Effect of BRCA1 and XPG mutations on treatment response to trabectedin and pegylated liposomal doxorubicin in patients with advanced ovarian cancer: exploratory analysis of the phase 3 OVA-301 study.

BACKGROUND: We investigated the association of BRCA1 and XPG mutations with response rate (RR), progression-free survival (PFS) and overall survival (OS) in a subset of patients from a phase 3 clinical trial comparing the efficacy and safety of trabectedin + pegylated liposomal doxorubicin (PLD) versus PLD alone in patients with recurrent ovarian cancer.

PATIENTS AND METHODS: A candidate array was designed based on the Breast Cancer Information Core database for BRCA mutation analyses. An exploratory analysis of BRCA1/XPG mutation status was conducted using a two-sided log-rank test and 0.05 significance in germline DNA samples from 264 women with failed first-line platinum-based chemotherapy, randomized (1 : 1) to trabectedin + PLD or PLD alone.

RESULTS: Overall, 41 (16%) of the 264 women had BRCA1(mut) (trabectedin + PLD: n = 24/135, 18%; PLD: n = 17/129; 13%) and 17 (6%) had XPG(mut) (trabectedin + PLD: n = 8/135, 6%; PLD: n = 9/129, 7%). A higher RR was observed in BRCA1(mut) patients (20/41; 49%) versus BRCA1(wt) patients (62/223; 28%). Within the BRCA1(mut) group, trabectedin + PLD-treated patients had longer PFS and longer OS than PLD-treated patients (median PFS 13.5 versus 5.5 months, P = 0.0002; median OS 23.8 versus 12.5 months, P = 0.0086), whereas in BRCA1(wt) patients, OS was not significantly different (median OS: 19.1 versus 19.3 months; P = 0.9377). There were no differences in OS or PFS of patients with XPG(mut) between the two treatment arms. However, trabectedin + PLD-treated patients with XPG(mut) had a trend toward shorter PFS (median PFS: 1.9 versus 7.5 months; P = 0.1666) and OS (median OS: 14.5 versus 20.7 months; P = 0.1774) than those with XPG(wt).

CONCLUSIONS: In this exploratory analysis, patients with recurrent ovarian cancer carrying the BRCA1(mut) had improved outcomes with trabectedin + PLD treatment compared with PLD alone. Prospective evaluation of BRCA status is likely an important evaluation for DNA-damaging agents and may significantly impact interpretation of clinical studies. XPG may be a biomarker of poor outcome in these patients.