The KIT gene is located on chromosome 4 and codes for a family of proteins, the receptor tyrosine kinases. KIT function is essential for normal melanocyte genesis and migration. KIT protein signaling also is important for the development of reproductive germ cells, early hematopoietic stem cells, immune mast cells, and interstitial cells of Cajal located in the gastrointestinal tract.
Available data suggest that patients with mutations affecting exons 11 or 13 of KIT may be more likely to achieve clinical benefit with KIT inhibition, Dr. Carvajal said. He added that greater expression of the mutant KIT allele, compared with the wild type, may be a marker of tumors more "addicted" to KIT activation and that may be more susceptible to inhibition.
"This work is still fairly new," he said.
Dr. Carvajal is a consultant to Novartis. Dr. Minor and Dr. Kluger said that they had no relevant disclosures.