IMpassion131: Trial did not meet the primary end point of PFS and disappointed the oncology community

Abstract No : Abstract: #LBA15

Indication : Breast cancer

Intervention : Atezolizumab

Company : Roche

Technology : PD-1/PD-L1 inhibitor


Of 651 randomised patients, 45% had PD-L1+ mTNBC, 48% were taxane pretreated, 31% had de novo mTNBC and 27% liver metastases. Adding atezo to PAC did not improve PFS or OS in either the PD-L1+ or ITT populations (Table). PFS results in subgroups were consistent with primary results. PAC exposure was not compromised by the addition of atezo. Grade 5 (2% placebo vs 2% atezo) and grade 3/4 AEs (43% vs 49%) were balanced between arms and the safety profile was consistent with known risks of each study drug.


Atezo + PAC did not improve PFS or OS vs placebo + PAC. No new safety signals were seen. Potential reasons for the contrast with the benefit seen in IMpassion130 (atezo + nab-paclitaxel) need further exploration.