An open-label, single center study with 99mTc-ADAPT6 and 99mTc-DARPinG3 SPECT and biopsies of primary tumour in HER2-positive Breast Cancer before system (chemo/targeted) therapy, where the primary endpoint of the study is to compare imaging properties of 99mTc-ADAPT6 and 99mTc-DARPin G3 SPECT in HER2-positive breast cancer patients.

The primary objectives are:

Compare SPECT/CT imaging properties of 99mTc-ADAPT6 and 99mTc-DARPin G3 in HER2-positive primary tumour of breast cancer patients before system (chemo/targeted) therapy.

The secondary objectives are:

To compare the SPECT/CT tumor imaging data with the data concerning HER2 expression obtained by immunohistochemistry (IHC) and/or fluorescent in situ hybridization (FISH) analysis of biopsy samples.

Inclusion Criteria:

1. Subject is > 18 years of age;

2. Diagnosis of primary breast cancer with possible lymph node metastases before system (chemo+targeted therapy);

3. Availability of results from HER2 status previously determined on material from the primary tumor: HER2-positive, defined as a DAKO HercepTest™ score of 3+ or FISH positive;

4. Sequential injection of 99mTc-ADAPT6 and 99mTc-DARPinG3 in the interval of 3-4 days in each HER2-positive breast cancer patient;

5. 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

6. 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;

7. Subject is capable to undergo the diagnostic investigations to be performed in the study;

8. Informed consent

Exclusion Criteria:

1. Second, non-breast malignancy 2. Active current autoimmune disease or history of autoimmune disease 3. 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 5. Administration of other investigational medicinal product within 30 days of screening 6. Ongoing toxicity > grade 2 from previous standard or investigational therapies, according to US National Cancer Institute's

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Women with primary HER2-positive breast cancer