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Objectives The Phase I safety, biodistribution and internal radiation dosimetry study in adult healthy Japanese males of flutemetamol (18F) injection, an in vivo β-amyloid imaging agent, is reported and compared with previously obtained Caucasian data.

We report on the biodistribution and internal radiation dosimetry in humans of [18F]fluciclovine, a synthetic L-leucine analogue being investigated as a potential diagnostic biomarker for neoplasia. Whole-body positron emission tomography (PET) scans of 6 healthy volunteers were acquired at up to 16 time points up to about 5 h after a bolus administration of [18F]fluciclovine (153.8 ± 2.2 MBq). Venous blood samples were taken up to about 4 h post-injection from which 18F activity concentrations in whole blood and plasma were measured. Urine was collected as voided up to 4 h post-injection, from which the excreted 18F activity was measured. Absolute values of the 18F activity contained in up to 11 source regions (brain, salivary glands, lung, heart, pancreas, spleen, liver, red bone marrow, kidneys, uterus and urinary bladder contents) were determined directly from quantitative analysis of the images. For each source region, the 18F activity decay-corrected and normalised to that injected, as a function of time, was fit by an analytical function which was subsequently integrated to yield the cumulated activity normalised to the injected activity. These normalised cumulated activities were then used as input to the Organ Level INternal Dose Assessment/EXponential Modelling (OLINDA/EXM) package to calculate the internal radiation dosimetry of each subject following the Medical Internal Radiation Dose (MIRD) schema. An effective dose was then estimated for each subject. [18F]Fluciclovine was clinically well tolerated in this study. Very little 18F was excreted with only a mean value of 3.3 % present in the urine at about 4 h post-injection; no activity within the intestinal contents was noted. The highest mean initial uptakes were measured in the liver (13.8 %), red bone marrow (11.1 %) and lung (7.1 %). The highest mean radiation absorbed doses per unit administered activity were received by the pancreas (102.2 μGy/MBq), the cardiac wall (51.7 μGy/MBq) and the uterine wall (44.6 μGy/MBq). The mean effective dose per unit administered activity was 22.1 μSv/MBq. The internal radiation dosimetry of [18F]fluciclovine appears acceptable for PET imaging.

The aim of the study presented was to investigate the brain uptake properties of the amyloid PET agent [F-18]flutemetamol in Japanese healthy controls and clinically probable Alzheimer's disease (AD) patients, and to make a comparison with the results of a previously performed study on Caucasian subjects. [F-18]flutemetamol was recently approved by the American Food and Drug Administration and the European Medicines Agency for visualization of amyloid in vivo. Since the first clinical study of [F-18]flutemetamol-an F-18 derivative of the PET tracer 11C-Pittsburgh Compound B targeting beta-amyloid--took place, several clinical studies have been performed, but few focusing on a Japanese population.In the Step A, three elderly healthy volunteers and three AD subjects underwent dynamic PET scanning 0-30 and 60-150 min after injection of 185 MBq [F-18]flutemetamol. The brain volume of distribution (V-T) was quantified using Logan's linear graphical analysis and as standardized uptake value ratios (SUVR) with a cerebellar reference. The optimal acquisition window was determined from brain time activity curves for Step B. In the Step B, 5 AD and 5 elderly healthy volunteers were scanned from 80 to 140 min after intravenous injection of [F-18]flutemetamol. The data from the two parts were pooled for estimation of overall efficacy.[F-18]Flutemetamol injection was shown to be safe-no serious adverse events were reported during this study. A simplified SUVR estimate of the uptake of [F-18]flutemetamol using a time window of 85-115 min post injection successfully discriminated AD cases from healthy volunteers. AD subjects showed an elevated tracer uptake in prefrontal cortex, the lateral temporal cortex and precuneus amongst other regions. No significant [F-18]flutemetamol PET differences could be seen between the Japanese AD cases in this study and those from an earlier Caucasian study, or between control subjects in Japanese and Caucasian studies.This study supports the use of [F-18]flutemetamol PET in Japanese population as a marker of the presence of fibrillar beta-amyloid. The lack of differences between the Japanese cohort and those from a previous Caucasian cohort supports the extrapolation of results from other Caucasian [F-18]flutemetamol PET studies to the Japanese population.