# IMpower133

Source: https://onco.cc/trials/impower133/  
OnCo record `impower133` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

IMpower133 was the first trial in decades to lengthen survival in extensive-stage small-cell lung cancer, by adding immunotherapy to chemotherapy.

## Summary

Median OS 12.3 vs 10.3 months (HR 0.70); PFS 5.2 vs 4.3 months. Established chemo-immunotherapy as first-line standard (FDA March 2019). The IMbrella A extension reported the first five-year survival data for chemo-immunotherapy in ES-SCLC, with a small tail of long-term survivors in the atezolizumab arm. Benefit was independent of PD-L1 and TMB.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-07
- Registry id: NCT02763579
- Phase: 3
- Setting: First-line extensive-stage SCLC: carboplatin-etoposide + atezolizumab vs carboplatin-etoposide + placebo
- Sponsor: Roche
- Enrolled: 403
- Result: OS 12.3 vs 10.3 months, HR 0.70.
- Outcomes: Overall survival: Atezolizumab + CE 12.3 months vs Placebo + CE 10.3 months, HR 0.7; Progression-free survival: Atezolizumab + CE 5.2 months vs Placebo + CE 4.3 months, HR 0.77
- Replication: Replicated by CASPIAN (durvalumab, 2019) and by serplulimab (ASTRUM-005), tislelizumab (RATIONALE-312), adebrelimab and toripalimab trials in China; the class effect is one of the best-replicated in SCLC.

## Sources

- ClinicalTrials.gov NCT02763579: https://clinicaltrials.gov/study/NCT02763579
- Five-year OS (IMbrella A): https://pubmed.ncbi.nlm.nih.gov/39306923/

## Connected records

- cancers: [Extensive-stage small-cell lung cancer](https://onco.cc/cancers/extensive-stage-sclc/), [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- technologies: [Immune checkpoint inhibitors](https://onco.cc/technologies/checkpoint-inhibitor/)
- drugs: [Atezolizumab](https://onco.cc/drugs/atezolizumab/), [Platinum + etoposide (EP / CE)](https://onco.cc/drugs/platinum-etoposide/)
- companies: [Roche / Genentech](https://onco.cc/companies/roche-genentech/)
- people: [Anne C. Chiang](https://onco.cc/people/anne-chiang/)
- key papers: [Durvalumab plus platinum-etoposide versus platinum-etoposide in first-line treatment of extensive-stage small-cell lung cancer (CASPIAN)](https://onco.cc/key-papers/paper-paz-ares-caspian-durvalumab-es-sclc-lancet-2019/), [First-Line Atezolizumab plus Chemotherapy in Extensive-Stage Small-Cell Lung Cancer](https://onco.cc/key-papers/paper-impower133-n-engl-j-med-2018/)
- trials: [CAPSTONE-1](https://onco.cc/trials/capstone-1/), [CREST: consolidation thoracic radiotherapy in extensive-stage small-cell lung cancer](https://onco.cc/trials/crest-thoracic-rt/)

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