The main objectives of this study are:

• To determine the recommended dose (RD) of FPA144 in participants with gastric or gastroesophageal cancer (hereafter referred to as gastric cancer)
• To evaluate the safety of escalating doses of FPA144 in participants with gastric cancer
• To characterize the pharmacokinetic (PK) profile of single and multiple doses of intravenously administered FPA144 in participants with gastric cancer

Key Inclusion Criteria:

• Histologically or cytologically confirmed gastric or gastroesophageal junction adenocarcinoma that is locally recurrent or metastatic and has progressed following standard treatment or is not appropriate for standard treatment
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1
• Adequate hematological, liver and kidney function. Measurable or non-measurable disease
• Archival tumor tissue for determination of FGFR2 status

Key Exclusion Criteria:

• Untreated or symptomatic central nervous system (CNS) metastases
• Clinically significant cardiac disease
• Peripheral sensory neuropathy >/= Common Terminology Criteria for Adverse Events (CTCAE) Grade 2
• Active infection requiring systemic treatment
• Known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)-related illness, or known active or chronic hepatitis B or C infection
• Prior treatment with any selective inhibitor of the fibroblast growth factor (FGF)-FGFR pathway
• Known abnormalities of the cornea that may pose an increased risk of developing a corneal ulcer
• Known positivity for human epidermal growth factor receptor 2 (HER2)
• Women who are pregnant or breastfeeding

De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.

Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.

Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.