Metal Chelate Conjugated Monoclonal Antibodies for Tumor Diagnosis and Therapy

肿瘤相关单克隆抗体（mAbs）作为恶性肿瘤细胞毒性药物的选择性载体是一种治疗药物。这一假设在动物模型系统中进行了测试，其中单克隆抗体针对与人类疾病相关的抗原。所使用的细胞杀伤剂是粒子发射放射性核素。在适当验证的小鼠肿瘤异种移植模型系统中评估其相对疗效。选择用于研究的放射性核素侧重于适当的α和β发射体。目前的研究主要集中在β -发射α粒子源Pb-212，以及与α发射器At-211平行的研究。正在进行的合作临床试验使用螯合剂1bm4 - dtpa（又名MX-DTPA或tixetan）来隔离Y-90， Y-90是一种高能纯放射放射性核素，在临床应用和商业产品Zevalin中得到了很好的应用。化学使泽伐林，第一个FDA批准的放射性标记抗体治疗，可能是由化学部门开发的。几乎所有正在进行的研究现在都使用第三代双功能螯合剂CHX-A（双prime） DTPA来隔离In-111、Y-90、Bi-213和Lu-177。目前已经开始和正在进行的研究继续验证使用Y-86生产的回旋加速器（由化学部门精制和纯化）在PET成像中使用CHX-A（双撇）DTPA。化学部最近报道了许多PET成像研究，关于Y-86用于靶向HER2和HER1（EGFR）的PET成像，用于卵巢癌、结直肠癌、胰腺癌、前列腺癌等多种疾病的可视化；Y-86靶向HER1(EGFR) PET成像治疗间皮瘤的相关研究已提交发表。为了补充用于免疫pet的Y-86的开发，化学部门继续研究开发一种新型的、优质的双功能螯合剂，用于Zr-89用于免疫pet，因为目前的技术很麻烦，并且在体内不稳定，导致释放的Zr-89骨沉积。新型双功能螯合剂和靶向放射治疗的连接剂的临床前评估主要是为了改进偶联化学功能基团的选择和放射性标记的改进。这些改进源于提供用于肽化学的试剂以及适用于放射性镧系元素和α粒子发射放射性核素的特定位点偶联策略。该科为特定位点的连锁策略（如点击化学和碳水化合物修饰策略）创建了许多新颖的连锁化学试剂。去年全面启动了At-211研究，同时升级了这种放射性核素的生产设施。化学部分之前报道了最稳定的At-211连接试剂N-Me-SAPS的验证；整个药物的重新合成促进了与先前的Pb-212研究平行的正在进行的治疗研究。该项目的进展导致了At-211标记曲妥珠单抗的剂量递增研究，并扩展到长期治疗研究。由于过去一年向该科增加了新的人员，生产活动没有分级，因此已经生产了at -211并提供给约翰霍普金斯大学的合作者，以便建立一个at -211使用者/研究人员联合体，这将加速评价这种放射性核素治疗潜力的进展。对使用Pb-212治疗弥漫性腹腔内疾病（如卵巢癌或胰腺癌）的高度广泛和集中的临床前研究仍在继续。对Bi-213的调查达到了一个成本效益点，加上国家供应不足，有效地迫使终止了对这种放射性核素的研究。尽管疗效显著，但Bi-213的全部用途和价值可能永远无法确定。随着FDA批准了一项I期临床试验的IND， Pb-212的开发继续向前推进，该临床试验由于NCI领导层的反应迟钝而被转移到UAB。为支持IND，该科完成了小鼠毒理学实验以及该科开发的许多附加文件、研究和标准操作程序。第一次使用Pb-212的i期临床试验正在积极招募和治疗患者。因此，第二次，本节已经在最前沿的真正新颖的转化临床研究。用特异性单克隆抗体评估Pb-212，使用联合放射标记单克隆抗体，以及它们与化疗药物的联合使用仍在系统地进行。假设单一剂量的单一靶向放射性核素缺乏癌症治疗的合理依据；联合治疗将显著提高治疗效果。单剂量Pb-212偶联临床相关抗体（如曲妥珠单抗或帕尼单抗）的模型系统中预期寿命的中位数已大幅增加；西妥昔单抗已从研究中剔除。Pb-212标记的曲妥珠单抗与吉西他滨联合提供了令人印象深刻的增强治疗效果；多剂量的Pb-212和吉西他滨提供了优化药物组合和计划延长生存期的重要证据。研究表明，Pb-212与紫杉醇联合用药可显著延长患者的生存期，并依赖于给药计划。同样，与卡铂联合也延长了生存期，并且正在进行中。报道了克服抗原异质性的多分子肿瘤靶点放射治疗；联合CC49(Delta)CH2和曲妥珠单抗放射标记Pb-212证明需要经验确定给药顺序以优化治疗效果，而不是依赖于无法预测体内肿瘤环境的体外研究。结果证实Pb-212疗法的治疗效果更好。bi - 213。该部门正在进行研究，以确定细胞水平上损伤反应和修复的生物学机制，以及高let辐射对细胞生物学的遗传调控。靶向Pb-212的初步基线研究表明，不仅双链断裂普遍存在，而且DNA修复机制受损，细胞凋亡增强，细胞周期受到影响。纳入吉西他滨复制先前的治疗研究证明了该药物如何促进治疗，而正在进行的将紫杉醇纳入治疗方案的研究评估了该药物对治疗机制的影响。研究继续扩大使用三功能显像剂结合放射性核素成像（SPECT或PET）和近红外染料（光学成像）纳入PEG片段。关于染料抗体偶联物的自聚集和信号猝灭特性的关键发现使大量文献受到质疑。这一进展为创建直接定量光学-放射双模态分子显像剂提供了对基础化学的实际理解。继续进行合作研究；提供试剂和/或专业知识，以方便所有研究人员迅速进行实验，以充分确定靶向放射治疗的临床影响。为此，该科继续与代谢科、NCI和路德维希研究所保持着非常强有力的合作，并已将这一活动充分扩展到与AREVAMed和UAB的合作关系，将Pb-212转化为治疗传播性卵巢癌的首个临床试验，同时将at -211合作扩展到约翰霍普金斯大学的研究人员。

Tumor associated monoclonal antibodies (mAbs) are therapeutic agents when used as selective carriers of cytotoxic agents to malignancies. This hypothesis is tested in animal model systems with mAbs directed toward antigens associated with human disease. The cytocidal agents employed are particle emitting radionuclides. The relative efficacy is evaluated in the appropriately validated murine tumor xenograft model system. The radionuclides chosen for study focus on appropriate alpha emitters and beta emitters. Current research focuses on the beta-emitting alpha particle source, Pb-212, and parallel studies with the alpha emitter, At-211. Ongoing collaborative clinical trials employ the chelating agent 1B4M-DTPA (aka MX-DTPA or tiuxetan) for sequestering Y-90, a high energy pure beta emitting radionuclide well established in clinical applications and in the commercial product, Zevalin. The chemistry that makes Zevalin, the 1st FDA approved radiolabeled antibody therapeutic, possible was developed by the Chemistry Section. Nearly