The main purpose of this study is to evaluate the effect of multiple doses of carbamazepine (a strong inducer of cytochrome P450 [CYP]3A4 and a weak inducer of CYP2C9) on the pharmacokinetics of a single oral dose of erdafitinib in healthy adult participants.

Inclusion Criteria:

• Healthy on the basis of physical examination, medical history, and vital signs (blood pressure, pulse, and body temperature) performed at screening
• Healthy on the basis of clinical laboratory tests performed at screening. If the results of the serum chemistry panel and hematology panel are outside the normal reference ranges, the participant may be included only if the investigator judges the abnormalities or deviations from normal to be not clinically significant. This determination must be recorded in the participant's source documents and initialed by the investigator. Participants must have sodium and phosphate levels within normal limits; hematological parameters (Hemoglobin, red blood cell [RBC] count, white blood cell [WBC] count, absolute neutrophil count, platelet count) within normal limits; and total bilirubin, alanine aminotransferase (ALT), aspartate amino transferase (AST), and alkaline phosphatase (ALP) serum levels lower than or equal to the upper limit of normal at screening
• Willing and able to adhere to the prohibitions and restrictions specified in this protocol
• Must agree to have a pharmacogenomic blood sample (5 milliliters [mL]) collected at screening to allow for pharmacogenomic analysis
• Non-smoker for at least 6 months before first study drug administration

Exclusion Criteria:

• History of depression or suicidal ideation
• History or current evidence of ophthalmic disorder, such as central serous retinopathy (CSR) or retinal vein occlusion, active wet age-related macular degeneration, diabetic retinopathy with macular edema, uncontrolled glaucoma, corneal pathology such as keratitis, keratoconjunctivitis, keratopathy, corneal abrasion, inflammation, or ulceration
• Use of any prescription or nonprescription medication (including vitamins and herbal supplements), except for paracetamol (a maximum of 3 doses per day of 500 milligram [mg] paracetamol, and no more than 3 gram [g] per week), hormonal replacement therapy and cetirizine (in case of allergic reactions), within 14 days before the first dose of the study drug is scheduled until completion of the study
• Received an experimental drug or used an experimental medical device within 1 month or within a period less than 5 times the drug's half-life, whichever is longer, before the first dose of the study drug is scheduled
• Known allergies, hypersensitivity, or intolerance to erdafitinib or carbamazepine or any of the excipients of the formulations

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency.

As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu