Biodistribution and Internal Radiation Dosimetry of (99m)Tc-IDA-D-[c(RGDfK)](2) (BIK-505), a Novel SPECT Radiotracer for the Imaging of Integrin α(v)β(3) Expression

Background: Integrin α(v)β(3) is a molecular marker for the estimation of tumor angiogenesis. (99m)Tc-IDA-D-[c(RGDfK)](2) (also known as BIK-505) is a recently developed radiotracer for single-photon emission computed tomography, with good affinity for integrin α(v)β(3). In this study, the authors investigated the whole-body distribution and internal radiation dosimetry of (99m)Tc-IDA-D-[c(RGDfK)](2) in elderly human participants. Materials and Methods: Six healthy volunteers underwent whole-body simultaneous anterior and posterior scans, preceded by transmission scans using cobalt-57 flood source, with a dual head gamma camera system, at 0, 1, 2, 4, 8, and 24 h postinjection of (99m)Tc-IDA-D-[c(RGDfK)](2) (injected radioactivity [mean ± SD] = 388.7 ± 29.3 MBq). Anterior and posterior images were geometrically averaged and attenuation corrected to delineate the regions of interest in the liver, gallbladder, kidneys, urinary bladder, spleen, brain, and large intestine. Radiation dose for each organ and the effective doses (EDs) were estimated using OLINDA/EXM 1.1 software. Results: High radiation doses of renal and biliary excretion tracks such as the urinary bladder wall, upper large intestine, kidneys, liver, and gallbladder wall (19.15 ± 6.84, 19.28 ± 4.78, 15.67 ± 0.90, 9.13 ± 1.71, and 9.09 ± 2.03 μGy/MBq, respectively) were observed. The ED and effective dose equivalent were 5.08 ± 0.53 and 7.11 ± 0.58 μSv/MBq, respectively. Conclusions: Dosimetry results were comparable to other radiolabeled peptides and were considered safe and efficient for clinical usage.