抗乳腺癌药物曲妥珠单抗诞生记
在曲妥珠单抗的诞生过程中，非基因泰克员工的肿瘤学家丹尼斯·斯拉蒙（Dennis Slamon）作出了巨大贡献，而基因泰克却差点扼杀了曲妥珠单抗……
一、被遗忘的neu基因
1982年，麻省理工学院温伯格实验室的帕代，从老鼠被称为神经母细胞瘤的肿瘤中分离出一种致癌基因，温伯格根据拥有这种基因的癌症类型，把它命名为neu基因（即日后著名的HER2）。neu基因是一个异类，大多致癌基因如ras和myc，都被隔离在细胞内，而neu基因编码的蛋白质却挂载细胞膜上，很大一段留在细胞外，任何药物都可以轻易地与之接触。neu是一个绝佳的目标，帕代同时也开发了对抗neu蛋白的抗体，只需要花不超过一个下午的时间，把neu抗体添加到神经母细胞瘤的细胞中，就可以确定结合的效果，但是他们从来没有做这样的实验。温伯格和帕代始终执迷于癌细胞的基本生物学，他们根本忘了neu实验。温伯格后来回忆道，当时真应该抽自己，如果更用功一些，不那么偏执就好了。
二、HER2基因的发现与基因泰克的茫然
1984年夏天，任职于基因泰克的德国科学家乌尔里希（Ullrich）发现了neu基因的人类同源基因，并注意到它与另一个生长调节基因相似（先前发现的人类表皮生长因子受体基因HER），于是把新发现的基因称为HER2。基因泰克善于利用细胞制造某种蛋白质或信号缺失或者水平过低的药物，如胰岛素，凝血因子，生长激素，而癌基因恰恰相反，它不是信息丢失，而是信息过剩，当时基因泰克尚未学会如何在人体细胞内灭活极度活跃的蛋白质。所以即使有了乌尔里希的HER2，但基因泰克却不知道要用它做什么，怎么做。
3、乌尔里希与斯拉蒙强强联手
1986年夏天，加利福尼亚大学洛杉矶分校的一场研讨会上，乌尔里希代表基因泰克讲述了分离HER2的故事，但听众还是希望制药公司能进一步研发出药物来。加利福尼亚大学洛杉矶分校的肿瘤学家丹尼斯·斯拉蒙（Dennis Slamon）一直在研究导致人类白血病的HTLV-1病毒，他深知杀灭病毒并不会治愈癌症，而杀死致癌基因或是解决问题的办法。斯拉蒙听了HER2的故事后，与乌尔里希达成协议：乌尔里希送给斯拉蒙基因泰克HER2的DNA探针，斯拉蒙测试自己样品的HER2活跃性，从而可以在致癌基因和人类癌症之间的鸿沟上架起桥梁。数月后，斯拉蒙在乳腺癌样本中发现了HER2的高度扩增，但并非所有的乳腺癌都如此。基于乳腺癌染色的模式，可以把乳腺癌清楚地分为HER2扩增标本和HER2无扩增的标本，即HER2阳性和HER2阴性。斯拉蒙对这种“开关”模式困惑不已，在研究了HER2阳性肿瘤和HER2阴性肿瘤的生物行为表现是否不同后，又探索到了一个异常的模式：发生乌尔里希基因扩增的乳腺肿瘤往往是更凶猛、更易转移、更容易致死的，HER2扩增标记的肿瘤预后最差。斯拉蒙的研究结果促使乌尔里希想知道如果能以某种方式关闭HER2的活性会发生什么？使用抗HER2药物中断信号，是否能组织癌细胞的生长？乌尔里希正在小心翼翼地靠近温伯格和帕代忘了执行的那个午后的实验。乌尔里希开始寻找能关闭HER2的药物，他想象中这种药物是一种特定的抗体蛋白质，于是乌尔里希走进了基因泰克的免疫部门……
4、第一次动物试验
就在乌尔里希在基因泰克免疫部门寻找药物的同时，斯拉蒙进行了另一个HER2表达癌症的重要实验，他把这些癌细胞植入小鼠，在小鼠体内，它们爆发形成了转移性肿瘤，重现了入侵性的人类癌症。1988年，基因泰克免疫部门成功生产了一种能结合和灭活HER2的鼠抗体。乌尔里希从第一批抗体中挑了几瓶送给斯拉蒙，斯拉蒙用这种抗体治疗培养皿中HER2过度表达的乳腺癌细胞，结果细胞停止生长，并且消退、死亡。更令人印象深刻的是，当他把HER2抗体注射给体内有肿瘤的活小鼠时，肿瘤也消失了。这是斯拉蒙和乌尔里希所期望的最完美的结果。抑制HER2在动物模型中奏效了。
5、基因泰克差点毁了曲妥珠单抗
斯拉蒙和乌尔里希此时已明确癌症靶向治疗的3个基本要素：致癌基因、专门启动该致癌基因的癌症和专门针对它的药物。两人都期望基因泰克能把握这次飞跃的机会，生产出新的蛋白质药物，清除致癌基因过度活跃的信号。然而乌尔里希却发现，基因泰克正在失去对治疗癌症的兴趣。当时，很多制药公司在试图利用关于癌细胞的生长机制的有限知识去开发药物，然而，这些药物不加区分地同时毒害癌细胞和正常细胞，不出所料，所有的药物都在临床试验中遭到了惨败。乌尔里希和斯拉蒙则致力于研究致癌基因和致癌基因的靶向抗体，这种研究更为复杂和具体，基因泰克担心这种资金投入若失败则将耗尽公司的财力，吸取了其他公司的前车之鉴，于是基因泰克撤回了大部分的癌症经费。
这个决定在公司内部造成了很大分歧。有一小部分的骨干科学家热忱地支持这个癌症项目，但是，基因泰克的高层希望集中精力发展比较简单的、更能够盈利的药物。HER2腹背受敌。乌尔里希心力交瘁之余离开了基因泰克。
