Hu? The whole PK/PD is the more data. Its true Anavex does not know why A2-73 respondes the way it does really into detail biotechnical speaking. But there are many drugs out there scientists don't understand why its working in the manner that it does.
For example Paracetamol. We do not know exactly how it works. We do not have to know everything about a drug before we consider it safe and it can be administered. In fact, paracetamol is pretty unsafe at doses higher than about 4,000 mg per day. We simply do not understand the human body well enough to understand the full activity of a drug and all of its effects.
Anavex is waiting for the go ahead for Rett and AD from the FDA not because they dont understand how exactly in detail its working.