Another toxin, a truncated form of Pseudomonas exotoxin A (ETA' or PE38), fused to a CD7 scFv fragment caused only approximately 20% cell death of primary leukemia-derived cells, and without further examination in in vivo model, implying that T-lineage leukemia cells may not be sensitive to ETA', or further improvement for the reported CD7 scFv is needed [24]. This evidence concerns the gene CD7 and leukemia.