而在加利福尼亚大学洛杉矶分校，斯拉蒙陷入了孤军奋战的境地。他虽然不是基因泰克公司的员工，却是最殚精竭虑地要支持HER2的研究。斯拉蒙在基因泰克公司饱受白眼，但他一意孤行、死缠烂打，经常从洛杉矶坐飞机过来，蹲守在走廊里试图寻找任何对他的鼠抗体感兴趣的人，但大多数基因泰克的科学家已经失去了兴趣。
但也不乏一小群科学家对他抱有信心，麻省理工学院毕业的遗传学家大卫·博茨泰因和分子生物学家亚特·莱文森，即为HER2项目强有力的支持者。斯拉蒙和莱文森使尽浑身解数，动用各种资源和关系终于说服了公司组建一个小的创业团队，推动HER2项目的进展。
6、人源化曲妥珠单抗的诞生
HER2项目的经费很少，只能一点一点地推进，几乎不为基因泰克高管所知。1989年，基因泰克的免疫学家迈克·谢泼德改进了HER2抗体的生产和纯化。但斯拉蒙知道，纯化的鼠抗体会在人体内引发强大的免疫反应，鼠抗体离人用的药物还差着很远。基因泰克的成员“人源化大师”保罗·卡特，是一个安静的29岁英国人，曾投师剑桥大学最先融合免疫细胞和癌细胞制成单抗的科学家塞萨尔·米尔斯坦，学到了这门人源化技术。在斯拉蒙和谢泼德的指导下，卡特开始研究鼠抗体人源化。1990年夏天，卡特取得了骄人的成绩，他做成了一个完全人源化的HER2抗体，随时可以用于临床试验。这个抗体已经是一个潜在的药物，团队成员决定为这个抗体起一个名字，为了体现这一药物的本质，其名字融合了HER2、拦截（intercept）和抑制剂（inhibitor）这3个英文单词，即赫赛汀（Herceptin）。
虽然历经艰辛，人源化曲妥珠单抗终于问世，然而杯具的是，基因泰克对于这一项目的积极性依然提不起来，甚至停止了经费赞助。
7、第一次临床试验
斯拉蒙的想法与基因泰克则完全不一样，无论有多少困难，他都想把临床试验推进下去。最后斯拉蒙得到了慈善家丽莉·塔蒂科夫（Lilly Tartikoff）和罗纳德·佩雷尔曼（Ronald Perelman）的资助，他开始寻找能够参加临床试验的患者。有位叫芭芭拉·布拉德菲尔德的乳腺癌患者，经样本分析后发现，她的肿瘤全是由HER2表达带来的。最后包括芭芭拉·布拉德菲尔德在内共37人参加了斯拉蒙的临床试验，其中还有一位50多岁坚信中草药疗效的中国妇女。除了芭芭拉·布拉德菲尔德以外，很多患者的效果并不理想，有的肿瘤大小保持不变，有的则只是骨痛减轻。试验协调员建议剔除一些不能量化的患者，最后只剩下6个人能继续完成6个月的试验。从临床试验的角度看，几乎已经失败了，主要终点没有达到，患者脱离太多。斯拉蒙似乎已经需要面对一个尴尬的现实，他一意孤行的临床试验并不成功，是否需要再继续下去，也许他当初想的都不能实现。
8、纳尔逊之死
虽然临床实验不顺利，但是，芭芭拉·布拉德菲尔德的治疗效果却非常好。截至1993年夏天，这一消息不胫而走，在乳腺癌患者群中快速扩散。乳腺癌患者支持团体掀起了一阵对曲妥珠单抗的狂热炒作和希望。乳腺癌活动家去敲基因泰克的大门，要求“特许使用治疗（compassionate use）”，敦促基因泰克发放试验阶段的药物给“无其他疗法可救的HER2阳性妇女”。但是，曲妥珠单抗尚未被批准，基因泰克不想冒险把未经批准的药物提供给患者。一位名叫纳尔逊的妇科医生发现自己是乳腺癌后，也申请“特许使用治疗”，但基因泰克坚持认为，只要没有确定她有HER2，就不能让她获得曲妥珠单抗。纳尔逊在乳腺癌纺织协会的帮助下，在一年之后终于测试其肿瘤是HER2阳性，然而消息来得太晚，纳尔逊尚未用到曲妥珠单抗就已经告别人世。
纳尔逊之死成为分水岭事件。一群义愤填膺的来自乳腺癌防治协会的妇女在1994年12月5日不顾一切地闯入基因泰克园区，为这位患者举行15辆车组成的“送葬”游行，车上载有她去世前戴着化疗头巾的画像。这是基因泰克成立以来最大的一场公关灾难。
9、“648”临床试验
纳尔逊事件后，1995年，基因泰克公司的科学家和高管组成的小型代表团前往华盛顿，会见全国乳腺癌联盟（NBCC）的主席弗朗西斯·维斯科。全国乳腺癌联盟是由强大的抗乳腺癌活动家组成的协会，基因泰克公司希望该联盟作为中间人牵线搭桥，协调他们和旧金山抗乳腺癌活动家的关系。维斯科向基因泰克提出了一项建议，基因泰克必须提供一个曲妥珠单抗的扩大施药方案，该方案将允许肿瘤学家对临床试验之外的患者实施治疗。而全国乳腺癌联盟将充当中间人，联系基因泰克和的癌症患者。维斯科愿意加入曲妥珠单抗的Ⅲ期临床试验的规划委员会，并利用全国乳腺癌联盟的网络，广泛招募接受试验的患者。