all ongoing studies now employ the 3rd generation bifunctional chelating agent, CHX-A (double prime) DTPA for sequestering In-111, Y-90, Bi-213, and Lu-177.Current studies initiated and ongoing continue to validate use of CHX-A (double prime) DTPA in PET imaging with the cyclotron produced (refined and purified by the Chemistry Section) Y-86. There have been a number of PET imaging studies recently reported by the Chemistry Section regarding the application of Y-86 for PET imaging targeting HER2 and HER1(EGFR) for visualizing a variety of diseases such ovarian, colorectal, pancreatic, prostate cancer; related studies on Y-86 for PET imaging targeting HER1(EGFR) for imaging mesothelioma has been submitted for publication. Complementary to the development of Y-86 for immunoPET, the Chemistry Section proceeds with study on the development of a novel and superior bifunctional chelating agent for use with Zr-89 for immunoPET as the current technology is cumbersome and not stable in vivo leading to bone deposition of the freed Zr-89.Pre-clinical evaluation of novel bifunctional chelating agents and linkers for targeted radiotherapy with isotopes of interest continues primarily to refine conjugation chemistry functional group options and radiolabeling improvements. These refinements stem from the provision of agents for peptide chemistry as well as for site-specific conjugation strategies amenable for use with both radio-lanthanides and alpha-particle emitting radionuclides. The Section has created a number of novel linkage chemistry agents for site-specific linkage strategies such as click chemistry and carbohydrate modification strategies.At-211 studies have been fully activated this past year while upgrading the production facilities for this radionuclide. The Chemistry section previously reported on validation of the most stable At-211 linker reagent, N-Me-SAPS; an entire re-synthesis of the agent facilitates the ongoing therapy studies parallel to the prior Pb-212 studies. Progress on this project has resulted in dose escalation studies with At-211 labeled trastuzumab that extend forward into long-term therapy studies. Production activities have been ungraded by the addition of new personnel to the Section over the past year to the point where At-211 has been produced and supplied to collaborators at Johns Hopkins in an effort to establish an At-211 users/ investigators consortium will accelerate progress on the evaluation of the therapy potentials of tis radionuclide.The highly extensive and focused pre-clinical investigation into the use of Pb-212 continues for the treatment of disseminated intraperitoneal disease, e.g., from either ovarian or pancreatic cancer. Investigation of Bi-213 reached a point of cost-effectiveness combined with failed national availability effectively forced termination of study of this radionuclide. Despite significant efficacy, the full range of use and value of Bi-213 will probably never be defined.Development of Pb-212 continues to move forward with FDA approval of an IND for a Phase I clinical trial that was relocated to UAB due to unresponsive leadership within the NCI. Murine toxicology experiments were completed by the Section in support of the IND along with numerous additional documents, studies, and SOPs developed by the Section. The Phase 1 trial, the first ever using Pb-212 is actively recruiting