The way I'm understanding the question is this...

Broadly speaking let's say Top Standard of Care improves patient outcomes by 55% versus doing nothing....I'm pulling that 55% out of my nether regions and I'm aware that this statement is ultimately pointless because there are too many moving parts to arrive at a simple %....but I'm going with it regardless because I think it will help illustrate the point of question being asked.

So Top SoC means a 55% improvement in patient outcomes hypotheically.  And let's if 208 was given to patients not receiving Top SoC and it improved outcomes on its own by 60%.....so in this manner 208 could be said to be superior on its own to Top SoC. 

Ultimately I agree with the original poster who noted it would not be ethical to deny patients Top SoC to prove a thesis that might ultimately prove to be inaccurate and lead to worse outcomes.