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IMpower150: What the Lung Cancer Trial Found
IMpower150 added atezolizumab to bevacizumab and chemotherapy in metastatic non-squamous lung cancer. It is a three-arm trial reported two arms at a time, which is why the contribution of each drug is hard to pin down.
Original commentary from the Cancer Explained editorial team.
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Three arms, and a comparison made in stages
IMpower150 randomised people to one of three regimens, all given every three weeks for four or six cycles and then continued as maintenance:
- atezolizumab with carboplatin and paclitaxel
- bevacizumab with carboplatin and paclitaxel
- atezolizumab with bevacizumab, carboplatin and paclitaxel
The trial specified the order in which those arms would be compared. The four-drug arm was tested against the bevacizumab arm first. This report covers that comparison, and only that comparison.
The populations the trial was built around
| Field | Detail |
|---|---|
| Trial | IMpower150 |
| Identifier | NCT02366143 |
| Phase | Phase 3 |
| Design | Randomised, open-label, three arms |
| Cancer type | Metastatic non-squamous non-small-cell lung cancer, no prior chemotherapy |
| Comparator | Atezolizumab, bevacizumab, carboplatin and paclitaxel against bevacizumab, carboplatin and paclitaxel |
| Primary endpoints | Progression-free survival in two populations, and overall survival in one |
The trial had co-primary endpoints, not one. Progression-free survival was tested in the "wild-type" group — everyone except those with EGFR or ALK changes — and separately in the part of that group whose tumours showed high activity of an immune-cell gene signature. Overall survival was tested in the wild-type group.
356 people in the wild-type group were assigned the four-drug regimen and 336 the three-drug one.
The progression-free survival result
Median progression-free survival was 8.3 months with the four-drug regimen and 6.8 months with bevacizumab plus chemotherapy. The hazard ratio was 0.62 (95% CI 0.52 to 0.74, p<0.001).
In the immune-signature-high group the gap was larger: 11.3 months against 6.8 months, hazard ratio 0.51 (95% CI 0.38 to 0.68, p<0.001).
Survival, and the groups usually left out
Median overall survival in the wild-type group was 19.2 months against 14.7 months, a hazard ratio for death of 0.78 (95% CI 0.64 to 0.96, p=0.02). That is about four and a half months.
Progression-free survival also favoured the four-drug arm in several groups that are often disappointing for immune drugs. It held across the full intention-to-treat population, which included people with EGFR or ALK changes. It held in people whose tumours had low or absent PD-L1, in those with a low immune-cell gene signature, and in those whose cancer had spread to the liver.
Why the contribution of each drug is hard to pin down
Four drugs went in together. This report does not include the arm that combined atezolizumab with chemotherapy but no bevacizumab, so it cannot separate what bevacizumab was adding.
Bevacizumab also brings its own constraints. It targets blood vessel growth, and the risks that come with that — bleeding, clots, raised blood pressure — mean some people cannot have it at all. Any decision about this regimen has to weigh that alongside the survival figures.
What to keep in perspective
- Open-label design. Everyone knew what they were receiving, which can shape how symptoms and side effects get recorded.
- The comparison is against bevacizumab plus chemotherapy, not against the simpler immunotherapy-plus-chemotherapy combinations that are common now.
- Four drugs mean a heavier schedule, more monitoring and more possible interactions.
- The immune-signature analysis used a research measure, not a test that is ordered in routine practice.
Questions about a four-drug regimen
- Why this combination rather than a simpler one?
- Am I someone who can safely have bevacizumab?
- Which of these four drugs would you drop first if I could not tolerate the schedule?
Sources
This article was written from the sources below, which were checked on the source-check date shown above.
How this article was prepared
Prepared by Cancer Explained's AI-assisted editorial system and checked against the sources listed below. This article has not been reviewed by a healthcare professional unless a named reviewer is specifically shown.
Cancer Explained is published by the National Cancer Information Foundation as a nonprofit-oriented public-interest education project. It is not a diagnostic service, does not recommend treatments, and is not for emergencies.
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Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
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Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
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