RT Journal Article
SR Electronic
T1 Monitoring Afatinib Treatment in HER2-Positive Gastric Cancer with <sup>18</sup>F-FDG and <sup>89</sup>Zr-Trastuzumab PET
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 936
OP 943
DO 10.2967/jnumed.112.110239
VO 54
IS 6
A1 Yelena Y. Janjigian
A1 Nerissa Viola-Villegas
A1 Jason P. Holland
A1 Vadim Divilov
A1 Sean D. Carlin
A1 Erica M. Gomes-DaGama
A1 Gabriela Chiosis
A1 Gregory Carbonetti
A1 Elisa de Stanchina
A1 Jason S. Lewis
YR 2013
UL http://jnm.snmjournals.org/content/54/6/936.abstract
AB We evaluated the ability of the PET imaging agent 89Zr-trastuzumab to delineate HER2-positive gastric cancer and to monitor the pharmacodynamic effects of the epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor afatinib. Methods: Using 89Zr-trastuzumab, 18F-FDG, or 3′-deoxy-3′-18F-fluorothymidine (18F-FLT PET), we imaged HER2-positive NCI-N87 and HER2-negative MKN74 gastric cancer xenografts in mice. Next, we examined the pharmacodynamic effects of afatinib in NCI-N87 xenografts using 89Zr-trastuzumab and 18F-FDG PET and comparing imaging results to changes in tumor size and in protein expression as monitored by Western blot and histologic studies. Results: Although 18F-FDG uptake in NCI-N87 tumors did not change, a decrease in 89Zr-trastuzumab uptake was observed in the afatinib-treated versus control groups (3.0 ± 0.0 percentage injected dose per gram (%ID/g) vs. 21.0 ± 3.4 %ID/g, respectively; P &lt; 0.05). 89Zr-trastuzumab PET results corresponded with tumor reduction, apoptosis, and downregulation of HER2 observed on treatment with afatinib. Downregulation of total HER2, phosphorylated (p)-HER2, and p-EGFR occurred within 24 h of the first dose of afatinib, with a sustained effect over 21 d of treatment. Conclusion: Afatinib demonstrated antitumor activity in HER2-positive gastric cancer in vivo. 89Zr-trastuzumab PET specifically delineated HER2-positive gastric cancer and can be used to measure the pharmacodynamic effects of afatinib.