I've not read Cho but in 2011 trial none of the control group given placebos experienced relief against most of those given the drug. That seems like not much of a placebo response to me.

The 2011 study was negative in its primary end-point. If you look at the results you'll see that the divergence between active and placebo groups only happened after the researchers unblinded the data at the 3 month point. Although they say that the patients were still blinded until the end, there are still some question marks about the study.