Abstract
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Objectives The bombesin analog BAY 86-4367 (3-Cyano-4-[18F]fluorobenzoyl-Ala(SO3H)-Ala(SO3H)-Ava-Gln-Trp-Ala-Val-NMeGly-His-Sta-Leu-NH2) is a F-18 labeled selective Gastrin-Releasing Peptide receptor (GRPr) antagonist. GRPr are overexpressed in prostate cancer but not in normal prostate tissue and represents a promising target for radiolabeled bombesin analogs. Human safety and metabolism were evaluated and biodistribution and excretion determined to estimate the radiation dosimetry for BAY 86-4367 based on human whole-body PET/CT measurements.
Methods 5 healthy male volunteers (age: 52±2 years) were imaged for up to 240 min using a Siemens Biograph 64 TruePoint PET/CT (7 bed positions/frame, 1 min/bed position, iterative reconstruction) after i.v. injection of 291±30 MBq BAY 86-4367. Whole body and organ-specific ROIs for organs showing uptake above general body uptake were created for each subject. Kinetic data for whole body and organs were fitted to exponential equations to determine the residence time. Dosimetry estimates for all target organs and effective dose were calculated using FDA approved OLINDA/EXM software.
Results No adverse events or changes in vital parameters due to BAY 86-4367 were observed. The tracer showed rapid blood clearance and tissue distribution within minutes. The calculated mean effective dose was 0.023±0.006 mSv/MBq. Peak tracer uptake was highest in liver (28%) and urinary bladder (23%) due to hepatobiliary and renal tracer excretion. Individual organ doses [mSv/MBq] were 0.24±0.14 for gall bladder wall, 0.092±0.014 for urinary bladder wall and 0.073±0.022 for the small intestine.
Conclusions BAY 86-4367 is well tolerated. A patient dose of 300 MBq yields an estimated radiation dose of 6.9±1.8 mSv which is below that of [18F] Fluoromethylcholine (11.1±1.8 mSv).
Research Support The trial was sponsored and supported by Bayer Schering Pharma AG, Berli
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