However, follow-up studies in animal models were initially disappointing. BRAF inhibitors that were effective in BRAF-driven adult melanomas made brain tumors worsevia an effect called paradoxical activation.
Further investigation revealed how tumor behavior depended on which type of BRAF mutation was involved. The first-generation drug that was effective in adult melanoma acted against point mutations in BRAF called V600E alterations. However, in most astrocytomas the mutation in the BRAF gene was different; it produced a fusion gene, designated KIAA1549-BRAF. When used against the fusion gene, the first-generation drug activated a cancer-driving biological pathway, the MAPK signaling cascade, and accelerated tumor growth.
By examining the molecular mechanisms behind drug resistance and working with the pharmaceutical industry, the current study's investigators identified a new, experimental second-generation BRAF inhibitor that disrupted the cancer-promoting signals from the fusion gene, and did not cause the paradoxical activation in the cell cultures and animal models.
This preclinical work result lays a foundation for multicenter clinical trials to test the mutation-specific targeting of tumors by this class of drugs in children with astrocytomas, said Sievert. As this effort progresses, it will benefit from CHOP's commitment to resources and collaborations that support data-intense research efforts.
The direction of brain tumor research over the past several ye
|Contact: John Ascenzi|
Children's Hospital of Philadelphia