Abstract
T60
Introduction: HER2, ER, PR in breast cancer cases demonstrates substantial protein overexpression by immunohistochemistry with co-expressed receptors including integrins in cancer cells. The Ga-68-αvβ3-IAC binds to αvβ3 integrin in breast cancer populations express integrins on the surface of tumors and are targetable by Ga-68-αvβ3-IAC. The integrin αvβ3 plays an important role in angiogenesis suggesting an important mechanism of action to detect breast cancer and define the angiogenic state.
Methods: In this pilot study 14 patients underwent PET/CT scans 45 minutes post intravenous injection with a dose range between 2-5 mCi of Ga-DOTAGA-IAC on two different days for staging. The maximum intensity projection was collected and described. For this clinical study, a well characterized Gallium-68 medical radioisotope was used for tumor visualization. Ga-68 is bound with a DOTAGA chelator to give rise to a novel PEG-DOTAGA αvβ3 integrin antagonist conjugate. 4-[2-(3,4,5,6-tetrahydropyrimidine-2-ylamino) ethyloxy] benzoyl-2-[N-(3-amino-neopenta-1-carbamyl)]-aminoethylsulfonyl-amino-b-alanine (IAC), pegylated with oxi-1,2-etinediil (PEG)4 covalently conjugated to 1,4,7,10-tetraazacyclododececane,1-(glutaric acid)-4,7,10-triacetic acid (DOTAGA) labeled with Ga, to a linear αvβ3 integrin antagonist peptidomimetic.
Results: The study found that the maximum intensity projection images show abnormal tracer uptake in the thorax region. The corresponding trans-axial CT and fused PET/CT images localized the tracer uptake in the retro-areolar region of breast. The SUV max range was between 3.2 and 5.49 and in metastatic axillary lymph nodes with a corresponding SUV max between 2.2-9.88. One of 14 patients showed only tracer avid liver lesions (SUV max: 7.45) probably because she underwent 15 sessions of chemotherapy. All patients obtained a T/B greater than 1 in the ROI and metastatic lesions.
Conclusions: Ga-68-αvβ3-IAC has the potential to image and stage breast cancer and metastatic lesions. It was hypothesized that the patient that did not show breast lesion may be the result of multiple chemotherapies. These important results suggests that this method could work in the future for disease management and might be superior to F-18 Fludeoxyglucose.