BRCA1 is both a prognostic and predictive biomarker of response to chemotherapy in sporadic epithelial ovarian cancer.

OBJECTIVES: We investigated the relationship between BRCA1 protein expression by immunohistochemistry (IHC) and clinical outcome following platinum and platinum/taxane chemotherapy in sporadic epithelial ovarian cancer (EOC). METHODS: BRCA1 IHC was performed on a cohort of 292 ovarian tumours from two UK oncology centres. BRCA1 protein expression levels were correlated with overall survival (OS), progression free survival (PFS) and clinical response to chemotherapy by multivariate analysis. RESULTS: EOC patients with absent/low BRCA1 protein expression (41%) had a better chance of clinical response following chemotherapy as compared to patients with high BRCA1 expression (odds ratio 2.47: 95%CI 1.10-5.55, p=0.029). Patients with absent/low BRCA1 had a higher probability of clinical response following single agent platinum compared to high BRCA1 expressing patients (68.5% vs. 46.8%), while addition of a taxane increased response rates independent of BRCA1. Overall, patients with absent/low BRCA1 had a better clinical outcome compared to patients with high BRCA1 protein expression in terms of both OS (HR=0.65: 95%CI 0.48-0.88, p=0.006) and PFS (HR=0.74, 95%CI 0.55-0.98, p=0.040). CONCLUSIONS: We confirm that absent/low BRCA1 protein expression is a favourable prognostic marker. However, we also provide the first evidence that absent/low BRCA1 protein expression in sporadic EOC patients predicts for an improved clinical response to chemotherapy.

BRCA1 and implications for response to chemotherapy in ovarian cancer.

OBJECTIVES: Treatment of epithelial ovarian cancer (EOC) remains a challenge, despite advances in surgery and chemotherapy. Hereditary ovarian cancer is primarily due to germline mutations in the BRCA1 tumour suppressor gene. In addition, sporadic EOC tumours display significant of loss of BRCA1 function due to epigenetic inactivation of the BRCA1 gene. This article reviews the preclinical and clinical evidence to support a role for BRCA1 as a potential predictive biomarker of response to both platinum and taxane based chemotherapy in EOC. METHODS: We conducted a Medline and Pubmed search for reports between 1990 and 2008 using the search terms: BRCA1 and hereditary ovarian cancer, BRCA1 and sporadic ovarian cancer, ovarian cancer and chemotherapy, ovarian cancer and taxanes, ovarian cancer and platinums, ovarian cancer and clinical response, BRCA1 and DNA damage, BRCA1 and DNA repair, BRCA1 and mitotic checkpoint. If reports identified by these criteria referred to other papers not in the initial search, then these were also reviewed if relevant to BRCA1 and ovarian cancer. RESULTS: The BRCA1 pathway plays a significant role in the development of both hereditary and sporadic EOC. Evidence suggests that BRCA1 is a potential biomarker of response to platinum chemotherapy in EOC with BRCA1 deficiency predicting for enhanced response. In contrast, initial evidence suggests that loss of BRCA1 function results in reduced response to antimicrotubule-based chemotherapy. The ability of BRCA1 to differentially modulate response to these agents involves loss of BRCA1 mediated DNA repair and mitotic checkpoint control, respectively. CONCLUSIONS: Standard first line treatment of EOC consists of a combination of platinum and taxane chemotherapy, however clinically useful biomarkers for predicting response to these agents have yet to be established. BRCA1 may prove useful as a biomarker in EOC for assigning chemotherapy treatments based on the presence or absence of BRCA1 function.