FAPI-CUP- Evaluating FAPI as a Novel Radiopharmaceutical for Cancer of Unknown Primary

Inclusion Criteria:

1. Participant has provided written informed consent
2. Participants aged 18 years or over at screening
3. Diagnosed with CUP based on a diagnostic work-up, including, but not limited to; adetailed clinical assessment; a CT scan of the chest/abdomen, and pelvis; pathologicalreview of tumour tissue; and other appropriate tests as per the Cancer Council OptimalCare Pathway guidelines
4. Has not commenced current line of systemic treatment
5. Eastern Cooperative Oncology Group performance status 0 - 2
6. Life expectancy greater than 3 months
7. Adequate hematologic and organ function to commence systemic treatment, defined by thefollowing laboratory results:
8. Haemoglobin ≥ 90g/L
9. Absolute neutrophil count ≥1.5 x 109/L
10. Platelet count ≥ 100 x 109/L
11. Creatinine clearance ≥ 30mL/min
12. Serum bilirubin ≤ 1.5 x upper limit of normal (ULN); patients with knownGilbert's disease may have a bilirubin ≥ 3.0 x ULN
13. Aspartate transaminase (AST) or alanine transaminase (ALT) ≤2 x ULN (or ≤ 5 x ULNin the presence of liver metastases)
14. Willing and able to comply with all study requirements, including all treatment andrequired assessments including follow-up procedures, in the investigator's judgment

Exclusion Criteria:

1. Uncontrolled medical or psychological conditions that may prevent commencement ofsystemic treatment.
2. Major surgical procedure within 6 weeks prior to study registration or activeinfection requiring systemic treatment a. Placement of vascular access devices is not considered major surgery.
3. Concurrent illness, including severe infection that may jeopardise the ability of theparticipant to undergo procedures outlined in this protocol with reasonable safety
4. Prior cancer diagnosis with the exception of:
5. Malignancy treated with curative intent and with no known active disease ≥ 3yearsand of low potential risk of recurrence
6. Adequately treated basal cell or squamous cell skin carcinoma or non-invasivemelanoma
7. Adequately treated non-muscle invasive bladder cancer (Tis, Ta and low grade T1tumours)
8. Adequately treated carcinoma in situ without evidence of disease
9. Cancer subjects with incidental histologic findings of prostate cancer that, inthe opinion of the Investigator, is not deemed to require active therapy (e.g.,incidental prostate cancer identified following cystoprostatectomy that istumour/node/metastasis stage ≤ pT2N0)
10. Greater than one prior line of systemic treatment
11. Known allergy or reaction to 18F or 68Ga tracer