Why it is so difficult to treat leukemia?
The T315l mutation of BCR/ABL gene produce the complete resistance of CML leukemia to all currently available BCR/ABL inhibitors.

There is a idea that is not yet tested for such patients - allogenic hematopoietic transplatation.

More information: 
http://www.ncbi.nlm.nih.gov/pubmed/20657522
http://www.ingentaconnect.com/content/maney/hem/pre-prints/1607845412Y.0000000050