- Pregnant or breast-feeding women will not be entered on this study; pregnancy tests must be obtained in girls who are post-menarchal; males or females of reproductive potential may not participate unless they have agreed to use an effective contraceptive method, while receiving study treatment and for 3 months after the last dose of JNJ-42756493 (erdafitinib); male subjects (with a partner of child-bearing potential) must use a condom with spermicide when sexually active and must not donate sperm from the first dose of study drug until 5 months after the last dose of study drug