Evaluation of p53 mutation as a predictive biomarker for outcome to chemotherapy in ovarian cancer.

10522 Background: There is increasing evidence that patients (pts) with wild type p53 have higher response rates to single agent carboplatin and may gain no benefit from the addition of paclitaxel chemotherapy. We tested two hypotheses in the context of a controlled clinical trial: 1) Tumours with wild-type p53 are more sensitive to platinum based chemotherapy than those with mutant p53, so will survive longer; 2) Pts whose tumours have mutant p53 benefit from the addition of paclitaxel to treatment, whilst those with wild type p53 do not. Methods: We collected 265 archival diagnostic tissue samples from pts that took part in the UK Medical Research Council ICON3 ovarian cancer trial comparing carboplatin or CAP (cyclophosphamide, doxorubicin, cisplatin) vs carboplatin plus paclitaxel. We examined the tissue for p53 mutations by genomic DNA sequencing of the coding exons and adjacent splice sites. Overall survival (OS) was updated for this study. A Cox regression model was applied in the analysis. Results...