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

In this exploratory analysis, patients with recurrent ovarian cancer carrying BRCA1^mut gene 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.BackgroundWe 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 methodsA 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.ResultsOverall, 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.ConclusionsIn 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.