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

The primary purpose of this study is to identify the recommended Phase 2 dose (RP2D) of JNJ-63723283 as a monotherapy (Phase 1a part) and to identify the RP2D of JNJ-63723283 when administered in combination with Erdafitinib (Phase 1b part).


Eligibility Criteria:
Inclusion Criteria:

* Radiographically, histologically, or cytologically confirmed advanced or refractory solid tumor(s) that is metastatic or unresectable, and previously received or was ineligible for standard treatment options. Participants with solid tumor(s) for which anti-PD-1 or anti-PD-L1 antibody as a monotherapy is approved in Japan are eligible.
* 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 and practicing a highly effective, preferably user-independent method of contraception (failure rate of less than (\<) 1 percent (%) per year when used consistently and correctly) and agrees to remain on a highly effective method while receiving study intervention and continue for 5 months following discontinuation of JNJ-63723283 or 3 months following discontinuation of erdafitinib, whichever is longer. Especially participants receiving erdafitinib must agree to use two contraceptive methods and one must be user-independent method; Examples of highly effective contraceptives include: user-independent methods: intrauterine device (IUD) or intrauterine contraceptive system (IUS) and user-dependent methods: combined (estrogen- and progestogen-containing) hormonal contraception or progesterone-containing hormonal contraception. c) Agree not to donate eggs (ova, oocytes), during the study and continue for 5 months following discontinuation of JNJ-63723283 or 3 months following discontinuation of erdafitinib, whichever is longer
* A male participant must wear a condom when engaging in any activity that allows for passage of ejaculate to another person and must agree not to donate sperm for 5 months following discontinuation of JNJ-63723283 or 5 months following discontinuation of erdafitinib, whichever is longer

Exclusion Criteria:

* Had prior treatment with an anti-PD-1 antibody, anti-PD-L1 antibody or anti-PDL2 antibody within 30 days of first study drug administration and/or has an ongoing Grade 2 or higher immunotherapy-related toxicity. If the subject has an experience of treatment with these agents, the subject must not have had severe immunotherapy-related toxicity
* History of or concurrent interstitial lung disease
* Active autoimmune disease or a documented history of autoimmune disease that requires 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 corticosteroids doses greater than (\>) 10 milligram per day (mg/day) prednisolone or equivalent), within 2 weeks before the planned first dose of study drug