1995年，基因泰克公司在这股它曾经长期抵制的力量的推动下，发起了3个独立的Ⅲ期临床试验测试曲妥珠单抗的效果。这3个试验中最关键的一个，是标为“648”的试验，它对新诊出罹患转移性乳腺癌的妇女进行了随机的分配——只进行标准化疗与化疗结合曲妥珠单抗治疗的对照试验。648试验在世界各地的150家乳腺癌诊室展开，试验将招收469名妇女，基因泰克为试验投入了1500万美元。
10、曲妥珠单抗蹒跚上市
1998年5月，美国临床肿瘤学会（ASCO）的第34次会议上，基因泰克公司公布648试验的数据。斯拉蒙被提名为压轴的发言者来介绍临床的进展。在关键的648研究中，曲妥珠单抗令一半妇女的肿瘤缩小了，而在对照组，只有1/3的妇女肿瘤缩小。乳腺癌的病程进展被延迟了4到7.5个月。在那些对标准的多柔比星和环磷酰胺方案发生严重耐药性的肿瘤患者身上，治疗效果最为显著：曲妥珠单抗和紫杉醇联合反应率增加了近50%，这在最近的临床经验中是闻所未闻的。生存率也随之水涨船高。接受曲妥珠单抗治疗的女性比对照组平均多活了4到5个月。虽然只延长了4个月的生命，但参加试验的都是中晚期、转移性癌症患者。
1998年9月，美国FDA批准了曲妥珠单抗上市。
为了纪念斯拉蒙做出的贡献，2008年，一部名为《生存证明》（Living Proof）的电影在美国上映。影片讲述了在1988年至1996年的8年时间中，斯拉蒙开发曲妥珠单抗的故事。
本文改编于印度裔美国医生、哥伦比亚大学医学院副教授、科学家、作家、2011年普利策奖获得者辛达塔·穆克吉（Siddhartha Mukherjee）《众病之王：癌症传》（The Emperor of All Maladies: A Biography of Cancer）第六部分：长期努力的硕果。
Herceptin (Trastuzumab) Development Timeline
1975: Georges Köhler and César Milstein, scientists at the Medical Research Council, Laboratory of Molecular Biology (Cambridge, UK), discovered the potential of using antibodies in vitro to fight disease.
1976: The research of Michael Bishop and Harold Varmus at the University of California San Francisco showed that disturbances in one or more members of a family of genes can lead to the transformation of a normal cell into a cancer cell.
1976: Genentech was founded by venture capitalist Robert A. Swanson and biochemist Dr. Herbert W. Boyer.
1981: Genentech scientists John McGrath and Art Levinson cloned and sequenced a portion of the human HER2 gene for the first time.
1984: Robert Weinberg and his team of scientists at the Massachusetts Institute of Technology discovered an unusual mutant rat gene encoding a tyrosine kinase that produced cancer features in transfected cells and named it "neu."
1984: Georges Köhler and César Milstein win the Nobel Prize in Medicine, "for theories concerning the specificity in development and control of the immune system and the discovery of the principle for production of monoclonal antibodies."
