Radiolabelled somatostatin analogue(s) for peptide receptor scintigraphy and radionuclide therapy.
BACKGROUND
Peptide receptor scintigraphy with the radioactive somatostatin analogue, [111In-DTPA0]octreotide, is a sensitive and specific technique to show in vivo the presence and abundance of somatostatin receptors on various tumours.


OBJECTIVE
With this technique primary tumours and metastases of neuroendocrine cancers as well as of many other cancer-types can be localised. This technique is currently used to assess the possibility of peptide receptor radionuclide therapy (PRRT) with repeated administrations of high doses of [111In-DTPA0)octreotide. 111In emits Auger and conversion electrons having a tissue penetration of 0.02-10 microns and 200 to 500 microns, respectively.


METHODS
Thirty end-stage patients with mostly neuroendocrine progressing tumours were treated with [111In-DTPA0]octreotide, up to a maximal cumulative patient dose of about 74 GBq, in a phase I trial.


RESULTS
There were no major clinical side effects after up to two years treatment, except that in a few patients a transient decline in platelets counts and lymphocyte subsets occurred. Promising beneficial effects on clinical symptoms, hormone production and tumour proliferation were found. Of the 21 patients who received a cumulative dose of more than 20 GBq, eight patients showed stabilisation of disease and six other patients a reduction in size of tumours. There is a tendency towards better results in patients whose tumours have a higher accumulation of the radioligand.


CONCLUSIONS
PRRT is feasible, also with 111In as radionuclide. Depending on the homogeneity of distribution of tumour cells expressing peptide receptors and the size of the tumour, beta-emitting radionuclides, e.g., 90Y, labelled to DOTA-chelated peptides, are also attractive candidates for PRRT. The first PRRT trials with [90Y-DOTA0,Tyr3]octreotide started recently.
Krenning
E P
EP
Department of Nuclear Medicine, University Hospital and Erasmus University Rotterdam, The Netherlands. krenning@nuge.azr.nl
de Jong
M
M
Kooij
P P
PP
Breeman
W A
WA
Bakker
W H
WH
de Herder
W W
WW
van Eijck
C H
CH
Kwekkeboom
D J
DJ
Jamar
F
F
Pauwels
S
S
Valkema
R
R
D000818:Animals; D006801:Humans; D007205:Indium Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008113:Liver Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000532:radiotherapy / Q000556:secondary; D018358:Neuroendocrine Tumors / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D015282:Octreotide / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D004369:Pentetic Acid / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D019275:Radiopharmaceuticals / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D051381:Rats; D018000:Receptors, Peptide / Q000032:analysis* / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000032:analysis / Q000378:metabolism
D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D018000:Receptors, Peptide; D017481:Receptors, Somatostatin; C071632:SDZ 215-811; D004369:Pentetic Acid; D015282:Octreotide