A Study to Evaluate the Safety, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of JNJ-63723283, an Anti-Programmed Cell Death (PD)-1 Monoclonal Antibody, as Monotherapy or in Combination With Erdafitinib in Japanese Participants With Advanced Solid Cancers

Inclusion Criteria:

• Radiographically, histologically, or cytologically confirmed advanced or refractorysolid tumor(s) that is metastatic or unresectable, and previously received or wasineligible for standard treatment options. Participants with solid tumor(s) forwhich anti-PD-1 or anti-PD-L1 antibody as a monotherapy is approved in Japan areeligible.

• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

• Thyroid function laboratory values within normal range

• A woman must be: a) Not of childbearing potential; b) Of childbearing potential andpracticing a highly effective, preferably user-independent method of contraception (failure rate of less than (<) 1 percent (%) per year when used consistently andcorrectly) and agrees to remain on a highly effective method while receiving studyintervention and continue for 5 months following discontinuation of JNJ-63723283 or 3 months following discontinuation of erdafitinib, whichever is longer. Especiallyparticipants receiving erdafitinib must agree to use two contraceptive methods andone must be user-independent method; Examples of highly effective contraceptivesinclude: user-independent methods: intrauterine device (IUD) or intrauterinecontraceptive system (IUS) and user-dependent methods: combined (estrogen- andprogestogen-containing) hormonal contraception or progesterone-containing hormonalcontraception. c) Agree not to donate eggs (ova, oocytes), during the study andcontinue for 5 months following discontinuation of JNJ-63723283 or 3 monthsfollowing discontinuation of erdafitinib, whichever is longer

• A male participant must wear a condom when engaging in any activity that allows forpassage of ejaculate to another person and must agree not to donate sperm for 5months following discontinuation of JNJ-63723283 or 5 months followingdiscontinuation of erdafitinib, whichever is longer

Exclusion Criteria:

• Had prior treatment with an anti-PD-1 antibody, anti-PD-L1 antibody or anti-PDL2antibody within 30 days of first study drug administration and/or has an ongoingGrade 2 or higher immunotherapy-related toxicity. If the subject has an experienceof treatment with these agents, the subject must not have had severeimmunotherapy-related toxicity

• History of or concurrent interstitial lung disease

• Active autoimmune disease or a documented history of autoimmune disease thatrequires systemic steroids or immunosuppressive agents

• Grade 3 or higher toxicity effects from previous treatment with immunotherapy

• Has taken immunosuppressive doses of systemic medications, such as corticosteroidsdoses greater than (>) 10 milligram per day (mg/day) prednisolone or equivalent),within 2 weeks before the planned first dose of study drug