# IMpassion031

Source: https://onco.cc/trials/impassion031/  
OnCo record `impassion031` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

IMpassion031 showed that adding the immune drug atezolizumab to chemotherapy before surgery for early triple-negative breast cancer raised the share of women whose tumour had disappeared at surgery from 41 to 58 percent, whatever their PD-L1 status.

## Summary

IMpassion031, trial NCT03197935 sponsored by Roche and Genentech and published in the Lancet in 2020, randomised 333 patients with previously untreated stage II or III triple-negative breast cancer to atezolizumab or placebo with nab-paclitaxel followed by doxorubicin and cyclophosphamide before surgery, with atezolizumab or observation after. Pathological complete response rose from 41 to 58 percent in all patients and from 49 to 69 percent in the PD-L1-positive subgroup, meeting the co-primary endpoint in the whole population but not the PD-L1-positive one at the prespecified boundary, with immune-related side effects as expected. It confirmed the KEYNOTE-522 finding that immunotherapy raises response rates in early disease regardless of PD-L1, but with no event-free survival benefit shown and the withdrawal of atezolizumab from metastatic breast cancer in 2021, pembrolizumab rather than atezolizumab became the standard. Whether the platinum-free backbone or the drug explains the smaller trial's limited uptake is a matter of debate.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-17
- Registry id: NCT03197935
- Phase: 3
- Setting: Early triple-negative breast cancer (tumours over 2 cm): neoadjuvant atezolizumab or placebo with nab-paclitaxel then doxorubicin and cyclophosphamide
- Sponsor: Roche / Genentech
- Enrolled: 333
- Result: Pathological complete response 58% vs 41% (all patients); 69% vs 49% in PD-L1-positive disease.
- Outcomes: Pathological complete response (all patients): Atezolizumab + chemotherapy 58% vs Placebo + chemotherapy 41%
- Replication: Consistent with KEYNOTE-522 on pathological complete response; event-free survival benefit not demonstrated.

## Sources

- ClinicalTrials.gov NCT03197935: https://clinicaltrials.gov/study/NCT03197935
- Mittendorf et al., IMpassion031 (Lancet 2020): https://doi.org/10.1016/S0140-6736(20)31953-X

## Connected records

- cancers: [Early triple-negative breast cancer](https://onco.cc/cancers/tnbc-early/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- targets: [PD-L1](https://onco.cc/targets/pdl1/)
- drugs: [Atezolizumab](https://onco.cc/drugs/atezolizumab/), [Cyclophosphamide](https://onco.cc/drugs/cyclophosphamide/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/)
- terms: [Pathologic complete response (pCR)](https://onco.cc/terms/pcr/)
- people: [Elizabeth A. Mittendorf](https://onco.cc/people/elizabeth-mittendorf/)

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JSON: https://onco.cc/api/v1/entities/impassion031.json