Imaging CXCR4 Expression in Subjects With Cancer Using 64 Cu-Plerixafor

In mouse models and in patients, expression of the chemokine receptor CXCR4 on various cancers has been correlated with aggressive biological behavior, including increased rates and certain sites of metastasis, and decreased survival. Plerixafor (Mozobil ; Genzyme; Cambridge, MA) has been identified as a specific inhibitor of CXCR4, and it is currently approved by the Food and Drug Administration as a stem-cell mobilizing agent in combination with granulocyte colony-stimulating factor in the treatment of non-Hodgkin's lymphoma and multiple myeloma. Our group has recently shown that plerixafor can be labeled with the positron-emitting radionuclide copper-64(64Cu) to form 64Cu-plerixafor, which can be used to visualize CXCR4-positive tumor xenografts in mice using small-animal positron emission tomography (PET). Determining CXCR4 expression in tumors using 64Cu-plerixafor and PET/computerized tomography (CT) scanning could be useful in predicting tumor behavior and responses to current and experimental therapies, including therapies targeting CXCR4, which could lead to more effective personalized cancer treatments.

This study s primary objective is to evaluate 64Cu-plerixafor as an imaging agent for quantifying CXCR4 expression in subjects (greater than or equal to 18 years of age) with cancer; at least 1 detectable solid tumor of greater than or equal to 1.5 cm in diameter found outside of the vertebral bodies, liver, gallbladder, kidney, and bladder; and tissue sample(s) of the tumors obtained since the first detection of the current occurrence/recurrence of disease. The secondary objectives are to correlate 64Cu-plerixafor standardized uptake value in the target lesion with the level of CXCR4 expression detected via immunohistochemistry and to calculate human dosimetry for 64Cu-plerixafor.

Tumor samples from less than or equal to75 subjects recruited from the National Cancer Institute and the Georgetown University Hospital will be evaluated for CXCR4 expression via immunohistochemistry. With the exception of subjects with adrenocortical carcinoma, evaluation of tissue for expression of CXCR4 will be required before PET scanning. Subjects who meet the eligibility criteria will continue onto the study. Five subjects with adrenocortical carcinoma and/or CXCR4-positive tumor samples will be administered an initial intravenous infusion of 64Cu-plerixafor (up to 8+0.8 mCi; 0.48+0.048 rem; not to exceed 5 g 64Cu-plerixafor) at Day 0. They will then undergo an initial low-dose transmission CT scan followed by 3 consecutive torso PET scans as soon as practical after the infusion, and 2 additional PET/CT scans at 4 hours +/- 1 hour and 24 hours +/- 3 hours post-infusion. Human dosimetry will be calculated based on these results, and the dose may be adjusted, not to exceed the calculated limit of a total effective dose of 5 rem, or the radiation exposure limit for each organ. The remaining subjects will be administered 64Cu-plerixafor at the same, or a newly calculated dose, and will undergo 1 PET/CT scan between 1 and 4 hours post-infusion, depending on the dosimetry results. All subjects will undergo an assessment at the NIH or by phone on study Day 14 3. Additionally, blood will be collected 3 more times at Day 7 2, Day 14 3 and Day 21 3 to measure blood cell counts, and urine collected once more at Day 7 2.