一项针对超过400名患有新血管性年龄相关性黄斑变性（AMD）患者的英国临床试验表明，单次放射治疗可以减少治疗该疾病所需的多次眼部注射次数。AMD影响着全球8%的成年人，是发达国家60岁以上人群中心性失明的主要原因。新血管性（或湿性）AMD是该疾病最晚期、最具侵袭性的形式，会导致新的血管长入黄斑，即眼睛后部感光细胞层。这些异常血管的血液和液体渗漏会导致视力快速、永久且严重丧失。该病症通常用眼内注射药物治疗，大多数患者需要每1-3个月注射一次才能有效控制病情。这些药物抑制血管内皮生长因子（VEGF），VEGF是血管渗漏和增生的关键驱动因素。研究人员在《柳叶刀》杂志上发表了他们的研究结果，他们建议SRT可以消除全球所有高收入国家每年180万次抗VEGF注射。

🚀 **单次放射治疗可减少眼部注射次数** 这项英国临床试验表明，单次放射治疗可以减少治疗新血管性年龄相关性黄斑变性（AMD）所需的多次眼部注射次数。AMD是发达国家60岁以上人群中心性失明的主要原因，新血管性（或湿性）AMD会导致新的血管长入黄斑，造成视力快速、永久且严重丧失。 传统的治疗方法是使用抗VEGF药物进行眼内注射，大多数患者需要每1-3个月注射一次才能有效控制病情。而这项研究表明，单次放射治疗可以有效减少眼部注射次数，减轻患者的治疗负担。

🤖 **机器人控制的立体定向放射治疗（SRT）系统** 该研究采用了一种机器人控制的SRT系统，该系统可以精确地将三束高度准直的5.33 Gy辐射束照射到目标区域，避免照射到晶状体，并确保辐射束在黄斑处重叠。为了稳定被治疗的眼睛，一个吸附式接触镜固定在角膜上，并连接到一个带有红外反射器的定位万向节。SRT设备跟踪反射器，如果眼睛移出位置，就会停止治疗。

📊 **研究结果表明SRT有效且安全** 研究人员将274名患者随机分配到接受16 Gy SRT治疗组，137名患者分配到接受相同安慰剂治疗组（不进行放射治疗）。所有患者在接受放射治疗后，都接受了标准剂量的抗VEGF药物雷珠单抗眼内注射。 研究结果表明，接受SRT治疗的患者在96周后平均需要注射10.7次，而传统药物治疗组平均需要注射13.3次。此外，两组患者的视力结果相当，并且在系统安全性方面也无显著差异。

👀 **未来展望：SRT有望成为AMD治疗的新选择** 该研究结果支持了类似的II期临床试验INTREPID的结果，INTREPID研究表明，通过SRT进行的16 Gy或24 Gy单次放射治疗，在随后的12个月内减少了29%的注射次数。 研究人员正在分析患者三年和四年随访检查的数据，这些数据表明随着时间的推移，注射频率的减少将带来更大的益处。然而，研究人员也指出，随着新型玻璃体内药物（如法利西单抗）或现有抗VEGF药物更高剂量的出现，SRT的益处可能会受到影响。

💡 **SRT的应用前景广阔，但仍需进一步研究** 尽管SRT在减少眼部注射次数方面显示出潜力，但目前仍需要更多研究来确认其长期效果和安全性。如果未来的研究能够证明SRT在减少抗VEGF注射次数、保持视力结果和安全性方面具有优势，那么SRT有望成为AMD治疗的新选择，为患者带来福音。

A single dose of radiation can reduce the number of eye injections needed to treat patients with neovascular age-related macular degeneration (AMD). That’s the conclusion of a UK-based clinical trial of more than 400 patients with the debilitating eye disease.

AMD affects 8% of adults globally, and is a leading cause of central blindness in people over 60 in developed nations. Neovascular (or wet) AMD, the most advanced and aggressive form of the disease, causes new blood vessels to grow into the macula, the light-sensing layer of cells inside the back of the eye. Leakage of blood and fluid from these abnormal vessels can lead to a rapid, permanent and severe loss of sight.

