A Study to Evaluate Safety, Tolerability, Dosimetry, and Preliminary Efficacy of the HER2 Directed Radioligand CAM-H2 in Patients With Advanced/Metastatic HER2-Positive Breast, Gastric, and Gastro-Esophageal Junction (GEJ) Cancer

1. Presence of frank leptomeningeal disease as a unique central nervous system feature or in association with brain parenchymal measurable lesion(s);

2. Symptomatic brain metastases; Note: Patients with asymptomatic treated and untreated brain metastases are eligible.

3. Previous local therapy for brain metastases, such as neurosurgery, stereotactic radiotherapy, or whole brain radiotherapy, administered within 6 weeks prior to administration of CAM-H2; Note: Previous therapy for brain metastases administered at least 6 weeks prior to CAM-H2 administration will be allowed.

4. For patients with brain metastases, any increase in corticosteroid dose during the 4 weeks prior to the first administration of CAM-H2.

Note: Corticosteroid treatment in a stable dose or decreasing dose for at least 4 weeks prior to the first administration of CAM-H2 is allowed.

5. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection requiring parenteral antibiotics or psychiatric illness/social situations that would limit compliance with study requirements;

6. Uncontrolled thyroid disease, defined as free triiodothyronine (T3) and free thyroxine (T4) \> 3 x ULN at screening;

7. Uncontrolled diabetes defined as a fasting serum glucose \> 2 x ULN or glycated hemoglobin levels \> 8.5% at screening;

8. Gastrointestinal (GI) tract disease resulting in an inability to take oral medication, malabsorption syndrome, a requirement for intravenous (IV) alimentation, prior surgical procedures affecting absorption, or uncontrolled inflammatory GI disease (eg, Crohn's, ulcerative colitis);

9. Current active hepatic or biliary disease (exception of patients with Gilbert's syndrome, asymptomatic gallstones, liver metastases, or stable chronic liver disease per Investigator assessment);

10. Ongoing peripheral neuropathy of Grade \> 2 according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0;

11. Severe and/or uncontrolled medical conditions or other conditions that could affect participation in the study such as:

* Symptomatic congestive heart failure of New York Heart Association Class III or IV;

* Unstable angina pectoris, symptomatic congestive heart failure, myocardial infarction within 6 months of start of study drug, serious uncontrolled cardiac arrhythmia, or any other clinically significant cardiac disease; or

* Liver disease, including cirrhosis and severe hepatic impairment;

12. Active (acute or chronic) or uncontrolled severe infections;

13. Known history of HIV, hepatitis B, or active hepatitis C virus at screening;

14. Prior investigational anticancer therapy within 4 weeks prior to the first administration of CAM-H2.

15. Patients who have had a major surgery or significant traumatic injury within 4 weeks prior to the first administration of CAM-H2, who have not recovered from side effects of any major surgery (defined as requiring general anesthesia), or have a major surgery planned during the course of the study;

16. Other malignancies within the past 3 years except for adequately treated carcinoma of the cervix or basal or squamous cell carcinomas of the skin or stage I uterine cancer;

17. Radiation therapy for metastatic disease foci outside the brain, administered within 3 weeks prior to the first administration of CAM-H2;

18. Known hypersensitivity to any of the study drugs (including inactive ingredients), including iodine allergy;

19. History of significant comorbidities that, in the Investigator's judgement, may interfere with study conduct, response assessment, or informed consent;

20. Unable or unwilling to complete the study procedures;

21. Patients that cannot be hospitalized in a radionuclide therapy room;

22. Patients with urinary incontinence;

23. Patients that are unable to comply with thyroid protective pre-medication;

24. Patients in whom bladder catheterization cannot be performed, or in patients who are unwilling to be catheterized if necessary;

25. Patients with contraindications for undergoing MRI or computed tomography (CT), including for receiving contrast agents; or

26. Patient is the Investigator or sub-Investigator, research assistant, pharmacist, study coordinator, or other staff or relative thereof, who is directly involved in the conduct of the study.

A Study to Evaluate Safety, Tolerability, Dosimetry, and Preliminary Efficacy of the HER2 Directed Radioligand CAM-H2 in Patients With Advanced/Metastatic HER2-Positive Breast, Gastric, and Gastro-Esophageal Junction (GEJ) Cancer

What this study is about

A Study to Evaluate Safety, Tolerability, Dosimetry, and Preliminary Efficacy of the HER2 Directed Radioligand CAM-H2 in Patients With Advanced/Metastatic HER2-Positive Breast, Gastric, and Gastro-Esophageal Junction (GEJ) Cancer

What this study is about