Facts and new hopes on selective FGFR inhibitors in solid tumors

Precision oncology relies on the identification of molecular alterations, responsible for tumor initiation and growth, which are suitable targets of specific inhibitors. The development of FGFR inhibitors represents an edifying example of the rapid evolution in the field of targeted oncology, with 10 different FGFR tyrosine kinase inhibitors actually under clinical investigation. In parallel, the discovery of FGFR activating molecular alterations (mainly FGFR3 mutations and FGFR2 fusions) across many tumor types, especially urothelial carcinomas and intrahepatic cholangiocarcinomas, widens the selection of patients that might benefit from selective FGFR inhibitors. The ongoing concomitant clinical evaluation of selective FGFR inhibitors in molecularly selected solid tumors brings new hopes for patients with metastatic cancer, for tumors so far excluded from molecularly guided treatments. Matching molecularly selected tumors with selective FGFR inhibitors has indeed led to promising results in phase I and II trials, justifying their registration to be expected in a near future, such as the recent accelerated approval of erdafitinib granted by the FDA for urothelial cancer. Widening our knowledge of the activity, efficacy, and toxicities relative to the selective FGFR tyrosine kinase inhibitors under clinical investigation, according to the exact FGFR molecular alteration, will be crucial to determine the optimal therapeutic strategy for patients suffering from FGFR-driven tumors. Similarly, identifying with appropriate molecular diagnostic, every single tumor harboring targetable FGFR alterations will be of utmost importance to attain the best outcomes for patients with FGFR-driven cancer.