1984: Genentech scientists Axel Ullrich and Peter Seeberg, in collaboration with Mike Waterfield at the Imperial Cancer Research Fund and Joseph Schlesinger at the Weizmann Institute, published the complete human EGF-R sequence in Nature.
1985: Following work that began in the early 1980s, a Genentech team of scientists, including Axel Ullrich and Art Levinson, clone the first full-length human HER2 gene. This achievement is described in a paper published in Science.
1985: Stu Aaronson at the National Institute of Health showed that the HER2/neu gene is frequently amplified in human breast tumors.
1987: Michael Shepard, Axel Ullrich and their teams at Genentech developed mouse 4D5, the parent of Herceptin, simultaneous with the discovery by Dr. Dennis Slamon at UCLA, and colleagues at the University of Texas Health Science Center, that linked HER2 over-expression with a more aggressive type of breast cancer found in approximately 25 percent of patients. Further work by Shepard's group demonstrated that the 4D5 could suppress the growth of HER-over-expressing tumor cells, and also enhance their sensitivity to killing by the host immune system. Further proof of concept was the demonstration by the Genentech and UCLA teams that radio-labeled 4D5 could localize to HER2-overexpressing tumors in patients.
1989: Michael Bishop and Harold Varmus were awarded the Nobel Prize in Medicine for their discovery that normal cells contain genes capable of becoming cancer genes.
1990: Len Presta, Paul Carter and Michael Shepard of Genentech create Herceptin by humanizing the 4D5 mouse antibody directed at HER2.
1992: Genentech filed an Investigational New Drug Application (IND) with the U.S. Food and Drug Administration (FDA) and Phase I clinical trials were initiated.
1993: Genentech initiated two Phase II clinical trials that evaluated the investigational anti-HER2 antibody as a single agent and in combination with chemotherapy in the relapsed setting.
1995: Genentech began enrollment of the Phase III pivotal trials for patients with HER2 over-expressing metastatic breast cancer.
