Testing the Role of FDG-PET/CT to Predict Response to Therapy Prior to Surgery for HER2-positive Breast Cancer, The DIRECT Trial

Inclusion Criteria:

• Patients (all genders) must be >= 18 years of age.

• Patient must have the ability to understand and the willingness to sign a writteninformed consent document. Patients with impaired decision-making capacity (IDMC)who have a legally authorized representative (LAR) or caregiver and/or family memberavailable will also be considered eligible.

• Patient must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2.

• Patient must have histologically confirmed HER2-positive primary invasive breastcarcinoma by American Society of Clinical Oncology (ASCO)/College of AmericanPathologists (CAP) guidelines that has been determined by local testing.

• Patient must have known (either positive or negative) hormone receptor (estrogenreceptor [ER] or progesterone receptor [PR]) status by local testing, per ASCO/CAPguidelines. Patients with either hormone receptor-positive or hormone receptor-negative HER2-positive breast cancer are eligible.

• Patient must have American Joint Committee on Cancer (AJCC) 8th Edition stageIIa-IIIc according to anatomic staging table at diagnosis and below criteria.

• Patients without nodal involvement (cN0) are eligible if T size > 2.0 cm (T2-4)

• Patients with nodal involvement (cN1-3) are eligible if T2-4

• Patients with clinical T4d are not eligible

• Patients with bilateral invasive breast cancers are eligible if both cancers areHER2-positive and at least one meets all protocol eligibility criteria and neithercancer renders the patient ineligible.

• Patients with multiple ipsilateral invasive tumors are eligible as long as alltumors are HER2-positive and at least one tumor focus meets all eligibilitycriteria. Multiple lesions that appear part of the same index tumor do not requireadditional biopsy/HER2 testing.

• Patient must plan to start a standard neoadjuvant pertuzumab (or other biosimilars)based regimen.

• Patients with a prior or concurrent malignancy whose natural history or treatmentdoes not have the potential to interfere with the safety or efficacy assessment ofthis imaging intervention are eligible for this trial.

• Patients with human immunodeficiency virus (HIV) on effective anti-retroviraltherapy with undetectable viral load within 6 months of registration are eligiblefor this trial.

• Patient must be participating in the trial at an institution which has agreed toperform the imaging research studies, completed the Eastern Cooperative OncologyGroup-American College of Radiology Imaging Network Cancer Center Group (ECOG-ACRIN)defined PET/CT scanner qualification procedures and received ECOG-ACRIN PET/CTscanner approval.

• For patients who completed the baseline (T0) FDG-PET/CT PRIOR to registration,neoadjuvant pertuzumab-based regimen must start after study registration andwithin 21 days after the T0 scan.

• Patients must not have used colony stimulating growth factors within 14days prior to completing a T0 scan done prior to registration.

Exclusion Criteria:

• Patient must not have any prior treatment for the current breast cancer, includingsurgery, chemotherapy, hormonal therapy, radiation or experimental therapy.

• Patient must not be pregnant or breast-feeding due to the potential harm to anunborn fetus and possible risk for adverse events in nursing infants with theteratogenic effects of FDG in addition to the radiation exposure during PET/CT. Allpatients of childbearing potential must have a blood test or urine study within 7days prior to registration to rule out pregnancy.

• NOTE: A pregnancy test within 7 days prior to the T0 scan is also required butwill only need to be done if a) the T0 scan is completed after studyregistration and b) if the pregnancy test done prior to registration iscompleted outside of the 7-day window.

A patient of childbearing potential is defined as anyone, regardless of sexual orientation or whether they have undergone tubal ligation, who meets the following criteria: 1) has achieved menarche at some point, 2) has not undergone a hysterectomy or bilateral oophorectomy; or 3) has not been naturally postmenopausal (amenorrhea following cancer therapy does not rule out childbearing potential) for at least 24 consecutive months (i.e., has had menses at any time in the preceding 24 consecutive months).

• Patient must not have any contraindication to FDG-PET/CT imaging which includesroutine glucose values > 200 mg/dL and severe claustrophobia.