Landmark 26 · Trial in people
QE3: coenzyme Q10 fails in Phase 3
No benefit in 600 people at two doses. Scores were no better than on placebo, and slightly worse. It was safe, but it did not work.
In short
A mitochondria-support supplement that looked promising in an earlier trial failed at scale, the cautionary tale that pushed the field to demand stronger evidence before Phase 3.
- What it is
- Trial in people
- Outcome
- Did not work
- When
- 2014
- Size
- 600 people · Phase 3
- Approach
- Help cells clean up
- Research lane
- Mitochondria & energy
- Trial registry
- NCT00740714
- Last checked
- 19 Oct 2026
The research record
This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".
Who
The Parkinson Study Group QE3 Investigators; M. Flint Beal, David Oakes, Ira Shoulson and colleagues; 67 North American sites.
What happened
600 people with early Parkinson's (NCT00740714) were randomised to placebo, 1,200 mg or 2,400 mg of coenzyme Q10 a day, all with 1,200 IU a day of vitamin E. They were followed for 16 months or until their disability needed dopamine drugs, which happened to 267 (94 on placebo, 87 on 1,200 mg, 86 on 2,400 mg). The main measure was change in total UPDRS (parts I-III); the trial was powered to detect a 3-point difference. Mean worsening was 6.9 points on placebo, 7.5 on 1,200 mg and 8.0 on 2,400 mg, with no significant difference (P = .49 and .21): both doses trended slightly worse. The supplement was safe and well tolerated. The trial was stopped after reaching a prespecified futility criterion.
Why it moved us toward a cure
It is the warning example. A mitochondrial-support idea (landmark 11) with a positive Phase 2 (landmark 102: 80 people, 16 months, 1,200 mg a day worsened 6.7 UPDRS points against 12.0 on placebo, P = .04 in a secondary comparison) did not hold up at scale. That pushed the field toward better biomarkers and proof of target engagement before large trials.
Outcome
Dead end. Coenzyme Q10 is not a disease-modifier in Parkinson's.
Sources
- Beal et al., JAMA Neurol 2014;71:543–552, DOI 10.1001/jamaneurol.2014.131
- PubMed 24664227 (abstract: design, numbers, futility stop, NCT00740714)
- Shults et al., Arch Neurol 2002;59:1541-1550, PubMed 12374491 (the earlier Phase 2)
- Alzforum, "Coenzyme Q10 Strikes Out in Phase 3 for Parkinson's"
- Not yet verified: the exact date of the futility stop; the full text.
How it connects
Built on
- tests Complex I deficiency in the Parkinson's brain · 1989
- builds on Coenzyme Q10 Phase 2 · 2002
Led to
None recorded.