Tumor response after [(90)Y-DOTA(0),Tyr(3)]octreotide radionuclide therapy in a transplantable rat tumor model is dependent on tumor size.

Abstract

UNLABELLED:

A promising application of radiolabeled somatostatin analogs is peptide receptor-targeted radionuclide therapy of somatostatin receptor-expressing tumors. A suitable radionuclide is (90)Y, which emits high-energy beta-particles with a pathlength of several millimeters in tissue, making it especially promising for treatment of large tumors.

METHODS:

We investigated the radiotherapeutic effect of different activities (111 and 370 MBq) of [(90)Y-1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (DOTA)(0),Tyr(3)]octreotide in Lewis rats bearing somatostatin receptor-positive rat pancreatic CA20948 tumors of different size (0.08-15 cm(2)) in their flank.

RESULTS:

Dose-dependent radiotherapeutic effects of (90)Y-labeled octreotide in this rat tumor model were found. Tumor control (100% complete response) was found in animals bearing tumors of 3-9 cm(2) (mean, 7.8 cm(2)) after intravenous injection of the highest activity (370 MBq [(90)Y-DOTA(0),Tyr(3)]octreotide). In rats bearing tumors of < or =1 cm(2) or > or =14 cm(2), the effects were less pronounced (50% and 0% complete response, respectively). In tumors of < or =1 cm(2) the (90)Y radiation energy will not be absorbed completely in the tumor, whereas in tumors of > or =14 cm(2) the increased number of clonogenic and probably hypoxic tumor cells may explain the failure to reach a cure.

CONCLUSION:

This study shows the ability of [(90)Y-DOTA(0),Tyr(3)]octreotide to control tumor growth, especially in medium-sized tumors. The effect of radionuclide therapy appeared to be dependent on tumor size at the onset of therapy.

• Authors: M de Jong, W A Breeman, B F Bernard, W H Bakker, T J Visser, P P Kooij, A van Gameren, E P Krenning
• Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine (J Nucl Med) Vol. 42 Issue 12 Pg. 1841-6 (Dec 2001) ISSN: 0161-5505 [Print] United States
• PMID: 11752083 (Publication Type: Journal Article)

Chemical References

• Radiopharmaceuticals
• Receptors, Somatostatin
• Yttrium Radioisotopes
• octreotide, DOTA-Tyr(3)-
• Octreotide

Topics

• Animals
• Dose-Response Relationship, Radiation
• Male
• Neoplasm Transplantation
• Octreotide (analogs & derivatives, therapeutic use)
• Pancreatic Neoplasms (mortality, radiotherapy)
• Radiopharmaceuticals (therapeutic use)
• Rats
• Rats, Inbred Lew
• Receptors, Somatostatin (radiation effects)
• Yttrium Radioisotopes (therapeutic use)