Because JNJ42756493 is also effective towards FGFR4 [20], these findings could be important when considering the use of JNJ42756493 as a first-line treatment; primary, activating mutations corresponding to gatekeeper replacements have been reported in rhabdomyosarcoma (FGFR4 V550L and V550E) and in breast cancer (FGFR4 V550M) [16, 38]. Here, FGFR4 is linked to breast carcinoma.