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IMpassion131 was the sister trial to the first immunotherapy success in breast cancer. It failed, and the approval it was meant to confirm was withdrawn.
IMpassion130 (nab-paclitaxel partner) had shown a PFS benefit in PD-L1-positive metastatic TNBC and won accelerated approval in 2019. IMpassion131 used conventional paclitaxel (which requires steroid premedication) and showed no PFS or OS benefit; OS trended worse in the atezolizumab arm. Roche withdrew the US TNBC indication in 2021. Pembrolizumab with chemotherapy (KEYNOTE-355) became the standard instead.
Lesson: the chemotherapy partner (steroid premedication, immunogenic cell death profile) and the PD-L1 assay (SP142 vs 22C3) can decide an immunotherapy trial; confirmatory trials must replicate the winning design.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
653 enrolled.
Not significant
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survival, PD-L1+ (investigator)primary | Atezolizumab + paclitaxel | 191 | 6 months | 0.82 (0.6 to 1.12) | 0.20 | link |
| Placebo + paclitaxel | 101 | 5.7 months | ||||
| Overall survival, PD-L1+ | Atezolizumab + paclitaxel | - | 22.1 months | 1.11 (0.76 to 1.64) | - | link |
| Placebo + paclitaxel | - | 28.3 months |
Shares Atezolizumab, Roche / Genentech, Immune checkpoint inhibitors and the tag failure.
Shares No accelerated approval for a combination without proof each part contributes, Atezolizumab, Roche / Genentech, Immune checkpoint inhibitors and the tag failure.
Shares No accelerated approval for a combination without proof each part contributes, Pembrolizumab, Immune checkpoint inhibitors and the tag failure.
Shares Pembrolizumab, Immune checkpoint inhibitors and the tag failure.
Shares Roche / Genentech and the tag failure.
Shares Accelerated approval and the tag failure.
Shares Pembrolizumab and the tag failure.
Shares Roche / Genentech and the tag failure.