99mTc-DARPinG3 SPECT/CT for Non-invasive HER2-AX in Breast Cancer With Metastatic Lymph Nodes Before Targeted Therapy

Inclusion Criteria:

* Subject is \> 18 years of age
* Diagnosis of primary breast cancer with lymph node metastases
* Availability of results from HER2 status previously determined on material from the primary tumor and metastatic LN, either a. HER2-positive, defined as a DAKO HercepTest™ score of 3+ or FISH positive or b. HER2-negative, defined as a DAKO HercepTest™ score of 0 or 1+; or else if 2+ then FISH negative
* Hematological, liver and renal function test results within the following limits: White blood cell count: \> 2.0 x 109/L; Hemoglobin: \> 80 g/L; Platelets: \> 50.0 x 109/L; ALT, ALP, AST: =\< 5.0 times Upper Limit of Normal; Bilirubin =\< 2.0 times Upper Limit of Normal; Serum creatinine: Within Normal Limits.
* A negative pregnancy test for all patients of childbearing potential. Sexually active women of childbearing potential participating in the study must use a medically acceptable form of contraception for at least 30 days after study termination
* Subject is capable to undergo the diagnostic investigations to be performed in the study
* Informed consent

Exclusion Criteria:

* Any system therapy (chemo-/targeted therapy)
* Second, non-breast malignancy
* Active current autoimmune disease or history of autoimmune disease
* Active infection or history of severe infection within the previous 3 months (if clinically relevant at screening) 4. Known HIV positive or chronically active hepatitis B or C
* Administration of other investigational medicinal product within 30 days of screening
* Ongoing toxicity \> grade 2 from previous standard or investigational therapies, according to US National Cancer Institute's