Successful nilotinib treatment in a child with chronic myeloid leukemia.

A 16-year-old female was diagnosed incedentally with chronic myeloid leukemia (CML) in the chronic phase. She showed complete remission after 3 months of nilotinib treatment. CML is a rare malignant neoplasm in pediatric age. It is characterized by a Philadelphia chromosome, which comes from a genetic translocation between chromosomes 9 and 22. This translocation results in an abnormal fusion called BCR-ABL oncogene which encodes a chimeric BCR-ABL protein. This protein is the underlying cause of CML. Nilotinib is a newly licensed drug for CML in adults. Structurally, it is similar to imatinib (the older tyrosine kinase inhibitor), but it is much more potent in inhibiting BCR-ABL due to its much increased affinity for its binding site. Specific guidelines for CML treatment in children have yet to be determined. In our patient, nilotinib was used as an off-label drug because it is not licensed for children. According to the pharmacokinetic response to drugs, children cannot be considered small adults irrespective of their weight. Off-label drug use based on evidence that it is the best treatment available is an important tool in the hands of expert treating physicians.