RT Journal Article SR Electronic T1 15O-Water PET Study of the Effect of Imatinib, a Selective Platelet-Derived Growth Factor Receptor Inhibitor, Versus Anakinra, an IL-1R Antagonist, on Water-Perfusable Tissue Fraction in Colorectal Cancer Metastases JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1144 OP 1149 DO 10.2967/jnumed.114.151894 VO 56 IS 8 A1 Mark Lubberink A1 Sanjeep S.V. Golla A1 My Jonasson A1 Kristofer Rubin A1 Bengt Glimelius A1 Jens Sörensen A1 Peter Nygren YR 2015 UL http://jnm.snmjournals.org/content/56/8/1144.abstract AB High interstitial fluid pressure (IFP) in colorectal cancer metastases may decrease the uptake and, thus, the effects of antitumor drugs. Imatinib, a selective inhibitor of platelet-derived growth factor receptors, and anakinra, an interleukin-1 receptor antagonist, respectively, increase drug uptake or decrease IFP in preclinical models of carcinoma. Drug-induced decrease in IFP in human metastases has not been objectively shown but should be reflected by an increase in water-perfusable tissue fraction (PTF) or tumor blood flow (TBF) using 15O-water PET/CT and kinetic modeling. Hence, the aim of this study was to assess the effects of imatinib and anakinra on PTF and TBF in colorectal cancer metastases in patients. Methods: Nine patients with documented progressive disease despite all established therapy underwent 15O-water PET/CT at baseline and at 2 d and 6–7 d after the start of oral administration of imatinib (400 mg/d). After a washout period of 1 wk, the protocol was repeated with anakinra (100 mg/d) subcutaneously. Six patients underwent a second baseline scan on the same day to assess reproducibility of PTF and TBF measurements. Volumes of interest were drawn over liver metastases and aorta. PTF and TBF were calculated using the standard single-tissue-compartment model. Results: Imatinib administration during 6–7 d increased PTF from 0.62 ± 0.12 to 0.69 ± 0.13, compared with baseline and day 2 (P = 0.02, Wilcoxon test). No significant changes were found in TBF. PTF values were no longer significantly different from baseline 1 wk after the last imatinib dosage. Anakinra induced no significant change in PTF or TBF. The repeatability coefficients of PTF and TBF in liver lesions were 22% and 28%, respectively. Conclusion: Imatinib increases PTF of colorectal cancer metastases in patients and hence may increase the delivery of antitumor drugs. 15O-water PET/CT and kinetic modeling provide insights into the microenvironment of human cancers.