It was slightly unclear but my understanding/interpretation is that even the patients at the lowest doses were included in the "50% of patients" comment. I'd guess that if you look at the later cohorts with higher doses that you'd see a much higher % of patients with enhanced p21 activation as they indicated in the statement below:
"Initial comparisons between early and latter cohorts support Cellceutix’s expectations that p53 activation is dependent on extent of exposure to Kevetrin."