The condition is treated with injections of drugs into the eye, with most people requiring an injection every 1–3 months to effectively control the disease. The drugs inhibit vascular endothelial growth factor (VEGF), a key driver of vascular leakage and proliferation. Reporting their findings in The Lancet, the investigators suggest that SRT could eliminate 1.8 million anti-VEGF injections per year globally across all high-income countries.

STAR treatment

The STAR (stereotactic radiotherapy for wet AMD) study, led by Timothy Jackson of King’s College London, is a double-blinded trial that enrolled patients with previously treated chronic active neovascular AMD from 30 hospitals in the UK. All participants received the robotic treatment, with or without delivery of 16 Gy of radiation, at one of three UK treatment centres.

The team used a robotically controlled SRT system that delivers three highly collimated 5.33 Gy radiation beams, targeted to avoid lens irradiation and overlapping at the macula. To stabilize the eye being treated, a suction-coupled contact lens was secured to the cornea and connected to a positioning gimble with infrared reflectors. The SRT device tracked the reflectors, stopping the treatment if the eye moved out of position.

The researchers randomly allocated 274 patients to receive the 16 Gy SRT treatment and 137 to receive identical sham treatment without radiation. Immediately afterwards, all patients received a standard dose of the anti-VEGF drug ranibizumab injected into the eye.

After radiotherapy, participants visited their recruiting hospital for follow-up exams every four weeks up to the 96-week primary endpoint. During these review sessions, patients received an intraocular injection of ranibizumab each time they needed retreatment. The researchers are continuing assessments at three and four years to determine the safety and long-term efficacy of this approach.

The final study analysis included 241 participants in the 16 Gy SRT group and 118 participants in the sham group, with total of 409 patients treated and forming the safety population. The findings are encouraging: patients who received SRT required a mean of 10.7 injections after 96 weeks, compared with 13.3 injections for the conventional drug-only group.

Reducing the burden of anti-VEGF treatment would be highly beneficial for both patients and hospitals. Preliminary analyses suggest that the cost of the SRT treatment may be more than offset by the reduction in injections. The authors plan to prepare a detailed cost evaluation.

Vision outcome for both cohorts was comparable. While the sham group had slightly less worsening of best corrected visual acuity at two years, there was no statistical difference between the two. The systemic safety was also similar in the two groups, with similar rates of adverse events. Evaluation using multimodal imaging determined that 35% of the SRT-treated participants and 12% of the sham group had retinal microvascular abnormalities.

The study outcome supports the findings of a similar phase II clinical trial, INTREPID, whose results were published in 2020. The INTREPID study of 230 randomized patients showed that a single radiation dose of 16 or 24 Gy administered by SRT reduced injections by 29% for the ensuing 12 months, compared with the control group.

Jackson tells Physics World that the researchers are currently analysing data from patients reporting for their three- and four-year anniversary examinations. The data suggest increasing benefit with respect to injection frequency over time. The investigators also note that the benefits of SRT may be eroded by the introduction of newer intravitreal drugs such as faricimab, or higher doses of existing anti-VEGF drugs, which have longer dosing intervals than ranibizumab.

Writing in an accompany commentary in The Lancet, Gui-shuang Ying and Brian VanderBeek of the University of Pennsylvania Perelman School of Medicine state: “The STAR study has indicated a potential alternative treatment paradigm that appears to significantly reduce treatment burden without impacting visual acuity outcomes over two years, but additional gaps in knowledge need to be addressed before the widespread adoption of this therapy.”

They add: “If the reduction in anti-VEGF injection rate, non-inferior visual acuity results and acceptable safe profile of SRT remain through future studies, the STAR study will be a foundational piece in advancing a promising adjunctive therapy forward. Patients eagerly await the day when the injection burden is reduced, and SRT might well be a path to getting there.”

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