Abstract 760: Analysis of ERG and SPOP subtypes in prostate cancer in the Colombian population and their possible implications on prognosis

Abstract

Abstract Prostate cancer (PCa) is the type of cancer with the highest incidence and mortality in our country. Current disease prognostic factors do not differentiate aggressive from indolent cases with sufficient certainty and for this reason, it has worked on a characterization of molecular subtypes that allows for a better classification. In localized PCa, fusions between the gene regulated by androgens TMPRSS2 and ERG, or mutations in SPOP (speckle type POZ, the gene that codes for an adapter protein of the Cullin-3-RING-Box1 complex) have been detected in different populations, which has been related to prognosis; however, we do not know the relevance of these molecular alterations in affected Colombians. These two alterations are described within the 7 subtypes reported by the TCGA and are considered mutually exclusive. Objective: Evaluate the presence of ERG and SPOP subtypes in prostate cancer in the Colombian population and correlate these findings with clinicopathological parameters. Methodology: For this study, FFPE radical prostatectomy samples from 112 patients with PCa were used, where the TMPRSS2-ERG fusions were studied by FISH, and in negative cases for fusion, mutations in exons 6 and 7 of SPOP were evaluated by sanger sequencing. Results: Fusion was detected in 71 patients (63.4%), this frequency of the ERG subtype was similar to that observed in the Caucasian population (40-60%). No statistically significant differences were found between the fusion state and the clinicopathological variables analyzed such as age, initial PSA, Gleason score, Gleason grade group, clinical and pathological tumor stage, lymph node involvement, biochemical recurrence-free survival, and overall survival. In the 41 (36.6%) cases negative for fusion, only one mutation (F133L) was detected in exon 7, which has previously been reported in 34 cases. Conclusions: The frequency of fusion of the ERG subtype detected in our population was 63.4%, no associations were found between the fusion state and the prognosis of the disease. Until now, 1 case has been detected a mutation of exon 7 of SPOP (2.4%). The low frequency of this subtype in Colombians could be explained by the reported variability in the frequency of these mutations according to the population (5% -20%). Citation Format: Wendy Montero Ovalle, Yenifer Segura Moreno, María Carolina Sanabria-Salas, Jorge Mesa López de Mesa, Rodolfo Varela Ramírez, Vilma Medina Boada, Martha Lucía Serrano López. Analysis of ERG and SPOP subtypes in prostate cancer in the Colombian population and their possible implications on prognosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 760.