2015年3月23日讯 /生物谷BIOON/ --Sirtex Medical公司最近遗憾的宣布其开发的新型微球载药系统在关于输送化疗药物治疗转移性结肠癌的临床研究中未能达到首要预期终点。消息一经公布，公司股价应声下跌仅60%。
根据公司方面透露的数据显示，公司希望利用其开发的SIR-Spheres载药系统输送一线化疗用药用于治疗转移性结肠癌，然而在这项有500名志愿者参加的临床研究中，载药系统组在无进展生存期这一关键指标上并未与对照组有显著性差别。所谓无进展生存期即患者接受治疗后病情没有恶化或者死亡发生所持续的时间，这也是目前癌症药物临床研究的黄金标准之一。此前，公司曾预计，一旦该载药系统能够与一线化疗用药联用，SIR-Spheres载药系统的市场规模将激增至现在的五倍。然而，现在看来公司对其寄予的厚望已成泡影。
不过，此次研究并非一无是处，公司表示SIR-Spheres载药系统治疗组在癌细胞肝转移方面达到了研究人员预计的第二预期终点。数据显示，患有转移性结肠癌的患者有90%死于肝功能衰竭，这也可能成为挽救SIR-Spheres载药系统的最后一根稻草。
此次研究中，研究人员选择使用SIR-Spheres载药系统包载钇-90经腿部动脉将药物输送至肝动脉部分，由于肿瘤部位血管孔径约为32微米，载药颗粒将可以富集在肿瘤区域，从而保证钇-90药物产生的β射线能够集中于肿瘤部位，在增强药效的同时保护其他健康组织不受影响。
Sirtex Medical公司表示将于晚些时候公布此次临床研究的全部数据。
详细英文报道：
Sirtex Medical's clinical trial of its microspheres for targeted delivery of radioactive particles did not live up to expectations. Investors dumped the Australian company's stock in a hurry beginning March 13. It began the following week at $15, or a stunning 60% lower than before the bad news was delivered.
The results of the trial show that adding the company's resin SIR-Spheres to first-line chemotherapy for metastatic colon cancer does not improve progression-free survival, or the amount of time following treatment until the disease worsens or the patient dies of any cause.
"The treatment right now is relegated more to a salvage setting," Sydney-based healthcare analyst Derek Jellinek told Bloomberg. Using the therapy as a first-line treatment alongside chemotherapy would quintuple its market potential, he added.
The SIR-Spheres are used to transport the radioactive element yttrium-90, which delivers beta radiation over a short distance (2.5 millimeters) at the site of liver tumors.
The SIR-Spheres are inserted into the liver's hepatic artery using a microcatheterthat travels through the leg's arteries. The spheres reach the liver tumor through the tumor's arterial blood supply. They then become implanted in the tumor because, at a median diameter of 32 microns, they are too large to pass through small blood vessels within the tumor, Sirtex says in a video on its website.
Then, the radiation begins. More than 90% of the radiation is delivered within the first 11 days. More than 10 million microspheres are deployed in each dose, and the targeted delivery minimizes damage to healthy liver tissue, Sirtex says.
Sirtex shares recovered slightly after the initial onslaught of selling. That's because the trial met a secondary endpoint related to efficacy against live tumors. That's significant because up to 90% of metastatic colon cancer patients die of liver failure, the company says. But the share price is still barely half of what it was before the bad news broke.
Full results of the trial of more than 500 people with metastatic colon cancer that had spread to the liver will be revealed at the American Society of Clinical Oncology meeting to be held May 29 to June 2.
Sirtex has annual revenues of close to $200 million thanks to the SIR-Sphere. Revenues would expand greatly if the therapy wasn't limited to use as a last resort.