RT Journal Article
SR Electronic
T1 Biodistribution and Dosimetry of Intraventricularly Administered <sup>124</sup>I-Omburtamab in Patients with Metastatic Leptomeningeal Tumors
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1794
OP 1801
DO 10.2967/jnumed.118.219576
VO 60
IS 12
A1 Pandit-Taskar, Neeta
A1 Zanzonico, Pat B.
A1 Kramer, Kim
A1 Grkovski, Milan
A1 Fung, Edward K.
A1 Shi, Weiji
A1 Zhang, Zhigang
A1 Lyashchenko, Serge K.
A1 Fung, Alex M.
A1 Pentlow, Keith S.
A1 Carrasquillo, Jorge A.
A1 Lewis, Jason S.
A1 Larson, Steven M.
A1 Cheung, Nai-Kong V.
A1 Humm, John L.
YR 2019
UL http://jnm.snmjournals.org/content/60/12/1794.abstract
AB Radiation dose estimations are key for optimizing therapies. We studied the role of 124I-omburtamab (8H9) given intraventricularly in assessing the distribution and radiation doses before 131I-omburtamab therapy in patients with metastatic leptomeningeal disease and compared it with the estimates from cerebrospinal fluid (CSF) sampling. Methods: Patients with histologically proven malignancy and metastatic disease to the central nervous system or leptomeninges who met eligibility criteria for 131I-omburtamab therapy underwent immuno-PET imaging with 124I-8H9 followed by 131I-8H9 antibody therapy. Patients were imaged with approximately 74 MBq of intraventricular 124I-omburtamab via an Ommaya reservoir. Whole-body PET images were acquired at approximately 4, 24, and 48 h after administration and analyzed for dosimetry calculations. Peripheral blood and CSF samples were obtained at multiple time points for dosimetry estimation. Results: Forty-two patients with complete dosimetry and therapy data were analyzed. 124I-omburtamab PET–based radiation dosimetry estimations revealed mean (±SD) absorbed dose to the CSF for 131I-8H9 of 0.62 ± 0.40 cGy/MBq, compared with 2.22 ± 2.19 cGy/MBq based on 124I-omburtamab CSF samples and 1.53 ± 1.37 cGy/MBq based on 131I-omburtamab CSF samples. The mean absorbed dose to the blood was 0.051 ± 0.11 cGy/MBq for 124I-omburtamab samples and 0.07 ± 0.04 cGy/MBq for 131I-omburtamab samples. The effective whole-body radiation dose for 124I-omburtamab was 0.49 ± 0.27 mSv/MBq. The mean whole-body clearance half-time was 44.98 ± 16.29 h. Conclusion: PET imaging with 124I-omburtamab antibody administered intraventricularly allows for noninvasive estimation of dose to CSF and normal organs. High CSF-to-blood absorbed-dose ratios are noted, allowing for an improved therapeutic index to leptomeningeal disease and reduced systemic doses. PET imaging–based estimates were less variable and more reliable than CSF sample–based dosimetry.