Primary platinum resistance and its prognostic impact in patients with recurrent ovarian cancer: an analysis of three prospective trials from the NOGGO study group.

OBJECTIVE Patients with platinum-resistant ovarian cancer (PROC) have a high need for reliable prognostic markers. Since significance of primary platinum resistance (PPR) versus secondary platinum resistance (SPR) was identified for patients receiving anti-angiogenic therapy, it has not been confirmed for chemotherapy only. METHODS PROC patients from 3 prospective trials of the NOGGO study group (TOWER, NOGGO-Treosulfan, and TRIAS) were included in this meta-analysis. Exploratory Cox and logistic regression analyses were performed to correlate progression-free survival (PFS) and overall survival (OS) with the timing when platinum resistance developed. RESULTS Of 477 patients, 264 (55.3%) were classified as PPR, compared to 213 (44.7%) with SPR. For patients receiving chemotherapy only, SPR was associated with a significantly longer median PFS of 3.9 compared to 3.1 months for PPR (hazard ratio [HR]=0.78; p=0.015). SPR versus PPR was confirmed to be an independent prognostic factor for better PFS in multivariate analysis (HR=0.74; p=0.029). Benefit from adding sorafenib to chemotherapy was mainly seen in PPR (HR=0.40; p<0.001) compared to SPR patients (HR=0.83; p=0.465). CONCLUSIONS Prognostic significance of SPR versus PPR could be elucidated for patients receiving chemotherapy only. In contrast to bevacizumab, the multi-kinase inhibitor sorafenib exhibits profound therapeutic efficacy in PPR patients indicating potential to overcome this negative prognostic impact.