1996: Critical efforts are undertaken to enroll patients into the trials, including:
March 1996: Researchers at Memorial Sloan Kettering co-authored a paper titled, "Phase II study of weekly intravenous recombinant humanized anti-p185HER2 monoclonal antibody in patients with HER2-neu-overexpressing metastatic breast cancer," which showed that the antibody was clinically active in women with HER2-neu-overexpressing metastatic breast cancer who had received prior therapy. The study provided evidence that targeting growth factor receptors caused regression of human cancer.
December 1996: Genentech initiated a partnership with diagnostics company DAKO to develop a commercial test to identify patients who overexpress the HER2 gene.
March 1997: Genentech completed enrollment of the Phase III pivotal trials for the anti-HER2 antibody (now known as Herceptin (Trastuzumab)).
May 1998: Genentech submitted a biologic license application (BLA) for Herceptin, and DAKO submitted a pre-market approval (PMA) application to the FDA for approval of the diagnostic HercepTest. The FDA designated Herceptin as a "Fast Track" product for the treatment of metastatic breast cancer. Herceptin treatment can result in heart problems, including those without symptoms (reduced heart function) and those with symptoms (congestive heart failure).
May 1998: Results from a Phase III investigational clinical trial of Herceptin were presented at the American Society of Clinical Oncology (ASCO) annual meeting. Results showed that Herceptin, in combination with chemotherapy, increased time to disease progression and response rates. Herceptin treatment can result in heart problems, including those without symptoms (reduced heart function) and those with symptoms (congestive heart failure).
July 1998: Genentech and Roche signed a licensing agreement giving Roche exclusive marketing rights for Herceptin outside of the United States.
September 1998: Herceptin received FDA approval for use in women with metastatic breast cancer who have tumors that overexpress the HER2 protein. It is indicated for treatment of patients both as first-line therapy in combination with paclitaxel chemotherapy and as a single agent for those who have received one or more chemotherapy regimens. Dako's HercepTest is approved simultaneously to aid in the identification of patients for Herceptin treatment. Herceptin was the first therapeutic antibody targeted to a specific (HER2) cancer-related molecular marker to receive FDA approval. Herceptin treatment can result in heart problems, including those without symptoms (reduced heart function) and those with symptoms (congestive heart failure). The risk and seriousness of these heart problems were highest in people who received both Herceptin and a certain type of chemotherapy (anthracycline). Some patients have had serious infusion reactions and lung problems; fatal infusion reactions have been reported. In most cases, these reactions occurred during or within 24 hours of receiving Herceptin.
May 2000: Genentech issued a letter to healthcare providers about reports of serious adverse events, including hypersensitivity, infusion and pulmonary reactions. Some patients have had serious infusion reactions and lung problems; fatal infusion reactions have been reported. In most cases, these reactions occurred during or within 24 hours of receiving Herceptin.
August 2000: European Commission approved Herceptin for the treatment of HER2-positive metastatic breast cancer.
December 2000: Enrollment of two Phase III clinical trials evaluating the potential use of Herceptin for the adjuvant treatment of early-stage HER2-positive breast cancer was initiated. Adjuvant therapy is given to women with early-stage (localized) breast cancer who have had initial treatment — surgery with or without radiation therapy — with the goal of reducing the risk of cancer recurrence and/or the occurrence of metastatic disease. The studies are sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health, and conducted by a network of researchers led by the National Surgical Adjuvant Breast and Bowel Project (NSABP) and the North Central Cancer Treatment Group (NCCTG).
March 2001: Further data from a pivotal Phase III clinical trial were published in the New England Journal of Medicine (NEJM) that showed a significant increase in survival for women with HER2-positive metastatic breast cancer who received Herceptin and chemotherapy over chemotherapy alone. Herceptin treatment can result in heart problems, including those without symptoms (reduced heart function) and those with symptoms (congestive heart failure). The risk and seriousness of these heart problems were highest in people who received both Herceptin and a certain type of chemotherapy (anthracycline).
March 2001: HERA, the third adjuvant trial of Herceptin, began enrollment.
