This is a multi-center, open-label, single-arm, Phase 1/2 study designed to evaluate the safety, radiation dosimetry, and preliminary diagnostic performance of [18F]FPyQCP in detecting colorectal cancer (CRC), gastric cancer (GC), pancreatic ductal adenocarcinoma (PDAC), invasive lobular breast cancer (ILC), and epithelial ovarian cancer (EOC).

Inclusion Criteria:

1. Participants provide informed consent and confirm that they are able and willing to comply with all protocol requirements.

2. Participants must be ≥ 18 years and < 80 years of age and competent to give informed consent.

3. Eastern Cooperative Oncology Group performance status ≤ 2.

4. Diagnosis of either CRC (confirmed by histopathology), GC (confirmed by histopathology), PDAC (confirmed by cytology or histopathology), ILC (confirmed by histopathology), or EOC (suspected or confirmed by cytology or histopathology).

5. Women of childbearing potential (WOCBP) should have a negative serum test at screening (Visit 1) and a negative urine pregnancy test at the PET/CT imaging visit (Visit 2) prior to [18F]FPyQCP administration.

6. WOCBP, and men who are sexually active with WOCBP, must agree to use a highly effective method(s) of contraception for the duration of the study

7. Cohort A specific: Participants with stage I-III (see Appendix 3) CRC, GC, PDAC, ILC, or EOC (stage IV disease is allowed in the setting of oligometastatic disease [5 or fewer known metastases) as assessed by conventional imaging within 8 weeks of [18F]FPyQCP administration.

8. Cohort B specific: Conventional imaging performed within 8 weeks of screening and no later than 24 hours before [18F]FPyQCP administration and available for upload to the central imaging vendor, including, at a minimum, a contrast-enhanced CT that includes the abdomen and pelvis.

9. Either:

   1. Treatment-naïve with at least stage IIB disease. Available biopsy sample or scheduled biopsy or surgical resection no later than Day 42.
   2. Following neoadjuvant therapy (with at least stage IIB disease at initial presentation) with scheduled biopsy or surgical resection no later than Day 42. [18F]FPyQCP PET/CT imaging should be performed as close to scheduled procedure as clinically feasible.
   3. Suspected recurrence after definitive therapy

Exclusion Criteria:

1. Participants administered any radioisotope within 5 physical half-lives prior to [18F]FPyQCP administration.
2. Participants administered any other IMP within 2 weeks or 5 half-lives, whichever is longest, prior to [18F]FPyQCP administration.
3. Participants who have recently received any other contrast agent (< 24 hours for intravenous agents and < 5 days for oral agents) before the day of [18F]FPyQCP administration.
4. Participants with a history of severe claustrophobia or panic attacks when in confined spaces.
5. Known hypersensitivity to [18F]FPyQCP or any of its constituents.
6. Participants with any medical condition or other circumstances at screening or in their past medical history that, in the opinion of the investigator, compromise obtaining reliable data, achieving study objectives, or study completion.
7. Known diagnosis of an autoimmune or inflammatory disorder that is expected to confound image interpretation per investigator judgment, excluding disorders directly related to the index cancer (e.g. tumor-associated pancreatitis or biliary stasis for PDAC).
8. Medical history of abdomino-pelvic or breast irradiation in the last 3 months.
9. Presence of any current implanted foreign material (e.g. stents, surgical clips) that may confound image interpretation per investigator judgment.
10. Significant renal or hepatic impairment.
11. Female participants who are breastfeeding, unless the participant commits to pumping breast milk and discarding it from injection to ≥ 24 hours from the time of the [18F]FPyQCP administration.
12. Cohort A Specific Exclusion Criteria: 12. No prior history of any other cancer, unless treated with curative-intent and disease-free for at least 5 years before Visit 1 (at least 1 year before Visit 1 for basal cell carcinoma, localized squamous cell carcinoma of the skin and in situ carcinoma of cervix).](streamdown:incomplete-link)