[(18)F]FPRGD2 PET/CT imaging of integrin αvβ3 levels in patients with locally advanced rectal carcinoma.
OBJECTIVE
Our primary objective was to determine if [(18)F]FPRGD2 PET/CT performed at baseline and/or after chemoradiotherapy (CRT) could predict tumour regression grade (TRG) in locally advanced rectal cancer (LARC). Secondary objectives were to compare baseline [(18)F]FPRGD2 and [(18)F]FDG uptake, to evaluate the correlation between posttreatment [(18)F]FPRGD2 uptake and tumour microvessel density (MVD) and to determine if [(18)F]FPRGD2 and FDG PET/CT could predict disease-free survival.


METHODS
Baseline [(18)F]FPRGD2 and FDG PET/CT were performed in 32 consecutive patients (23 men, 9 women; mean age 63 ± 8 years) with LARC before starting any therapy. A posttreatment [(18)F]FPRGD2 PET/CT scan was performed in 24 patients after the end of CRT (median interval 7 weeks, range 3 - 15 weeks) and before surgery (median interval 4 days, range 1 - 15 days).


RESULTS
All LARC showed uptake of both [(18)F]FPRGD2 (SUVmax 5.4 ± 1.5, range 2.7 - 9) and FDG (SUVmax 16.5 ± 8, range 7.1 - 36.5). There was a moderate positive correlation between [(18)F]FPRGD2 and FDG SUVmax (Pearson's r = 0.49, p = 0.0026). There was a moderate negative correlation between baseline [(18)F]FPRGD2 SUVmax and the TRG (Spearman's r = -0.37, p = 0.037), and a [(18)F]FPRGD2 SUVmax of >5.6 identified all patients with a complete response (TRG 0; AUC 0.84, 95 % CI 0.68 - 1, p = 0.029). In the 24 patients who underwent a posttreatment [(18)F]FPRGD2 PET/CT scan the response index, calculated as [(SUVmax1 - SUVmax2)/SUVmax1] × 100 %, was not associated with TRG. Post-treatment [(18)F]FPRGD2 uptake was not correlated with tumour MVD. Neither [(18)F]FPRGD2 nor FDG uptake predicted disease-free survival.


CONCLUSIONS
Baseline [(18)F]FPRGD2 uptake was correlated with the pathological response in patients with LARC treated with CRT. However, the specificity was too low to consider its clinical routine use.
Department of Medical Physics, Division of Nuclear Medicine and Oncological Imaging, B35 Domaine universitaire du Sart Tilman, 4000, Liege, Belgium.
Nadia
N
Withofs
Division of Radiation Oncology, Department of Medical Physics, CHU Liège, Liège, Belgium.
Philippe
P
Martinive
Division of Radiation Oncology, Department of Medical Physics, CHU Liège, Liège, Belgium.
Jean
J
Vanderick
Department of Pathology, CHU Liège, Liège, Belgium.
Noëlla
N
Bletard
Department of Pathology, CHU Liège, Liège, Belgium.
Irène
I
Scagnol
CYCLOTRON Research Centre, University of Liège, Liège, Belgium.
Frédéric
F
Mievis
CYCLOTRON Research Centre, University of Liège, Liège, Belgium.
Fabrice
F
Giacomelli
Division of Radiation Oncology, Department of Medical Physics, CHU Liège, Liège, Belgium.
Philippe
P
Coucke
Department of Pathology, CHU Liège, Liège, Belgium.
Philippe
P
Delvenne
Laboratory of Tumour and Developmental Biology, GIGA-Research, University of Liège, Liège, Belgium.
Didier
D
Cataldo
Molecular Imaging Program at Stanford (MIPS), Radiology Department, Stanford University, Stanford, CA, USA.
Sanjiv S
SS
Gambhir
Department of Medical Physics, Division of Nuclear Medicine and Oncological Imaging, B35 Domaine universitaire du Sart Tilman, 4000, Liege, Belgium. rhustinx@chu.ulg.ac.be.
Roland
R
Hustinx
D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D005260:Female; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D010456:Peptides, Cyclic; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D014057:Tomography, X-Ray Computed
C000610710:FB-mini-PEG-E(c(RGDyK))2; D039302:Integrin alphaVbeta3; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals
Angiogenesis; Integrin; PET; RGD; Rectal cancer