Single Microdose Trial- CXCR4 PET Tracer - Pharmacokinetics and Pharmacodynamics of [68Ga]Ga-R54, a Radiopharmaceutical Directed Toward CXCR4 in Patients With Advanced Solid Neoplasia.

Inclusion Criteria:

* Patients \> 18 years
* Patients with histological diagnosis of solid neoplasm (breast, lung, colon, ovary, pancreas) in advanced stages or multiple myeloma evaluated by PET/CT with \[18F\]FDG carried out in the 3 months prior to enrollment. The neoplasm must express the CXCR4 receptor by immunohistochemistry
* Patients with ECOG performance status 0-2, able to undergo the scheduled diagnostic procedure (PET/CT with \[68Ga\]Ga-R54).
* Patients with alkaline phosphatase (AP), alanine aminotransferase (ALT), and aspartate aminotransferase \<3 x upper limit of reference range and total bilirubin \<2.0 mg/dL
* Patients with creatinine \< 1.5 x upper limit of reference range or 24-hour creatinine clearance \> 50 mL/min
* Negative serum pregnancy test (b-hCG) for women of childbearing age before administration of \[68Ga\]Ga-R54).
* Signature of informed consent indicating that the patient (or legal representative) has been informed of all aspects pertinent to the study
* Willingness and ability to comply with scheduled visits, laboratory tests and other study procedures.

Exclusion Criteria:

* Presence of active infections (e.g. requiring antibiotic therapy) or other serious concomitant illness, which, in the opinion of the investigator, would place the patient at undue risk or interfere with the study
* Declared chronic active hepatitis (hepatitis B / C)
* Declared active autoimmune diseases
* Recovery from major trauma including surgery within 4 weeks of study enrollment
* Presence of neurodegenerative diseases
* Pregnancy and/or breastfeeding
* Any conditions that in the opinion of the investigator could hinder compliance with the study protocol
* Patients who have not signed consent to participate in the study