and treating patients. Thus, for a second time, this Section has been at the forefront of truly novel translational clinical research.Evaluation of Pb-212 with specific mAbs, use of combined radiolabeled mAbs, and their combinations with chemotherapeutics continues systematically. The hypothesis that single doses of a single, targeted radionuclide lacks a rational basis for cancer therapy; combined modality therapies will achieve significant therapeutic enhancements. Substantial increases in median life expectancy in model systems with single doses of Pb-212 conjugated to clinically relevant antibodies, e.g., trastuzumab or panitumumab have been achieved; cetuximab has been eliminated from study. Pb-212 labeled trastuzumab in combination with gemcitabine provided impressive enhanced therapeutic efficacy; multi-dosing of Pb-212 and gemcitabine provided significant evidence that optimization of drug combination and scheduling extends survival. Studies combining administration of Pb-212 with paclitaxel resulted in significant extension of survival with a dependence on administration scheduling. Similarly, combination with carboplatin also extended survival and is ongoing. Delivery of radiation to multiple molecular tumor targets overcoming antigen heterogeneity was reported; combining, CC49(Delta)CH2 and trastuzumab radiolabeled with Pb-212 demonstrated the requirement for empirical determination of administration order to optimize therapeutic efficacy vs. reliance on in vitro studies that fail to predict in vivo tumor environments.Results have confirmed superior therapeutic response from Pb-212 therapies. Bi-213. Studies to define the biological mechanisms at the cellular level of both damage response and repair as well as genetic regulation of the cell biology in response to high-LET radiation are ongoing by the Section. Initial baseline studies of targeted Pb-212 revealed that not only are double strand break prevalent, but that the DNA repair mechanisms are compromised, that apoptosis is enhanced, and that cell cycle impacted. Inclusion of gemcitabine replicating prior therapy studies demonstrated how that drug promoted therapy, while ongoing studies integrating taxol into the therapy regimen assess the impact of that drugs mechanism on this therapy.Studies continue to expand use trifunctional imaging agents combining radionuclidic imaging (SPECT or PET) and NIR dye (Optical imaging) to incorporate a PEG moiety. Critical discoveries regarding self-aggregation and signal quenching properties of dye-antibody conjugates put a significant body of literature in doubt. This advance provides actual understanding of fundamental chemistry for creation of directly quantitative optical-radiological dual modality molecular imaging agents.Collaborative studies continue to be executed; reagents and/or expertise are supplied to facilitate all researchers to expeditiously perform experiments to fully define the clinical impact of targeted radiation therapy. To this end, the Section continues to enjoy very strong and potent collaborations with the Metabolism Branch, NCI and with the Ludwig Institute, and has fully extended this activity to a collaborative relationship with AREVAMed and UAB to translate Pb-212 into its first clinical trial for treatment of disseminated ovarian cancer while extending At-211 collaborations to researchers at Johns Hopkins.