Abstract 2702: Mutations of SPOP, FOXA1 and IDH1 are associated with prostate cancer metastasis and biochemical outcomes
Authors: Ma Jinlu , Han Suxia , Sui Xin , Lu Wenyan , Li Yonghe , Xu Bo 
Published: July 2017

Recent genomic studies have shed light on cataloging genomic alterations in prostate cancer. Mechanistic studies allow the use of this information to subclassify the heterogeneous prostate tumors for optimized treatment planning. Speckle-Type POZ Protein (SPOP), Forkhead Box Protein A1 (FOXA1) and Isocitrate Dehydrogenase 1 (IDH1) are among the genes that show frequent point mutations in primary prostate cancers. However, the clinical significance of these gene mutations in cancer patients is less clear. To determine the whether SPOP, FOXA1 and IDH1 mutations are associated with clinical outcomes in prostate cancer, we pyro-sequenced the three genes in prostate cancer patients and evaluated the clinical and prognostic significance. 198 patients from the first hospital of Xi’An Jiaotong University (China) were analyzed. All patients were newly diagnosed with prostate cancer from January 2010 to December 2015. No patient was lost to follow-up. The average follow-up time after the primary diagnosis was 27 months. The Fisher’s exact tests were used to compare categorical data. The risk of metastasis among patients with SPOP, FOXA1 and IDH1 mutations was evaluated using univariate and multivariate logistic regression models. The prognostic significance of clinical and gene mutations was determined using multivariate Cox regression analysis. SPOP mutations were found in 16 patients (8.1%), with all of the mutations clustered in the substrate-binding MATH domain. FOXA1 mutationswere found in nine patients (4.5%), and were clustered in the Forkhead domain. IDH1 mutations were detected in three patients (1.5%). Mutation frequencies of SPOP, FOXA1 and IDH1 were associated with prostate-specific antigen (PSA), a biochemical marker of prostate tumor presence/risk which is decided by Gleason Score, T stage and PSA level, along with prostate cancer PSA failure and metastasis. Among patients with SPOP mutation, 56.3% showed metastasis at the time of diagnosis of primary cancer, compared to only 11.5% of patients with wild-type SPOP. Similarly, the probabilities of FOXA1 and IDH1 mutations with metastasis were

approximately 44.4% and 66.7% versus 13.8% and 14.4%, respectively, comparing to their wild-type counterparts. The metastasis risk for patients with SPOP mutation was 1.27 times of the SPOP wild-type patients (P = 0.003). We also found that patients with SPOP (P &lt; 0.0001) and FOXA1 (P = 0.0403) mutations showed higher risk of PSA failure compared with wild-type. The PSA failure risk for patients with SPOP mutation was 35.49 times of the SPOP wild-type patients. In contrast, IDH1 mutation was not associated with PSA failure (P = 0.054). Multivariate analyses demonstrate that SPOP mutation is an independent factor that is associated with prostate cancer metastasis and PSA failure recurrence. These findings underscore the clinical significance for profiling SPOP, FOXA1 and IDH1.

Note: This abstract was not presented at the meeting.

Citation Format: Jinlu Ma, Suxia Han, Xin Sui, Wenyan Lu, Yonghe Li, Bo Xu. Mutations of SPOP, FOXA1 and IDH1 are associated with prostate cancer metastasis and biochemical outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2702. doi:10.1158/1538-7445.AM2017-2702