Study to Evaluate Safety and Dosimetry of [18F]GEH121224 in Patients With Locally Advanced or Metastatic Breast Cancer

The study described in this protocol is a Phase 1, single center clinical trial to evaluate the safety and potential of [18F]GEH121224 as a PET radiotracer for the diagnostic imaging of HER2 positive breast cancer lesions. A group of 6 patients will be selected to perform a dosimetry study with [18F]GEH121224 followed by another group of 6 patients in a test-retest study. The results of this study will provide crucial information to guide the development of [18F]GEH121224 for the detection of HER2 status in advanced breast cancer patients. This study will use established methods for characterizing the radiation dosimetry, biodistribution and basic pharmacokinetics of a radiotracer.

Inclusion Criteria:Female patients aged ≥18 yearsWillingness and ability to comply with study procedures and signed and dated informed consentFor women of child-bearing potential, negative urine pregnancy test at screening and o on the day of investigational medicinal product (IMP) administration (with the result known before IMP administration) and willingness to use contraception (barrier, abstinence, non-hormonal) for 3 weeks after injection of [18F]GEH121224Life expectancy >3 monthsDiagnosis of locally advanced or metastatic breast cancerTarget lesion diameter of ≥15 mm that has not been previously treated with radiotherapyHistologically confirmed locally advanced/metastatic breast cancer with a biopsy within the past 12 months confirming HER2-positive status by either IHC or FISH from primary tumorPreviously received no more than 1 prior lines of systemic chemotherapy (including anti HER2 therapy) for metastatic breast cancerEastern Cooperative Oncology Group (ECOG) performance status 0 to 2Adequate organ function as defined by:Hemoglobin ≥10 g/dL White blood cell count ≥3.0 × 109/L Platelet count ≥75 × 109/L Serum creatinine ≤1.4 mg/dL Aspartate aminotransferase and alanine aminotransferase ≤2× upper limit of normal (ULN) Total bilirubin ≤2× ULN or 3.0 mg/dL in patients with Gilbert's syndromeAt least one lesion is fluorodeoxyglucose (FDG)-avidExclusion Criteria:Patient has a primary non-breast malignancy (small dermatological malignancies such as basal cell carcinoma <10 mm are allowed)Pregnancy or breast-feeding or, for women of child-bearing potential, unwillingness to use an acceptable form of birth controlChronically active hepatitis B or CCurrent history of drug or alcohol abuse or any active liver diseaseAdministration of other IMP within 30 days of screeningSystemic therapy including anti-HER2 therapy within 2 weeks before enrollmentOngoing toxicity > grade 2 from previous standard or investigational therapies, according to National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) version 5.0History of cardiac disease (myocardial infarction, arrhythmias requiring therapy, symptomatic valvular disease, cardiomyopathy, or pericarditis)Evidence of significant medical condition, ongoing severe disease, or laboratory finding that, in the opinion of the Investigator, makes it undesirable for the patient to participate in the studySevere claustrophobia, inability to lie flat or fit into the scanner (e.g., body weight ≥350 lbs [160 kg]), or any other inability to tolerate the PET scanKnown allergies to any product used in this study or any constituents of GEH121224 (18F) Injection