The purpose of this study is to evaluate whether a new type of imaging study, called 18F-Clofarabine (CFA) PET/CT, can be used to image cancer pyrimidine metabolism in participants.

PET (positron emission tomography) imaging is a way of looking at cancers that can reveal cancer metabolism. Presently, however, there are no imaging agents in routine use to look at an aspect of cancer metabolism (pyrimidine metabolism) that dictates whether certain cancer drugs, e.g., gemcitabine, are likely to be taken into the cancer cells. This clinical trial will be testing whether 18F-Clofarabine (CFA) could be an imaging agent to measure this aspect of cancer metabolism.

The participants will receive a CFA injection into a vein in their arm. The imaging drug is attracted to and taken into certain cells in the body, including cancer cells. 18F-Clofarabine (CFA) is experimental because it is not approved by the Food and Drug Administration (FDA).

The participants will be observed for side effects, and about 1 hour later, they will receive a PET/CT scan. Additionally, they will be contacted the next day to inquire again about any side effects. If the participant's routine care involves repeat imaging of cancer, then the CFA PET/CT scan will be repeated at that time, which could be up to 365 days after the first CFA PET/CT scan.

Inclusion Criteria:

• Histologically or cytologically proven metastatic cancer (including carcinoma, adenocarcinoma, sarcoma, or neuroendocrine cancer).

• Subjects must have metastatic disease, confirmed by imaging, typically a CT scan of the chest/abdomen/pelvis.

• Subjects must have measurable disease per RECIST 1.1

• Over 18 years of age

• ECOG performance status 0-1

• Adequate organ function as defined by the following criteria (labs may be no more than 4 weeks prior to the screening date):

  • Serum aspartate transaminase (AST; serum glutamic oxaloacetic transaminase [SGOT]) and serum alanine transaminase (ALT; serum glutamic pyruvic transaminase [SGPT]) <= 2.5 x laboratory upper limit of normal (ULN)
  • Total serum bilirubin <= 2.0 x ULN
  • Absolute neutrophil count (ANC) >= 1500/uL
  • Platelets >= 75,000/uL
  • Hemoglobin >= 8.0 g/dL
  • Serum calcium <= 12.0 mg/dL
  • Serum creatinine <= 2.9 mg/dL

• Subjects must have the ability to understand and the willingness to sign a written informed consent document

• Patient is able to remain still for the duration of the imaging procedure (up to one hour).

Exclusion Criteria:

• Within 6 months prior to enrollment on this study: myocardial infarction, severe/unstable angina, severe peripheral vascular disease (claudication) or procedure on peripheral vasculature, coronary/peripheral artery bypass graft, New York Heart Association grade II or greater congestive heart failure, cerebrovascular accident or transient ischemic attack, clinically significant bleeding or pulmonary embolism.
• Pregnancy or breastfeeding (pregnant or breastfeeding women are excluded from this study because study drugs have the potential for teratogenic or abortifacient effects.
• Other severe acute or chronic medical or psychiatric conditions or laboratory abnormalities that may increase the risk associated with study participation or study drug administration, or may interfere with the interpretation of study results, and in the judgment of the investigator would make the patient inappropriate for entry into this study.

This is a feasibility study of a novel PET-scan imaging agent and IPD is not needed for interpretation of the data