Interstitial wires releasing diffusing alpha emitters combined with chemotherapy improved local tumor control and survival in squamous cell carcinoma-bearing mice

The objective of this study was to examine the combined effect of diffusing alpha-emitter radiation therapy (DART) together with the chemotherapeutic agent cisplatin on tumor development.

BALB/c mice bearing squamous cell carcinoma tumors were treated with radium 224 ((224)Ra-)-loaded stainless steel wires, releasing short-lived, alpha-emitting atoms from their surface. A concomitant regimen of cisplatin doses (5 mg/kg per dose) was given intravenously for the evaluation of the combined effect. Animals were monitored for tumor growth and survival.

First, the authors observed that alpha particles and cisplatin inhibited SQ2 cell proliferation in vitro and promoted apoptosis. Treatment of tumor-bearing mice indicated that, when a regimen of 2 separate doses of cisplatin was given concomitantly with a single intratumoral (224)Ra-loaded wire, there was moderate tumor growth inhibition relative to what was observed from each treatment alone. When tumors were treated with 2 radioactive wires positioned near the tumor base and a similar drug administration, the growth arrest effect intensified, and there also was a significant increase in survival rates. The combined treatment reduced both local tumor growth and metastatic spread to the lungs.

Antitumor activity and overall survival of metastatic tumor-bearing mice were improved significantly by the combined treatment. These results highlight the potential benefit of alpha radiation-based radiotherapy in combination with chemotherapeutic drugs for anticancer treatment.