I.e., the smaller number of patients in the trial should make it much more difficult to attain stat sig results yet the results were robust enough to do just that.
I would disagree with this.
I would think that such small numbers increase your chance of seeing a result that is not representative of the "true" outcome as would be revealed by a large trial. In a sense, the result here is driven by the 4 control patients... if by chance they're a tightly knit group of 4 with very similar (but somewhat atypical) outcomes (ie. low st. dev.), then they could be the driving reason for the statistical significance.
Put it this way: if these results were stat sig from 4 patients on drug and 12 on the control, there would be significant skepticism (rightly in my mind) about a company touting a stat sig result. I don't see why having 12 patients on drug and 4 on control makes it any more comforting.