Systematic review and meta-analysis of PFS in metastatic breast cancer by local investigators versus blinded independent central review

Progression-free survival (PFS) is a widely accepted primary endpoint in metastatic breast cancer (mBC) trial; however, it is susceptible to assessment bias. To reduce this risk, blinded independent central review (BICR) is often incorporated into trial designs. A systematic review and meta-analysis of phase 2 or 3 randomized clinical trials (RCTs) including patients with HR-positive/HER2-negative mBC with progression following CDK4/6 inhibitor therapy compared BICR- and investigator-assessed PFS. Outcomes of the analysis were the discrepancy index (DI; ratio of hazard ratios for BICR- versus investigator-assessed PFS) and the absolute difference in median PFS between the 2 assessments. A total of 21 RCTs with 9165 patients met the inclusion criteria. No statistically significant difference was observed between investigator- and BICR-assessed PFS overall, with a DI of 1.02 (p=0.57), which was consistent across meta-regression analyses. The authors conclude that these results suggest that both BIVR- and investigator-assessment approaches yield comparable PFS estimates among patients with HR-positive/HER2-negative mBC.