Quintanal-Villalonga A, et al. - Since the response to therapy is not seen in all lung adenocarcinomas harboring epidermal growth factor receptor (EGFR) mutations, researchers focused on predictive biomarkers of therapeutic results, as well as on new treatments sensitizing these tumors to EGFR inhibition. A cooperative interaction between EGFR and Fibroblast Growth Factor Receptor (FGFR)4 was described, which leads to their reciprocal activation with pro-oncogenic outcomes in vitro and in vivo. This cooperation was independent of EGFR activating mutations and increased resistance to various EGFR inhibitors. In vitro and in vivo, the synergistic impacts of the combination of EGFR and FGFR inhibitors were evident in high FGFR4-expressing, EGFR-activated tumors, at the therapeutic level. Correlated with these findings, the presence of high FGFR4 expression on tumors was related to earlier relapse in patients treated with EGFR inhibitors.