and advanced-stage (Ⅲ/Ⅳ) of RCC patients (pts). Methods: 36 tumor specimens were obtained from individual pts diagnosed RCC, including 22 tissues paired with blood samples. Somatic mutations were identified via targeted next generation sequencing with Acornmed panel including 808 genes associated with tumor development. Sequencing data were analyzed to call tumor specific single nucleotide variants (SNV), small insertions and deletions (InDels), copy number alterations (CNA) and chromosomal rearrangements. Clinical data of a cohort from TCGA who had RCC was collected and analyzed. Results: Among the 36 pts enrolled, 61% were early-stage group and 39% were advanced-stage group. The most frequently mutated genes in RCC were VHL (50%), PBRM1 (14%), BAP1 (11%), TP53 (11%) and PIK3CA (6%). Truncating mutations were the most frequent alterations accounting for 66% (33/50) of genetic alterations. Mutations in VHL, BAP1, PBRM1 and TP53 were shared by both early and advanced RCC. While mutations in PIK3CA, CDKN2C, EGFR, FAMCA, GRIN2A, KDM6A, SOX17, TSC1 and APC were only detected in early stage group. KNSTRN, KRAS, MYD88, NF2, ATM, PTEN and STAT5B mutations were only detected in advanced group. Among 22 plasma samples, genomic alterations were detected in 40.9% (9/22) of pts postoperatively, such as TP53, PIK3CA, PTEN, and APC. Functional annotation clustering revealed that 4/9 in these genes were tumor suppressors, which negatively regulated apoptosis. Pts with genomic alterations in TP53 (p = 0.0034), PIK3CA (p = 0.0015) or PTEN (p = 0.00017) had worse OS significantly (TCGA). Conclusions: VHL, PBRM1, BAP1 were the most important driver genes mainly detected in all stages of RCC. The heterogeneity between early and advanced-stage may be related with clinical status. Gene alterations in plasma ctDNA postoperatively should have the potential to stratify patients with different prognostic outcome.

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