Local control of lung derived tumors by diffusing alpha-emitting atoms released from intratumoral wires loaded with radium-224.
OBJECTIVE
Diffusing alpha-emitters radiation therapy (DART) is a new form of brachytherapy enabling the treatment of solid tumors with alpha radiation. The present study examines the antitumoral effects resulting from the release of alpha emitting radioisotopes into solid lung carcinoma (LL2, A427, and NCI-H520).


METHODS
An in vitro setup tested the dose-dependent killing of tumor cells exposed to alpha particles. In in vivo studies, radioactive wires (0.3 mm diameter, 5 mm long) with (224)Ra activities in the range of 21-38 kBq were inserted into LL/2 tumors in C57BL/6 mice and into human-derived A427 or NCI-H520 tumors in athymic mice. The efficacy of the short-lived daughters of (224)Ra to produce tumor growth retardation and prolong life was assessed, and the spread of radioisotopes inside tumors was measured using autoradiography.


RESULTS
The insertion of a single DART wire into the center of 6- to 7-mm tumors had a pronounced retardation effect on tumor growth, leading to a significant inhibition of 49% (LL2) and 93% (A427) in tumor development and prolongations of 48% (LL2) in life expectancy. In the human model, more than 80% of the treated tumors disappeared or shrunk. Autoradiographic analysis of the treated sectioned tissue revealed the intratumoral distribution of the radioisotopes, and histological analysis showed corresponding areas of necrosis. In vitro experiments demonstrated a dose-dependent killing of tumors cells exposed to alpha particles.


CONCLUSIONS
Short-lived diffusing alpha-emitters produced tumor growth retardation and increased survival in mice bearing lung tumor implants. These results justify further investigations with improved dose distributions.
Cooks
Tomer
T
Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Schmidt
Michael
M
Bittan
Hadas
H
Lazarov
Elinor
E
Arazi
Lior
L
Kelson
Itzhak
I
Keisari
Yona
Y
D000512:Alpha Particles / Q000627:therapeutic use*; D000818:Animals; D001345:Autoradiography; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007856:Lead Radioisotopes / Q000493:pharmacokinetics; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011883:Radium / Q000493:pharmacokinetics / Q000627:therapeutic use*; D013910:Thorium
D007856:Lead Radioisotopes; C026062:thorium X; D013910:Thorium; D011883:Radium