December 2001: Genentech received FDA approval to include, in the product label, data that showed an improved median overall survival for women with HER2-positive metastatic breast cancer treated initially with Herceptin and chemotherapy, compared to chemotherapy alone (median 25.1 months compared to 20.3 months). Worsening of low white blood cell counts associated with chemotherapy has also occurred. Herceptin can cause low amniotic fluid levels and harm to the fetus when taken by a pregnant woman. The most common side effects associated with Herceptin were fever, nausea, vomiting, infusion reactions, diarrhea, infections, increased cough, headache, fatigue, shortness of breath, rash, low white and red blood cells, and muscle pain.
December 2001: BCIRG 006, the fourth adjuvant trial of Herceptin, began enrollment.
August 2002: Genentech received FDA approval to include information about a breast cancer gene-detection test method called FISH (fluorescence in situ hybridization) in the Herceptin product labeling.
May 2005: Results from a joint analysis of the Phase III NSABP and NCCTG clinical trials evaluating the addition of Herceptin to standard adjuvant therapy for early-stage HER2-positive breast cancer were presented at the ASCO annual meeting. According to this 3-year planned joint analysis, Herceptin in combination with chemotherapy significantly reduced the risk of cancer recurrence. Some patients have had serious infusion reactions and lung problems; fatal infusion reactions have been reported. In most cases, these reactions occurred during or within 24 hours of receiving Herceptin.
August 2005: Genentech issued a letter to healthcare providers informing them of updated cardiotoxicity information related to the use of Herceptin, obtained from the Phase III NSABP study (B-31). Herceptin treatment can result in heart problems, including those without symptoms (reduced heart function) and those with symptoms (congestive heart failure). The risk and seriousness of these heart problems were highest in people who received both Herceptin and a certain type of chemotherapy (anthracycline). In one study with Herceptin and certain types of chemotherapy, an inadequate blood supply to the heart occurred.
February 2006: Based on results from the joint analysis of the NSABP and NCCTG trials, Genentech filed a supplemental Biologics License Application (sBLA) with the FDA for Herceptin for the adjuvant treatment of early-stage HER2-positive breast cancer.
November 2006: The FDA approved Herceptin as part of a treatment regimen containing doxorubicin, cyclophosphamide, and paclitaxel for the adjuvant treatment of patients with early-stage HER2-positive, node-positive breast cancer based on the joint analysis of the NSABP and NCCTG studies. Herceptin can cause low amniotic fluid levels and harm to the fetus when taken by a pregnant woman. Patients should talk to their doctor if they are pregnant or become pregnant while taking Herceptin.
December 2006: Genentech submitted an sBLA with the FDA based on the global HERA study to potentially expand Herceptin's use in the adjuvant treatment of early-stage HER2-positive breast cancer.
June 2007: Genentech submitted two sBLAs to the FDA based on the global BCIRG 006 trial to potentially expand Herceptin's use in the adjuvant treatment of early-stage HER2-positive breast cancer.
January 2008: Based on the HERA one-year data, the FDA approved Herceptin as a single agent for the adjuvant treatment of early-stage HER2-positive node-positive breast cancer or node-negative (ER/PR-negative or with one high-risk feature) following multi-modality, anthracycline-based therapy. Herceptin also may be administered as a single agent in an every-three-week dosing schedule for one year. Patients receiving their first dose of Herceptin may have chills and fever as well as nausea, vomiting, pain, headache, dizziness, shortness of breath, low blood pressure, rash, and weakness.
May 2008: Based on the results of the BCIRG 006 study, the FDA approved two new Herceptin-containing regimens for the adjuvant treatment of early-stage HER2-positive node-positive or node-negative (ER/PR-negative or with one high-risk feature) breast cancer. The first regimen is in combination with docetaxel and carboplatin, (also known as TCH for Taxotere, carboplatin, and Herceptin) which does not contain an anthracycline (doxorubicin) component. The second is part of a treatment regimen containing anthracycline (doxorubicin), cyclophosphamide, and docetaxel (AC-TH). In comparison to AC-TH, TCH provided a similarly effective treatment option. Worsening of low white blood cell counts associated with chemotherapy has also occurred.
October 2008: More than 420,000 women with HER2-positive breast cancer have been treated with Herceptin worldwide.
October 2010: The FDA approved Herceptin in combination with cisplatin and capecitabine or 5-fluorouracil, for the treatment of patients with HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma, who have not received prior treatment for metastatic disease.