Development of a real-time polymerase chain reaction assay for prediction of the uptake of meta-[(131)I]iodobenzylguanidine by neuroblastoma tumors.
OBJECTIVE
The suitability of neuroblastoma patients for therapy using radiolabeled meta-iodobenzylguanidine (MIBG) is determined by scintigraphy after the administration of a tracer dose of radioiodinated MIBG whose uptake is dependent upon the cellular expression of the noradrenaline transporter (NAT). As a possible alternative to gamma camera imaging, we developed a novel molecular assay of NAT expression. mRNA extracted from neuroblastoma biopsy samples, obtained retrospectively, was reverse transcribed, and NAT-specific cDNA was quantified by real-time PCR, referenced against the expression of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase. EXPERMENTAL DESIGN: Tumor specimens from 54 neuroblastoma patients were analyzed using real-time PCR, and NAT expression was compared with the corresponding diagnostic scintigrams.


RESULTS
Forty-eight of 54 (89%) of tumors showed MIBG uptake by scintigraphy. NAT expression was found to be significantly associated with MIBG uptake (P < 0.0001, Fisher's exact test). None of the samples from the six tumors that failed to concentrate MIBG expressed detectable levels of the NAT (specificity = 1.0). However, of the 48 MIBG uptake-positive tumors, only 43 (90%) expressed NAT (sensitivity = 0.9). The real-time PCR test has a positive predictive value of 1.0 but a negative predictive value of 0.55.


CONCLUSIONS
The results indicate that whereas this method has substantial ability to predict the capacity of neuroblastoma tumors to accumulate MIBG, confirmation is required in prospective studies to determine more accurately the predictive strength of the test and its role in the management of patients with neuroblastoma.
Carlin
Sean
S
Departments of Radiation Oncology and Child Health, University of Glasgow, Cancer Research UK Beatson Laboratories, Glasgow G61 1BD, United Kingdom.
Mairs
Rob J
RJ
McCluskey
Anthony G
AG
Tweddle
Deborah A
DA
Sprigg
Alan
A
Estlin
Christine
C
Board
Julian
J
George
Rani E
RE
Ellershaw
Caroline
C
Pearson
Andrew D J
AD
Lunec
John
J
Montaldo
Paolo G
PG
Ponzoni
Mirco
M
van Eck-Smit
Berthe L
BL
Hoefnagel
Cees A
CA
van den Brug
Marieke D
MD
Tytgat
Godelieve A M
GA
Caron
Huib N
HN
D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D001706:Biopsy; D001932:Brain Neoplasms / Q000188:drug therapy; D001943:Breast Neoplasms / Q000188:drug therapy; D045744:Cell Line, Tumor; D017931:DNA Primers / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D006801:Humans; D009447:Neuroblastoma / Q000188:drug therapy*; D050484:Norepinephrine Plasma Membrane Transport Proteins; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D027981:Symporters / Q000378:metabolism
D000970:Antineoplastic Agents; D017931:DNA Primers; D018076:DNA, Complementary; D050484:Norepinephrine Plasma Membrane Transport Proteins; D012333:RNA, Messenger; C493227:SLC6A2 protein, human; D027981:Symporters; D019797:3-Iodobenzylguanidine