CLEOPATRA
Adding a second HER2 antibody, pertuzumab, extended survival by 16 months, the largest gain ever seen in metastatic breast cancer at the time.
PFS 18.7 vs 12.4 months (HR 0.68); final OS 57.1 vs 40.8 months (HR 0.69); 8-year landmark OS 37% vs 23%. Defined first-line 'THP' until DESTINY-Breast09 (2025).
- Median 18.7 vs 12.4 months with Pertuzumab + trastuzumab + docetaxel compared with Placebo + trastuzumab + docetaxel; about 6.3 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 32 percent lower chance of the event at any given time (hazard ratio 0.68, likely range 0.58 to 0.8).
- This is a surrogate endpoint: it measures the cancer being controlled or absent on scans and tests, which often, but not always, translates into living longer.
- Median 57.1 vs 40.8 months with Pertuzumab arm compared with Placebo arm; about 16.3 months longer for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 31 percent lower chance of the event at any given time (hazard ratio 0.69, likely range 0.58 to 0.82).
- Overall survival counts deaths from any cause, so it is the most direct measure of whether a treatment helps people live longer.
- These results apply to the people the trial enrolled: First-line HER2+ metastatic breast cancer: pertuzumab + trastuzumab + docetaxel vs placebo + trastuzumab + docetaxel. People in a different situation may not see the same effect.
- The trial selected people by a biomarker (HER2); the result should not be assumed for people whose cancer does not have it.
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.
808 participants enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Progression-free survivalprimary | Pertuzumab + trastuzumab + docetaxel | 402 | 18.7 months | 0.68 (0.58–0.8) | — | link |
| Placebo + trastuzumab + docetaxel | 406 | 12.4 months | ||||
| Overall survival (final) | Pertuzumab arm | — | 57.1 months | 0.69 (0.58–0.82) | — | link |
| Placebo arm | — | 40.8 months |
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