# IMpassion131

Source: https://onco.cc/trials/impassion131/  
OnCo record `impassion131` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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 It failed, and the approval it was meant to confirm was withdrawn.

## Summary

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.

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-06
- Tags: failure; lesson:partner-and-biomarker
- Registry id: NCT03125902
- Phase: 3
- Setting: First-line metastatic TNBC: atezolizumab + paclitaxel vs paclitaxel
- Sponsor: Roche
- Enrolled: 653
- Result: PFS HR 0.82 (not significant); OS trend unfavourable; US indication withdrawn 2021.
- Outcomes: Progression-free survival, PD-L1+ (investigator): Atezolizumab + paclitaxel 6 months vs Placebo + paclitaxel 5.7 months, HR 0.82; Overall survival, PD-L1+: Atezolizumab + paclitaxel 22.1 months vs Placebo + paclitaxel 28.3 months, HR 1.11
- Replication: Failed to replicate IMpassion130; the discordance is attributed to the taxane partner (steroid premedication with paclitaxel) and chance.

## Notes

- Primary results (Annals of Oncology 2021): 651 patients randomised 2 to 1 to atezolizumab or placebo with paclitaxel 90 mg/m2; 45 percent PD-L1-positive. Investigator-assessed progression-free survival in the PD-L1-positive population 6.0 versus 5.7 months (hazard ratio 0.82, p 0.20); final overall survival 22.1 versus 28.3 months (hazard ratio 1.11, 0.76 to 1.64). Three UK sites (Guy's, the Christie, Mount Vernon).

## Sources

- ClinicalTrials.gov NCT03125902: https://clinicaltrials.gov/study/NCT03125902
- Annals of Oncology 2021: https://www.annalsofoncology.org/article/S0923-7534(21)02073-7/fulltext
- IMpassion131 primary results (Annals of Oncology 2021): https://doi.org/10.1016/j.annonc.2021.05.801

## Connected records

- cancers: [Metastatic triple-negative breast cancer](https://onco.cc/cancers/tnbc-metastatic/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Atezolizumab](https://onco.cc/drugs/atezolizumab/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/)
- companies: [Roche / Genentech](https://onco.cc/companies/roche-genentech/)
- terms: [Accelerated approval](https://onco.cc/terms/accelerated-approval/), [Combined positive score (CPS)](https://onco.cc/terms/cps/)
- trials: [IMpassion130](https://onco.cc/trials/impassion130/), [KEYNOTE-355](https://onco.cc/trials/keynote-355/)
- key papers: [Primary results from IMpassion131, a double-blind, placebo-controlled, randomised phase III trial of first-line paclitaxel with or without atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer](https://onco.cc/key-papers/paper-impassion131-ann-oncol-2021/)
- roadmaps: [Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem](https://onco.cc/roadmaps/tnbc-roadmap/)
- ideas: [Harmonise PD-L1 testing for triple-negative breast cancer around one scored assay, with external quality assurance](https://onco.cc/ideas/idea-tnbc-pd-l1-assay-harmonisation/), [No accelerated approval for a combination without proof each part contributes](https://onco.cc/ideas/idea-tr2-contribution-of-components-mandate/)

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