"They are presenting Full Part A data at the Conf and only prelim Part B. The abstract including info re: Part B would not be proper, thus the change."
Also, the sentence was incorrect in context. Read: "The primary outcome of the study is safety, and ANAVEX 2-73 was well tolerated. In the secondary outcome endpoints preliminary analysis of data from subjects to date shows an average improvement of the MMSE score at week 12 in PART B (week 17 from baseline). "
They go from talking about Part A to Part B and confuse the two in the first abstract. A decision was made to stick to the context of Part A. The old sentence made it seem like the secondary outcome endpoints of Part A were being justified by results of the Part B study. See how that would be confusing or even incorrect?