Caveats of cross-study-comparison should not be underestimated!!!
Daco trial vs. cytarabine has been plagued by unexplained geographical differences.
As for the difference in age brackets, here is my idea why it happened:
If both drugs have similar mechanism of action, an even larger size of the trial is required to separate the responses.
The signal was stronger in the older population because of slightly lower toxicity of deci vs cyta and this is obviously much more important for the older population.
The above reasons do not apply to our trial, with different mechanisms of action the combination therapy should clearly separate much better in our trial.