BRCA1, RAP80, and AEG-1 mRNA expression in resectable muscle-invasive bladder cancer (MIBC) patients (p) treated with neoadjuvant cisplatin-based chemotherapy.

Abstract

4579 Background: Cystectomy remains the standard treatment in MIBC and only a minority of p are treated with neoadjuvant chemotherapy, suggesting that predictive markers of chemotherapy outcome are needed. Low BRCA1 mRNA expression is associated with an improvement in survival in bladder cancer p treated with cisplatin-based chemotherapy. However, BRCA1 function can be modulated by other DNA repair genes. RAP80 is required for the accumulation of BRCA1 to sites of DNA breaks, and cells depleted of RAP80 exhibit hypersensitivity to irradiation. AEG-1 can induce BRCA1 expression and cause chemoresistance. Methods: Paraffin-embedded pre-treatment tumor samples were collected by transurethral resection from 65 p with resectable MIBC stage T2-4N0M0 treated with neoadjuvant cisplatin-based chemotherapy. Gene expression levels of BRCA1, RAP80 and AEG-1 were quantified by real-time quantitative PCR. Expression levels were divided into terciles and correlated with median survival (MS). Results: 33 p were treated with cisplatin, methotrexate and vinblastine (CMV) and 32 p with cisplatin and gemcitabine. Chemotherapy was followed by cystectomy in 60 p. Overall MS was not reached and 5-year survival was 51%. MS was 45 months (m) and 5-year survival was 27% in 21 p with high BRCA1 mRNA levels vs 168 m and 59% in 44 p with low and intermediate levels (p=0.05). MS was 50 m in 15 p with high AEG-1 levels, 45 m in 15 p with intermediate levels, and was not reached in 18 p with low levels, although these differences were not statistically significant (p=0.3). No differences in MS were observed according to RAP80 mRNA levels. Conclusions: BRCA1 can be a useful marker to predict the efficacy of neoadjuvant chemotherapy. Cisplatin-based chemotherapy should be recommended in p with low/intermediate BRCA1 expression. Further studies with larger numbers of p are warranted to elucidate the role of AEG-1 in this setting.