OnCo
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MONARCH 3

Abemaciclib roughly doubled the time to progression when added to an aromatase inhibitor; the survival gain of about 13 months narrowly missed statistical significance.

PFS 28.2 vs 14.8 months (HR 0.54). Final OS 66.8 vs 53.7 months (HR 0.80, P=0.066), not statistically significant at the prespecified threshold despite a 13-month numerical difference.

Setting
First-line postmenopausal HR+/HER2- advanced breast cancer: abemaciclib + NSAI vs placebo + NSAI
Phase
Phase 3
Sponsor
Eli Lilly
Registry
Headline result
PFS HR 0.54; OS 66.8 vs 53.7 months, HR 0.80 (NS).
Reported
2017
Enrolled
493
Replication
MONARCH 2 (abemaciclib + fulvestrant after endocrine progression) did show a significant OS benefit (HR 0.76).

Outcomes

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In plain words
What these results mean for people, not percentages
493 people took part
Progression-free survivalprimarysurrogate endpoint
  • Median 28.2 vs 14.8 months with Abemaciclib + NSAI compared with Placebo + NSAI; about 13.4 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 46 percent lower chance of the event at any given time (hazard ratio 0.54, likely range 0.42 to 0.7).
  • 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.
Overall survivalsurvival endpoint
  • Median 66.8 vs 53.7 months with Abemaciclib + NSAI compared with Placebo + NSAI; about 13.1 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 20 percent lower chance of the event at any given time (hazard ratio 0.8, likely range 0.62 to 1.03).
  • The likely range for the hazard ratio crosses 1, so the difference could be due to chance.
  • Overall survival counts deaths from any cause, so it is the most direct measure of whether a treatment helps people live longer.
Be careful
  • These results apply to the people the trial enrolled: First-line postmenopausal HR+/HER2- advanced breast cancer: abemaciclib + NSAI vs placebo + NSAI. 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.

493 participants enrolled.

Progression-free survivalprimary
HR 0.54 (0.42–0.7)
Abemaciclib + NSAI
28.2 mo
Placebo + NSAI
14.8 mo
Source
Overall survival
HR 0.8 (0.62–1.03) · p = 0.066
Abemaciclib + NSAI
66.8 mo
Placebo + NSAI
53.7 mo
EndpointArmnValueHR (95% CI)pSource
Progression-free survivalprimaryAbemaciclib + NSAI32828.2 months0.54 (0.42–0.7)link
Placebo + NSAI16514.8 months
Overall survivalAbemaciclib + NSAI66.8 months0.8 (0.62–1.03)0.066
Placebo + NSAI53.7 months
Replication
MONARCH 2 (abemaciclib + fulvestrant after endocrine progression) did show a significant OS benefit (HR 0.76).

Connected

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