The purpose of this study is to see whether 89Zr-ss-pertuzumab is safe in people with HER2+ cancer.

Inclusion Criteria:

• Biopsy proven HER2-positive or HER2-low primary malignancy or metastatic disease

Note: HER2 positivity is defined according to American Society of Clinical Oncology guidelines or ERBB2 amplification on next generation sequencing Note: HER2-low is defined as low HER2 expression, with immunohistochemistry (IHC) 1+ or IHC 2+ and in situ hybridization [ISH]-negative, including FISH.

• Biopsy proven primary malignancy or metastatic disease
• At least one malignant lesion on CT, MR, or FDG PET/CT within 60 days of protocol enrollment
• Age 18 years or greater
• ECOG performance of 0-2

Exclusion Criteria:

• Creatinine > 2 times normal limit (obtained with 8 weeks of enrollment)
• AST/ALT > 2 times normal limit (obtained with 8 weeks of enrollment)
• Life expectancy < 3 months
• Pregnancy or lactation
• Patients who cannot undergo PET/CT due to weight limits (over 450 pounds)

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.