抗癌嗽口水可防口内溃疡癌变

    最近芝加哥大学的研究人员在美国临床肿瘤学会议上宣布，由Onyx和辉瑞制药公司共同研制的嗽口水ONYX-015具有预防口腔内溃疡部位癌变的功能。

    ONYX-015含有一种被基因改造了的病毒，可以在癌细胞内大量复制并杀死癌细胞。正常细胞与癌细胞的一个区别就是后者的p53肿瘤抑制基因失活了，p53是人体自身所特有的、重要的肿瘤抑制基因，能够控制细胞过度增殖从而起到防癌目的，一旦该基因发生细微的改变或突变，就有可能丧失抑制肿瘤发生的功能。

    口腔癌发病前先表现为发育异常性损伤。嗜烟者，喜欢嚼咀烟草和酗酒的人都是口腔溃疡和口腔癌症的高危人群，嗽口水可以直接与细胞接触以阻止癌症的发生。一项由Onyx资助的试验让10位做过组织活体切片的病人每周使用一次ONYX-015嗽口水，共使用12周。结果显示其中有三位病人病情有所好转，另外一位在继续再接受了12周的进一步治疗后也表现出好转的迹象。在整个治疗期间没有发现ONYX-015有明显的临床毒性。

    该产品现正进行针对头颈部癌症的第三阶段临床试验及针对许多其他的不同的癌症迹象的第一、二阶段床试验。共有三百多位患者接受了测试，他们的适应性都很好，虽然会有体温升高及打寒颤的副作用，但这些情况都比较好处理的。

    据该试验的执行总裁说，在对晚期头颈部癌症患者进行的ONYX-015的二期临床试验结果表明，有10%的患者的肿瘤消失了，24%的患者的肿瘤至少缩小了一半。如果结合化学疗法，这种药的疗效会更好。

    Anti-Cancer Mouthwash Effective in Early Trial
    SAN FRANCISCO (Reuters) - A genetically engineered mouthwash is effective in keeping mouth sores from becoming cancerous, researchers said here on Tuesday.

    The mouthwash is a formulation of ONYX-015, a virus that has been engineered to replicate in and kill cancer cells that have a dysfunctional p53 tumor-suppressor gene-- while sparing normal cells that have a functioning p53 gene.

    ONYX-015 is being jointly developed by Onyx and Pfizer Inc.
    Researchers from the University of Chicago reported the results from a small trial of 10 patients here at a meeting of the American Society of Clinical Oncology (news - web sites).

    Since oral cancer is frequently preceded by growths called dysplastic lesions, the idea was to find out if a novel gene therapy for killing cancer cells would work as a mouthwash --which comes into direct contact with the cells--to prevent the development of cancer.

    Heavy smokers, tobacco chewers and drinkers are at highest risk for developing the lesions and cancer of the mouth.

    The p53 gene is considered one of the body‘s most important naturally occurring tumor-suppressor genes. These genes are believed to help control runaway growth of cells and thereby prevent cancer. But when slight changes, or mutations, to the p53 gene occur, it is believed to lose its tumor-preventing effectiveness.

    The data presented on Tuesday were from 10 patients who were given ONYX-015 as a mouthwash once a week for 12 weeks after which tissues were biopsied and patients who showed improvement continued the therapy for another 12 weeks.

    So far, two of the patients in the trial have seen their mouth patches disappear.

    Improvements in the severity of the patches was shown in four patients, three had progression of disease despite therapy, and one had initial improvement followed by progression, according to the study.

    No significant clinical toxicity has so far been observed in the trial, which was funded by Onyx.

    ``We have been able to develop viruses that target the mutations that cause most cancers,‘‘ Hollings Renton, Onyx‘s chief executive, told Reuters.

    The product is currently in a Phase III clinical trial for head and neck cancer and in Phase I and II clinical trials for a number of different additional cancer indications.

    ``It has been tested in over 300 patients altogether. It is well-tolerated. Elevated temperature and chills are the side effects and they are manageable,‘‘ Renton said.

    In previously reported results from a Phase II trial of ONYX-015 in patients with advanced head and neck cancer, 10% saw their tumors disappear and 24% saw their tumors shrink by at least 50%, the CEO said.

    But even better results were found when the drug was combined with chemotherapy, he noted.