Avelumab in Metastatic or Locally Advanced Solid Tumors (JAVELIN Solid Tumor JPN)

Inclusion Criteria:

* Signed written informed consent
* Male or female participants aged greater than or equal to (\>=) 20 years
* For dose escalation part: Histologically or cytologically proven metastatic or locally advanced solid tumors, for which no standard therapy exists or standard therapy has failed
* For expansion part:

  * Availability of fresh and archive tumor in formalin fixed paraffin embedded tissue
  * With histologically or cytologically confirmed recurrent or refractory unresectable Stage IV gastric or gastro-esophageal junctional adenocarcinoma (according to American Joint Committee on Cancer/Union Internationale Contre le Cancer \[UICC\] 7th edition) and whose disease progressed after one or two prior chemotherapy regimen(s) involving both fluoropyrimidines and platinum
  * Presence of at least 1 measurable lesion according to RECIST version 1.1
  * Participants should not have severe peritoneal metastases. The following criteria were applied:

    * No clinical ileus or subileus
    * No moderate-to-severe ascites (participants with ascites restricted to the perihepatic space or pelvic cavity)
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 at the trial entry and an estimated life expectancy of at least 3 months
* Adequate hematological, hepatic and renal function as defined in the protocol
* All participants must agree to use effective means of contraception with their partner from entry into the trial through 6 months after the last dose of avelumab

Exclusion Criteria:

* Concurrent treatment with a non-permitted drug
* Prior therapy with any antibody/drug targeting T cell co-regulatory proteins (immune checkpoints)
* Concurrent anticancer treatment or concurrent systemic therapy with steroids or other immunosuppressive agents, or use of any investigational drug within 30 days before the start of trial treatment. Short-term administration of steroids (that is, for allergic reactions or the management of immune-related adverse events \[irAE\]) is allowed
* Previous malignant disease within the last 5 years with the exception of adequately treated non-melanoma skin cancer, in situ cancer, or other cancer
* Non-oncology vaccine therapies for prevention of infection disease (e.g. seasonal flu vaccine, human papilloma virus vaccine) within 4 weeks of study drug administration. Vaccination while on study is also prohibited except for administration of the inactivated influenza vaccine.
* Pregnancy or lactation period
* Known alcohol or drug abuse
* Clinically significant (that is, active) cardiovascular disease
* All other significant diseases (for example, inflammatory bowel disease), which, in the opinion of the investigator, might impair the participant's tolerance of trial treatment
* Any psychiatric condition that would prohibit the understanding or rendering of informed consent
* Legal incapacity or limited legal capacity
* Other protocol defined exclusion criteria could apply