在過去的40年中,，輻射一直是治療致命的腦瘤即膠質(zhì)母細(xì)胞瘤最有效的方法,。但是,，雖然定位技術(shù)已得到改進(jìn),，輻射光束仍然必須通過健康的腦組織才能到達(dá)腫瘤部位,，患者在出現(xiàn)嚴(yán)重副作用之前只能容忍少量的輻射,。
近日，圣安東尼奧得克薩斯大學(xué)健康科學(xué)中心大學(xué)的研究人員開發(fā)出一種能將納米粒子輻射直接遞送到腦腫瘤部位,，并將其保持在腫瘤部位,。該方法使得腫瘤本身接受到高水平的輻射，其輻射劑量是目前癌癥患者放射治療劑量的20到30倍,，同時(shí)該技術(shù)并不會(huì)影響腦部其它大面積的健康組織,。
該研究最近發(fā)表在Neuro-Oncology雜志上，實(shí)驗(yàn)室研究獲得成功結(jié)果已經(jīng)足夠讓他們著手準(zhǔn)備開始在癌癥治療和研究中心開展一項(xiàng)臨床試驗(yàn),，該研究報(bào)告的通訊作者,、CTRC神經(jīng)腫瘤科專家Andrew Brenner醫(yī)學(xué)博士將會(huì)主持這項(xiàng)臨床試驗(yàn)。
Brenner博士說：我們發(fā)現(xiàn)可以在動(dòng)物模型中使用更高的輻射劑量,，動(dòng)物實(shí)驗(yàn)中這一劑量很安全,，同時(shí)能夠完全消除腫瘤。輻射由錸-186的同位素產(chǎn)生,，錸-186半衰期很短,。一旦放置在腫瘤內(nèi)，錸發(fā)出的輻射能延伸出幾毫米,。
但是簡(jiǎn)單地把錸放入腦瘤中,，由于微小顆粒（錸）將很快被血流清除，無法將錸保留在腦瘤組織內(nèi),，因而錸將無法發(fā)揮正常工作,。這個(gè)問題由解決核醫(yī)學(xué)醫(yī)師William T. Phillips醫(yī)師和放射科的生物化學(xué)家Beth A. Goins博士、醫(yī)療物理學(xué)家和耳鼻咽喉科的Ande Bao博士以及所有德克薩斯大學(xué)健康科學(xué)中心醫(yī)學(xué)部的醫(yī)藥化學(xué)家共同合作完成,。他們將錸封裝在微乎其微的脂肪分子或脂質(zhì)體中（約100納米寬）,。
Brenner博士說：“這項(xiàng)技術(shù)是獨(dú)一無二的，只有我們可以讓這些脂質(zhì)體擁有很高水平的放射性,。
醫(yī)生們希望夏季來臨的時(shí)候就能開展臨床試驗(yàn),。（生物谷：Bioon）
doi:10.1093/neuonc/nos060
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Rhenium-186 liposomes as convection-enhanced nanoparticle brachytherapy for treatment of glioblastoma.
Yasmin M Ramdzan, Saskia Polling, Cheryl P Z Chia, Ivan H W Ng, Angelique R Ormsby, Nathan P Croft, Anthony W Purcell, Marie A Bogoyevitch, Dominic C H Ng, Paul A Gleeson, Danny M Hatters.
Although external beam radiation is an essential component to the current standard treatment of primary brain tumors, its application is limited by toxicity at doses more than80 Gy. Recent studies have suggested that brachytherapy with liposomally encapsulated radionuclides may be of benefit, and we have reported methods to markedly increase the specific activity of rhenium-186 (186Re)–liposomes. To better characterize the potential delivery, toxicity, and efficacy of the highly specific activity of 186Re-liposomes, we evaluated their intracranial application by convection-enhanced delivery in an orthotopic U87 glioma rat model. After establishing an optimal volume of 25 μL, we observed focal activity confined to the site of injection over a 96-hour period. Doses of up to 1850 Gy were administered without overt clinical or microscopic evidence of toxicity. Animals treated with 186Re-liposomes had a median survival of 126 days (95% confidence interval [CI], 78.4–173 days), compared with 49 days (95% CI, 44–53 days) for controls. Log-rank analysis between these 2 groups was highly significant (P = .0013) and was even higher when 100 Gy was used as a cutoff (P < .0001). Noninvasive luciferase imaging as a surrogate for tumor volume showed a statistically significant separation in bioluminescence by 11 days after 100 Gy or less treatment between the experimental group and the control animals (χ2[1, N= 19] = 4.8; P = .029). MRI also supported this difference in tumor size. Duplication of tumor volume differences and survival benefit was possible in a more invasive U251 orthotopic model, with clear separation in bioluminescence at 6 days after treatment (χ2[1, N= 9] = 4.7; P = .029); median survival in treated animals was not reached at 120 days because lack of mortality, and log-rank analysis of survival was highly significant (P = .0057). Analysis of tumors by histology revealed minimal areas of necrosis and gliosis. These results support the potential efficacy of the highly specific activity of brachytherapy by 186Re-liposomes convection-enhanced delivery in glioma.
